Methods and apparatus for handling exemption services and data channel events associated with an IMS DC in a wireless communication system

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Embodiments herein provide a method and a system for handling exemption services and data channel events associated with an IMS DC. The method includes configuring a UE (102) with a PS data exemption service list. Further, determining whether a PS data off status is activated and whether the IMS DC is not exempted in the PS data exemption service list. Further, transmitting a re-INVITE message to a network apparatus (302) for modifying an existing IMS DC session when the PS data off status is activated and the IMS DC is not exempted in the PS data exemption service list. In addition, transmitting the re-INVITE message to the network apparatus (302) for retaining only audio and video media in a SDP of the existing IMS DC session, when the PS data off status is activated and the IMS DC is not exempted in the PS data exemption service list.

Description

METHODS AND APPARATUS FOR HANDLING EXEMPTION SERVICES AND DATA CHANNEL EVENTS ASSOCIATED WITH AN IMS DC IN A WIRELESS COMMUNICATION SYSTEM

[0001] This application is based on and derives the benefit of Indian Provisional Applications 202341073403 filed on 27th October 2023, 202341073415 filed on 27th October 2023, and 202341074296 filed on 31st October 2023 the contents of which are incorporated herein by reference. The present disclosure is related to wireless communication. More particularly, the present disclosure is related to a method and system for handling exemption services and data channel events associated with an IP multimedia subsystem (IMS) data channel (DC).

[0002] 5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in “Sub 6GHz” bands such as 3.5GHz, but also in “Above 6GHz” bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

[0003] At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

[0004] Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

[0005] Moreover, there has been ongoing standardization in air interface architecture / protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture / service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

[0006] As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

[0007] Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

[0008] The present disclosure relates to wireless communication systems and, more specifically, the present disclosure relates to handle exemption services and data channel events associated with an IMS DC in a wireless communication system.

[0009] The principal object of the embodiments herein is to handle exemption services and data channel events associated with an IP multimedia subsystem (IMS) data channel (DC).

[0010] Yet another object of the embodiments herein is to configure both the UE and the network (for example, IMS AS, DCSF, DCMF, etc.) with a PS data exemption list.

[0011] Yet another object of the embodiments herein is to determine an event that the PS data off status is activated and the IMS DC is not included in the exempted list. The UE will then issue a Re-INVITE to maintain only audio and video streams while eliminating the SDP of the IMS DC, rather than terminating the entire IMS session as part of user equipment enforcement.

[0012] Yet another object of the embodiments herein is to determine when the PS data off status is activated and the IMS DC is not part of the exempted list. The IMS AS will then send a Re-INVITE to retain only audio and video streams and remove the SDP of the IMS DC, instead of terminating the entire IMS session as part of network enforcement.

[0013] Yet another object of the embodiments herein is to determine if the PS data off status is activated and the IMS DC is included in the exempted list, but there are specific applications that need to be blocked over the IMS DC. The DCSF will then remove the SDP of those applications from the established session while allowing other exempted applications to continue.

[0014] Yet another object of the embodiments herein is to enable the IMS AS to expose the IMS DC services that is supports along with a number of IMPUs that it supports by subscribing to a network resource function (NRF) or a home subscriber server (HSS).

[0015] Yet another object of the embodiments herein is to enable third party networks (for example, DCAS / NEF / AF) to create a profile with the NRF or HSS, where the profile includes the list if IMPUs, IMS DC services, and IMS AS types expected to the NRF or HSS.

[0016] Yet another object of the embodiments herein is to enable the NRF or HSS to determine an appropriate IMS AS for the third party networks based on the profile received, where the third party networks can subscribe to IMS DC event(s) supported by the IMS AS via the NRF or HSS.

[0017] Yet another object of the embodiments herein is to handle an admission control for the maximum number of registered UEs and a maximum number of concurrent PDU sessions for a network slice defined by an S-NSSAI in hierarchal architecture deployment.

[0018] In one aspect, the objectives are achieved by providing a method for handling exemption services associated with an IP multimedia subsystem (IMS) data channel (DC). The method includes configuring a user equipment (UE) with a packet switch (PS) data exemption service list using a device management procedure or a pre-configuration. The PS data exemption service list comprises an IMS DC available for the UE. Further, the method includes determining whether a PS data off status is activated. Further, the method includes determining whether the IMS DC is not exempted in the PS data exemption service list. Further, the method includes transmitting a re-INVITE message to a network apparatus associated with the UE for modifying an existing IMS DC session including a session description protocol (SDP) for a multimedia telephony service media when the PS data off status is activated and when the IMS DC is not exempted in the PS data exemption service list. The multimedia telephony service media includes audio, video media, and messaging. In addition, the method includes transmitting the re-INVITE message to the network apparatus for retaining only audio and video media in the SDP of the existing IMS DC session, when the PS data off status is activated and when the IMS DC is not exempted in the PS data exemption service list.

[0019] In an embodiment, the re-INVITE message is configured to modify the media session by removing the SDP of the IMS DC while retaining SDP for audio and video media.

[0020] In an embodiment, the method includes determining whether the video media is not exempted in the PS data exemption service list. Further, the method includes transmitting a re-INVITE message to the network apparatus associated with the UE for modifying an existing IMS DC session including the SDP for audio and the video media, when the PS data off status is activated and when the video media is not exempted in the PS data exemption service list. In addition, the method includes transmitting the re-INVITE message to the network apparatus for retaining only audio and removing the video media in the SDP of the existing IMS DC session, when the PS data off status is activated and when the video media is not exempted in the PS data exemption service list.

[0021] In an embodiment, the network apparatus comprises at least one of an IMS application server (AS), a data channel signalling function (DCSF), and a data channel media function (DCMF).

[0022] In an embodiment, the method includes dynamically updating the PS data exemption service list based on network policies received from the network apparatus or user preferences provided by a user of the UE. In addition, the method includes activating the PS data off status based on the user preferences of the user of the UE or the network policy enforced by the network apparatus.

[0023] In one aspect, the objectives are achieved by providing a method for handling exemption services associated with an IP multimedia subsystem (IMS) data channel. The method includes configuring an IMS application server (AS) with a packet switch (PS) data exemption service list by an operator, wherein the PS data exemption service list comprises the IMS DC available for the network apparatus. Further, the method includes determining whether a PS data off status is activated. Further, the method includes determining whether the IMS DC is not exempted in the PS data exemption list. Further, the method includes generating a re-INVITE message to retain audio and video media components of the IMS session including SDP for the multimedia telephony service media while removing the session description protocol (SDP) associated with the IMS DC, instead of releasing the entire IMS session. The multimedia telephony service media includes audio, video media, and messaging. In addition, the method includes transmitting the re-INVITE message to a user equipment (UE) associated with the network apparatus to retain audio and video media components of the IMS session while removing the SDP associated with the IMS DC, instead of releasing the IMS session entirely, when the PS data off status is activated when the IMS DC is not in the PS data exemption service list.

[0024] In one aspect, the objectives are achieved by providing a method for handling data channel events associated with an IP multimedia subsystem (IMS) data channel. The method includes registering with a network resource function (NRF) by sending a network function (NF) register channel message to the NRF. The NF register channel message comprises a list of IMS Public User Identities (IMPUs), an indication of IMS DC support and a plurality of IMS DC events supported by the network apparatus. Further, the method includes receiving a session event control message from a third network apparatus. The third network apparatus obtains details of the network apparatus from the NRF based on the list of IMPUs and a capability of the IMS DC. In addition, the method includes generating a session event control notify message to be transmitted to the third network apparatus. The session event control notify message enables the third network apparatus to subscribe to at least one IMS DC event of the plurality of IMS DC events supported by the network apparatus.

[0025] In an embodiment, the plurality of IMS DC events comprise at least one of an IMS DC establishment, an IMS DC update, and an IMS DC release.

[0026] In an embodiment, the method includes determining whether the third network apparatus is untrusted. In addition, the method includes generating an event exposure subscribe request to be transmitted to the third network apparatus if the third network apparatus is untrusted. The event exposure subscribe request comprises an event ID indicating the plurality of IMS DC events and an event filter for one subscriber or a list of subscribers.

[0027] In an embodiment, the method includes generating an IMS UECM registration message to be transmitted to a home subscriber server (HSS). The IMS UECM registration message includes a list of a plurality of events supported by the network apparatus. Further, the method includes receiving a subscribe request message from the third network apparatus. The third network apparatus obtains details of the network apparatus from the HSS based on the list of the plurality of events supported by the network apparatus. In addition, the method includes transmitting a notify request message to the third network apparatus. The notify request message enables the third network apparatus to subscribe to at least one event of the plurality of events supported by the network apparatus.

[0028] In one aspect, the objectives are achieved by providing a method for generating a discovery request message. The discovery request message comprises at least one of a list of IP multimedia public identities (IMPUs), an IMS data communication (IMS DC) service, and an IMS AS type expected by the third network apparatus. Further, the method includes transmitting the discovery request message to a network repository function (NRF). Further, the method includes subscribing to all IMS AS instances received from the NRF. The subscribing includes sending a session event control request message. The session event control request message includes an event identifier indicating a session establishment request event and an event filter applicable to one subscriber corresponding to the event identifier or a list of subscribers corresponding to the event identifier. In addition, the method includes receiving a session event control message from a network apparatus. The NRF determines the network apparatus based on the support list of IMPUs, the plurality of IMS DC events, and the IMS AS type expected provided in the discovery request message. The session event control notify message enables the third network apparatus to subscribe to at least one IMS DC event of the plurality of IMS DC events supported by the network apparatus.

[0029] In an embodiment, the third network apparatus comprises at least one of a dynamic channel assignment scheme (DCAS), a network exposure function (NEF), and an application function (AF).

[0030] In an embodiment, the plurality of IMS DC events comprise at least one of an IMS DC establishment, an IMS DC update, and an IMS DC release.

[0031] In an embodiment, the method includes transmitting a session establishment request event message to the NRF for subscribing to the NRF, wherein the session event control message comprises an event ID and an event filter for one subscriber or a list of subscribers.

[0032] In an embodiment, the method includes generating a subscribe request message to be transmitted to a network apparatus. The third network apparatus obtains details of the network apparatus from the HSS based on a list of a plurality of events supported by the network apparatus. In addition, the method includes receiving a notify request message from the network apparatus. The notify request message enables the third network apparatus to subscribe to at least one event of the plurality of events supported by the network apparatus.

[0033] In one aspect, the objectives are achieved by providing a UE for handling exemption services associated with an IP multimedia subsystem (IMS) data channel (DC). The UE includes a processor, a memory coupled to the processor, and a UE controller communicatively coupled to the processor and the memory. The UE controller configures the UE with a packet switch (PS) data exemption service list using a device management procedure or a pre-configuration. The PS data exemption service list comprises an IMS DC available for the UE. Further, the UE controller determines whether a PS data off status is activated. Further, the method includes determining whether the IMS DC is not exempted in the PS data exemption service list. Further, the UE controller transmits a re-INVITE message to a network apparatus associated with the UE for modifying an existing IMS DC session including SDP for a multimedia telephony service media when the PS data off status is activated and when the IMS DC is not exempted in the PS data exemption service list. The multimedia telephony service media includes audio, video media, and messaging. In addition, the UE controller transmits the re-INVITE message to the network apparatus for retaining only audio and video media in a session description protocol (SDP) of the existing IMS DC session, when the PS data off status is activated and when the IMS DC is not exempted in the PS data exemption service list.

[0034] In one aspect, the objectives are achieved by providing an IP multimedia subsystem (IMS) application server (AS) for handling exemption services associated with an IMS data channel. The IMS AS includes a processor, a memory, and an IMS controller communicatively coupled to the processor and the memory. The IMS controller configures the IMS AS with a packet switch (PS) data exemption service list by an operator, wherein the PS data exemption service list comprises the IMS DC available for the network apparatus. Further, the IMS controller determines whether a PS data off status is activated. Further, the method includes determining whether the IMS DC is not exempted in the PS data exemption list. Further, the IMS controller generates a re-INVITE message to retain audio and video media components of the IMS session including SDP for a multimedia telephony service media while removing the SDP associated with the IMS DC, instead of releasing the entire IMS session. The multimedia telephony service media includes audio, video media, and messaging. In addition, the IMS controller transmits the re-INVITE message to a user equipment (UE) associated with the network apparatus to retain audio and video media components of the IMS session while removing the SDP associated with the IMS DC, instead of releasing the IMS session entirely, when the PS data off status is activated when the IMS DC is not in the PS data exemption service list.

[0035] In one aspect, the objectives are achieved by providing a network apparatus for handling data channel events associated with an IP multimedia subsystem (IMS) data channel. The network apparatus includes a processor, a memory, and a first controller communicatively coupled to the processor and the memory. The first controller registers with a network resource function (NRF) by sending a network function (NF) register channel message to the NRF. The NF register channel message comprises a list of IMS Public User Identities (IMPUs), an indication of IMS DC support and a plurality of IMS DC events supported by the network apparatus. Further, the first controller receives a session event control message from a third network apparatus. The third network apparatus obtains details of the network apparatus from the NRF based on the list of IMPUs and a capability of the IMS DC. In addition, the first controller generates a session event control notify message to be transmitted to the third network apparatus. The session event control notify message enables the third network apparatus to subscribe to at least one IMS DC event of the plurality of IMS DC events supported by the network apparatus.

[0036] In one aspect, the objectives are achieved by providing a third network apparatus for handling data channel events associated with an IP multimedia subsystem (IMS) data channel. The third network apparatus includes a processor, a memory, and a second controller communicatively coupled to the processor and the memory. The second controller generates a discovery request message. The discovery request message comprises at least one of a list of IP multimedia public identities (IMPUs), an IMS data communication (IMS DC) service, and an IMS AS type expected by the third network apparatus. Further, the second controller transmits the discovery request message to a network repository function (NRF). Further, the second controller subscribes to all IMS AS instances received from the NRF. The subscribing includes sending a session event control request message. The session event control request message includes an event identifier indicating a session establishment request event and an event filter applicable to one subscriber corresponding to the event identifier or a list of subscribers corresponding to the event identifier. In addition, the second controller receives a session event control message from a network apparatus. The NRF determines the network apparatus based on the support list of IMPUs, the plurality of IMS DC events, and the IMS AS type expected provided in the discovery request message. The session event control notify message enables the third network apparatus to subscribe to at least one IMS DC event of the plurality of IMS DC events supported by the network apparatus.

[0037] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications be made within the scope of the embodiments herein.

[0038] In an embodiment, a method performed by a network resource function (NRF) entity in a communication system, the method comprising: receiving, from an internet protocol (IP) multimedia subsystem (IMS) application server (AS) supporting an IMS data channel (DC), a register message including a support for a list of IMS public user identities (IMPUs) and the IMS DC; storing a profile of the IMS AS; transmitting, to the IMS AS, a response message for the register message; receiving, from a network function (NF) entity, a request message including an input for discovering the IMS AS, the input corresponding to at least one of the list of the IMPUs, a service of the IMS DU, or an expected NF type; and based on the profile, transmitting, to the NF entity, a list of the IMS AS supporting the IMS DC and the IMPUs requested by the request message; wherein the NF entity subscribes with all the IMS AS received from the NRF entity.

[0039] In an embodiment, a method performed by a network function (NF) entity in a communication system, the method comprising: receiving, from an untrusted application function (AF) entity, a subscribe request message for a subscription to a network exposure function (NEF) entity, transmitting, to a network resource function (NRF) entity, a request message including an input for discovering an internet protocol (IP) multimedia subsystem (IMS) application server (AS) supporting an IMS data channel (DC), the input corresponding to at least one of a list of IMS public user identities (IMPUs), a service of the IMS DC, or an expected NF type; based on a profile stored in the NRF entity, receiving, from the NRF entity, a list of the IMS AS supporting the IMS DC and the IMPUs requested by the request message; transmitting, to the IMS AS, an event control message for the subscription with all the IMS AS received from the NRF entity; and receiving, from the IMS AS, a notification message.

[0040] In an embodiment, a method performed by an internet protocol (IP) multimedia subsystem (IMS) application server (AS) in a communication system, the method comprising: transmitting, to a network resource function (NRF) entity, a register message including a support for a list of IMS public user identities (IMPUs) and an IMS data channel (DC), while registering to the NRF entity; receiving, from the NRF entity, a response message for the register message, receiving, from a network function (NF) entity, an event control message to subscribe with all the IMS AS received from the NRF entity; performing an establishment of the IMS DC and an observation of an event; and receiving, from a network function (NF) entity, a notification message, wherein the IMS AS supports the IMS DC, wherein the NF entity is at least one of a data channel media functions (DCSF) entity or a trusted application function (AF) entity.

[0041] In an embodiment, a network resource function (NRF) entity in a communication system, the NRF entity comprising: a processor; and a controller coupled with the processor, the controller configured to: receive, from an internet protocol (IP) multimedia subsystem (IMS) application server (AS) supporting an IMS data channel (DC), a register message including a support for a list of IMS public user identities (IMPUs) and the IMS DC; store a profile of the IMS AS; transmit, to the IMS AS, a response message for the register message; receive, from a network function (NF) entity, a request message including an input for discovering the IMS AS, the input corresponding to at least one of the list of the IMPUs, a service of the IMS DU, or an expected NF type; and based on the profile, transmit, to the NF entity, a list of the IMS AS supporting the IMS DC and the IMPUs requested by the request message; wherein the NF entity subscribes with all the IMS AS received from the NRF entity.

[0042] In an embodiment, a network function (NF) entity in a communication system, the NF entity comprising: a processor; and a controller coupled with the processor, the controller configured to: receive, from an untrusted application function (AF) entity, a subscribe request message for a subscription to a network exposure function (NEF) entity, transmit, to a network resource function (NRF) entity, a request message including an input for discovering an internet protocol (IP) multimedia subsystem (IMS) application server (AS) supporting an IMS data channel (DC), the input corresponding to at least one of a list of IMS public user identities (IMPUs), a service of the IMS DC, or an expected NF type; based on a profile stored in the NRF entity, receive, from the NRF entity, a list of the IMS AS supporting the IMS DC and the IMPUs requested by the request message; transmit, to the IMS AS, an event control message for the subscription with all the IMS AS received from the NRF entity; and receive, from the IMS AS, a notification message.

[0043] In an embodiment, an internet protocol (IP) multimedia subsystem (IMS) application server (AS) in a communication system, the IMS AS comprising: a processor; and a controller coupled with the processor, the controller configured to: transmit, to a network resource function (NRF) entity, a register message including a support for a list of IMS public user identities (IMPUs) and an IMS data channel (DC), while registering to the NRF entity; receive, from the NRF entity, a response message for the register message, receive, from a network function (NF) entity, an event control message to subscribe with all the IMS AS received from the NRF entity; perform an establishment of the IMS DC and an observation of an event; and receive, from a network function (NF) entity, a notification message, wherein the IMS AS supports the IMS DC, wherein the NF entity is at least one of a data channel media functions (DCSF) entity or a trusted application function (AF) entity.

[0044] According to an embodiment of the disclosure, a wireless communication can be performed efficiently. Especially, a handling exemption services and data channel events associated with an IMS DC in a wireless communication system.

[0045] These and other features, aspects, and advantages of the present embodiments are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

[0046] Fig. 1 is a block diagram that illustrates a schematic of a UE implemented to carry out the disclosed subject matter according to an embodiment as disclosed herein.

[0047] Fig. 2 is a block diagram that illustrates a schematic of an IMS AS implemented to carry out the disclosed subject matter according to an embodiment as disclosed herein.

[0048] Fig. 3 is a block diagram that illustrates a schematic of a network apparatus implemented to carry out the disclosed subject matter according to an embodiment as disclosed herein.

[0049] Fig. 4 is a block diagram that illustrates a schematic of a third network apparatus implemented to carry out the disclosed subject matter according to an embodiment as disclosed herein.

[0050] Fig. 5 is a sequence diagram that illustrates a sample sequence of events of procedures for handling PS data off exemption for the IMS data channel according to an embodiment as disclosed herein.

[0051] Fig. 6 is a sequence diagram that illustrates a process of the DCSF subscribing to get IMS DC events for one subscriber or multiple subscribers according to an embodiment as disclosed herein.

[0052] Fig. 7 is a sequence diagram that illustrates a process of an untrusted AF / third party subscribing to get IMS DC events for one subscriber or multiple subscribers according to an embodiment as disclosed herein.

[0053] Fig. 8 is a flow diagram that illustrates a method for handling exemption services associated with the IMS DC by the UE according to an embodiment as disclosed herein.

[0054] Fig. 9 is a flow diagram that illustrates a method for handling exemption services associated with the IMS DC by the IMS AS according to an embodiment as disclosed herein.

[0055] Fig. 10 is a flow diagram that illustrates a method for handling data channel events associated with the IMS DC by the network apparatus according to an embodiment as disclosed herein.

[0056] Fig. 11 is a flow diagram that illustrates a method for handling data channel events associated with the IMS DC by the third network apparatus according to an embodiment as disclosed herein.

[0057] Fig. 12 is a sequence diagram that illustrates a sample sequence of events that is expected to take place in a typical network deployment where a hierarchical architecture is deployed by the network according to the prior art.

[0058] Fig. 13 is a sequence diagram that illustrates a sample sequence of events that is expected to take place in a typical network deployment where a hierarchical architecture is deployed by the network according to the embodiments as disclosed herein.

[0059] It may be noted that to the extent possible, like reference numerals have been used to represent like elements in the drawing. Further, those of ordinary skill in the art will appreciate that elements in the drawing are illustrated for simplicity and may not have been necessarily drawn to scale. For example, the dimension of some of the elements in the drawing may be exaggerated relative to other elements to help to improve the understanding of aspects of the invention. Furthermore, the elements may have been represented in the drawing by conventional symbols, and the drawings may show only those specific details that are pertinent to the understanding the embodiments of the invention so as not to obscure the drawing with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

[0060] IMS has been established for a considerable duration, and nearly all major operators have implemented their networks to deliver a range of services, including the widely utilized VOLTE service. Currently, IMS is evolving to meet the specific demands of 5G verticals, enabling the introduction of various new services. The IMS Data channel is being utilized alongside traditional voice and video calls. This IMS Data channel will facilitate numerous applications such as Remote Support, Remote Surgery, Remote Examination, and Augmented Reality with control, as well as Machine Control and Virtual Reality with collaboration.

[0061] 3GPP SA4 WG has studied the IMS DC capability and TS 26.114 has been updated to explain how this IMS DC can be realized and SA2 WG has provided the architecture for IMS Data Channel.

[0062] In release 19, 3GPP SA2 is examining a key issue regarding the management of PS Data Off for the IMS Data channel. The primary concern outlined in TR 23.700-77 pertains to the exemption of PS data off for services utilizing IMS DC. This investigation focuses on the necessary enhancements to the IMS architecture and procedures to facilitate PS data off for services operating over the IMS DC. Specifically, the study will assess the potential modifications to the existing 3GPP PS Data Off Exempt service information, such as the list of services exempt from PS data off, to accommodate 3GPP PS Data Off for services delivered via the IMS data channel.

[0063] In Rel 19, 3GPP SA2 is studying two KIs on how IMS network can provide a mechanism where third party or network function can subscribe and get event notifications about IMS DC for subscribers or group of subscribers.

[0064] TR 23.700-77:

[0065] Existing solutions lack an extensible IMS mechanism that accommodates IMS events within the framework of DC communication. This study examines the necessary architectural improvements to the IMS architecture to facilitate an extensible mechanism, allowing applications to subscribe to and receive notifications regarding IMS events pertinent to IMS services in the realm of DC communication. Also, current solutions do not assess the implications for IMS architecture, interfaces, and procedures required to enable IMS capability exposure in the context of IMS data channel sessions.

[0066] Further, 3GPP Release 15 introduced the concept of "Network Slicing," enabling telecommunications service providers to establish dedicated networks for specific customers (such as MVNOs or enterprises) or services (including eMBB, URLLC, and mMTC). These dedicated networks comprise various network functions tailored to meet the requirements of the specialized service. A collection of these network functions is referred to as a "Network Slice," which is identified by the S-NSSAI (Single Network Slice Selection Assistance Information) within a 3GPP network.

[0067] These slices are distinguished by a combination of standard and proprietary characteristics as outlined in a "slice template." The GSMA has established a "Generic Network Slice Template" (GST) that delineates standardized slice attributes applicable to a range of services supported by 3GPP. Among the attributes specified by the GST are "Number of Terminals" and "Number of Sessions." The "Number of Terminals" attribute indicates the maximum number of user equipment (UEs) that can concurrently utilize the network slice. In a similar vein, the "Number of Sessions" attribute specifies the maximum number of Protocol Data Unit (PDU) sessions that can simultaneously operate within the network slice. These attributes are critical for network planning, as operators must ensure that the resources allocated to the network slice are adequate to accommodate the capacity defined by these parameters.

[0068] To implement these attributes, 3GPP Rel-17 introduces a functional entity known as the "Network Slice Admission Control Function (NSACF)," which oversees and regulates the number of User Equipment's (UEs) or sessions associated with a network slice. The NSACF is configured with a maximum limit for UEs per network slice and is anticipated to be referenced by the Access and Mobility Management Function (AMF) when permitting a UE to join the network. Likewise, the NSACF is set with a maximum number of sessions allowed per network slice and is expected to be consulted by the Session Management Function (SMF) during the activation of a Protocol Data Unit (PDU) session. This process applies to all network slices that are governed by the quotas established by these attributes or the Network Slice Admission Control (NSAC). In the terminology used by 3GPP, the "Number of Terminals" can denote either the "Number of UEs" or the "Number of Registrations" based on the access type. Similarly, the "Number of Sessions" may indicate the "Number of PDU Sessions." These terms are utilized interchangeably throughout this document.

[0069] In accordance with 3GPP TS 23.501 and TS 23.502 in Release 17, the NSACF is responsible for managing the number of User Equipments (UEs) registered to a network slice. It ensures that this number remains within the predefined maximum limit, as determined by requests from the AMF. The NSACF may also track the count of registered UEs by utilizing access type information provided by the AMF. The NSACF similarly manages the current number of PDU Sessions for each network slice, adjusting it as necessary to ensure that it remains within the maximum limit permitted for that slice, in accordance with requests received from the SMF.

[0070] The count of UE registrations in 5G is conducted whenever a UE registers with the 5GC, regardless of whether a PDU session is established. In contrast, for EPS, the registration count occurs only when the UE initiates a PDN connection. The GSMA has clarified this process by introducing a new requirement stating that the UE registration count in 5GS will only be considered when at least one PDU session or PDN connection is established by the UE. To meet the requirement of counting registered UEs only when there is at least one PDU session or PDN connection, 3GPP has outlined two potential options in TS 23.501 Clause 5.15.11.5a.

[0071] Hence, is desirable to address the above mentioned problems and disadvantages or at least provide a useful alternative.

[0072] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with a plurality of other embodiments to form new embodiments. The term “or” as used herein, refers to a non-exclusive or, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples are not be construed as limiting the scope of the embodiments herein.

[0073] As is traditional in the field, embodiments are described and illustrated in terms of blocks that carry out a described function or functions.　These blocks, which referred to herein as managers, units, modules, hardware components or the like, are physically implemented by analog and / or digital circuits such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits, and the like, and optionally be driven by firmware and software. The circuits, for example, be embodied in a plurality of semiconductor chips, or on substrate supports such as printed circuit boards, and the like.　The circuits constituting a block be implemented by dedicated hardware, or by a processor (e.g., a plurality of programmed microprocessors and associated circuitry), or by a combination of dedicated hardware to perform some functions of the block and a processor to perform other functions of the block. Each block of the embodiments be physically separated into two or more interacting and discrete blocks without departing from the scope of the proposed method.　Likewise, the blocks of the embodiments be physically combined into more complex blocks without departing from the scope of the proposed method.

[0074] The accompanying drawings are used to help easily understand various technical features and it is understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the proposed method is construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. used herein to describe various elements, these elements are not be limited by these terms. These terms are generally used to distinguish one element from another.

[0075] The various actions, acts, blocks, steps, or the like in the method is performed in the order presented, in a different order or simultaneously. Further, in some embodiments, some of the actions, acts, blocks, steps, or the like are omitted, added, modified, skipped, or the like without departing from the scope of the proposed method.

[0076] In the prior art, current solutions do not provide an extensible IMS mechanism that integrates IMS events into the DC communication framework. This explores the architectural enhancements needed for the IMS architecture to support a flexible mechanism, enabling applications to subscribe to and receive notifications about IMS events relevant to IMS services within DC communication. Furthermore, existing solutions fail to evaluate the impacts on IMS architecture, interfaces, and procedures necessary for facilitating IMS capability exposure in the context of IMS data channel sessions.

[0077] Embodiments disclosed herein provides a system and methods for handling PS data off exemption for IMS data channel. The proposed solution ensures that the IMS network and the UE effectively implement the PS data off exemption for the IMS data channel within the 5G Core (5GC). This method involves both the UE and the network being equipped with a list of services that are to be exempt from PS data off when the status is active. During registration or re-registration, the UE receives an active PS data off status, and the network remains synchronized with the UE regarding this status. The UE has established an IMS session that includes audio, video, and an IMS data channel for transporting specific applications. Both the UE and the network permit only those services that are configured for PS data off exemption. Additionally, the method encompasses updates to the configurations of both the UE and the network, indicating that certain applications previously exempted or the IMS data channel as a whole have been removed. In cases where the IMS data channel has been eliminated or only includes applications that are exempted, the UE will send a Re-invite, retaining only the exempted services such as audio or video, while removing other applications that were previously part of the exempted services.

[0078] The abbreviations used in the embodiment are:

[0079] UE- User Equipment

[0080] 3gpp- 3rd Generation Partnership Project

[0081] S-CSCF- Serving - Call Session Control Function

[0082] P-CSCF- Proxy- Call Session Control Function

[0083] I-CSCF- Interrogative-- Call Session Control Function

[0084] HSS- Home Subscriber Subsystem

[0085] IMS- IP Multimedia Subsystem

[0086] AS- Application Server

[0087] DCSF- Data Channel Signalling Function

[0088] DCMF- Data Channel Media Function

[0089] IMS is there from long time and almost all big operators have deployed their network to provide various services including the most popular VOLTE service. Now IMS is getting evolved to cater the 5G vertical requirements to offer various new services for which IMS Data channel is getting used along with normal voice call and video call. This IMS DC will help a various scenario like Remote Support, Remote Surgery, Remote Examination, and AR with control, Machine Control, VR with collaboration etc.

[0090] 3GPP SA4 WG has studied the IMS DC capability and TS 26.114 has been updated to explain how this IMS DC can be realised and SA2 WG has provided the architecture for IMS Data Channel.

[0091] In release 19, 3GPP SA2 is studying one KI on how to address the PS Data Off for IMS Data channel. The key issue in TR 23.700-77 is handling of PS data off exemption for services over IMS DC. The key issue studies how IMS architecture, procedures need to be enhanced to support PS data off for services over IMS DC. In particular, the key issue will study whether and how to enhance the current 3GPP PS Data off Exempt service information (e.g. list of 3GPP PS Data off Exempt services) to support 3GPP PS Data Off for services over IMS data channel.

[0092] The present disclosure addresses the existing challenges by providing solutions for the PS data off exemption for IMS DC.

[0093] Embodiments herein disclose an extensible IMS mechanism supporting IMS events in the context of DC communication. Embodiments herein disclose architectural enhancement(s) to the IMS architecture to support an extensible mechanism that enables applications to subscribe to and receive reports about IMS events related to IMS services in the context of DC communication. Embodiments herein identify one or more IMS events that Network Function / Application function can subscribe to. The IMS events can include events related to a specific IMS subscriber / groups of IMS subscribers. Handling of groups of IMS subscribers is FFS. Embodiments herein disclose event subscription mechanisms. When the IMS event is related to IMS specific subscriber(s) this includes functionality to determine the IMS NF(s) / Nodes serving the specific IMS subscriber(s) for which the specific event was requested.

[0094] Embodiments herein investigate the impact on IMS architecture, interfaces, and procedures to support IMS capability exposure in the context of IMS data channel session. Embodiments herein disclose enhancements to the IMS architecture, interfaces and procedures to expose IMS network capabilities in IMS data channel establishment, update and release related scenarios. Embodiments herein study whether and how an application server can request to use the bootstrap data channel and download a specific application.

[0095] TS 23.228 Annex AA.2.4.1 is already addressing the scenario where IMS AS which supports IMS DC is exposing service Nimsas_SessionEventControl using which the network function, or any node can subscribe for a particular subscriber and get event notification when that particular subscribers establishes or releases the IMS DC.

[0096] But at present, DCSF is assumed to be implicitly subscribed to get these event notifications. But there is no solution defined where DCSF does explicit subscriptions. Hence it is proposed that ISM AS which supports IMS DC need to be registered in the NRF which it's profile will mention the list of subscribers (IMPUs) it supports for IMS DC. Then before DCSF does explicit subscriptions with IMS AS, it will discover using NRF. During discovery DCSF will provide the IMPU as the input so that NRF will filter only those IMS AS which supports those mentioned IMPUs. In another embodiment, it is proposed that the DCSF retrieves the list of IMS AS from the HSS by providing the list of IMPUs and IMS DC as input. After list of IMS AS is received by DCSF from NRF or HSS then DCSF will subscribe with all the IMS AS received from NRF or HSS by providing the IMPU or list of IMPUs for which it needs to be informed when subscribers are establish or update or relase the IMS DC. When the subscribers establish or releases IMS DC then IMS AS will notify in Nimsas_SessionEventControl_Notify. If the subscriber establishes multiple sessions associated with IMS DC, then the IMS AS will provide notifications for each session separately by providing a session id for each session whether IMS DC is established or updated to released etc.

[0097] In case of trusted AF (where the AF or third party is in the operator's trusted domain), it can directly discover IMS AS and subscribe like the proposal was done for DCSF using NRF or HSS.

[0098] In case of an untrusted AF, it is proposed that it will subscribe with NEF by sending Nnef_EventExposure_Subscribe request service operation. The NEF will then discover IMS AS and on receiving event notification in Nimsas_SessionEventControl_Notify service operation, it will forward to the AF using Nnef_EventExposure_Subscribe_Notify service operation. Similar to DCSF, the NEF may discover the IMS AS from the HSS by providing the list of IMPUs and IMS DC as an input. Instead of IMPUs, if the NEF receives GPSI or some other identfiers for privacy purpose from an Untrusted NF then NEF will conevrts to IMPUs before discovering and subscribing with IMS AS.

[0099] In some cases, the DCSF / Trusted AF / NEF can subscribe with IMS AS only for IMS DC establishment event (Event ID: IMS DC establishment). When one of the subscriber establishes IMS DC and IMS AS notifies to DCSF / Trusted AF / NEF then again for that particular IMS session, the DCSF / Trusted AF / NEF can again subscribe for IMS DC update and release event (Event ID: IMS DC update or release). In this case, on the same subscriber establishing multiple session associated with IMS DC, the DCSF / trusted AF / NEF receives the notifications from the IMS AS for each session. But for each session DCSF / Trusted AF / NEF again subscribes for an IMS DC update and release and accordingly receives a notification on the subscriber updating or releasing the IMS DC in that particular session.

[0100] Examples of the subscription details can be, but not limited to:

[0101] - Event ID: IMS DC establishment or update or release

[0102] - Event Filter: For one subscriber (IMPU) or list of subscribers (IMPUs)

[0103] Fig. 1 is a block diagram that illustrates a schematic of a UE (102) implemented to carry out the disclosed subject matter according to an embodiment as disclosed herein. For instance, the UE (102) may include, but not limited to a smartphone, a tablet, a laptop, a personal computer (PC), a television, a connected car, an IOT device, and the like. As shown, the UE (102) includes a processor (104), a memory (106), an I / O interface (108), and a UE controller (110). Each component is explained in further detail below.

[0104] The processor (104) communicates with the memory (106), the I / O interface (108) and the UE controller (110). The processor (104) is configured to execute instructions stored in the memory (106) and to perform various processes. The processor (104) may include one or a plurality of processors, may be a general-purpose processor, such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit such as a graphics processing unit (GPU), a visual processing unit (VPU), and / or an Artificial intelligence (AI) dedicated processor such as a neural processing unit (NPU).

[0105] The memory (106) includes storage locations to be addressable through the processor (104). The memory (106) is not limited to a volatile memory and / or a non-volatile memory. Further, the memory (106) may include a plurality of computer-readable storage media. The memory (106) may include non-volatile storage elements. For example, non-volatile storage elements may include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable (EEPROM) memories.

[0106] The I / O interface (108) transmits the information between the memory (106) and external peripheral devices. The peripheral devices are the input-output devices associated with the UE (102). Further, the UE controller (110) communicates with the I / O interface (108) and the memory (106). The UE controller (110) may be communicatively coupled to the memory (106) and the processor (104). The UE controller (110) is an innovative hardware that is realized through the physical implementation of both analog and digital circuits, including logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive and active electronic components, as well as optical components.

[0107] In an embodiment, the UE controller (110) configures the UE (102) with the PS data exemption service list using a device management procedure or a pre-configuration. For instance, the PS data exemption service list includes an IMS DC available for the UE (102). The PS data exemption service list refers to a list of services, applications, or data traffic that are exempted from being treated under regular data usage policies. The IMS DC enables the exchange of real-time data as part of multimedia communication systems. The IMS may refer to an architectural framework used to deliver IP based multimedia services (for example, voice, video, messaging, etc.) over networks. The DC refers to a communication path used for transmitting non-media data during the IMS sessions.

[0108] In an embodiment, the UE controller (110) determines whether a PS data off status is activated. The PS data off status refers to a network setting or feature of the UE (102) that disables the use of packet-switched data services. Thus, the UE (102) will not be able to access the internet, send / receive data over networks (4G, 5G), and use services that require a mobile data connection. The PS data off status may be a useful feature for controlling a data usage of the UE (102).

[0109] In an embodiment, the UE controller (110) determines whether services over the the IMS DC is not exempted in the PS data exemption service list. Based on this, the UE controller (110) transmits a re-INVITE message to a network apparatus (302). For instance, the network apparatus (302) includes an IMS AS, a data channel signalling function (DCSF), and a data channel media function (DCMF). The DCSF refers to a functionality within the IMS that handles the signaling required for setting up and managing the data channels. This may include channel maintenance monitoring, monitoring for changes in network conditions, ensuring channel stability throughout the IMS session, and the like. If the IMS session(s) require modifications (for example, switch to a new channel, switch to a different data transmission type, etc.), the DCSF handles the necessary signaling. The DCMF is responsible for managing data transmissions over the data channels established during the IMS sessions or communication sessions. The DCMF ensures that the data is transmitted efficiently and in compliance with network policies or security requirements. The DCMF may also perform processing (such as data format conversions, encryption / decryption, compression, etc.) on the data being transmitted to ensure optimal transmission.

[0110] In an embodiment, the UE controller (110) sends the re-INVITE message to the network apparatus (302) linked to the UE (102) to alter an ongoing IMS session, which includes a session description protocol (SDP) for a multimedia telephony service media. For example, the multimedia telephony service media may include audio media, video media, messaging, and the like. This re-INVITE message is transmitted when the PS data off status is enabled and the IMS DC is absent from the PS data exemption service list. The SDP is a standard format used to describe multimedia communication sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiations. The SDP may include information such as the media types (audio, video), the media format, transport protocols, timing details, and the like.

[0111] In an embodiment, the UE controller (110) sends the re-INVITE message to the network apparatus (302) to maintain only audio and video media within the SDP of the current IMS session. This re-INVITE message is transmitted when the PS data off status is enabled and the IMS DC is absent from the PS data exemption service list.

[0112] Fig. 2 is a block diagram that illustrates a schematic of an IMS AS (202) implemented to carry out the disclosed subject matter according to an embodiment as disclosed herein. The IMS AS is responsible for providing value-added services such as voice over IP (VoIP), video calling, instant messaging, presence services, multimedia conferencing, push-to-talk, and the like. These services may be specific to users or customized for different network environments.

[0113] As shown, the IMS AS (202) includes the processor (104), the memory (106), the I / O interface (108), and the IMS controller (210). The IMS controller (210) communicates with the I / O interface (108) and the memory (106). The IMS controller (210) may be communicatively coupled to the memory (106) and the processor (104). The IMS controller (210) is an innovative hardware that is realized through the physical implementation of both analog and digital circuits, including logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive and active electronic components, as well as optical components.

[0114] In an embodiment, the IMS controller (210) configures the IMS AS (202) with the PS data exemption service list by an operator. The PS data exemption service list includes services over the IMS DC that is accessible for the IMS AS (202). This list identifies services, applications, or data traffic that are not subject to standard data usage regulations. The IMS DC facilitates the real-time exchange of data within multimedia communication systems. The IMS itself is an architectural framework designed to provide IP-based multimedia services, such as voice, video, and messaging, across various networks. The DC denotes a communication pathway utilized for the transmission of non-media data during IMS sessions.

[0115] In an embodiment, the IMS controller (210) determines whether a PS data off status is activated. The PS data off status pertains to a network configuration or capability of the IMS AS (202) that prevents the utilization of packet-switched data services. This feature can be beneficial for managing the data consumption of the IMS AS (202).

[0116] In an embodiment, the IMS controller (210) determines whether the services over the IMS DC is not exempted in the PS data exemption list. The IMS controller (210) generates a re-INVITE message to preserve the audio and video media components of the IMS session, which includes the SDP for the multimedia telephony service media. The SDP is a standard format used to describe multimedia communication sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiations. This process involves eliminating the SDP linked to the IMS DC, rather than terminating the entire IMS session. The IMS controller (210) then sends the re-INVITE message to the UE (102) linked to the IMS AS (202) to maintain the audio and video media components of the IMS session. This occurs while eliminating the SDP related to the IMS DC, rather than completely terminating the IMS session, when the PS data off status is activated and the IMS DC is not exempted in the PS data exemption service list.

[0117] Fig. 3 is a block diagram that illustrates a schematic of a network apparatus (302) implemented to carry out the disclosed subject matter according to an embodiment as disclosed herein. For instance, the network apparatus (302) may be an IMS AS (202), a DCSF, a DCMF, and the like. As shown, the network apparatus (302) includes the processor (104), the memory (106), the I / O interface (108), and a first controller (310). The first controller (310) communicates with the I / O interface (108) and the memory (106). The first controller (310) may be communicatively coupled to the memory (106) and the processor (104). The first controller (310) is an innovative hardware that is realized through the physical implementation of both analog and digital circuits, including logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive and active electronic components, as well as optical components.

[0118] In an embodiment, the first controller (310) registers the network apparatus (302) with a network resource function (NRF) by sending a network function (NF) register message to the NRF. The NF register message includes a list of IMS Public User Identities (IMPUs), an indication of IMS DC support, IMS DC events supported by the network apparatus (302), and the like. The NRF provides a centralized repository and discovery mechanism for the NFs within the 5G core. The NRF is responsible for enabling service discovery, load balancing, and resource management in a flexible and dynamic 5G network. By facilitating communication between NFs, the NRF ensures that the network operates efficiently and reliably.

[0119] The list of IMPUs are unique identifiers associated with users in the IMS. These public identities allow users to be identified when accessing services such as Voice over IP (VoIP), video calls, messaging, or other multimedia services over IP networks. IMPUs play a critical role in addressing users within the IMS framework. Further, the IMS DC events include an IMS DC establishment, an IMS DC update, an IMS DC release, and the like. IMS DC establishment refers to the process of setting up a new data channel between IMS entities to support the transmission of media or other data types (for example, messaging or real-time data) in an IMS session. IMS DC update refers to the process of modifying an existing data channel within an ongoing IMS session. IMS DC release refers to the process of terminating an established data channel in IMS, either at the end of a session or due to some other event (for example, session timeout, user termination, network-triggered release, etc.). These IMS DC events are essential in managing the lifecycle of media and data flows in an IMS-based network, ensuring efficient use of resources and optimal service delivery.

[0120] In an embodiment, the first controller (310) receives a session event control subscription message from a third network apparatus. The session event control subscription message includes at least one IMS DC event supported by the network apparatus (302). The session event control message is used to manage the entire lifecycle of multimedia sessions. They are mainly implemented using SIP, allowing the network apparatus (302) to establish, modify, monitor, and terminate sessions while also supporting event-driven communication, such as notifications for call status, presence, or messaging. These messages ensure seamless communication and resource management in IMS-based services like VoLTE, video calls, and messaging services. Further, the third network apparatus obtains details or an address of the network apparatus (202) from the NRF based on the list of IMPUs and a capability of the IMS DC by sending a NF discovery message to the NRF.

[0121] In an embodiment, the first controller (310) generates a session event control notify message to be transmitted to the third network apparatus. The session event control notify message is used to inform users / subscribers about changes in the state of sessions or events they have subscribed to within the IMS. It enables real-time, event-driven updates, allowing users to stay informed about events like presence changes, message waiting indicators, session progress, registration status, and the like. The session event control notify message plays a vital role in session and event control, ensuring smooth service delivery and interaction within the IMS. Further, the session event control notify message enables the third network apparatus to receive details of a subscribed event that occurred in the network apparatus (302). Thus, a connection is duly established between the network apparatus (302) and the third party network apparatus via the NRF.

[0122] Fig. 4 is a block diagram that illustrates a schematic of a third network apparatus (402) implemented to carry out the disclosed subject matter according to an embodiment as disclosed herein. For instance, the third party network apparatus (402) may include a dynamic channel assignment scheme (DCAS), a network exposure function (NEF), an application function (AF), and the like. The DCAS dynamically allocates radio frequency channels to users. The DCAS improves spectral efficiency and maximizes the utilization of available channels. The NEF enables the secure exposure of network services and capabilities to external applications, such as those belonging to third-party service providers, other networks, or customer applications. NEF provides an interface for external applications to interact with the network apparatus (302) in a controlled and secure way. Further, the AF interacts with a Policy Control Function (PCF) to request policy and charging rules for specific applications or services. The AF represents external applications or services that require specific network policies, such as those related to quality of service (QoS), bandwidth allocation, and charging rules.

[0123] As shown, the third network apparatus (402) includes the processor (104), the memory (106), the I / O interface (108), and a second controller (410). The second controller (410) communicates with the I / O interface (108) and the memory (106). The second controller (410) may be communicatively coupled to the memory (106) and the processor (104). The second controller (410) is an innovative hardware that is realized through the physical implementation of both analog and digital circuits, including logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive and active electronic components, as well as optical components.

[0124] In an embodiment, the second controller (410) generates a discovery request message to be transmitted to the NRF. The discovery message is a signaling message used for enabling the efficient identification and discovery of available network services and resources. For instance, the discovery request message includes a list of IMPUs, an indication of IMS DC service, and an IMS AS type expected by the third network apparatus (402).

[0125] In an embodiment, the second controller (410) subscribes to all IMS AS instances received from the NRF. The subscribing includes sending a session event control subscription request message to the NRF. For instance, the session event control subscription request message may include an event identifier and an event filter. The event identifier indicates a session establishment request event. The session establishment request event involves the exchange of signaling messages that provide information necessary for setting up a communication link, negotiating parameters, and ensuring that the session meets the required quality and policy standards. This is fundamental for facilitating real-time communication services within the IMS. Further, the event filter is applicable to one subscriber corresponding to the event identifier or a list of subscribers corresponding to the event identifier.

[0126] In an embodiment, the second controller (410) obtains a session event control notify message from the network apparatus (302). The NRF identifies the network apparatus (302) by referencing the support list of IMPUs, the IMS DC events, and the anticipated IMS AS type included in the discovery request message. The session event control notify message allows the third network apparatus (402) to subscribe to receive details of a subscribed event that occurred in the network apparatus (302).

[0127] In an embodiment, the second controller (410) creates a subscribe request message intended for transmission to the network apparatus (302). The third network apparatus (402) retrieves information about the network apparatus (302) from the HSS, utilizing a list of various events that the network apparatus (302) supports. After the HSS receives and confirms the subscribe request message, the second controller (410) receives a notify request message from the HSS. The notify request message allows the third network apparatus (402) to subscribe to at least one of the multiple events supported by the network apparatus (302).

[0128] PS data off exemption is optional feature which is already supported by 3GPP for various services and below are examples of services.

[0129] Multimedia telephony service Voice;

[0130] SMS over IMS;

[0131] USSD over IMS (USSI);

[0132] Multimedia telephony service Video;

[0133] Services over IMS Data Channel;

[0134] Particular IMS services not defined by 3GPP, where each such IMS service is identified by an IMS communication service identifier;

[0135] Device Management over PS;

[0136] Management of USIM files over PS (e.g. via Bearer Independent Protocol); and

[0137] IMS Supplementary Service configuration via the Ut interface using XCAP.

[0138] TS 23.228 Annex X has described how both UE and network can successfully execute PS data off exemption feature for one particular service. In this case both UE and network will be provisioned with list of services which will be exempted when the PS data off enabled. These provisioning can be separate for home network and roaming network. UE shall mention its PS data off state (active / inactive or enable / disable) to network during registration or re-registration. If the PS data off state is active then both UE and network enforce uplink and downlink packet by not allowing the packets which is not exempted as per provisioning configuration. To be precise the IMS as part of the network handles the PS data off exemption services.

[0139] Now it is proposed that to provide IMS data channel as part of PS data off exemption, IMS data channel or services over IMS data channel will be added and the updated provisioning will be made available to UE and network for enforcement of uplink and downlink packet. In the network either IMS AS which supports the IMS data channel or DCSF or DCMF or enhanced MRF will address the PS data off exemption services. There are multiple applications are transported over IMS data channel. So it may happen that some operators are only interested to give exemptions to some light weight application and want to block high bandwidth consumed application. In this case it is proposed that both UE and network will be provisioned with the exact application id (identifying the application transported / supported over IMS data channel) so that only those applications will be exempted when PS data off state is active.

[0140] Services are dynamically added and removed as part of the provisioning. If the IMS data channel is established along with audio and / or video call and then IMS data channel is removed from the exempted services then it is proposed that instead of releasing the entire IMS session, UE or network should send Re-INVITE by only keeping the exempted service like m=audio and / or m=video line in the SDP. Similarly if IMS DC is already established and multiple applications are binded / associated and some applications are removed from the exemption services then it is proposed that UE or network should sent Re-INVITE by only keeping exempted application.

[0141] Similarly when video service is removed from PS data off exempted services then instead of releasing the entire IMS session, it is proposed that UE or network should send Re-INVITE by only keeping m-audio in SDP.

[0142] Fig. 5 is a sequence diagram that illustrates a sample sequence of events of procedures for handling PS data off exemption for the IMS data channel according to an embodiment as disclosed herein. As shown in the sequence diagram, the UE (102) is in communication with the network apparatus (302). At step 1, both the UE (102) and the network apparatus (302) has been provisioned with the list of services which need to be exempted from PS data off when status is active. It includes IMS Data channel as a whole or individual application id transported / supported over IMS data channel

[0143] At step 2, the UE (102) provided PS data off status =active in Registration / Re-Registration and network apparatus (302) is in sync with the UE (102) about the status

[0144] At step 3, the UE (102) established IMS session includes audio, video and IMS data channel transporting some application. Both the UE (102) and the network apparatus (302) allows only the service configured for PS data off exemption

[0145] At step 4, the UE (102) and the network apparatus (302) has been updated with configuration where some of the application which were exempted earlier or IMS Data channel as a whole got removed

[0146] At step 5, the UE (102) shall send re-INVITE keeping the only exempted services like audio or video if IMS DC has been removed or keep only application in the IMS DC which has been exempted by removing the other application which got removed from the exempted service.

[0147] In an embodiment, for clarity the other node of IMS networks like P-CSCF, I-CSCF, S-CSCF, HSS is not shown in Fig. 5.

[0148] In an embodiment it is proposed that to provide IMS data channel as part of PS data off exemption, IMS data channel or services over IMS data channel will be added and the updated provisioning will be made available to the UE (102) and the network apparatus (302) for enforcement of uplink and downlink packet.

[0149] In an embodiment, it is proposed that in the network apparatus (302), either IMS AS which supports the IMS data channel or DCSF or DCMF or enahnced MRF will address the PS adat off exemption services.

[0150] In an embodiment, it is possible that here are multiple applications are transported over IMS data channel. So it may happen that some operators are only intrested to give exemptions to some light weight application and want to block high bandwidth consumed application. In this case it is proposed that both the UE (102) and the network apparatus (302) will be provisioned with the exact application id (identifying the application transported / supported over IMS data channel) so that only those applications will be exempted when PS data off state is active.

[0151] In an embodiment, services are dynalically added and removed as part of the provisioning. If the IMS data channel is established along with audio and / or video call and then IMS data channel is remoed from the exempted services then it is proposed that instead of releasig the entire IMS session, the UE (102) or the network apparatus (302) should send Re-INVITE by only keeping the exempted service like m=audio and / or m=video line in the SDP.

[0152] In an embodiment, if the IMS DC is already established and multiple applications are binded / associated nad some applications are removed from the exemption services then it is proposed that the UE (102) or the network apparatus (302) should sent Re-INVITE by only keeping exempted application.

[0153] In an embodiment, when MULTIMEDIA TELEPHONY SERVICE Video service is removed from PS data off exempted services then instead of releasing the entire IMS session, it is proposed that the UE (102) or the network apparatus (302) should send Re-INVITE by only keeping m-audio in SDP.

[0154] In an embodiment, if the IMS data channel is established without accompanying audio or video or session based message service then the UE (102) or the network apparatus (302) should release the IMS session when IMS data channel is removed from the PS data off exempted service.

[0155] In an embodiment, it is proposed that IMS UPDATE method can be used by the UE (102) or the network apparatus (302) instead of Re-INVITE while modifying the session parameter (updating SDP by keeping only PS data off exempted service).

[0156] Fig. 6 is a sequence diagram that illustrates a process of the DCSF (604) subscribing to get IMS DC events for one subscriber or multiple subscribers according to an embodiment as disclosed herein. As shown in the sequence diagram, the IMS AS (202), NRF (602), and DCSF (604) are in communication with each other. The DCSF (604) may also be referred to as a trusted AF.

[0157] In step 1, the IMS AS (202) sends the support for list of IMPUs and IMS DC in Nnrf_NFManagement_NFRegister channel while registering to NRF (602). In step 2, the NRF (602) will store IMS AS profile. In step 3, the NRF (602) will provide Nnrf_NFManagement_NFRegister response to the IMS AS (202). In step 4, the DCSF (604) / trusted AF discover the IMS AS (202) by sending the input as list of IMPUs, IMS DC service and expected NF type to the DCSF (604) in the Nnrf_NFDiscovery_Request. In step 5, the NRF (602) provides the list of IMS AS which supports IMS DC and the IMPUs asked by DCSF (604) / Trusted AF in Nnrf_NFDiscovery_Request Response.

[0158] In step 6, the DCSF (604) will subscribe with all the IMS AS (202) received from the NRF (602) by sending Nimsas_SessionEventControl (Event ID: IMS DC establishment or update or release, Event Filter: For one subscriber (IMPU) or list of subscribers (IMPUs). In step 7, one of the subscribers establishes or released IMS DC and the event is observed by the IMS AS (202). In step 8, the IMS AS (202) will notify by sending Nimsas_SessionEventControl_Notify to the DCSF (604). If the subscriber establishes multiple sessions associated with IMS DC, then the IMS AS (202) will provide notification for each of the session separately by providing session id regarding for each session whether for each session IMS DC is established or updated to released etc.

[0159] Fig. 7 is a sequence diagram that illustrates a process of an untrusted AF (704) / third party subscribing to get IMS DC events for one subscriber or multiple subscribers according to an embodiment as disclosed herein. As shown in the sequence diagram, the IMS AS (202), the NRF (602), NEF (702), and the untrusted AF (704) are in communication with each other.

[0160] In step 1, the IMS AS (202) sends the support for list of IMPUs and IMS DC in the Nnrf_NFManagement_NFRegister channel while registering to the NRF (602). In step 2, the NRF (602) will store the IMS AS profile. In step 3, the NRF (602) will provide Nnrf_NFManagement_NFRegister response to the IMS AS (202). In step 4, the untrusted AF (704) subscribes to the NEF (702) by sending Nnef_EventExposure_Subscribe request (Event ID: IMS DC establishment or update or release, Event Filter: For one subscriber (IMPU) or list of subscribers (IMPUs). In step 5, the NEF (702) provides a response by sending the Nnef_EventExposure_Subscribe response.

[0161] In step 6, the NEF (702) discovers the IMS AS (202) by sending the input as list of IMPUs, IMS DC service and expected NF type is the DCSF (604) in Nnrf_NFDiscovery_Request. In step 7, the NRF (602) provides the list of IMS AS (202) which supports IMS DC and the IMPUs asked by NEF (702) in Nnrf_NFDiscovery_Request Response. In step 8, the NEF (702) will subscribe with all the IMS AS (202) received from the NRF (602) by sending Nimsas_SessionEventControl (Event ID: IMS DC establishment or update or release, Event Filter: For one subscriber (IMPU) or list of subscribers (IMPUs). In step 9, one of the subscribers establishes or released IMS DC and the event is observed by the IMS AS (202). In step 10, the IMS AS (202) will notify by sending Nimsas_SessionEventControl_Notify to the NEF (702). If the subscriber establishes multiple sessions associated with the IMS DC, then the IMS AS (202) will provide notifications for each session separately by providing session id regarding each session whether IMS DC is established or updated to released etc. In step 11, the NEF (702) will provide or forward the notification report received from the IMS AS (202) by sending Nnef_EventExposure_Subscribe_Notify.

[0162] Fig. 8 is a flow diagram that illustrates a method for handling exemption services associated with the IMS DC by the UE (102) according to an embodiment as disclosed herein. The method includes steps (802-810). Each step is explained in further detail below.

[0163] At step (802), the UE (102) is configured with the PS data exemption service list using a device management procedure or a pre-configuration. For example, the PS data exemption service list contains an IMS DC available to the UE (102). The PS data exemption service list is a list of services, applications, or data traffic that are exempt from standard data usage restrictions. The IMS DC allows for the sharing of real-time data as part of multimedia communication systems. The term IMS may refer to an architectural framework for delivering IP-based multimedia services (such as phone, video, and messaging) via networks. The DC is a communication route used to send non-media data during IMS sessions.

[0164] At step (804), the UE (102) determines whether a PS data off status is activated. The PS data off status is a network configuration or feature on the UE (102) that prevents the operation of packet-switched data services. As a result, the UE (102) will be unable to access the internet, send / receive data via networks (4G, 5G), or utilize services that need a mobile data connection. The PS data off state may be important for managing the data usage associated with the UE　(102).

[0165] At step (806), the UE (102) determines whether services over the IMS DC is not exempted in the PS data exemption service list.

[0166] At step (808), the UE (102) transmits a re-INVITE message to the network apparatus (302) linked to the UE (102) to alter an ongoing IMS session, which includes a session description protocol (SDP) for a multimedia telephony service media. The re-INVITE message is issued when the PS data off status is activated and the IMS DC is not on the PS data exemption service list. The SDP is a standard format for describing multimedia communication sessions in order to announce them, invite them, and initiate other types of multimedia sessions. The SDP may contain information such as media kinds (audio and video), media formats, transport protocols, time parameters, and the like.

[0167] At step (810), the UE (102) transmits the re-INVITE message to the network apparatus (302) to maintain only audio and video media within the SDP of the current IMS session. This re-INVITE message is transmitted when the PS data off status is enabled and the IMS DC is absent from the PS data exemption service list.

[0168] Fig. 9 is a flow diagram that illustrates a method for handling exemption services associated with the IMS DC by the IMS AS (202) according to an embodiment as disclosed herein. The method includes steps (902-910). Each step is explained in further detail below.

[0169] At step (902), the IMS AS (202) is configured with the PS data exemption service list by an operator. The PS data exemption service list contains services over the IMS DC, which is available to the IMS AS (202). This list identifies applications, services, or data traffic that do not comply with typical data use laws. The IMS DC enables the real-time interchange of data in multimedia communication systems. The IMS is an architectural framework for delivering IP-based multimedia services such as phone, video, and messaging over several networks. The DC is a communication channel used to transmit non-media data during IMS sessions.

[0170] At step (904), the IMS AS (202) determines whether a PS data off status is activated. The PS data off state is a network setting or capability of the IMS AS (202) that disables the use of packet-switched data services. This function can help manage the　data consumption associated with the IMS AS　(202).

[0171] At step (906), the IMS AS (202) generates a re-INVITE message to preserve the audio and video media components of the IMS session, which includes the SDP for multimedia telephony service media. The SDP is a standard format for describing multimedia communication sessions in order to announce them, invite them, and initiate other types of multimedia sessions. Instead of cancelling the entire IMS session, this step includes removing the SDP associated with the IMS DC.

[0172] At step (908), the IMS AS (202) transmits the re-INVITE message to the UE (102) linked to the IMS AS (202) to maintain the audio and video media components of the IMS session. When the PS data off status is enabled and the IMS DC is not on the PS data exemption service list, this occurs when removing the SDP associated with the IMS DC rather than ending the IMS session entirely.

[0173] Fig. 10 is a flow diagram that illustrates a method for handling data channel events associated with the IMS DC by the network apparatus (302) according to an embodiment as disclosed herein. The method includes steps (1002-1006). Each step is explained in further detail below.

[0174] At step (1002), the network apparatus (302) registers with the NRF (602) by sending a NF register message to the NRF (602). The NF register message includes a list of IMPUs, an indication of IMS DC support, IMS DC events supported by the network apparatus (302), and the like. The NRF (602) serves as a centralized store and discovery mechanism for NFs within the 5G core. The NRF (602) enables service discovery, load balancing, and resource management in a flexible and dynamic 5G network. By allowing communication between NFs, the NRF (602) guarantees that the network functions efficiently and consistently.

[0175] The IMPU list contains unique IDs for users in the IMS. These public identities enable users to be identified while accessing IP-based services such as Voice over IP (VoIP), video calls, texting, and other multimedia. IMPUs play an important role in addressing users inside the IMS system. Further, the IMS DC events include an IMS DC establishment, an IMS DC update, an IMS DC release, and the like.

[0176] IMS DC establishment　is the process of creating a new data channel between IMS entities to facilitate the transfer of media or other data kinds (such as message or real-time data) during an IMS session. IMS DC update is the process of changing an existing data channel within an active IMS session. IMS DC release is the process of closing an established data channel in IMS, either at the conclusion of a session or in response to another event (for example, session timeout, user termination, network-triggered release, etc.). These IMS DC events are critical for controlling the lifespan of media and data flows in an IMS-based network, resulting in more effective resource use and improved service delivery.

[0177] At step (1104), the network apparatus (302) receives a session event control subscription message from a third network apparatus. The session event control subscription message encompasses at least one IMS DC event that is supported by the network apparatus (302). This message plays a crucial role in overseeing the complete lifecycle of multimedia sessions. Primarily utilizing SIP, it enables the network apparatus (302) to create, modify, monitor, and conclude sessions, while also facilitating event-driven communication, including notifications related to call status, presence, or messaging. These messages are vital for ensuring efficient communication and resource management in IMS-based services such as VoLTE, video conferencing, and messaging applications. Additionally, the third network apparatus retrieves information or the address of the network apparatus (202) from the NRF by sending an NF discovery message to the NRF, based on the list of IMPUs and the capabilities of the IMS DC.

[0178] At step (1106), the network apparatus (302) generates a session event control notify message to be transmitted to the third network apparatus. The session event control notify message serves to alert users and subscribers regarding modifications in the status of sessions or events they have opted into within the IMS framework. This mechanism facilitates real-time, event-driven notifications, keeping users updated on occurrences such as presence updates, message waiting alerts, session advancements, registration statuses, and similar events. The session event control notify message is essential for effective session and event management, ensuring seamless service provision and interaction within the IMS. Additionally, this message allows the third network apparatus (402) to obtain information about a subscribed event that has taken place in the network apparatus (302). Consequently, a connection is effectively established between the network apparatus (302) and the third network apparatus (402) through the NRF.Fig. 11 is a flow diagram that illustrates a method for handling data channel events associated with the IMS DC by the third network apparatus (402) according to an embodiment as disclosed herein. For instance, the third party network apparatus (402) may include a DCAS, a NEF (702), an AF, and the like. The method includes steps (1102-1108). Each step is explained in further detail below.

[0179] At step (1102), the third network apparatus (402) generates a discovery request message. The discovery message is a signaling message that allows for the rapid identification and discovery of accessible network services and resources. For instance, the discovery request message includes a list of IMPUs, an IMS DC service, and an IMS AS type expected by the third network apparatus (402).

[0180] At step (1104), the third network apparatus (402) transmits the discovery request message generated in step (1102) to the NRF (602).

[0181] At step (1106), the third network apparatus (402) subscribes to all IMS AS instances received from the NRF (602). The subscribing includes sending a session event control subscription request message to the NRF (602). For instance, the session event control subscription request message may include an event identifier and an event filter. The event identifier　refers to a session setup request event. The session establishment　request event entails the exchange of signaling messages that contain information needed to create a communication link, negotiate parameters, and ensure that the session fulfils the requisite quality and policy criteria. This is critical for enabling real-time communication services in the IMS. Further, the event filter applies to either a single subscriber matching the event identifier or a group of subscribers matching the event identifier.

[0182] At step (1108), the third network apparatus (402) receives a session event control notify message from the network apparatus (302). The NRF (602) identifies the network apparatus　(302) using the support list of IMPUs, the IMS DC events, and the predicted IMS AS type from the discovery request message. The session event control message enables the third network apparatus　(402) to subscribe to receive details of a subscribed event that occurred in the network apparatus (302).

[0183] Embodiments disclosed herein provides a system and methods for NSAC in hierarchical architecture. The present method ensures that 5G system is correcting handling the admission control for the maximum number of registered UEs and maximum number of concurrent PDU sessions for a network slice defined by an S-NSSAI in hierarchal architecture deployment.

[0184] The abbreviations used in the embodiment are:

[0185] NSACF - Network Slice Admission Control Function

[0186] 3gpp- 3rd Generation Partnership Project

[0187] NSSAI- Network Slice Selection Assistance Information

[0188] S-NSSAI- Single - Network Slice Selection Assistance Information

[0189] SMF+PGW-C- Session Management Function supporting IWK of 5GC and EPC

[0190] PDU- Protocol Data Unit

[0191] PDN- Packet Data Network

[0192] Fig. 12 is a sequence diagram that illustrates a sample sequence of events that is expected to take place in a typical network deployment where a hierarchical architecture is deployed by the network according to the prior art. As shown in the sequence diagram, an SMF+PGW-C (1202), a NSACF (1204), and a primary NSACF (1206) are in communication with each other.

[0193] At step 1, quota (local maximum number) for the number of the UE (102) with minimum one PDU session / PDN connection is exceeded and for number of PDU session is available at the NSACF (1204). Quota (local maximum number) for number of the UE (102) with minimum one PDU session / PDN connection is available and for number of PDU session is not available at the primary NSACF (1206). At step 2, the SMF+PGW-C (1202) receive a PDU session establishment request which trigger it to perform NSAC for maximum number of UE (102) with minimum one PDU session / PDN connection and maximum number of PDU session. At step 3, the SMF+PGW-C (1202) sends Nnsacf_NSAC_NumOfPDUsUpdate_Request to the NSACF (1204). At step 4, as option 2 is configured, the NSACF (1204) performs NSAC for both max number of UEs with minimum one PDU Session / PDN connection and max number of PDU Sessions. The NSACF (1204) check and found that it does not have quota for number of UEs with minimum one PDU Session / PDN connection. Hence, it needs to trigger Primary NSACF.

[0194] At step 5, the NSACF (1204) checks if it has not discovered the primary NSACF (1206) earlier, will do discover and selection of the primary NSACF (1206). At step 6, the NSACF (1204) sends Nnsacf_NSAC_NumOfPDUsUpdate_Request to the primary NSACF (1206). At step 7, as option 2 is configured the primary NSACF (1206) checks for the max number of UEs with minimum one PDU session / PDN connection and max number of PDU session. At step 8, the primary NSACF (1206) finds that quota for number of PDU session is not available and hence it sends reject response in Nnsacf_NSAC_NumOfPDUsUpdate_Response. At step 9, the NSACF (1204) didn't get update of local of maximum number from the primary NSACF (1206) and received reject response. At step 10, the NSACF (1024) sends reject to the SMF+PGW-C (1202).

[0195] In an embodiment, as explained in the background section, in the option 2 , the SMF+PGW-C (1202) sends Nnsacf_NSAC_NumOfPDUsUpdate to the NSACF (1024) and the NSACF (1204) supports handling both for the number of UEs with at least one PDU Session / PDN Connection and number of PDU session for the S-NSSAI. In the case of Hierarchical architecture deployment, if the quota is exceeded at the NSACF (1204), the NSACF (1204) sends the scenario Nnsacf_NSAC_NumOfPDUsUpdate to the primary NSACF (1206). After receiving response from the primary NSACF (1206), the NSACF (1204) provides the successful or unsuccessful response accordingly.

[0196] In a particular scenario if quota for the number of UEs with at least one PDU Session / PDN Connection at the NSACF (1204) is exceeded but quota for number of PDU session is available then the NSACF (1204) checks with the primary NSACF (1206) by sending Nnsacf_NSAC_NumOfPDUsUpdate message. The primary NSACF (1206) does not know the exact quota status of the NSACF (1204) and hence it checks the quota for both the number of UEs with at least one PDU Session / PDN Connection and number of PDU session. If at the primary NSACF (1206) quota for PDU session is exceeded then it will reject the request which in turn will be rejected by the NSACF (1204) towards SMF which is wrong because the PDU quota was available at the NSACF (1204) and the request could have been handled.

[0197] Also it may happen that when the primary NSACF (1206) receives the Nnsacf_NSAC_NumOfPDUsUpdate request from the NSACF (1204) with Option 2 is configured then as part of NSAC handling the primary NSACF (1206) may update the local maximum number for both number of UEs with at least one PDU Session / PDN Connection and for number of PDU session which is wrong. Because only one of the quota was exceeded at NSACF but it received quotas for both.

[0198] Example:

[0199] Scenario 1:

[0200] Precondition:

[0201] - Hierarchical architecture is deployed and option 2 solution is selected by operator

[0202] - Quota for number of UEs with at least one PDU Session / PDN Connection is exceeded at the NSACF (1204) and for number of PDU session is available

[0203] - Quota for number of UEs with at least one PDU Session / PDN Connection is available at the primary NSACF (1206) and for number of PDU session is exceeded

[0204] In this case when the NSACF (1204) sends Nnsacf_NSAC_NumOfPDUsUpdate to the Primary NSACF (1206), the primary NSACF (1206) does the quota check for both number of UEs with at least one PDU Session / PDN Connection and for number of PDU session. As quota has been exceeded for number of PDU session, the primary NSACF (1206) rejects the request. The NSACF (1204) also reject the request even if the number of PDU session quota was available with itself.

[0205] Scenario 2:

[0206] Precondition:

[0207] - Hierarchical architecture is deployed and option 2 solution is selected by operator

[0208] - Quota for number of UEs with at least one PDU Session / PDN Connection is available at the NSACF (1204) and for number of PDU session is exceeded

[0209] - Quota for number of UEs with at least one PDU Session / PDN Connection is exceeded at the primary NSACF (1206) and for number of PDU session is available

[0210] In this case when the NSACF (1204) sends Nnsacf_NSAC_NumOfPDUsUpdate to the Primary NSACF (1206), the primary NSACF (1206) does the quota check for both number of UEs with at least one PDU Session / PDN Connection and for number of PDU session. As quota has been exceeded for of UEs with at least one PDU Session / PDN Connection, the primary NSACF (1206) rejects the request. The NSACF (1204) also reject the request even if the of quota for number UEs with at least one PDU Session / PDN Connection quota was available with itself.

[0211] In an embodiment, the call flow is explained where the NSACF (1204) quota for number UE with minimum one PDU session / PDN connection is exceeded and the primary NSACF (1206) number of PDU session quota is not available. But the reverse case is also possible which means the quota for number of PDU session may exceeded at the NSACF (1204) and the primary NSACF (1206) number of UE with minimum one PDU session / PDN connection quota is available.

[0212] Fig. 13 is a sequence diagram that illustrates a sample sequence of events that is expected to take place in a typical network deployment where a hierarchical architecture is deployed by the network according to the embodiments as disclosed herein. In the hierarchical architecture if the NSACF (1204) and the primary NSACF (1206) is configured with option 2 then the NSACFs (1204, 1206) will do the NSAC for both number of UEs with at least one PDU Session / PDN Connection and for number of PDU session when receive Nnsacf_NSAC_NumOfPDUsUpdate message. In this case when the NSACF (1204) receives Nnsacf_NSAC_NumOfPDUsUpdate from the SMF+PGW-C (1202) and one of the quota (between number of UEs with at least one PDU Session / PDN Connection and for number of PDU session) is exceeded then it is proposed that the NSACF (1204) provides some indication for the quota which has been exceeded in the Nnsacf_NSAC_NumOfPDUsUpdate while sending to the primary NSACF (1206). If the primary NSACF (1206) finds the indication then even if Option 2 is configured, still it is proposed for the primary NSACF (1206) to do NSAC only for the received indication. If the NSACF (1204) has indicated UE count, then the primary NSACF (1206) will do NSAC for UE count and if the NSACF (1204) has indicated PDU count then the primary NSACF (1206) will do NSAC for PDU count.

[0213] At step 1, quota (local maximum number) for number UE with minimum one PDU session / PDN connection is exceeded and for number of PDU session is available at the NSACF (1204). Quota (local maximum number) for number UE with minimum one PDU session / PDN connection is available and for number of PDU session is not available at the primary NSACF (1206). At step 2, the SMF+PGW-C (1202) receive a PDU session establishment request which trigger it to perform NSAC for maximum number of UE with minimum one PDU session / PDN connection and maximum number of PDU session. At step 3, the SMF+PGW-C (1202) sends Nnsacf_NSAC_NumOfPDUsUpdate_Request to the NSACF (1204). At step 4, as option 2 is configured, the NSACF (1204) performs NSAC for both max number of UEs with minimum one PDU Session / PDN connection and max number of PDU Sessions. The NSACF (1204) check and found that it does not have quota for number of UEs with minimum one PDU Session / PDN connection. Hence it needs to trigger the primary NSACF (1206). At step 5, the NSACF (1204) if has not discovered the primary NSACF (1206) earlier, will do discover and selection of the primary NSACF (1206).

[0214] At step 6, the NSACF (1204) sends Nnsacf_NSAC_NumOfPDUsUpdate_Request to the primary NSACF (1206). In this message, the NSACF (1204) will add indication to perform NSAC for UE count with minimum one PDU session / PDN connection (because this UE quota is exceeded at the NSACF (1204) and it expect update of local maximum number of UE with min one PDU session / PDN connection from the primary NSACF (1206)). At step 7, based on the indication for UE count with minimum one PDU session / PDN connection, the primary NSACF (1206) does NSAC only for max number of UE count even if option 2 is configured. At step 8, the primary NSACF (1206) update local maximum number of UEs with minimum one PDU session / PDN connection. At step 9, the NSACF (1204) used available quota of PDU session from itself and using the updated local maximum number of UEs, it performs NSAC and send successful response. At step 10, the NSACF (1204) sends successful response to the SMF+PGW-C (1202).

[0215] In an embodiment, the call flow is explained where the NSACF (1204) quota for number UE with minimum one PDU session / PDN connection is exceeded and the primary NSACF (1206) number of PDU session quota is not available. But the reverse case is also possible which means the quota for number of PDU session may exceeded at the NSACF (1204) and the primary NSACF (1206) number of UE with minimum one PDU session / PDN connection quota is available.

[0216] In an embodiment, it is proposed that when NSACF (1204) receives Nnsacf_NSAC_NumOfPDUsUpdate from the SMF+PGW-C (1202) and one of the quota (between number of UEs with at least one PDU Session / PDN Connection and for number of PDU session) is exceeded then it is proposed that the NSACF (1204) provides some indication for the quota which has been exceeded in the Nnsacf_NSAC_NumOfPDUsUpdate while sending to the primary NSACF (1206).

[0217] In an embodiment, it is proposed that if the primary NSACF (1206) finds the indication then even if Option 2 is configured, still it is proposed for the primary NSACF (1206) to do NSAC only for the received indication. If the NSACF (1204) has indicated UE count, then the primary NSACF (1206) will do NSAC for UE count and if the NSACF (1204) has indicated PDU count then the primary NSACF (1206) will do NSAC for PDU count.

[0218] In an embodiment, it is proposed that the NSACF (1204) does not send any indication even if quota for number of UEs with at least one PDU Session / PDN Connection is exceeded and the primary NSACF (1206) does NSAC for both number of UEs with at least one PDU Session / PDN Connection and for number of PDU session. If the primary NSACF (1206) rejected the request for both number of UEs with at least one PDU Session / PDN Connection and number of PDU session the NSACF reject the request by sending to the SMF+PGW-C (1202).

[0219] In an embodiment, it is proposed that NSACF does not send any indication even if quota for number of UEs with at least one PDU Session / PDN Connection is exceeded and the primary NSACF (1206) does NSAC for both number of UEs with at least one PDU Session / PDN Connection and for number of PDU session. If the primary NSACF (1206) rejected the request for only number of UEs with at least one PDU Session / PDN Connection then the NSACF (1204) reject the request by sending to the SMF+PGW-C (1202) because at the NSACF (1202) also the quota for number of UEs with at least one PDU Session / PDN Connection is not available.

[0220] In an embodiment, it is proposed that the NSACF (1204) does not send any indication even if quota for number of UEs with at least one PDU Session / PDN Connection is exceeded and the primary NSACF (1206) does NSAC for both number of UEs with at least one PDU Session / PDN Connection and for number of PDU session. If the primary NSACF (1206) rejected the request for only number of PDU sessions then the NSACF (1204) successfully handle the request by sending to the SMF+PGW-C (1202) because at the NSACF (1204) has available quota for the number of PDU sessions.

[0221] In an embodiment, it is proposed that the NSACF (1204) does not send any indication even if quota for number of PDU Session is exceeded and the primary NSACF (1206) does NSAC for both number of UEs with at least one PDU Session / PDN Connection and for number of PDU session. If the primary NSACF (1206) rejected the request for only number of PDU Session then the NSACF (1204) reject the request by sending to the SMF+PGW-C (1202) because at the NSACF (1204) also the quota for number PDU Session is not available.

[0222] In an embodiment, it is proposed that the NSACF (1204) does not send any indication even if quota for number of PDU Session is exceeded and the primary NSACF (1206) does NSAC for both number of UEs with at least one PDU Session / PDN Connection and for number of PDU session. If the primary NSACF (1206) rejected the request for only number of UEs with at least one PDU Session / PDN Connection then the NSACF (1204) successfully handle the request by sending to the SMF+PGW-C (1202) because at the NSACF (1204) has available quota for the number of UEs with at least one PDU Session / PDN Connection then the NSACF (1204).

[0223] In an embodiment, though the NSACF (1204) provides the indication to the primary NSACF (1206) in Nnsacf_NSAC_NumOfPDUsUpdate service operation, there can be a new service operation be defined or some existing service operation be used to provide this indication.

[0224] In an embodiment, option 1 may be configured for the communication between the NSACF (1204) and the primary NSACF (1206) which means the primary NSACF (1206) will always receive two separate service operation Nnsacf_NSAC_NumOfUEsUpdate and Nnsacf_NSAC_NumOfPDUsUpdate from the NSACF (1204) to perform the NSACF (1204) for maximum number of UE when min one PDU session / PDN connection is established and maximum number of PDU session. In this case, the quota which has been exceeded at the NSACF (1204), the same corresponding service operation will be sent to the primary NSACF (1206) so that in response the primary NSACF (1206) can update the local maximum number. Based on that local maximum number, the NSACF (1204) can perform NSAC and send successful response to the SMF+PGW-C (1202).

[0225] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described herein.

Claims

1.A method performed by a network resource function (NRF) entity in a communication system, the method comprising:receiving, from an internet protocol (IP) multimedia subsystem (IMS) application server (AS) supporting an IMS data channel (DC), a register message including a support for a list of IMS public user identities (IMPUs) and the IMS DC;storing a profile of the IMS AS;transmitting, to the IMS AS, a response message for the register message;receiving, from a network function (NF) entity, a request message including an input for discovering the IMS AS, the input corresponding to at least one of the list of the IMPUs, a service of the IMS DU, or an expected NF type; andbased on the profile, transmitting, to the NF entity, a list of the IMS AS supporting the IMS DC and the IMPUs requested by the request message;wherein the NF entity subscribes with all the IMS AS received from the NRF entity.2.The method of claim 1,wherein the NF entity is at least one of a data channel media functions (DCSF) entity or a trusted application function (AF) entity,3.The method of claim 1,wherein the request message includes at least one of an event identifier or an event filter,wherein the event identifier is for at least one of an establishment, an update or a release of the IMS DC, andwherein the event filter is for at least one of an IMPU or the list of the IMPUs.4.A method performed by a network function (NF) entity in a communication system, the method comprising:receiving, from an untrusted application function (AF) entity, a subscribe request message for a subscription to a network exposure function (NEF) entity,transmitting, to a network resource function (NRF) entity, a request message including an input for discovering an internet protocol (IP) multimedia subsystem (IMS) application server (AS) supporting an IMS data channel (DC), the input corresponding to at least one of a list of IMS public user identities (IMPUs), a service of the IMS DC, or an expected NF type;based on a profile stored in the NRF entity, receiving, from the NRF entity, a list of the IMS AS supporting the IMS DC and the IMPUs requested by the request message;transmitting, to the IMS AS, an event control message for the subscription with all the IMS AS received from the NRF entity; andreceiving, from the IMS AS, a notification message.5.The method of claim 4,wherein the NF entity is at least one of a data channel media functions (DCSF) entity or a trusted AF entity, andwherein the IMS AS is registered to the NRF entity by providing support for the list of the IMPUs and the IMS DC.6.The method of claim 4, further comprising:transmitting, to the untrusted AF entity, a report message of the notification message,wherein the request message includes at least one of an event identifier or an event filter,wherein the event identifier is for at least one of an establishment, an update or a release of the IMS DC, andwherein the event filter is for at least one of an IMPU or the list of the IMPUs.7.A method performed by an internet protocol (IP) multimedia subsystem (IMS) application server (AS) in a communication system, the method comprising:transmitting, to a network resource function (NRF) entity, a register message including a support for a list of IMS public user identities (IMPUs) and an IMS data channel (DC), while registering to the NRF entity;receiving, from the NRF entity, a response message for the register message,receiving, from a network function (NF) entity, an event control message to subscribe with all the IMS AS received from the NRF entity;performing an establishment of the IMS DC and an observation of an event; andreceiving, from a network function (NF) entity, a notification message,wherein the IMS AS supports the IMS DC,wherein the NF entity is at least one of a data channel media functions (DCSF) entity or a trusted application function (AF) entity.8.A network resource function (NRF) entity in a communication system, the NRF entity comprising:a processor; anda controller coupled with the processor, the controller configured to:receive, from an internet protocol (IP) multimedia subsystem (IMS) application server (AS) supporting an IMS data channel (DC), a register message including a support for a list of IMS public user identities (IMPUs) and the IMS DC;store a profile of the IMS AS;transmit, to the IMS AS, a response message for the register message;receive, from a network function (NF) entity, a request message including an input for discovering the IMS AS, the input corresponding to at least one of the list of the IMPUs, a service of the IMS DU, or an expected NF type; andbased on the profile, transmit, to the NF entity, a list of the IMS AS supporting the IMS DC and the IMPUs requested by the request message;wherein the NF entity subscribes with all the IMS AS received from the NRF entity.9.The NRF entity of claim 8,wherein the NF entity is at least one of a data channel media functions (DCSF) entity or a trusted application function (AF) entity,10.The NRF entity of claim 8,wherein the request message includes at least one of an event identifier or an event filter,wherein the event identifier is for at least one of an establishment, an update or a release of the IMS DC, andwherein the event filter is for at least one of an IMPU or the list of the IMPUs.11.A network function (NF) entity in a communication system, the NF entity comprising:a processor; anda controller coupled with the processor, the controller configured to:receive, from an untrusted application function (AF) entity, a subscribe request message for a subscription to a network exposure function (NEF) entity,transmit, to a network resource function (NRF) entity, a request message including an input for discovering an internet protocol (IP) multimedia subsystem (IMS) application server (AS) supporting an IMS data channel (DC), the input corresponding to at least one of a list of IMS public user identities (IMPUs), a service of the IMS DC, or an expected NF type;based on a profile stored in the NRF entity, receive, from the NRF entity, a list of the IMS AS supporting the IMS DC and the IMPUs requested by the request message;transmit, to the IMS AS, an event control message for the subscription with all the IMS AS received from the NRF entity; andreceive, from the IMS AS, a notification message.12.The NF entity of claim 11,wherein the NF entity is at least one of a data channel media functions (DCSF) entity or a trusted AF entity, andwherein the IMS AS is registered to the NRF entity by providing support for the list of the IMPUs and the IMS DC.13.The NF entity of claim 11, wherein the controller is further configured to:transmit, to the untrusted AF entity, a report message of the notification message,wherein the request message includes at least one of an event identifier or an event filter,wherein the event identifier is for at least one of an establishment, an update or a release of the IMS DC, andwherein the event filter is for at least one of an IMPU or the list of the IMPUs.14.An internet protocol (IP) multimedia subsystem (IMS) application server (AS) in a communication system, the IMS AS comprising:a processor; anda controller coupled with the processor, the controller configured to:transmit, to a network resource function (NRF) entity, a register message including a support for a list of IMS public user identities (IMPUs) and an IMS data channel (DC), while registering to the NRF entity;receive, from the NRF entity, a response message for the register message,receive, from a network function (NF) entity, an event control message to subscribe with all the IMS AS received from the NRF entity;perform an establishment of the IMS DC and an observation of an event; andreceive, from a network function (NF) entity, a notification message,wherein the IMS AS supports the IMS DC,wherein the NF entity is at least one of a data channel media functions (DCSF) entity or a trusted application function (AF) entity.

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