Method and apparatus for supporting standalone IMS data channel session in wireless communication system

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Embodiments herein disclose systems and methods for ensuring that the IMS network and the UE handles standalone IMS Data Channel session by defining IMS architecture, interfaces, and procedures to support standalone IMS data channel sessions. In an embodiment, the method performed by an internet protocol (IP) multimedia subsystem (IMS) application server (AS) for supporting standalone IMS data channel (IMS DC) session. The method includes receiving, from a home subscriber server　(HSS), subscription information for a user equipment (UE); determining whether the UE is authorized to use the standalone IMS DC session based on the subscription information of the UE; and in case that the UE is not authorized to use the standalone IMS DC session, rejecting a request for establishment of the standalone IMS DC session.

Description

METHOD AND APPARATUS FOR SUPPORTING STANDALONE IMS DATA CHANNEL SESSION IN WIRELESS COMMUNICATION SYSTEM

[0001] Embodiments disclosed herein relate to internet protocol (IP) Multimedia Subsystems (IMS) in 3rdGeneration Partnership Project (3GPP) networks, and more particularly to systems and methods for ensuring that IMS network and a User Equipment (UE) handles standalone IMS Data Channel session.

[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] Most network operators have deployed their network to provide various services using IP Multimedia Subsystem (IMS), including the most popular Voice over Long-Term Evolution (VOLTE) service. Now, the IMS is evolving to cater 5G vertical requirements to offer various new services for which IMS Data channel (DC) is getting used along with normal voice and video calls. This IMS DC will help various scenarios, such as, but not limited to, Remote Support, Remote Surgery, Remote Examination, Augmented reality (AR) with control, Machine Control, Virtual Reality (VR) with collaboration, and so on.

[0009] The principal object of embodiments herein is to disclose systems (or wireless network) and methods for ensuring that an IMS network and a UE handles standalone IMS Data Channel session by defining IMS architecture, interfaces, and procedures to support standalone IMS data channel sessions.

[0010] Another object of embodiments herein is to support standalone IMS bootstrap and application data channel sessions without accompanying audio / video / messaging media in an IMS session, including the establishment and termination of standalone IMS data channel sessions.

[0011] Another object of embodiments herein is to negotiate support of standalone IMS data channel between the UE and the IMS network, wherein the negotiation includes the ability to add audio / video / messaging media to an established standalone IMS data channel.

[0012] Another object of embodiments herein is to establish a (standalone) application data channel without accompanying bootstrap data channel.

[0013] Another object of embodiments herein is to establish a (standalone) bootstrap data channel without accompanying application data channel.

[0014] Another object of embodiments herein is to add audio / video / messaging media to an established standalone IMS data channel session.

[0015] Another object of embodiments herein is to remove audio / video / messaging media from the IMS session that also contains IMS data channel media.

[0016] Another object of embodiments herein is to define or configure new service data in a Home Subscriber Server　(HSS) for support of standalone data channel or extend existing MMTel service data.

[0017] Accordingly, the embodiments herein provide a method performed by an internet protocol (IP) multimedia subsystem (IMS) application server (AS) for supporting standalone IMS data channel (IMS DC) session in a wireless communication system. The method includes receiving, from a home subscriber server　(HSS), subscription information for a user equipment (UE); determining whether the UE is authorized to use the standalone IMS DC session based on the subscription information of the UE; and in case that the UE is not authorized to use the standalone IMS DC session, rejecting a request for establishment of the standalone IMS DC session.

[0018] Accordingly, the embodiments herein provide a method performed by a user equipment (UE) for supporting standalone internet protocol (IP) multimedia subsystem (IMS) data channel (IMS DC) session in a wireless communication system. The method includes transmitting, to an IMS application server (AS), a request for establishment of the standalone IMS DC session; and receiving, from the IMS AS, a reject message to the request, in case that a user equipment (UE) is not authorized to use the standalone IMS DC session based on subscription information of the UE from a home subscriber server (HSS).

[0019] Accordingly, the embodiments herein provide an internet protocol (IP) multimedia subsystem (IMS) application server (AS) for supporting standalone IMS data channel (IMS DC) session in a wireless communication system. The IMS AS includes a transceiver; and at least one processor coupled to the transceiver and configured to: receiv3, from a home subscriber server　(HSS), subscription information for a user equipment (UE), determine whether the UE is authorized to use the standalone IMS DC session based on the subscription information of the UE, and in case that the UE is not authorized to use the standalone IMS DC session, reject a request for establishment of the standalone IMS DC session.

[0020] Accordingly, the embodiments herein provide a user equipment (UE) for supporting standalone internet protocol (IP) multimedia subsystem (IMS) data channel (IMS DC) session in a wireless communication system. The UE includes a transceiver; and at least one processor coupled to the transceiver and configured to: transmit, to an IMS application server (AS), a request for establishment of the standalone IMS DC session, and receive, from the IMS AS, a reject message to the request, in case that a user equipment (UE) is not authorized to use the standalone IMS DC session based on subscription information of the UE from a home subscriber server (HSS).

[0021] Accordingly, the embodiments herein provide a method for supporting Standalone IMS (IMS DC) session in a wireless network. The method includes downloading, by an IMS application server (AS), a subscription information from a Home Subscriber Server (HSS) for a user. Further, the method includes determining, by the IMS AS, whether the user of a user equipment (UE) is authorized to use the standalone IMS DC session. In an embodiment, the method includes allowing the user of the UE to use the standalone IMS DC session, upon determining that the user of the UE is authorized to use the standalone IMS DC session. In another embodiment, the method includes sending a request reject with a cause code upon determining that the user of the UE is not authorized to use the standalone IMS DC session.

[0022] Accordingly, the embodiments herein provide a method for supporting Standalone IMS DC session in a wireless network. The method includes determining, by a User Equipment (UE), that the UE does not provide a media line (m) for at least one of: an audio, a video and a text in a Session Description Protocol (SDP) offer and providing an SDP offer for an application data channel session and a bootstrap data channel.

[0023] Accordingly, the embodiments herein provide an IMS application server (AS) including an IMS DC session controller coupled with a processor and a memory. The IMS DC session controller is configured to download a subscription information from a HSS for a user. Further, the IMS DC session controller is configured to determine whether the user of the UE is authorized to use the standalone IMS DC session. In an embodiment, the IMS DC session controller is configured to allow the user of the UE to use the standalone IMS DC session, upon determining that the user of the UE is authorized to use the standalone IMS DC session. In another embodiment, the IMS DC session controller is configured to send a request reject with a cause code upon determining that the user of the UE is not authorized to use the standalone IMS DC session.

[0024] Accordingly, the embodiments herein provide a UE including an IMS DC session controller coupled with a processor and a memory. The IMS DC session controller is configured to determine that the UE does not provide a media line (m) for at least one of: an audio, a video and a text in a Session Description Protocol (SDP) offer and providing an SDP offer for a bootstrap data channel and an application data channel.

[0025] 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 at least one embodiment and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the scope thereof, and the embodiments herein include all such modifications.

[0026] Embodiments herein 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 following illustratory drawings. Embodiments herein are illustrated by way of examples in the accompanying drawings, and in which:

[0027] FIG. 1 is a schematic diagram of a wireless network for supporting a Standalone an IMS DC session, according to the embodiments as disclosed herein;

[0028] FIG. 2 shows various hardware components of an IMS application server (AS), according to the embodiments as disclosed herein;

[0029] FIG. 3 shows various hardware components of a UE, according to the embodiments as disclosed herein;

[0030] FIG. 4 is a flow chart illustrating a method for supporting Standalone IMS DC session by the IMS AS, according to the embodiments as disclosed herein;

[0031] FIG. 5 is a flow chart illustrating a method for supporting Standalone the IMS DC session by the UE, according to the embodiments as disclosed herein;

[0032] FIG. 6 depicts a sequence diagram for an example scenario of adding MMTeL Media to Standalone IMS Data Channel Session, according to the embodiments as disclosed herein; and

[0033] FIG. 7 depicts a sequence diagram for an example scenario of removing all MMTel Media from IMS Data Channel Session, according to the embodiments as disclosed herein.

[0034] 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. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0035] The words / phrases "exemplary", "example", "illustration", "in an instance", "and the like", "and so on", "etc.", "etcetera", "e.g.,", "i.e.," are merely used herein to mean "serving as an example, instance, or illustration. Any embodiment or implementation of the present subject matter described herein using the words / phrases "exemplary", "example", "illustration", "in an instance", "and the like", "and so on", "etc.", "etcetera", "e.g.," , "i.e.," is not necessarily to be construed as preferred or advantageous over other embodiments.

[0036] Whether or not a certain feature or element was limited to being used only once, it may still be referred to as "one or more features" or "one or more elements" or "at least one feature" or "at least one element." Furthermore, the use of the terms "one or more" or "at least one" feature or element do not preclude there being none of that feature or element, unless otherwise specified by limiting language including, but not limited to, "there needs to be one or more쪋" or "one or more elements is required."

[0037] Reference is made herein to some "embodiments." It should be understood that an embodiment is an example of a possible implementation of any features and / or elements of the present disclosure. Some embodiments have been described for the purpose of explaining one or more of the potential ways in which the specific features and / or elements of the proposed disclosure fulfill the requirements of uniqueness, utility, and non-obviousness.

[0038] Use of the phrases and / or terms including, but not limited to, "a first embodiment," "a further embodiment," "an alternate embodiment," "one embodiment," "an embodiment," "multiple embodiments," "some embodiments," "other embodiments," "further embodiment", "furthermore embodiment", "additional embodiment" or other variants thereof do not necessarily refer to the same embodiments. Unless otherwise specified, one or more particular features and / or elements described in connection with one or more embodiments may be found in one embodiment or may be found in more than one embodiment, or may be found in all embodiments, or may be found in no embodiments. Although one or more features and / or elements may be described herein in the context of only a single embodiment, or in the context of more than one embodiment, or in the context of all embodiments, the features and / or elements may instead be provided separately or in any appropriate combination or not at all. Conversely, any features and / or elements described in the context of separate embodiments may alternatively be realized as existing together in the context of a single embodiment.

[0039] Any particular and all details set forth herein are used in the context of some embodiments and therefore should not necessarily be taken as limiting factors to the proposed disclosure.

[0040] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises... a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

[0041] Embodiments herein may be described and illustrated in terms of blocks which carry out a described function or functions.　These blocks, which may be 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 may optionally be driven by a firmware. The circuits may, for example, be embodied in one or more semiconductor chips, or on substrate supports such as printed circuit boards and the like.　The circuits constituting a block may be implemented by dedicated hardware, or by a processor (e.g., one or more 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 may be physically separated into two or more interacting and discrete blocks without departing from the scope of the disclosure.　Likewise, the blocks of the embodiments may be physically combined into more complex blocks without departing from the scope of the disclosure.

[0042] It should be noted that elements in the drawings are illustrated for the purposes of this description and ease of understanding and may not have necessarily been drawn to scale. For example, the flowcharts / sequence diagrams illustrate the method in terms of the steps required for understanding of aspects of the embodiments as disclosed herein. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the present embodiments so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Furthermore, in terms of the system, one or more components / modules which comprise the system may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the present embodiments so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0043] The accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any modifications, equivalents, and substitutes in addition to those which are particularly set out in the accompanying drawings and the corresponding description. Usage of words such as first, second, third etc., to describe components / elements / steps is for the purposes of this description and should not be construed as sequential ordering / placement / occurrence unless specified otherwise.

[0044] Referring now to the drawings, and more particularly to FIGS. 1 through 7, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.

[0045] The embodiments herein achieve a method for supporting Standalone IMS DC session by an IMS AS. The method includes obtaining a subscription information from a Home Subscriber Server　(HSS). Further, the method includes determining whether a user of a UE is authorized to use the standalone IMS DC session. In an embodiment, the method includes allowing the user of the UE to use the standalone IMS DC session, upon determining that the user of the UE is authorized to use the standalone IMS DC session. In another embodiment, the method includes sending a request reject with a cause code upon determining that the user of the UE is not authorized to use the standalone IMS DC session.

[0046] In an embodiment, the IMS AS downloads the subscription information from HSS and checks whether the user is authorized to use standalone IMS DC session and if not reject the request with appropriate cause code

[0047] In an embodiment, the SDP (Session description protocol) update of m line for audio or video media like addition or removal based on whether session is downgraded to only standalone IMS DC or standalone IMS DC is upgraded to IMS session

[0048] In an embodiment, the Standalone IMS DC establishment without any m line for audio or video

[0049] The embodiments herein achieve systems and methods for ensuring that the IMS network and the UE handles standalone IMS Data Channel session by defining IMS architecture, interfaces, and procedures to support standalone IMS data channel sessions.

[0050] FIG. 1 is a schematic diagram of a wireless network (1000) for supporting a Standalone an IMS DC session, according to the embodiments as disclosed herein.

[0051] In Rel 19, 3GPP SA2 is studying one key indicator (KI) on how to address the standalone IMS data channel session. This key issue aims to study enhancements of IMS architecture, interfaces, and procedures to support standalone IMS data channel session.

[0052] Embodiments herein support standalone IMS bootstrap and application data channel sessions without accompanying audio / video / messaging media in an IMS session, which includes studying the establishment and termination of standalone IMS data channel sessions.

[0053] Embodiments herein negotiate support of standalone IMS data channel between UE and IMS network, wherein the negotiation should include the ability to add audio / video / messaging media to an established standalone IMS data channel.

[0054] Embodiments herein disclose the establishment of a (standalone) application data channel without accompanying bootstrap data channel. Embodiments herein disclose establishment of a (standalone) bootstrap data channel without accompanying application data channel.

[0055] Embodiments herein disclose methods and systems for adding audio / video / messaging media to an established standalone IMS data channel session. Embodiments herein disclose removal of audio / video / messaging media from an IMS session that also contains IMS data channel media. Embodiments herein define new service data in the HSS for support of standalone data channel or extend existing MMTel service data.

[0056] TS 23.228 Annex AC 7 describes how bootstrap data channel and application data channels can be established which assumes that the IMS data channel is always accompanied by audio / video / messaging etc. In a standalone IMS bootstrap and application data channel session, the UE (100a) shall not provide any m line for audio or video or text in a SDP offer and only provide SDP offer for bootstrap and application data channel session. While establishing the standalone IMS DC session if a S-CSCF or IMS AS (200) compatible to provide the IMS DC (MMTEL AS extended to provide IMS DC) or a DCSF (300) found that a user is not authorized to get IMS DC service from a subscription profile then, the session is rejected with appropraite error codes, or with an indication in an existing header, or a new header which the UE (100) can show in the display to the user.

[0057] In Rel 18, the already IMS DC capability negotiattion has been defined. There is no further negotiation is needed only for the standalone IMS DC session. For adding any audio or video or messaging media to the already standalone IMS DC session, the UE can provide SDP offer by adding m line for each corresponding media in a Re-INVITE message (for example). It is proposed that when a m-line for any media is added to an established IMS DC session, these new m-lines should kept on top of the SDP offer.

[0058] For example, the SDP for already existing bootstrap data channel and application data channel appaers to be follow:

[0059] m=application 52718 UDP / DTLS / SCTP webrtc-datachannel

[0060] b=AS:500

[0061] a=candidate:1 1 UDP 2130706431 192.0.2.156 52718 typ host

[0062] a=ice-ufrag:8hhY

[0063] a=ice-pwd:asd88fgpdd777uzjYhagZg

[0064] a=max-message-size:1024

[0065] a=sctp-port:5000

[0066] a=setup: actpass

[0067] a=fingerprint:SHA-1 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB

[0068] a=tls-id: abc3de65cddef001be82

[0069] a=dcmap:10 subprotocol="http"

[0070] m=application 52720 UDP / DTLS / SCTP webrtc-datachannel

[0071] b=AS:1000

[0072] a=candidate:1 1 UDP 2130706431 192.0.2.156 52720 typ host

[0073] a=ice-ufrag:9uB6

[0074] a=ice-pwd: YH75Fviy6338Vbrhrlp8Yh

[0075] a=max-message-size:1024

[0076] a=sctp-port:5000

[0077] a=setup: actpass

[0078] a=fingerprint:SHA-1 BC:8A:99:A0:E3:28:CA:B3:09:20:1B:FD:21:D5:AC:B6:F3:5E:45:AF

[0079] a=tls-id: cd3bea56dced0f35d224

[0080] a=dcmap:38754 max-time=150;label="low latency"

[0081] a=dcmap:7216 max-retr=5;label="low loss"

[0082] a=3gpp-qos-hint:loss=0.01;latency=100

[0083] For example, the SDP offer of the Re-INVITE message may look like below (by adding audio). Similarly, for the video or message can be added.

[0084] m=audio 49152 RTP / AVP 97 98

[0085] a=tcap:1 RTP / AVPF

[0086] a=pcfg:1 t=1

[0087] a=rtpmap:97 AMR / 8000 / 1

[0088] a=fmtp:97 mode-change-capability=2; max-red=220

[0089] a=rtpmap:98 AMR / 8000 / 1

[0090] a=fmtp:98 mode-change-capability=2; max-red=220; octet-align=1

[0091] a=ptime:20

[0092] a=maxptime:240

[0093] m=application 52718 UDP / DTLS / SCTP webrtc-datachannel

[0094] b=AS:500

[0095] a=candidate:1 1 UDP 2130706431 192.0.2.156 52718 typ host

[0096] a=ice-ufrag:8hhY

[0097] a=ice-pwd:asd88fgpdd777uzjYhagZg

[0098] a=max-message-size:1024

[0099] a=sctp-port:5000

[0100] a=setup: actpass

[0101] a=fingerprint:SHA-1 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB

[0102] a=tls-id: abc3de65cddef001be82

[0103] a=dcmap:10 subprotocol="http"

[0104] m=application 52720 UDP / DTLS / SCTP webrtc-datachannel

[0105] b=AS:1000

[0106] a=candidate:1 1 UDP 2130706431 192.0.2.156 52720 typ host

[0107] a=ice-ufrag:9uB6

[0108] a=ice-pwd: YH75Fviy6338Vbrhrlp8Yh

[0109] a=max-message-size:1024

[0110] a=sctp-port:5000

[0111] a=setup: actpass

[0112] a=fingerprint:SHA-1 BC:8A:99:A0:E3:28:CA:B3:09:20:1B:FD:21:D5:AC:B6:F3:5E:45:AF

[0113] a=tls-id: cd3bea56dced0f35d224

[0114] a=dcmap:38754 max-time=150;label="low latency"

[0115] a=dcmap:7216 max-retr=5;label="low loss"

[0116] a=3gpp-qos-hint:loss=0.01;latency=100

[0117] Similarly to remove from the already established any audio or video or messaging media which is present with the IMS DC session then either media or all media can be removed by the UE (100) by sending Re-INVITE with the SDP offer by removing m line (port =0) for corresponding media then the session will be left with IMS DC session only.

[0118] For example, the already audio media is present along with IMS DC session,

[0119] m=audio 49152 RTP / AVP 97 98

[0120] a=tcap:1 RTP / AVPF

[0121] a=pcfg:1 t=1

[0122] a=rtpmap:97 AMR / 8000 / 1

[0123] a=fmtp:97 mode-change-capability=2; max-red=220

[0124] a=rtpmap:98 AMR / 8000 / 1

[0125] a=fmtp:98 mode-change-capability=2; max-red=220; octet-align=1

[0126] a=ptime:20

[0127] a=maxptime:240

[0128] m=application 52718 UDP / DTLS / SCTP webrtc-datachannel

[0129] b=AS:500

[0130] a=candidate:1 1 UDP 2130706431 192.0.2.156 52718 typ host

[0131] a=ice-ufrag:8hhY

[0132] a=ice-pwd:asd88fgpdd777uzjYhagZg

[0133] a=max-message-size:1024

[0134] a=sctp-port:5000

[0135] a=setup: actpass

[0136] a=fingerprint:SHA-1 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB

[0137] a=tls-id: abc3de65cddef001be82

[0138] a=dcmap:10 subprotocol="http"

[0139] m=application 52720 UDP / DTLS / SCTP webrtc-datachannel

[0140] b=AS:1000

[0141] a=candidate:1 1 UDP 2130706431 192.0.2.156 52720 typ host

[0142] a=ice-ufrag:9uB6

[0143] a=ice-pwd: YH75Fviy6338Vbrhrlp8Yh

[0144] a=max-message-size:1024

[0145] a=sctp-port:5000

[0146] a=setup: actpass

[0147] a=fingerprint:SHA-1 BC:8A:99:A0:E3:28:CA:B3:09:20:1B:FD:21:D5:AC:B6:F3:5E:45:AF

[0148] a=tls-id: cd3bea56dced0f35d224

[0149] a=dcmap:38754 max-time=150;label="low latency"

[0150] a=dcmap:7216 max-retr=5;label="low loss"

[0151] a=3gpp-qos-hint:loss=0.01;latency=100

[0152] For example, the SDP offer of Re-INVITE may look like below (by removing audio). Similarly for the video or the message can be removed.

[0153] m=audio 0 RTP / AVP 97 98

[0154] a=tcap:1 RTP / AVPF

[0155] a=pcfg:1 t=1

[0156] a=rtpmap:97 AMR / 8000 / 1

[0157] a=fmtp:97 mode-change-capability=2; max-red=220

[0158] a=rtpmap:98 AMR / 8000 / 1

[0159] a=fmtp:98 mode-change-capability=2; max-red=220; octet-align=1

[0160] a=ptime:20

[0161] a=maxptime:240

[0162] m=application 52718 UDP / DTLS / SCTP webrtc-datachannel

[0163] b=AS:500

[0164] a=candidate:1 1 UDP 2130706431 192.0.2.156 52718 typ host

[0165] a=ice-ufrag:8hhY

[0166] a=ice-pwd:asd88fgpdd777uzjYhagZg

[0167] a=max-message-size:1024

[0168] a=sctp-port:5000

[0169] a=setup: actpass

[0170] a=fingerprint:SHA-1 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB

[0171] a=tls-id: abc3de65cddef001be82

[0172] a=dcmap:10 subprotocol="http"

[0173] m=application 52720 UDP / DTLS / SCTP webrtc-datachannel

[0174] b=AS:1000

[0175] a=candidate:1 1 UDP 2130706431 192.0.2.156 52720 typ host

[0176] a=ice-ufrag:9uB6

[0177] a=ice-pwd: YH75Fviy6338Vbrhrlp8Yh

[0178] a=max-message-size:1024

[0179] a=sctp-port:5000

[0180] a=setup: actpass

[0181] a=fingerprint:SHA-1 BC:8A:99:A0:E3:28:CA:B3:09:20:1B:FD:21:D5:AC:B6:F3:5E:45:AF

[0182] a=tls-id: cd3bea56dced0f35d224

[0183] a=dcmap:38754 max-time=150;label="low latency"

[0184] a=dcmap:7216 max-retr=5;label="low loss"

[0185] a=3gpp-qos-hint:loss=0.01;latency=100

[0186] Similarly, it is proposed that to establish bootstrap data channel without any application data channel it is proposed that the UE (100) does not provide any SDP by adding m line for application data channel which means only SDP offer should have m line for bootstrap data channel.

[0187] For example, the SDP of offering only IMS bootstrap data channel appears to be following:

[0188] m=application 52718 UDP / DTLS / SCTP webrtc-datachannel

[0189] b=AS:500

[0190] a=candidate:1 1 UDP 2130706431 192.0.2.156 52718 typ host

[0191] a=ice-ufrag:8hhY

[0192] a=ice-pwd:asd88fgpdd777uzjYhagZg

[0193] a=max-message-size:1024

[0194] a=sctp-port:5000

[0195] a=setup: actpass

[0196] a=fingerprint:SHA-1 4A:AD:B9:B1:3F:82:18:3B:54:02:12:DF:3E:5D:49:6B:19:E5:7C:AB

[0197] a=tls-id: abc3de65cddef001be82

[0198] a=dcmap:10 subprotocol="http"

[0199] Similarly, it is proposed that to establish application data channel without bootstrap data channel it is proposed that the UE (100) does not provide any SDP by adding m line for bootstrap data channel which means only SDP offer should have m line for application data channel but both the UE should exchange with each other using SIP OPTIONS or other method indicating about the availability of application present in both terminal before establishment of IMS application data channel.

[0200] For example, SDP of offering only IMS application data channel.

[0201] m=application 52720 UDP / DTLS / SCTP webrtc-datachannel

[0202] b=AS:1000

[0203] a=candidate:1 1 UDP 2130706431 192.0.2.156 52720 typ host

[0204] a=ice-ufrag:9uB6

[0205] a=ice-pwd: YH75Fviy6338Vbrhrlp8Yh

[0206] a=max-message-size:1024

[0207] a=sctp-port:5000

[0208] a=setup: actpass

[0209] a=fingerprint:SHA-1 BC:8A:99:A0:E3:28:CA:B3:09:20:1B:FD:21:D5:AC:B6:F3:5E:45:AF

[0210] a=tls-id: cd3bea56dced0f35d224

[0211] a=dcmap:38754 max-time=150;label="low latency"

[0212] a=dcmap:7216 max-retr=5;label="low loss"

[0213] a=3gpp-qos-hint:loss=0.01;latency=100

[0214] Similarly it is proposed that the existing MMTEL which has been extended to provide IMS DC session should be kept supporting standalone IMS bootstrap and application data channel instead of creating a new service profile.

[0215] In the Rel 18, when the scenario of an already established audio / video call is upgraded by the UE (100) by offering SDP with addition of m line for IMS DC or the IMS session is initiated by the UE (100) by offering the SDP with additional of m lines for each corresponding media like audio, video and IMS DC and IMS AS (200) or the DCSF (300) finding that the user is not authorized to use IMS DC, at present, the IMS AS (200) deletes the DC related media and proceeds with normal audio & video call. But when the user receives this response (183 session in progress or 200 OK to SIP INVITE) and finds that m line for IMS DC is not present (or in m line port has been made to 0), then the UE (100) will not be able to identify whether the remote party has not accepted the IMS DC session or IMS DC has been removed (because its subscription is not supported). Hence, it is proposed that either the S-CSCF (as part of CNSA (core network service authorization)) or the IMS-AS (200) adds an indication in an existing header or a new header to inform the UE (100) that the IMS DC removal is because of subscription disabled.

[0216] FIG. 2 shows various hardware components of the IMS AS (200), according to the embodiments as disclosed herein. In an embodiment, the IMS AS (200) includes a processor (210), a communicator (220), a memory (230), and an IMS DC session controller (240). The processor (210) is coupled with the communicator (220), the memory (230), and the IMS DC session controller (240).

[0217] The IMS DC session controller (240) downloads the subscription information from the Home Subscriber Server (HSS) (400) for the user. Further, the IMS DC session controller (240) determines whether the user of the UE (100) is authorized to use the standalone IMS DC session. Upon determining that the user of the UE (100) is authorized to use the standalone IMS DC session, the IMS DC session controller (240) allows the user of the UE (100) to use the standalone IMS DC session. In another embodiment, upon determining that the user of the UE (100) is not authorized to use the standalone IMS DC session, the IMS DC session controller (240) sends a request reject with a cause code. In an embodiment, the request is rejected with the cause code is embedded in an existing SIP (Session Initiation Protocol) response.

[0218] Further, the IMS DC session controller (240) receives a request message including the SDP offer having the media description for at least one of the bootstrap data channel and the application data channel from the UE (100). In an embodiment, updating the media line for the audio or the video includes adding the media line for the audio or the video or removing the media line for the audio or the video based on whether the standalone IMS DC is upgraded to the IMS session or the session is downgraded to only standalone IMS DC. The request message includes a SIP re-INVITE request message.

[0219] In an embodiment, the standalone IMS data channel session towards peer UE is updated by adding MMTel media to the session. All MMTel media(s) is removed from the IMS data channel session towards peer UE if the standalone IMS data channel session is supported.

[0220] The IMS DC session controller (240) is 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 may optionally be driven by firmware.

[0221] The processor (210) may include one or a plurality of processors. The one or the 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 AI-dedicated processor such as a neural processing unit (NPU). The processor (210) may include multiple cores and is configured to execute the instructions stored in the memory (230).

[0222] Further, the processor (210) is configured to execute instructions stored in the memory (230) and to perform various processes. The communicator (220) is configured for communicating internally between internal hardware components and with external devices via one or more networks. The communicator (220) includes a transceiver. The memory (230) also stores instructions to be executed by the processor (210). The memory (230) may include non-volatile storage elements. Examples of such 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. In addition, the memory (230) may, in some examples, be considered a non-transitory storage medium. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. However, the term "non-transitory" should not be interpreted that the memory (230) is non-movable. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in Random Access Memory (RAM) or cache).

[0223] Although FIG. 2 shows various hardware components of the IMS AS (200) but it is to be understood that other embodiments are not limited thereon. In other embodiments, the IMS AS (200) may include less or more number of components. Further, the labels or names of the components are used only for illustrative purposes and does not limit the scope of the invention. One or more components can be combined together to perform the same or substantially similar function in the IMS AS (200).

[0224] FIG. 3 shows various hardware components of the UE (100), according to the embodiments as disclosed herein. The UE (100) can be, for example, but not limited to a laptop, a desktop computer, a notebook, a Device-to-Device (D2D) device, a vehicle to everything (V2X) device, a smartphone, a foldable phone, a smart TV, a tablet, an immersive device, and an internet of things (IoT) device. In an embodiment, the UE (100) includes a processor (310), a communicator (320), a memory (330), and an IMS DC session controller (340). The processor (310) is coupled with the communicator (320), the memory (330), and the IMS DC session controller (340).

[0225] The IMS DC session controller (340) determines that the UE (100) does not provide the media line (m) for at least one of: the audio, the video and the text in the SDP offer and provides an SDP offer for the bootstrap data channel and the application data channel.

[0226] Further, the IMS DC session controller (340) provides the SDP offer by adding m line for each corresponding media in a Re-INVITE message for adding at least one of: the audio media, the video media and the messaging media to the already existing standalone IMS DC session to make it to IMS session.

[0227] Further, the IMS DC session controller (340) provides the SDP offer by removing m line for each corresponding media in a Re-INVITE message for removing at least one of: the audio media, the video media and the messaging media to the already existing IMS session to make it to standalone IMS DC session.

[0228] The IMS DC session controller (340) is 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 may optionally be driven by firmware.

[0229] The processor (310) may include one or a plurality of processors. The one or the 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 AI-dedicated processor such as a neural processing unit (NPU). The processor (310) may include multiple cores and is configured to execute the instructions stored in the memory (330).

[0230] Further, the processor (310) is configured to execute instructions stored in the memory (330) and to perform various processes. The communicator (320) is configured for communicating internally between internal hardware components and with external devices via one or more networks. The communicator (320) includes a transceiver. The memory (330) also stores instructions to be executed by the processor (310). The memory (330) may include non-volatile storage elements. Examples of such 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. In addition, the memory (330) may, in some examples, be considered a non-transitory storage medium. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. However, the term "non-transitory" should not be interpreted that the memory (330) is non-movable. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in Random Access Memory (RAM) or cache).

[0231] Although FIG. 3 shows various hardware components of the UE (100) but it is to be understood that other embodiments are not limited thereon. In other embodiments, the UE (100) may include a less or more number of components. Further, the labels or names of the components are used only for illustrative purposes and does not limit the scope of the invention. One or more components can be combined together to perform the same or substantially similar function in the UE (100).

[0232] FIG. 4 is a flow chart (S400) illustrating a method for supporting the Standalone IMS DC session by the IMS AS (200), according to the embodiments as disclosed herein. The operations (S402-S408) are handled by the IMS DC session controller (240).

[0233] At S402, the method includes downloading the subscription information from the HSS (400) for the user. At S404, the method includes determining whether the user of the UE (100) is authorized to use the standalone IMS DC session. Upon determining that the user of the UE (100) is authorized to use the standalone IMS DC session, at S406, the method includes allowing the user of the UE (100) to use the standalone IMS DC session. Upon determining that the user of the UE (100) is not authorized to use the standalone IMS DC session, at S408, the method includes sending the request reject with the cause code.

[0234] FIG. 5 is a flow chart (S500) illustrating a method for supporting Standalone the IMS DC session by the UE (100), according to the embodiments as disclosed herein. The operation (S502) is handled by the IMS DC session controller (340).

[0235] At S502, the method includes determining that the UE (100) does not provide the media line (m) for at least one of: the audio, the video and the text in the SDP offer and providing an SDP offer for the bootstrap data channel and the application data channel.

[0236] FIG. 6 depicts a sequence diagram for an example scenario of adding MMTeL Media to Standalone IMS Data Channel Session, according to the embodiments as disclosed herein.

[0237] When the standalone IMS data channel session between two UEs (100a, 100b) is ongoing, any of the UE may add some MMTel media, e.g., audio, video, messaging, into the IMS session, which turns the standalone IMS data channel session to IMS data channel session. The sequence diagram includes of, in step 1, the method includes establishing the standalone IMS DC session between the first UE (i.e., UE-1) and the second UE (UE-2), which does not include MMTel media. In step 2, sending SIP re-INVITE request by the UE-1, which includes an SDP offer containing the media description of both application data channel and MMTel media description. In step 3, handling the SIP re-INVITE request by the IMS AS, the DCSF, and the UE-2, The re-INVITE request is received by the IMS AS from the UE-1, through P-CSCF, I / S-CSCF, wherein re-INVITE request includes audio, video, or SDP offer for application DC. Additionally, the DC routing decision is also taken in the following steps and notify to the DCSF (for example:Nimsas_SessionEventControl_Notify (Media Change Request Event, SessionID, EventInitiator, MediaInfoList). Moreover, DCSF decides whether DC is provided and determines DC control policy and allows the DC e2e application stream to be exposed to remote party (for example (Nimsas_Session EventControl_Notifyresponse). Further, IMS AS re-INVITE or updating the audio, video, or SDP offer for application DC and re-INVITE or updating the audio, video, or SDP offer for application DC for terminating network or UE-2, hence further terminating network negotiation.In step 4, the first UE-A sends 200 OK response to the UE-2 through the IMS AS, if the UE-2 accepts the session update indicating the MMTel media has been added. Additionally, notifying Media Change SuccessEvent, SessionID, MediaInfoList (for example: Nimsas_Session EventContol_Notify, Nimsas_SessionEventControl_Notify_response).

[0238] In other words, step 1, the standalone application data channel has been established between UE-A and UE-B. At step 2, the UE-A sends SIP re-INVITE which include the media description of both standalone application data channel and audio / video / messaging media description. At step 3, the IMS AS, DCSF and UE-B handles the SIP re-INVITE as specified in clause AC.7.2.1. At step 4, the UE-B sends 200 responses to UE-A through IMS AS, indicating the call has been established. IMS AS sends notify message to DCSF as specified in Rel-18.

[0239] FIG. 7 depicts a sequence diagram for an example scenario of removing all MMTel Media from IMS Data Channel Session, according to the embodiments as disclosed herein.

[0240] Figure depicts an IMS DC session between two UEs (UE1 and UE 2) is ongoing, any of the UE may remove all MMTel media (for example audio, video, messaging) from the IMS session, which turns the IMS DC session to standalone IMS DC session. In step 1, establishing an IMS DC session between the UE 1 and UE 2, which includes MMTel and application DC media. In step 2, the UE 2 sends SIP re-INVITE request with an SDP offer containing media information for MMTel media and application data channel, which sets the port number of MMTel media stream to zero. In step 3, the IMS AS the DCSF and the UE 2 handles the SIP re-INVITE request. In step 4, if the UE 2accepts the session update, the UE-2 sends 200OK response to the UE-1 through the IMS AS, indicating the MMTel media has been removed.

[0241] In other words, at step 1, an IMS DC session has been established between the UE-A and the UE-B, which include audio / video and IMS DC media. At step 2, the UE-A sends SIP re-INVITE with an SDP containing media information for audio / video media and data channel, which sets the port number of audio / video media stream to zero, as specified in RFC 3264. At Step 3, the IMS AS, DCSF and UE-B handles the SIP re-INVITE. At step 4, the UE-B sends 200 responses to UE-A through IMS AS, indicating the audio / video media has been removed. IMS AS sends notify message to DCSF as specified in Rel-18.

[0242] The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the network elements. The elements include blocks which can be at least one of a hardware device, or a combination of hardware device and software module.

[0243] The embodiment disclosed herein describes systems and methods for ensuring that the IMS network and the UE handles standalone IMS Data Channel session by defining IMS architecture, interfaces, and procedures to support standalone IMS data channel sessions. Therefore, it is understood that the scope of the protection is extended to such a program and in addition to a computer readable means having a message therein, such computer readable storage means contain program code means for implementation of one or more steps of the method, when the program runs on a server or mobile deviceor any suitable programmable device. The method is implemented in at least one embodiment through or together with a software program written in e.g., Very high speed integrated circuit Hardware Description Language (VHDL) another programming language, or implemented by one or more VHDL or several software modules being executed on at least one hardware device. The hardware device can be any kind of portable device that can be programmed. The device may also include means which could be e.g., hardware means like e.g., an ASIC, or a combination of hardware and software means, e.g. an ASIC and an FPGA, or at least one microprocessor and at least one memory with software modules located therein. The method embodiments described herein could be implemented partly in hardware and partly in software. Alternatively, the invention may be implemented on different hardware devices, e.g., using a plurality of CPUs.

[0244] 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 should and 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 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 an internet protocol (IP) multimedia subsystem (IMS) application server (AS) for supporting standalone IMS data channel (IMS DC) session in a wireless communication system, the method comprising:receiving, from a home subscriber server　(HSS), subscription information for a user equipment (UE);determining whether the UE is authorized to use the standalone IMS DC session based on the subscription information of the UE; andin case that the UE is not authorized to use the standalone IMS DC session, rejecting a request for establishment of the standalone IMS DC session.2.The method of claim 1, wherein the standalone IMS DC session is used to establish data channel without multimedia telephony (MMTel) media.3.The method of claim 1, further comprising:receiving, from the UE, a request message including a session description protocol (SDP) offer, wherein the SDP offer includes a media description for at least one of a bootstrap data channel and an application data channel from the UE.4.The method of claim 1,wherein the request is rejected with a cause code is embedded in a session initiation protocol (SIP) response.5.The method of claim 1,wherein the standalone IMS DC session towards peer UE is updated by adding MMTel media to the standalone IMS DC session, andwherein all MMTel media is removed from an IMS DC session towards peer UE if the standalone IMS DC session is supported.6.The method of claim 3, wherein the request message includes a SIP re-INVITE request message.7.The method of claim 1, further comprising:updating a media line for an audio or a video,wherein updating the media line for the audio or the video includes,adding the media line for the audio or the video or removing the media line for the audio or the video based on whether the standalone IMS DC session is upgraded to an IMS DC session or the IMS DC session is downgraded to the standalone IMS DC session.8.The method of claim 7, wherein in case that the UE subscription is not authorized to use the standalone IMS DC session, the media line is removed, and the bootstrap data channel and the application data channel are removed.9.A method performed by a user equipment (UE) for supporting standalone internet protocol (IP) multimedia subsystem (IMS) data channel (IMS DC) session in a wireless communication system, the method comprising:transmitting, to an IMS application server (AS), a request for establishment of the standalone IMS DC session; andreceiving, from the IMS AS, a reject message to the request, in case that the UE is not authorized to use the standalone IMS DC session based on subscription information of the UE from a home subscriber server (HSS).10.The method of claim 9, wherein transmitting, to the IMS AS, the request for the establishment of the standalone IMS DC session includes:determining not to include a media description for at least one of an audio, a video and a text in a session description protocol (SDP) offer; andtransmitting the SDP offer for an application data channel session and a bootstrap data channel.11.The method of claim 9, further comprising:transmitting, to the IMS AS, an SDP offer by adding a media description for each corresponding media in a Re-INVITE message for adding at least one of an audio media, a video media and a messaging media to the standalone IMS DC session to make it to an IMS DC session.12.The method of claim 9, further comprising:transmitting, to the IMS AS, an SDP offer by removing a media description for each corresponding media in a Re-INVITE message for removing at least one of an audio media, a video media and a messaging media from an existing IMS session to make it to a standalone IMS DC session.13.An internet protocol (IP) multimedia subsystem (IMS) application server (AS) for supporting standalone IMS data channel (IMS DC) session in a wireless communication system, the IMS AS comprising:a transceiver; andat least one processor coupled to the transceiver and configured to:receive, from a home subscriber server　(HSS), subscription information for a user equipment (UE),determine whether the UE is authorized to use the standalone IMS DC session based on the subscription information of the UE, andin case that the UE is not authorized to use the standalone IMS DC session, reject a request for establishment of the standalone IMS DC session.14.The IMS AS of claim 13, wherein the standalone IMS DC session is used to establish data channel without multimedia telephony (MMTel) media.15.A user equipment (UE) for supporting standalone internet protocol (IP) multimedia subsystem (IMS) data channel (IMS DC) session in a wireless communication system, the UE comprising:a transceiver; andat least one processor coupled to the transceiver and configured to:transmit, to an IMS application server (AS), a request for establishment of the standalone IMS DC session, andreceive, from the IMS AS, a reject message to the request, in case that the UE is not authorized to use the standalone IMS DC session based on subscription information of the UE from a home subscriber server (HSS).

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