Method and apparatus for handling pdu session in wireless communication system

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. A method performed by a user equipment (UE) is provided. The method includes receiving a protocol data unit (PDU) session release command message associated with a PDU session during a UE-requested PDU session release procedure associated with the PDU session, and in case that an access type information element (IE) is included in the PDU session release command message and the PDU session has user-plane resources established on a first access different from a second access indicated in the access type IE in the PDU session release command message, proceeding the UE-requested PDU session release procedure and a network-requested PDU session release procedure.

Description

METHOD AND APPARATUS FOR HANDLING PDU SESSION IN WIRELESS COMMUNICATION SYSTEM

[0001] Embodiments as disclosed herein relate to handling collisions in wireless communication networks, and more particularly to handling collisions when releasing at least one Protocol Data Unit (PDU) session, on receiving at least one re-activation requested from the network.

[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] In existing mechanisms, a User Equipment (UE) can be configured with a Multi-Access (MA) PDU session, wherein the UE may obtain service on the access from Third Generation Partnership Project (3GPP) and non-3GPP. The network entity (i.e., Session Management Function (SMF)) can be configured to release at least one user plane of the MA PDU session specific to the access. The SMF, receives the PDU session release request from the UE, wherein the SMF has already sent PDU session release command to release the user plane of the MA PDU session specific to access. The SMF may ignore the UE initiated PDU session release request and continue with the SMF initiated PDU session release command. The UE may release the PDU session, but user plane of the MA PDU session specific to access (non-3GPP) is released but PDU session is still active at the SMF, which causes the PDU session out of sync between UE and the network and may cause e.g. the MT paging for the access to be still active at the SMF.

[0009] Currently, if the UE receives the PDU session release command with the access type IE (wherein the access type being different from the access over the established user plane) while UE-requested PDU session is sent, the UE may proceed with PDU session release initiated by both UE and the network, else the UE initiated PDU session is stopped. As the SMF ignores the UE requested PDU session release command when it has send the PDU session release command (even to release user plane for specific access by including access type IE), the UE will not receive acknowledgment for the PDU session release request through PDU session release command. The UE may release the user plane of the MA PDU session specific to the access (e,g non-3GPP) received in the PDU session release command. In an instance, the UE may stick to the PDU session release for an additional sixteen seconds (e.g. for T3592 timer expiry), which may cause a bad user experience. While the timer is running, the UE may not be able to establish the PDU session on receiving the user request.

[0010] Also, the UE may receive network initiated PDU session release command with the 5GSM cause #39 reactivation requested during the UE initiated PDU session release request. As the release may carry 5GSM cause #39 reactivation requested, the UE will initiate the PDU session establishment procedure. The UE initiated PDU session release request is issued despite UE doesn't wants the PDU session, which may cause additional signaling to keep the PDU session active which is not required by the UE.

[0011] In existing mechanisms, the collision may happen due to a network-requested PDU session release procedure and the UE requested PDU session release procedure. On receiving a PDU session release request message after sending a PDU session release command message to the UE, and if the PDU session Identity (ID) in the PDU session release request message is same as the PDU session ID in the PDU session release command message, the SMF may ignore the PDU session release request message and proceed with the network requested PDU session release procedure.

[0012] The SMF requests the UE to reactivate a PDU session. The SMF may set the fifth-generation session management (5GSM) cause Information Element (IE) of the PDU session release command to "#39 reactivation requested" in the PDU session release command message to the UE to indicate the reason for releasing the PDU session. Also, the SMF may include 5GSM cause #39　"reactivation requested" in the following cases: If the selected Session and Service Continuity (SSC) support mode of the PDU session is "SSC mode 2" and the SMF requests the relocation of SSC mode 2 PDU session anchor with the different PDU sessions as specified in 3GPP　TS　23.502, the SMF may include 5GSM cause #39　"reactivation requested".

[0013] Based on the local policy and the user subscription data, if the SMF decides to release the PDU session based on the following: after determining that the UE has moved between a tracking area in Narrow Band (NB)-N1 mode and a tracking area in (Wide band) WB-N1 mode; the UE has moved between a tracking area in NB-S1 mode and a tracking area in WB-N1 mode; the UE has moved between a tracking area in WB-S1 mode and a tracking area in NB-N1 mode; PDU session is not only for control plane CIoT 5GS optimization any more, the SMF may include the 5GSM cause value #39 "reactivation requested" in the 5GSM cause IE of the PDU SESSION RELEASE COMMAND message. The terms "N1 mode" and "S1 mode" refer to different ways the UE can access the network. N1 mode refers to Standalone mode with direct connection between 5G RAN and 5G Core.

[0014] The UE may re-initiate the UE-requested PDU session establishment procedure with: the PDU session type associated with the released PDU session; the SSC mode associated with the released PDU session; the Data Network Name (DNN) associated with the released PDU session; and the S-NSSAI associated with (if available in roaming scenarios) a mapped S-NSSAI if provided in the UE-requested PDU session establishment procedure of the released PDU session. So, the UE will have to unnecessarily establish the new PDU session as requested by network (by including 5GSM cause #39) for which UE had earlier requested a release.

[0015] The principal object of the embodiments herein is to disclose methods and systems for handling a collision between a User Equipment (UE) and a wireless communication network while releasing at least one Protocol Data Unit (PDU) session.

[0016] Another object of the embodiments herein is to disclose methods and systems for releasing at least one PDU session, on receiving at least one re-activation request from the network.

[0017] Another object of the embodiments herein is to disclose methods and systems for handling a collision between a User Equipment (UE) and a wireless communication network while releasing at least one Protocol Data Unit (PDU) session, wherein the SMF may ignore the UE requested PDU session release during the SMF requested PDU session release procedure, if the SMF request is for the PDU session release (for both 3GPP access and non-3GPP access).

[0018] Another object of the embodiments herein is to disclose methods and systems for handling a collision between a User Equipment (UE) and a wireless communication network while releasing at least one Protocol Data Unit (PDU) session, wherein the SMF may process both the UE requested PDU session release and the SMF requested PDU session release if the SMF request is for the specific access PDU session release (for non-3GPP access).

[0019] In an embodiment, a method performed by a user equipment (UE) is provided. The method includes receiving a protocol data unit (PDU) session release command message associated with a PDU session during a UE-requested PDU session release procedure associated with the PDU session, and in case that an access type information element (IE) is included in the PDU session release command message and the PDU session has user-plane resources established on a first access different from a second access indicated in the access type IE in the PDU session release command message, proceeding the UE-requested PDU session release procedure and a network-requested PDU session release procedure.

[0020] In an embodiment, a method performed by a session management function (SMF) is provided. The method includes transmitting a protocol data unit (PDU) session release command message associated with a PDU session, receiving a PDU session release request message associated with the PDU session, and in case that an access type information element (IE) is included in the PDU session release command message and the PDU session has user-plane resources established on a first access different from a second access indicated in the access type IE in the PDU session release command message, proceeding a user equipment (UE)-requested PDU session release procedure and a network-requested PDU session release procedure.

[0021] In an embodiment, a UE in a wireless communication system is provided. The UE includes a transceiver and a processor. The processor is configured to receive, via the transceiver, a protocol data unit (PDU) session release command message associated with a PDU session during a UE-requested PDU session release procedure associated with the PDU session, and in case that an access type information element (IE) is included in the PDU session release command message and the PDU session has user-plane resources established on a first access different from a second access indicated in the access type IE in the PDU session release command message, proceed the UE-requested PDU session release procedure and a network-requested PDU session release procedure.

[0022] In an embodiment, a session management function (SMF) in a wireless communication system is provided. The SMF includes a transceiver and a processor. The processor is configured to transmit, via the transceiver, a protocol data unit (PDU) session release command message associated with a PDU session, receive, via the transceiver, a PDU session release request message associated with the PDU session, and in case that an access type information element (IE) is included in the PDU session release command message and the PDU session has user-plane resources established on a first access different from a second access indicated in the access type IE in the PDU session release command message, proceed a user equipment (UE)-requested PDU session release procedure and a network-requested PDU session release procedure.

[0023] 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 spirit thereof, and the embodiments herein include all such modifications.

[0024] The embodiment discloses a method for handling a collision in a wireless communication network while releasing at least one Protocol Data Unit (PDU) session, the method comprising: receiving, by a Session Management Function (SMF) (610), at least one PDU session release request message, on sending at least one PDU session release command with a Procedure Transaction Identity (PTI) Information Element (IE) set to "no procedure transaction identity assigned"; and releasing, by the SMF (610), the at least one PDU session requested by a User Equipment (UE) (600) and the at least one PDU session requested by the wireless communication network.

[0025] The embodiment discloses a Session Management Function (SMF) (610) comprising: a processor (612); a memory (616); and wherein the processor (612) is configured to: receive at least one PDU session release request message, on sending at least one PDU session release command with a Procedure Transaction Identity (PTI) Information Element (IE) set to "no procedure transaction identity assigned"; and release the at least one PDU session requested by a User Equipment (UE) (600) and the at least one PDU session requested by the network.

[0026] The embodiment discloses a User Equipment (UE) (600) comprising: a processor (602); a memory (606); and wherein the processor (602) is configured to: receive at least one PDU session release command from the SMF with the Procedure Transaction Identity (PTI) Information Element (IE) set to "no procedure transaction identity assigned"; and request at least one PDU session release request, wherein the PDU session ID in the received at least one PDU session release command is same as the UE requested PDU session release request.

[0027] 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:

[0028] FIG. 1 is an example flow diagram in which the SMF may ignore the PDU session release request message and proceed with the network-requested PDU session release procedure, according to existing arts;

[0029] FIG. 2A is an example flow diagram in which the SMF may ignore the PDU session release request message with the access type IE set to 3GPP and proceed with the network-requested PDU session release procedure, according to existing arts;

[0030] FIG. 2B is an example flow diagram in which the SMF may ignore the PDU session release request message with the access type IE set to non 3GPP and proceed with the network-requested PDU session release procedure, according to existing arts;

[0031] FIG. 3 is an example flow diagram for handling a collision between the UE and the network requested PDU session release, on receiving the re-activation request from the network, according to embodiments as disclosed herein;

[0032] FIG. 4 is an example flow diagram for handling the collision between the UE and the network requested PDU session release, while receiving 5GSM cause 39 "re-activation request" from the SMF, according to embodiments as disclosed herein;

[0033] FIG. 5A is an example flow diagram for handling the collision between the UE and the network requested PDU session release, while receiving PTI IE set to "No procedure transaction identity assigned", with the access type set to 3GPP from the SMF, according to embodiments as disclosed herein;

[0034] FIG. 5B is an example flow diagram for handling the collision between the UE and the network requested PDU session release, while receiving PTI IE set to "No procedure transaction identity assigned", with the access type set to non-3GPP from the SMF, according to embodiments as disclosed herein;

[0035] FIG. 5C is an example flow diagram for handling the collision between the UE and the network requested PDU session release, while receiving PTI IE set to "No procedure transaction identity assigned", with the access type set to 3GPP from the SMF and UE registered over non-3GPP, according to embodiments as disclosed herein;

[0036] FIG. 5D is an example flow diagram for handling the collision between the UE and the network requested PDU session release, while receiving PTI IE set to "No procedure transaction identity assigned", with the access type set to non-3GPP from the SMF and UE registered over 3GPP, according to embodiments as disclosed herein; and

[0037] FIG. 6 is an example block diagram illustrating the interaction of the UE with the SMF for handling the collision in the wireless communication network, according to embodiments as disclosed herein.

[0038] 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 can 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.

[0039] For the purposes of interpreting this specification, the definitions (as defined herein) will apply and whenever appropriate the terms used in singular will also include the plural and vice versa. It is to be understood that the terminology used herein is for the purposes of describing particular embodiments only and is not intended to be limiting. The terms "comprising", "having" and "including" are to be construed as open-ended terms unless otherwise noted.

[0040] 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.

[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] Embodiments herein disclose methods and systems for handling a collision between a User Equipment (UE) and a wireless communication network while releasing at least one Protocol Data Unit (PDU) session. Referring now to the drawings, and more particularly to FIGs. 3 through 8, where similar reference characters denote corresponding features consistently throughout the figures, there are shown at least one embodiment.

[0045] Embodiments herein disclose methods and systems for handling a collision between a User Equipment (UE) and a wireless communication network while releasing at least one Protocol Data Unit (PDU) session. On receiving PDU session release request message (after sending a PDU session release command message to the UE, and the PDU session ID in the PDU session release request message same as the PDU session ID in the PDU session release command message), the SMF may perform a UE request and ignore PDU session release command message sent by the SMF. The UE initiated PDU session release procedure progresses and the SMF initiated PDU session release is ignored.

[0046] Consider that the UE receives the PDU session release command message with the PTI IE set to "No procedure transaction identity assigned" during the UE-requested PDU session release procedure, wherein the PDU session indicated in the PDU session release command message is same as the PDU session that the UE requested to release.

[0047] Consider that the Access type IE is included in the PDU session release command message. If the PDU session is an MA PDU session with the user-plane resources established on the access is different from the access indicated in the Access type IE in the PDU session release command message, the UE may proceed with both the UE-requested PDU session release procedure and network-requested PDU session release procedure. Otherwise, the UE may ignore the downlink PDU session release message (i.e., PDU session release command message) and continue with the UE initiated PDU session release procedure.

[0048] FIG. 1 is an example flow diagram in which the SMF may ignore the PDU session release request message and proceed with the network-requested PDU session release procedure. As illustrated, in step 0, the SMF can send a PDU session release command message to the UE for the PDU session ID (pdu id) 'x' with the 5GSM cause #39 "re-activation requested". In step 1, the SMF can receive a PDU session release request message for PDU session ID 'x' which was initiated by the UE, and can cause a collision of the PDU session release request initiated by the UE and network function (e.g., SMF or AMF). In step 2, the SMF may ignore the PDU session release request message and proceed with the network-requested PDU session release procedure. The network-requested PDU session release procedure for PDU session ID 'x' is completed. In step 3, the UE may re-initiate the UE-requested PDU session establishment procedure for the PDU session ID 'x'. In step 1, the UE intended to release the PDU session but because network initiated PDU session release was processed by the UE, the UE is required to unnecessarily re-establish the PDU session without the need from the UE application, incurring unnecessary signaling load and resources on the UE and network.

[0049] Hence, the same issue can be encountered in LTE / EPC, when the MME is sending DEACTIVATE EPS BEARER CONTEXT REQUEST (In step 0, PDU Session Release Command is replaced with DEACTIVATE EPS BEARER CONTEXT REQUEST message). If the EPS bearer indicated in the DEACTIVATE EPS BEARER CONTEXT REQUEST message is the default EPS bearer and UE sends the PDN connection disconnect request (replace PDU Session Release request in step 1 with PDN connection disconnect request) for the same established beater (PDU session disconnect request is for the same established default bearer which MME wants to release). In such a case, the UE will try to establish a new PDN connection by sending PDN connection establishment request to the MME if cause #39 "reactivation requested" is included in the DEACTIVATE EPS BEARER CONTEXT REQUEST. This may not be required if the UE wants to disconnect the PDN connection.

[0050] As per TS 24.501, a collision of network-requested PDU session release procedure and UE-requested PDU session release procedure occurs in the following scenario: if the SMF receives a PDU session release request message after sending a PDU session release command message to the UE, and the PDU session ID in the PDU session release request message is the same as the PDU session ID in the PDU session release command message, the SMF may ignore the PDU session release request message and proceed with the network-requested PDU session release procedure.

[0051] In MA (multi access) PDU session release, the UE can only release the complete PDU session by sending a PDU session release request, for both the accesses (3GPP access and non-3GPP access). The SMF can release user plane resource on specific access by sending PDU session release command and including specific access in the access type IE (information element). In this case, the SMF also include access (3GPP or non-3GPP or both) in the PDU session release command.

[0052] Therefore, when the SMF receives PDU session release request from the UE (while it already send (or sending or initiated) PDU session release command for the same PDU session (determined by PDU session ID)), the SMF ignores the PDU session release request from the UE and proceeds with the network initiated PDU session release procedure. Hence, the UE wants to release PDU session, and the SMF / Network wants to release user plane resource on specific access, then one of the access will not be released, and the UE might have to send the PDU session release request again after timer expiry (e.g. upon timer T3582 timer expiry).

[0053] For an instance, the UE may send a PDU session release request and the SMF initiated PDU session release command to release user plane resource of 3GPP Access. In the access, the SMF has included 3GPP access in PDU session release command. The UE may clear the user plane resource for 3GPP access PDU, and the PDU session will be active on non-3GPP. The UE can send the PDU session release request and a SMF initiated PDU session release command to release the user plane resource of the non-3GPP Access. In the access, the SMF has included a non-3GPP access in the PDU session release command. Hence, the UE will clear the user plane resource for non-3GPP access, and the PDU session will be active on 3GPP. The UE is registered on SA and, PDU ID 'x' (i.e., an MA PDU Session) is established with User Plane (UP) resource setup over 3GPP and non-3GPP.

[0054] FIG. 2A is an example flow diagram in which the SMF may ignore the PDU session release request message with the access type IE set to 3GPP and proceed with the network-requested PDU session release procedure. In step 0, the SMF can send a PDU session release command message to the UE for PDU session ID 'x' with the access type IE set to 3GPP. In step 1, the SMF can receive a PDU session release request message for PDU session ID 'x' which was initiated by the UE, which can cause collision of the PDU session release request initiated by the UE and the network function (e.g., SMF or AMF). In step 2, the SMF may ignore the PDU session release request message from the UE and proceed with the network-requested PDU session release procedure. The network-requested PDU session release procedure for PDU session ID 'x' is completed. The UE may clear the user plane resources for 3GPP, while the user plane resource for non-3GPP is active. In such a case, the UE may clear the user plane resource for 3GPP access PDU, and the PDU session will be active on non-3GPP. For release of non-3GPP PDU session, the UE might have to send the PDU session release request again after timer expiry (e.g timer T3582 expiry). For UE-requested procedure, the UE releases the complete PDU session by sending the PDU session release request, which is for both 3GPP and non-3GPP accesses. So, the intended result after this procedure is that the whole MA PDU is released for both 3GPP and non-3GPP accesses.

[0055] FIG. 2B is an example flow diagram in which the SMF may ignore the PDU session release request message with the access type IE set to non 3GPP and proceed with the network-requested PDU session release procedure. Consider that the UE is registered on Stand-alone (SA) and initially, PDU ID 'x' which is MA PDU Session, is established with User Plane (UP) resource setup over 3GPP and non-3GPP. In step 0, the SMF can send PDU session release command message to the UE for PDU session ID 'x' and Access type IE set to non 3GPP. In step 1, the SMF may receive a PDU session release request message for PDU session ID 'x' which was initiated by the UE, which can cause collision of the PDU session release request initiated by the UE and initiated from the network function (e.g., SMF or AMF). In step 2, the SMF may ignore the PDU session release request message from the UE and proceed with the network-requested PDU session release procedure. The network-requested PDU session release procedure for PDU session ID 'x' is completed. The UE may clear user plane resources for non-3GPP, while the user plane resource for 3GPP is active. In such a case, the UE will clear the user plane resource for non-3GPP access PDU and PDU session will be active on 3GPP. The UE might have to send the PDU session release request again after timer expiry for release of 3GPP PDU session. For UE-requested procedure, the UE releases complete PDU session by sending PDU session release request, which is for both 3GPP and non-3GPP accesses. So, the intended result after this procedure is that the whole MA PDU is released.

[0056] Hence, there is a need in the art for solutions which will overcome the above-mentioned drawback(s), among others.

[0057] FIG. 3 is an example flow diagram for handling a collision between the UE (600) and the wireless communication network requested PDU session release, on receiving the re-activation request from the network. As illustrated in step 0, the SMF 610 can send a PDU session release command message to the UE for PDU session ID 'x' and 5GSM cause #39 "reactivation requested". The SMF 610 receives a PDU session release request message for PDU session ID 'x'. The SMF 610 honors the UE 600 request PDU session release request and ignores the Network initiated PDU session release procedure (i.e., ignore PDU session release command with PTI set to "No procedure transaction identity assigned"). In step 1, the UE 600 may ignore the downlink PDU session release message (ignore PDU session release command with PTI set to "No procedure transaction identity assigned) and continue with the UE 600 initiated PDU session release procedure for PDU session ID 'x'.

[0058] The SMF 610 receives the PDU session release request message after sending a PDU session release command message to the UE, wherein the PDU session ID in the PDU session release request message is the same as the PDU session ID in the PDU session release command message. The SMF 610 has included a 5GSM cause #39　"reactivation requested" in the PDU session release command message to the UE 600. The SMF 610 may ignore the cause #39　"reactivation requested" and send the PDU session release command message to the UE 600.

[0059] The SMF 610 receives the PDU session release request message after sending the PDU session release command message to the UE 600. The PDU session ID in the PDU session release request message can be the same as the PDU session ID in the PDU session release command message. The SMF 610 includes 5GSM cause #39　"reactivation requested" in the PDU session release command message to the UE 600. The SMF 610 proceeds with both the UE and the network PDU session release procedure and does not include 5GSM cause #39　"reactivation requested" in the PDU session release command, which had been send by the SMF 610 in response to the UE initiated PDU session release.

[0060] The UE 600 receives a PDU session release command message with 5GSM cause value is #39 "reactivation requested" during the UE-requested PDU session release procedure. The PDU session indicated in PDU session release command message is the PDU session that the UE had requested to release. The UE 600 may ignore the 5GSM cause value is #39 "reactivation requested" in PDU session release command message and proceed with the network requested PDU session release procedure. The UE 600 may not re-establish the PDU session. The UE 600 may abort the UE-requested PDU session release procedure and stop the timer T3582 and proceed with the network-requested PDU session release procedure

[0061] In an embodiment herein, the UE 600 does not reactivate the PDU session even if it receives 5GSM cause #39　"reactivation requested" because the UE has determined not to establish / maintain this PDU session based on an indication from upper layers (i.e., application processor) or modem / NAS layer decision / determination.

[0062] In an embodiment disclosed herein, consider that the Mobility Management Entity (MME) receives a PDN disconnect request message during the EPS bearer context deactivation procedure. The Evolved Packet System (EPS) bearer is indicated in the deactivate EPS bearer context request message EPS bearer belonging to the PDN connection. Consider that the UE wants to disconnect. If the EPS bearer indicated in the deactivate EPS bearer context request message is the default EPS bearer and the MME indicate ESM cause value is #39 "reactivation requested", the MME may proceed with both PDN DISCONNECT REQUEST, EPS bearer context deactivation procedure.

[0063] Consider that the MME receives a PDN disconnect request message during the EPS bearer context deactivation procedure, and the EPS bearer is indicated in the deactivate EPS bearer context request message. Consider that the EPS bearer belongs to the PDN connection that the UE wants to disconnect from, and the EPS bearer indicated in the deactivate EPS bearer context request message is the default EPS bearer. The MME indicates that the ESM cause value is #39 "reactivation requested", the MME may proceed with both the PDN disconnect request, and EPS bearer context deactivation procedure. The MME may not include #39 "reactivation requested" in the response, when sending response to the PDN disconnect request.

[0064] The UE 600 receives a deactivate EPS bearer context request message with ESM cause value #39 "reactivation requested" for the default bearer during the UE-requested PDU disconnect procedure. The EPS bearer ID indicated in deactivate EPS bearer context request message belongs to the PDN connection session that the UE had requested to disconnect from. The UE ignores the ESM cause value is #39 "reactivation requested" in the deactivate EPS bearer context request message and proceeds with the network requested deactivate EPS bearer context request. The UE may not re-establish the PDN connection. The UE may abort the UE-requested PDU session release procedure, stop the timer T3492, and proceed with the network-requested deactivate EPS bearer context request procedure.

[0065] In an embodiment herein, the UE 600 does not reactivate the PDN connection (by sending PDN establishment request) session even if it receives ESM cause #39　"reactivation requested" in the deactivate EPS bearer context request for default bearer, because the UE has determined not to establish / maintain this PDN connection based on an indication from upper layers (i.e., application processor) or modem / NAS layer decision / determination.

[0066] FIG. 4 is an example flow diagram for handling the collision between the UE and the network requested PDU session release, while receiving 5GSM cause 39 "re-activation request" from the SMF 610. As illustrated, in steps 1 and 2, the PDU session release request (PDU ID: x) is sent by the UE 600. At the same time, the network initiates PDU session release command (PDU ID: x) 5GSM Cause 39 "reactivation requested"). On detecting the occurrences of the collision, in step 3, the UE may ignore 5GSM cause 39" reactivation requested" and continue with the network initiated PDU session release procedure. In step 4, the PDU session release complete is sent from the UE.

[0067] The SMF 610 receives a PDU session release request message after sending a PDU session release command message with the PTI IE set to "No procedure transaction identity assigned" to the UE. The PDU session ID in the PDU session release request message can be the same as the PDU session ID in the PDU session release command message.

[0068] As illustrated, if the access type IE is included in the PDU session release command message and the PDU session is a MA PDU session, wherein the user-plane (UP) resources is established on an access different from the access indicated in the Access type IE in the PDU session release command message. The SMF may proceed with both the UE-requested PDU session release procedure and network-requested PDU session release procedure. Otherwise, the SMF may ignore the PDU session release request message and proceed with the network-requested PDU session release procedure.

[0069] FIG. 5A is an example flow diagram for handling the collision between the UE and the network requested PDU session release, while receiving PTI IE set to "No procedure transaction identity assigned", with the access type set to 3GPP from the SMF 610. As illustrated, the SMF may proceed with both the UE-requested PDU session release procedure and network-requested PDU session release procedure.

[0070] Initially, the PDU ID (which is set to 'x' (which is an MA PDU Session)) is established with the User Plane (UP) resource setup over 3GPP and non-3GPP. In step 0, the SMF sends a PDU session release command message to the UE with the PTI IE set to "No procedure transaction identity assigned"for PDU session ID 'x' and Access type IE included as 3GPP. In step 1, the SMF 610 receives a PDU session release request message for PDU session ID 'x' over 3GPP or non-3GPP access. The SMF may proceed with both the UE-requested PDU session release procedure and the network-requested PDU session release procedure. The procedure is depicted in Table 1 as follows:

[0071] MA PDU Session.- PDU ID 'x'- User Plane (UP) resources established over 3gpp and non-3gppAccess in the Access Type IE in PDU Session release CommandAccess over which UE requests PDU Session Release:Final Action3GPP3GPP or Non-3GPP accessSMF may proceed with both the UE-requested PDU session release procedure and network-requested PDU session release procedure

[0072] FIG. 5B is an example flow diagram for handling the collision between the UE and the network requested PDU session release, while receiving PTI IE set to "No procedure transaction identity assigned", with the access type set to non-3GPP from the SMF. As illustrated, the SMF 610 may proceed with both the UE-requested PDU session release procedure and the network-requested PDU session release procedure. Initially, the PDU ID (which is set to 'x' and can be an MA PDU Session) is established with User Plane (UP) resource setup over 3GPP and non-3GPP access.

[0073] In step 0, the SMF 610 can send a PDU session release command message to the UE with the PTI IE set to "No procedure transaction identity assigned" for PDU session ID 'x' and Access type IE included as non-3GPP. In step 1, the SMF 610 receives a PDU session release request message for PDU session ID 'x' over 3GPP or non-3GPP access. The SMF 610 may proceed with both the UE-requested PDU session release procedure and the network-requested PDU session release procedure. The procedure is depicted in Table 2 as follows:

[0074] MA PDU Session.- PDU ID 'x'- User Plane (UP) resources established over 3GPP and non-3GPPAccess Type IE in the PDU Session release CommandAccess over which UE requests PDU Session Release:Final ActionNon-3GPP3GPP or non-3GPPSMF may proceed with both the UE-requested PDU session release procedure and network-requested PDU session release procedure

[0075] FIG. 5C is an example flow diagram for handling the collision between the UE 600 and the network requested PDU session release, while receiving PTI IE set to "No procedure transaction identity assigned", with the access type set to 3GPP from the SMF and UE registered over non-3GPP. As illustrated, the SMF 610 may proceed with both the UE-requested PDU session release procedure and network-requested PDU session release procedure.

[0076] Initially, the PDU ID 'x' (which is an MA PDU Session) is established with User Plane (UP) setup over non-3GPP. In step 0, the SMF 610 can send a PDU session release command message to the UE 600 with with the PTI IE set to "No procedure transaction identity assigned"for PDU session ID 'x' and Access type IE included as 3GPP. In step 1, the SMF 610 receives the PDU session release request message for PDU session ID 'x' over non-3GPP access. The SMF 610 may proceed with both the UE-requested PDU session release procedure and network-requested PDU session release procedure. Table 3 depicts the above process.

[0077] MA PDU Session.- PDU ID 'x'- User Plane (UP) resources established over non-3GPPAccess Type IE in PDU Session release CommandAccess over which UE requests PDU Session Release:Final Action3GPPNon-3GPP or non-3GPP accessSMF may proceed with both the UE-requested PDU session release procedure and network-requested PDU session release procedure

[0078] FIG. 5D is an example flow diagram for handling the collision between the UE and the network requested PDU session release, while receiving PTI IE set to "No procedure transaction identity assigned", with the access type set to non-3GPP from the SMF and UE registered over 3GPP. As illustrated, the SMF 610 may proceed with both the UE-requested PDU session release procedure and the network-requested PDU session release procedure.

[0079] Initially, the PDU ID 'x' (which can be an MA PDU Session) is established with User Plane (UP) setup over 3GPP. In step 0, the SMF 610 can send a PDU session release command message to the UE 600 with the PTI IE set to "No procedure transaction identity assigned" for PDU session ID 'x' and Access type IE included as non-3GPP. In step 1, the SMF 610 receives a PDU session release request message for PDU session ID 'x' over 3GPP access or non-3GPP access. The SMF 610 may proceed with both the UE-requested PDU session release procedure and the network-requested PDU session release procedure. Table 4 depicts the above process.

[0080] MA PDU Session.- PDU ID 'x'- User Plane (UP) resources established over 3GPPAccess Type IE in NW PDU Session CommandAccess over which UE requests PDU Session Release:Final Actionnon-3GPP3GPP or non-3GPPSMF may proceed both the UE-requested PDU session release procedure and network-requested PDU session release procedure

[0081] FIG. 6 is an example block diagram illustrating the interaction of the UE with the SMF for handling the collision in the wireless communication network. As illustrated, the UE 600 comprises a processor 602, a communication interface unit 604 and a memory 606. The UE 600 can be a stand-alone device or can be integrated with another device / smart device such as, but not limited to, a computer, a laptop, a smart phone, a phone, an IoT device, a wearable device, a vehicle infotainment system, a TV, a camera, and so on.

[0082] The memory 606 program code / program instructions that can be executed on the processor 602 for handling the collision in the wireless communication network.

[0083] The memory 606 may include one or more computer-readable storage media. The memory 606 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.

[0084] The communication interface unit 604 can be configured to establish communication between the UE 600 and the SMF 610 through the AMF 608 with the external entities using the communication network.

[0085] The processor 602 can be at least one of a single processer, a plurality of processors, multiple homogeneous or heterogeneous cores, multiple CPUs of different kinds, special media, and other accelerators. Further, the plurality of processing units 602 may be located on a single chip or over multiple chips. The processor 602 may execute the program code stored in the memory to perform the one or more steps for handling the collision in the wireless communication network.

[0086] The Access and Mobility Management Function (AMF) 608 is one of the control plane network functions (NF) of the 5G core network (5GC). The 5G AMF, is an evolution of 4G MME, continuing with the Control Plane and User Plane Separation, and with further simplifications like moving the Sessions Management functions to the SMF and, providing common SBA interfaces.

[0087] The SMF 610 comprises a processor 612, a communication interface unit 614, and a memory 616. In an embodiment herein, when the SMF 610 receives a PDU session release request (UE requested PDU session release request) and the PDU session is an MA PDU session from the UE. The SMF can initiate the network-requested PDU session release procedure (through PDU session release command with the PTI IE set to "No procedure transaction identity assigned" to the UE). Also, the SMF can initiate the network-requested PDU session release procedure PDU session release procedure for the same PDU session ID (i.e., PDU session ID in the PDU session release request message is the same as the PDU session ID in the PDU session release command). The SMF may proceed with both UE requested PDU session release procedure and network initiated PDU session release procedure.

[0088] In an embodiment herein, the SMF can receive the PDU session release request message, after sending the PDU session release command message with the PTI IE set to "No procedure transaction identity assigned" to the UE. The PDU session ID in the PDU session release request message can be the same as the PDU session ID in the PDU session release command message.

[0089] Consider that the Access type IE is included in the PDU session release command message and the PDU session is an MA PDU session. The PDU session release command having user-plane (UP) resources can be established on an access that is different from the access indicated in the Access type IE in the PDU session release command message. The SMF may proceed with both the UE-requested PDU session release procedure and network-requested PDU session release procedure.

[0090] In an embodiment herein, consider that the UE receives the PDU session release command message during the UE-requested PDU session release procedure. The PDU session indicated in the PDU session release command message can be the same as the PDU session that the UE requested PDU session release. The UE may ignore the 5GSM cause #39　"reactivation requested in the PDU session release command if included.

[0091] In another embodiment, if the SMF received the PDU session release request message after sending a PDU session release command message with the PTI IE set to "No procedure transaction identity assigned" to the UE, and the PDU session ID in the PDU session release request message is the same as the PDU session ID in the PDU session release command message.

[0092] If the Access type IE is included in the PDU session release command message and the PDU session is an MA PDU session and having user-plane resources established on the access different from the access indicated in the Access type IE in the PDU session release command message, the SMF may proceed both the UE-requested PDU session release procedure and network-requested PDU session release procedure. Otherwise, the SMF may ignore the PDU session release request message and proceed with the network-requested PDU session release procedure.

[0093] In an embodiment herein, consider that the UE receives the PDU session release command message with the PTI IE set to "No procedure transaction identity assigned" during the UE-requested PDU session release procedure. The PDU session indicated in the PDU session release command message can be the same as the PDU session that the UE requests to release. The UE may ignore the 5GSM cause #39　"reactivation requested in the PDU session release command if included.

[0094] In an embodiment herein, the UE receives the PDU session release command message with the PTI IE set to "No procedure transaction identity assigned", wherein the UE has already requested for the PDU session release procedure. The PDU session indicated in the PDU session release command message can be the same as the PDU session that the UE has requested to release, wherein the UE may ignore all 5GSM causes if included.

[0095] In an embodiment, the network initiated PDU session release is determined by the PDU session release command with the PTI IE set to "No procedure transaction identity assigned" to the UE.

[0096] In an embodiment, When the UE receives a DEACTIVATE EPS BEARER CONTEXT REQUEST message including ESM cause　#39 "reactivation requested" during the PDN disconnect procedure, and the EPS bearer indicated in the DEACTIVATE EPS BEARER CONTEXT REQUEST message is a dedicated EPS bearer belonging to the PDN connection the UE wants to disconnect, the UE ignore the ESM cause#39 "reactivation requested" and may not initiate PDN connectivity request.

[0097] 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.

[0098] The embodiments disclosed herein describe methods and systems for handling a collision between a User Equipment (UE) and a wireless communication network while releasing at least one Protocol Data Unit (PDU) session. 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 device or 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.

[0099] 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 and examples, those skilled in the art will recognize that the embodiments and examples disclosed herein can be practiced with modification within the scope of the embodiments as described herein.

Claims

1.A method performed by a user equipment (UE) in a wireless communication system, the method comprising:receiving a protocol data unit (PDU) session release command message associated with a PDU session during a UE-requested PDU session release procedure associated with the PDU session; andin case that an access type information element (IE) is included in the PDU session release command message and the PDU session has user-plane resources established on a first access different from a second access indicated in the access type IE in the PDU session release command message, proceeding the UE-requested PDU session release procedure and a network-requested PDU session release procedure.2.The method of claim 1, wherein the PDU session is a multi-access (MA) PDU session.3.The method of claim 1, wherein the PDU session release command massage includes information indicating that no procedure transaction identity is assigned.4.The method of claim 1, wherein the proceeding of the UE-requested PDU session release procedure and the network-requested PDU session release procedure comprises ignoring reactivation requested information included in the PDU session release command message.5.A method performed by a session management function (SMF) in a wireless communication system, the method comprising:transmitting a protocol data unit (PDU) session release command message associated with a PDU session;receiving a PDU session release request message associated with the PDU session; andin case that an access type information element (IE) is included in the PDU session release command message and the PDU session has user-plane resources established on a first access different from a second access indicated in the access type IE in the PDU session release command message, proceeding a user equipment (UE)-requested PDU session release procedure and a network-requested PDU session release procedure.6.The method of claim 5, further comprising:in case that the access type IE is not included in the PDU session release command message or the PDU session does not have the user-plane resources established on the first access different from the second access indicated in the access type IE in the PDU session release command message, ignoring the UE-requested PDU session release procedure and proceeding the network-requested PDU session release procedure.7.The method of claim 5, wherein the PDU session is a multi-access (MA) PDU session.8.The method of claim 5, wherein the PDU session release command massage includes information indicating that no procedure transaction identity is assigned.9.A user equipment (UE) comprising:a transceiver; anda processor coupled with the transceiver and configured to:receive, via the transceiver, a protocol data unit (PDU) session release command message associated with a PDU session during a UE-requested PDU session release procedure associated with the PDU session, andin case that an access type information element (IE) is included in the PDU session release command message and the PDU session has user-plane resources established on a first access different from a second access indicated in the access type IE in the PDU session release command message, proceed the UE-requested PDU session release procedure and a network-requested PDU session release procedure.10.The UE of claim 9, wherein the PDU session is a multi-access (MA) PDU session.11.The UE of claim 9, wherein the PDU session release command massage includes information indicating that no procedure transaction identity is assigned.12.The UE of claim 9, wherein, to proceed the UE-requested PDU session release procedure and the network-requested PDU session release procedure, the processor is configured to ignore reactivation requested information included in the PDU session release command message.13.A session management function (SMF) comprising:a transceiver; anda processor coupled with the transceiver and configured to:transmit, via the transceiver, a protocol data unit (PDU) session release command message associated with a PDU session,receive, via the transceiver, a PDU session release request message associated with the PDU session, andin case that an access type information element (IE) is included in the PDU session release command message and the PDU session has user-plane resources established on a first access different from a second access indicated in the access type IE in the PDU session release command message, proceed a user equipment (UE)-requested PDU session release procedure and a network-requested PDU session release procedure.14.The SMF of claim 13, wherein the processor is further configured to:in case that the access type IE is not included in the PDU session release command message or the PDU session does not have the user-plane resources established on the first access different from the second access indicated in the access type IE in the PDU session release command message, ignore the UE-requested PDU session release procedure and proceed the network-requested PDU session release procedure.15.The SMF of claim 13, wherein the PDU session is a multi-access (MA) PDU session, andwherein the PDU session release command massage includes information indicating that no procedure transaction identity is assigned.

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