Method and user equipment for handling conflicts in MA PDU session release process

Abstract

A method and user equipment for handling conflicts in the MA PDU session release process are proposed. If the Access Type IE is included in the PDU session release command message, and the PDU session is an MA PDU session with user plane resources established on an access different from the access indicated in the Access Type IE of the PDU session release command message, then the UE continues the UE-requested PDU session release process and the network-requested PDU session release process. Otherwise, the UE aborts the UE-requested PDU session release process, stops timer T3582, and continues the network-requested PDU session release process.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application No. 63 / 181,39, filed on April 29, 2021, entitled “UE-requested PDU Session Release Procedure and Network-requested PDUSession Release Procedure,” the subject matter of which is incorporated herein by reference. Technical Field

[0003] The disclosed embodiments relate generally to wireless communications, and more particularly to methods for handling conflicts between a UE-requested multi-access (MA) protocol data unit (PDU) session release procedure and a network-requested MA PDU session release procedure. Background Art

[0004] Wireless communication networks have grown exponentially over the years. Long-term evolution (LTE) systems offer high peak data rates, low latency, improved system capacity, and low operating costs due to simplified network architecture. LTE systems, also known as 4G systems, also provide seamless integration with older wireless networks, such as GSM, CDMA, and universal mobile telecommunication systems (UMTS). In LTE systems, the evolved universal terrestrial radio access network (E-UTRAN) includes multiple evolved Node-Bs (eNodeB / eNB) that communicate with multiple mobile stations known as user equipment (UE). The 3rd generation partner project (3GPP) network typically includes a mix of 2G / 3G / 4G systems. The Next Generation Mobile Network (NGMN) committee has decided to focus future NGMN activities on defining the end-to-end requirements for 5G new radio (NR) systems.

[0005] In 5G / NR, a PDU session defines the association between a UE and a data network that provides PDU connection services. PDU session establishment is a parallel process to the PDN connection (bearer) process in 4G / LTE. Each PDU session is identified by a PDU session ID (PSI) and may include multiple QoS flows and QoS rules. Each PDU session can be established over a 5G access network (e.g., a 3GPP radio access network (RAN), or over a non-3GPP RAN). The network / UE can initiate different PDU session processes, such as PDU session establishment, PDU session modification, and PDU session release, to manage PDU sessions.

[0006] Operators are seeking ways to balance data traffic between mobile networks and non-3GPP accesses in a way that is transparent to users and reduces mobile network congestion. In 5GS, UEs can be connected to 3GPP accesses and non-3GPP accesses simultaneously (using 3GPP NAS signaling), so 5GS is able to take advantage of these multiple accesses to improve user experience and optimize traffic distribution across various accesses. Therefore, 3GPP introduced MA PDU sessions in 5GS. MA PDU sessions can be configured to use one 3GPP access network or one non-3GPP access network at a time, or one 3GPP access network and one non-3GPP access network at the same time.

[0007] MA PDU sessions can be established on 3GPP access and non-3GPP access simultaneously, or one at a time. Therefore, the user plane resources of an MA PDU session can be established on both accesses or only on 3GPP or non-3GPP access. For an established MA PDU session, the 5GS can initiate a PDU session release procedure to release one specific access type or both access types for the MA PDU session. However, when the UE receives a PDU SESSION RELEASE COMMAND message from the network during a UE-requested MA PDU session release procedure for the same PDU session, different UE behaviors are required in different scenarios.

[0008] Find a solution. Summary of the invention

[0009] A method for handling a conflict between a UE-requested MA PDU session release procedure and a network-requested MA PDU session release procedure is proposed. During the UE-requested PDU session release procedure, a conflict is detected when the UE receives a PDU session release command message with the procedure transaction ID (PTI) IE set to "unallocated procedure transaction identifier" and the PDU session indicated in the PDU session release command message is the same as the PDU session requested by the UE to release. If the access type IE is included in the PDU session release command message and the PDU session is an MA PDU session and has user plane resources established on an access different from the access indicated in the access type IE in the PDU session release command message, the UE continues the UE-requested PDU session release procedure and the network-requested PDU session release procedure. Otherwise, the UE aborts the UE-requested PDU session release procedure and stops the timer T3582 and continues the network-requested PDU session release procedure.

[0010] In one embodiment, the UE maintains an MA PDU session in a 5G system (5G system, 5GS). The MA PDU session has a PSI. The UE sends a PDU session release request message to the 5GS for the UE-requested PDU session release procedure for the MA PDU session. The PDU session release request message indicates the PSI and the PTI value assigned by the UE. The UE receives a PDU session release command message from the 5GS for the network-requested PDU session release procedure for the MA PDU session. For the same MA PDU session, the UE detects a conflict between the UE-requested PDU session release procedure and the network-requested PDU session release procedure. The UE continues the UE-requested PDU session release procedure and the network-requested PDU session release procedure when the conditions are met, otherwise it terminates the UE-requested PDU session release procedure and continues the network-requested PDU session release procedure.

[0011] The method and user equipment for handling conflicts in the MA PDU session release process provided by the present invention can avoid the adverse effects on the MAPDU caused by simply terminating the UE request process and continuing the network request process in the prior art when a conflict occurs.

[0012] Other embodiments and advantages are described in the detailed description that follows. This summary is not intended to define the invention. The invention is defined by the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings illustrate embodiments of the present invention, wherein like numerals refer to like components.

[0014] Figure 1An exemplary 5G network supporting MA PDU session management and a method for handling conflicts in a PDU session release procedure for an MA PDU session according to one novel aspect are illustrated.

[0015] Figure 2 A simplified block diagram of a UE and network entities according to an embodiment of the present invention is illustrated.

[0016] Figure 3 One embodiment of handling conflicts in a PDU session release procedure for an MA PDU session in accordance with one novel aspect is illustrated.

[0017] Figure 4 Another embodiment of handling conflicts in a PDU session release procedure for an MA PDU session in accordance with one novel aspect is illustrated.

[0018] Figure 5 is a flow chart of a method for handling a conflict of a PDU session release procedure of an MA PDU session according to one novel aspect of the present invention. DETAILED DESCRIPTION

[0019] Reference will now be made in detail to some embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

[0020] Figure 1 An exemplary 5G network 100 supporting MA PDU session management and a method for handling conflicts in MA PDU session release procedures according to one novel aspect are illustrated. The 5G NR network 100 includes a UE 101, a 3GPP access 102 (e.g., 3GPP RAN), a non-3GPP access 103 (e.g., non-3GPP RAN), an access and mobility management function (AMF) 110, a session management function (SMF) 111, a non-3GPP interworking function (N3IWF) 112, a user plane function (UPF) 113, and a 5G core (5GC) data network 120. The AMF 110 communicates with a base station in the 3GPP access 102, the SMF 111, and the UPF 113 for access and mobility management of wireless access devices in the 5G network 100. SMF 111 is mainly responsible for interacting with the decoupled data plane, creating, updating and deleting PDU sessions, and managing session contexts with UPF 113. N3IWF 112, which interfaces with the 5G core network control plane functions, is responsible for routing messages outside the 5G RAN.

[0021] In the Access Stratum (AS) layer, the RAN provides radio access to the UE 101 through the radio access technology (RAT). In the Non-Access Stratum (NAS) layer, the AMF 110 and the SMF 111 communicate with the RAN and the 5GC for access and mobility management of wireless access devices in the 5G network 100 and PDU session management. The 3GPP access 102 may include a base station (gNB or eNB) providing radio access to the UE 101 through various 3GPP RATs including 5G, 4G, and 3G / 2G. The non-3GPP access 103 may include an access point (AP) providing radio access to the UE 101 through a non-3GPP RAT including WiFi. The UE 101 can obtain access to the data network 120 through the 3GPP access 102, the AMF 110, the SMF 111, and the UPF 113. UE 101 may obtain access to data network 120 through non-3GPP access 103, N3IWF 112, AMF 110, SMF 111, and UPF 113. UE 101 may be equipped with a single radio frequency (RF) module or transceiver or multiple RF modules or transceivers for services via different RAT / CNs. In some examples, UE 101 may be a smart phone, a wearable device, an Internet of Things (IoT) device, a tablet, etc.

[0022] The 5GS network is a packet-switched (PS) Internet Protocol (IP) network. This means that the 5GS network transmits all data traffic in the form of IP packets and provides users with always-on IP connectivity. When a UE joins an evolved packet system (EPS) network, a packet data network (PDN) address (i.e., an address that can be used on the PDN) is assigned to the UE to connect to the PDN. In 4G, EPS defines a default EPS bearer to provide always-on IP connectivity. In 5G, the PDU session establishment process is a parallel process to the PDN connection process in 4G. The PDU session defines the association between the UE and the data network that provides the PDU connection service. Each PDU session is identified by a PDU session ID and may include multiple QoS flows and QoS rules.

[0023] Each PDU session can be established through 3GPP RAN or through non-3GPP RAN for radio access. 5G session management (5GSM) of PDU sessions for 3GPP access and non-3GPP access is managed by AMF and SMF through NAS signaling. Operators are seeking ways to balance data traffic between mobile networks and non-3GPP access in a way that is transparent to users and reduces mobile network congestion. In 5GS, the UE can be connected to 3GPP access and non-3GPP access at the same time (using 3GPP NAS signaling), so 5GS is able to take advantage of these multiple accesses to improve user experience and optimize traffic distribution across various accesses. Therefore, 3GPP introduced MA PDU sessions in 5GS. MA PDU sessions use one 3GPP access network or one non-3GPP access network at a time, or one 3GPP access network and one non-3GPP access network at the same time.

[0024] MA PDU sessions can be established on 3GPP access and non-3GPP access simultaneously, or one at a time. Therefore, the user plane resources of an MA PDU session can be established on both accesses or only on 3GPP or non-3GPP access. For an established MA PDU session, the 5GS can initiate a PDU session release procedure to release one specific access type or both access types for the MA PDU session. However, when the UE receives a PDU Session Release Command message from the network during a UE-requested MA PDU Session Release procedure for the same PDU session, different UE behaviors are required in different scenarios.

[0025] According to a novel aspect, UE behavior is proposed to handle the conflict of the UE requested MA PDU session release procedure and the network requested MA PDU session release procedure (as shown in 130). During the UE requested PDU session release procedure, when the UE receives a PDU session release command message with the PTI IE set to "Unassigned Procedure Transaction Identifier" and the PDU session (ID) indicated in the PDU SESSIONRELEASE COMMAND message is the same as the PDU session (ID) requested by the UE to release, a conflict is detected. If the access type IE is included in the PDU session release command message and the PDU session is an MA PDU session and has user plane resources established on an access different from the access indicated in the access type IE in the PDU session release command message, the UE continues with the UE requested PDU session release procedure and the network requested PDU session release procedure (140). Otherwise, the UE aborts the UE requested PDU session release procedure and stops the timer T3582 and continues with the network requested PDU session release procedure (150).

[0026] Figure 2 The diagram illustrates a simplified block diagram of a wireless device (e.g., UE 201 and network entity 211) according to an embodiment of the present invention. The network entity 211 may be a base station and / or an AMF / SMF. The network entity 211 has an antenna 215 for transmitting and receiving radio signals. A radio frequency (RF) transceiver module 214 coupled to the antenna receives RF signals from the antenna 215, converts them into baseband signals and sends the baseband signals to the processor 213. The RF transceiver 214 also converts the baseband signals received from the processor 213 into RF signals and sends them to the antenna 215. The processor 213 processes the received baseband signals and calls different functional modules to perform functions in the base station 211. The memory 212 includes volatile computer-readable storage media and non-volatile computer-readable storage media, storing program instructions and data 220 to control the operation of the base station 211. In Figure 2 For example, in the example of, the network entity 211 also includes a protocol stack 280 and a set of control function modules and circuits 290. The protocol stack 280 includes a NAS layer for communicating with the AMF / SMF / MME entity connected to the core network and the radio, a Radio Resource Control (RRC) layer for high-level configuration and control, a Packet Data Convergence Protocol / Radio Link Control (PDCP / RLC) layer, a Media Access Control (MAC) layer, and a Physical (PHY) layer. In one example, the control function modules and circuits 290 include a PDU session processing circuit 291 that handles the PDU establishment, modification, and release processes, and a configuration and control circuit 292 that provides different parameters to configure and control the UE, including mobility management and PDU session management related functions.

[0027] Similarly, UE 201 has a memory 202, a processor 203, and a radio frequency (RF) transceiver module 204. The RF transceiver 204 is coupled to an antenna 205, receives an RF signal from the antenna 205, converts it into a baseband signal, and sends the baseband signal to the processor 203. The RF transceiver 204 also converts the baseband signal received from the processor 203 into an RF signal and sends it to the antenna 205. The processor 203 processes the received baseband signal and calls different functional modules and circuits to perform functions in the UE 201. The memory 202 includes a volatile computer-readable storage medium and a non-volatile computer-readable storage medium, and stores program instructions and data 210 to be executed by the processor to control the operation of the UE 201. Suitable processors include, for example, dedicated processors, digital signal processors (DSP), multiple microprocessors, microprocessors associated with one or more DSP cores, controllers, microcontrollers, application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) circuits and other types of integrated circuits (IC) and / or state machines. A processor associated with software can be used to implement and configure the features of UE 201.

[0028] UE 201 also includes a protocol stack 260 and a set of control function modules and circuits 270. Protocol stack 260 includes a NAS layer for communicating with an AMF / SMF / MME entity connected to a core network, an RRC layer for high-level configuration and control, a PDCP / RLC layer, a MAC layer, and a PHY layer. The control function modules and circuits 270 may be implemented and configured by software, firmware, hardware, and / or a combination thereof. The control function modules and circuits cooperate with each other when executed by a processor through program instructions contained in a memory to allow UE 201 to perform embodiments and functional tasks and features in a network.

[0029] In one example, the control function module and circuit 270 includes a PDU session processing circuit 271 that performs MA PDU session establishment, modification and release procedures with the network, and a configuration and control circuit 272 that processes configuration and control parameters for mobility management and session management. When a conflict between a UE-requested MA PDU session release procedure and a network-requested MA PDU session release procedure for the same MA PDU session is detected, the UE decides whether to continue with both PDU session release procedures, or to abort the UE-requested PDU session release procedure and only perform the network-requested PDU session release procedure.

[0030] A MA PDU session in 5GS can be established after the UE registers with the network through 3GPP and non-3GPP access types belonging to the same PLMN. The UE establishes an MA PDU session by initiating a PDU session establishment procedure with the network on a 3GPP or non-3GPP access type and activating an MA PDU session in a single step. Activation of the MA PDU connection service refers to the establishment of user plane resources on 3GPP access and non-3GPP access. In another embodiment, the UE registers with the network through 3GPP and non-3GPP access types belonging to different PLMNs. The MA PDU session is first established on one access type and then on another access type in two separate steps. In yet another embodiment, the UE registers with the network through 3GPP access and non-3GPP access types belonging to the same PLMN, and establishes an MA PDU session to the same PLMN through 3GPP access type and non-3GPP access type in two separate steps. An MA PDU session uses one 3GPP access network or one non-3GPP access network at a time, or uses one 3GPP access network and one non-3GPP access network at the same time. In addition, the UE and the network may support the Access Traffic Steering Switching and Splitting (ATSSS) functionality to allocate traffic for an established MA PDU session over 3GPP access and non-3GPP access. An MA PDU session is active when user plane resources for the MA PDU session are established on at least one access type.

[0031] For an established MA PDU session, the 5GS can initiate a PDU Session Release procedure to release one specific access type or both access types of the MA PDU session. For the UE-requested PDU Session Release procedure, it always releases the entire MAPDU, for example, user plane resources on both accesses are released. For the UE-requested PDU Session Release procedure, the SMF will not include the Access Type IE in the PDU Session Release Command message. Please note that for the UE-requested procedure, it does not matter through which access the UE sends the PDU Session Release Request (PDU SESSION RELEASE REQUEST), and the expected result after this procedure is that the entire MA PDU is released. On the other hand, for the network-requested PDU Session Release procedure, the entire MA PDU session or part of the MA PDU session (i.e., only a single access / branch of the MA PDU) can be released. The Access Type IE in the PDU Session Release Command message can indicate which access / branch of the MA PDU session is to be released, and it does not matter on which access the PDU Session Release Command message is sent.

[0032] Figure 3 An embodiment of handling conflicts in the MA PDU session release process according to one novel aspect is illustrated. In step 311, UE 301 registers with the 5GS network via a 3GPP access type. In step 312, UE 301 registers with the 5GS network via a non-3GPP access type. In step 313, an MA PDU session with PSI=5 is established between UE 301 and the 5GS network, and user plane resources can be established on both 3GPP and non-3GPP accesses, or only on 3GPP access, or only on non-3GPP access.

[0033] In step 321, UE 301 initiates a UE-requested PDU session release procedure by sending a PDU SESSION RELEASE REQUEST message to the network. Note that the UE-requested PDU session release procedure is used to release the entire MA PDU session, for example, across two accesses / branches, regardless of which access the UE sends the PDU SESSION RELEASE REQUEST message through. In addition, the PDU SESSION RELEASE REQUEST message carries a currently unused PTI value (e.g., PTI=77), as well as a PSI value (e.g., PSI=5) identifying the MA PDU session to be released. PTI is used as a UE-assigned identifier for UE-requested PDU session establishment, modification, and release procedures in 5G / NR. Here, PTI=77 indicates a specific UE-requested PDU session release procedure. When the PDU session release procedure is triggered, UE 301 starts the T3582 timer.

[0034] In step 331, UE 301 receives a PDU session release command message for the same MA PDU (PSI=5) after triggering the UE-requested PDU session release procedure but before the procedure is completed. In step 341, UE 301 determines that a conflict occurs between the UE-requested PDU session release procedure and the network-requested PDU session release procedure. In the UE-requested PDU session release procedure, a conflict is detected when the UE receives a PDU session release command message with the PTI IE set to "No procedure transaction identity assigned" and the PDU session indicated in the PDU session release command message is the same as the PDU session requested by the UE (PSI=5). Note that since the PDU session release command message does not carry the PTI, the UE knows that the command is not a response to the UE-requested PDU session release procedure (identified by PTI=77). The UE knows that such a command is another PDU session release procedure with PSI=5 and is requested by the network.

[0035] Conventionally, upon detecting a conflict between two PDU Session Release procedures for the same PDU Session, the UE simply aborts its own procedure and proceeds with the network requested procedure. However, for MA PDUs, this does not always produce the desired result, e.g., releasing the entire MA PDU Session. In a novel aspect, the UE 301 needs to further determine the state of the MA PDU Session and the content of the PDU Session Release Command message, and then decide whether the conditions are met to proceed with both procedures (Option 1), or to proceed only with the network requested procedure and abort the UE requested procedure (Option 2).

[0036] If the conditions are met in the following scenarios, the UE 301 selects option 1. In the first scenario, the PDU session is a MAPDU session, and user plane resources are established on both 3GPP access and non-3GPP access, and the access type IE is included in the PDU session release command message, and the access type IE indicates 3GPP access. If the UE aborts the UE-requested PDU session release procedure and only proceeds with the network-requested PDU session release procedure, the MA PDU will not be released, and the MA PDU with the non-3GPP branch will continue to exist after the procedure. Similarly, if the access type IE indicates non-3GPP access, then if the UE aborts the UE-requested PDU session release procedure and only proceeds with the network-requested PDU session release procedure, the MA PDU will not be released, and the MA PDU with the 3GPP branch will continue to exist after the procedure.

[0037] In the second scenario, the PDU session is an MA PDU session and has user plane resources established only on 3GPP access, and the access type IE is included in the PDU session release command message, and the access type IE indicates non-3GPP access. If the UE aborts the UE requested PDU session release procedure and only continues with the network requested PDU session release procedure, the MAPDU will not be released and the MA PDU with 3GPP leg will continue to exist after the procedure.

[0038] In the third scenario, the PDU session is an MA PDU session and has user plane resources established only on non-3GPP access, and the access type IE is included in the PDU session release command message, and the access type IE indicates 3GPP access. If the UE aborts the UE-requested PDU session release procedure and only continues with the network-requested PDU session release procedure, the MAPDU will not be released and the MA PDU with non-3GPP leg will continue to exist after the procedure.

[0039] Therefore, in the above three cases, UE 301 selects option 1 and continues the UE-requested PDU session release procedure and the network-requested PDU session release procedure. To continue the network-requested PDU session procedure, in step 351, UE 301 sends a PDU SESSION RELEASE COMPLETE message in response to the PDU SESSION RELEASE COMMAND message sent by the network in step 331 to complete the network-requested PDU session release procedure for MA PDU. To continue the UE-requested PDU session procedure, in step 361, UE 301 receives a PDU SESSION RELEASE COMMAND message from the network, which carries PTI=77 and PSI=5 as a response to the PDU SESSION RELEASE REQUEST message sent by the UE in step 321. In step 362, the UE sends another PDU SESSION RELEASE COMPLETE message to the network to complete the UE-requested PDU session procedure for MA PDU. Note that the PDU release procedure requested by the network may only release part of the user plane resources of the MA PDU, and the remaining user plane resources of the MA PDU will be released by the PDU session release procedure requested by the UE.

[0040] In summary, if the Access Type IE is included in the PDU Session Release Command message and the PDU session is a MAPDU session and has user plane resources established on an access different from the access indicated in the Access Type IE in the PDU Session Release Command message, the UE 301 continues with the UE requested PDU session release procedure and the network requested PDU session release procedure. Otherwise, the UE 301 selects option 2. In step 381, the UE 301 aborts the UE requested PDU session release procedure and stops timer T3582. In step 382, ​​the UE 301 continues with the network requested PDU session procedure and sends a PDU Session Release Complete message in response to the PDU Session Release Command message sent by the network in step 331 to complete the network requested PDU session release procedure for the MA PDU. Note that step 382 may also occur before step 381.

[0041] Figure 4 Another embodiment of handling conflicts in the MA PDU session release process according to one novel aspect is illustrated. Steps 411 to 441 are similar to Figure 3 4. The process of step 311 to step 341 of the embodiment of the present invention is to establish an MA PDU session with PSI=5, and the UE 401 detects a conflict between the UE-requested PDU session procedure and the network-requested PDU session procedure for the same MA PDU session, and the UE 401 decides to continue both procedures. In order to continue the network-requested PDU session procedure, in step 451, the UE 401 sends a PDU session release complete message in response to the PDU session release command message sent by the network in step 431, thereby completing the network-requested PDU session release procedure for the MA PDU. In order to continue the UE-requested PDU session procedure, the UE 401 waits for another PDU session release command message carrying PTI=77 and PSI=5. Meanwhile, the timer T3582 continues to run. If the UE 401 does not receive the PDU session release command message when the timer expires, in step 461, the UE 401 retransmits another PDU session release request message carrying PTI=77, PSI=5. In step 462, UE 401 receives a PDU session release command message carrying PTI = 77 and PSI = 5 from the network. In step 463, UE 401 sends a PDU session release complete message to the network to complete the PDU session release process requested by the UE.

[0042] Figure 51 is a flowchart of a method for handling a conflict of an MA PDU session release procedure according to a novel aspect of the present invention. In step 501, the UE maintains an MA PDU session in a 5G system (5G system, 5GS). The MA PDU session has a PSI. In step 502, the UE sends a PDU session release request message to the 5GS for a UE-requested PDU session release procedure for the MA PDU session. The PDU session release request message indicates the PSI and the PTI value assigned by the UE. In step 503, the UE receives a PDU session release command message from the 5GS for a network-requested PDU session release procedure for the MA PDU session. In step 504, the UE detects a conflict between a UE-requested PDU session release procedure and a network-requested PDU session release procedure for the same MA PDU session. In step 505, the UE continues the UE-requested PDU session release procedure and the network-requested PDU session release procedure when the conditions are met, otherwise the UE-requested PDU session release procedure is terminated and the network-requested PDU session release procedure is continued.

[0043] Although the present invention has been described in conjunction with certain specific embodiments for guiding purposes, the invention is not limited thereto. Therefore, various modifications, amendments and combinations of the various features of the described embodiments may be implemented without departing from the scope of the invention as set forth in the claims.

Claims

1. A method for handling conflicts in a multiple access protocol data unit session release process, comprising: Maintaining a multiple access protocol data unit session by a user equipment in a 5G system, wherein the multiple access protocol data unit session has a protocol data unit session ID (PSI); Sending a release request message for a protocol data unit session release request procedure requested by a user equipment for the multiple access protocol data unit session to the 5G system, wherein the protocol data unit session release request message indicates the PSI and a procedure transaction ID (PTI) value allocated by the user equipment; receiving a protocol data unit session release command message from the 5G system for a network-requested protocol data unit session release procedure for the multiple access protocol data unit session; Detecting a conflict between a protocol data unit session release procedure requested by the user equipment and a protocol data unit session release procedure requested by the network for the same multi-access protocol data unit session; as well as When the conditions are met, the protocol data unit session release process requested by the user equipment and the protocol data unit session release process requested by the network are continued; otherwise, the protocol data unit session release process requested by the user equipment is terminated and the protocol data unit session release process requested by the network is continued, Wherein the condition is met when the multiple access protocol data unit has user plane resources established on one access type, and wherein an access type IE is included in the protocol data unit session release command message and indicates another access type.

2. The method according to claim 1, characterized in that The conflict is detected when the protocol data unit session release command message is received during a protocol data unit session release procedure requested by the user equipment.

3. The method according to claim 1, characterized in that The conflict is detected when the PTI IE of the protocol data unit session release command message is set to "unassigned process transaction identifier".

4. The method according to claim 1, characterized in that The condition is met when the multiple access protocol data unit has user plane resources established on both 3GPP and non-3GPP access, and wherein an access type IE is included in the protocol data unit session release command message and indicates a 3GPP-only or non-3GPP-only access type.

5. The method according to claim 1, characterized in that The condition is met when the multiple access protocol data unit has user plane resources established on a 3GPP access type, and wherein an access type IE is included in the protocol data unit session release command message and indicates a non-3GPP access type.

6. The method according to claim 1, characterized in that The condition is met when the multiple access protocol data unit has user plane resources established on a non-3GPP access type, and wherein an access type IE is included in the protocol data unit session release command message and indicates a 3GPP access type.

7. The method according to claim 1, characterized in that In response to the protocol data unit session release command, the user equipment sends a protocol data unit session release complete message to complete the protocol data unit session release process requested by the network.

8. The method according to claim 1, characterized in that In response to the protocol data unit session release request message, the user equipment receives a second protocol data unit session release command.

9. The method according to claim 8, characterized in that In response to the second protocol data unit session release command, the user equipment sends a second protocol data unit session release completion message to complete the protocol data unit session release process requested by the user equipment.

10. A user equipment for handling conflicts in a multiple access protocol data unit session release process, comprising: A protocol data unit session processing circuit, configured to maintain a multiple access protocol data unit session in a 5G system, wherein the multiple access protocol data unit session has a protocol data unit session ID (PSI); a transmitter, configured to send a release request message for a protocol data unit session release request procedure requested by a user equipment for the multiple access protocol data unit session to the 5G system, wherein the protocol data unit session release request message indicates the PSI and a procedure transaction ID (PTI) value allocated by the user equipment; a receiver, configured to receive a protocol data unit session release command message from a 5G system for a network requested protocol data unit session release procedure for the multiple access protocol data unit session; as well as a control circuit, configured to detect a conflict between a protocol data unit session release process requested by the user equipment and a protocol data unit session release process requested by the network for the same multi-access protocol data unit session, wherein the user equipment continues the protocol data unit session release process requested by the user equipment and the protocol data unit session release process requested by the network when a condition is met, otherwise the protocol data unit session release process requested by the user equipment is terminated and the protocol data unit session release process requested by the network is continued, Wherein the condition is met when the multiple access protocol data unit has user plane resources established on one access type, and wherein an access type IE is included in the protocol data unit session release command message and indicates another access type.

11. The user equipment according to claim 10, characterized in that: The conflict is detected when the protocol data unit session release command message is received during a protocol data unit session release procedure requested by the user equipment.

12. The user equipment according to claim 10, characterized in that The conflict is detected when the PTI IE of the protocol data unit session release command message is set to "unassigned process transaction identifier".

13. The user equipment according to claim 10, characterized in that The condition is met when the multiple access protocol data unit has user plane resources established on both 3GPP and non-3GPP access, and wherein an access type IE is included in the protocol data unit session release command message and indicates a 3GPP-only or non-3GPP-only access type.

14. The user equipment according to claim 10, characterized in that: The condition is met when the multiple access protocol data unit has user plane resources established on a 3GPP access type, and wherein an access type IE is included in the protocol data unit session release command message and indicates a non-3GPP access type.

15. The user equipment according to claim 10, characterized in that The condition is met when the multiple access protocol data unit has user plane resources established on a non-3GPP access type, and wherein an access type IE is included in the protocol data unit session release command message and indicates a 3GPP access type.

16. The user equipment according to claim 10, characterized in that In response to the protocol data unit session release command, the user equipment sends a protocol data unit session release complete message to complete the protocol data unit session release process requested by the network.

17. The user equipment according to claim 10, characterized in that In response to the protocol data unit session release request message, the user equipment receives a second protocol data unit session release command.

18. The user equipment according to claim 17, characterized in that In response to the second protocol data unit session release command, the user equipment sends a second protocol data unit session release completion message to complete the protocol data unit session release process requested by the user equipment.

19. A user equipment for handling conflicts in a multiple access protocol data unit session release process, comprising: The processor is coupled to the memory and the transceiver, and the memory stores program instructions and data. When the program instructions and data are executed by the processor, the user equipment executes the method described in any one of claims 1-9.

20. A non-volatile computer-readable storage medium storing program instructions and data, which, when executed by a processor of a user device that processes conflicts in a multiple access protocol data unit session release process, enables the user device to execute the method as described in any one of claims 1 to 9 above.

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