Wireless communication methods and corresponding user equipment

Abstract

This invention provides a wireless communication method and a corresponding user equipment. The wireless communication method includes: maintaining an MA PDU session by the user equipment in a 5G system; triggering a first PDU session release process by sending a PDU session release request message to the network; receiving a PDU session release command message from the network in response to the PDU session release request, wherein the PDU session release command message indicates the release of the entire MA PDU session; and maintaining user plane resources for the MA PDU session on 3GPP access, wherein the UE does not release the MA PDU session in response to the received PDU session release command message indicating the release of the entire MA PDU session. The wireless communication method and corresponding user equipment of this invention can correctly release the MA PDU session.

Description

[Technical Field]

[0001] The disclosed embodiments relate to wireless communication, and more specifically to a method for deactivation processing of a multi-access (MA) PDU session for a MAPDU with a PDN leg. [Background Technology]

[0002] 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 a simplified network architecture. LTE systems, also known as 4G systems, also provide seamless integration with legacy wireless networks such as GSM, CDMA, and Universal Mobile Telecommunications System (UMTS). In LTE systems, the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) comprises multiple evolved Node-Bs (eNodeBs or eNBs) that communicate with multiple mobile stations (called User Equipment (UEs)). 3GPP networks typically include a hybrid of 2G / 3G / 4G systems. The Next Generation Mobile Networks (NGMN) committee has decided to focus future NGMN activities on defining the end-to-end requirements for 5G New Radio (NR) systems (5GS). 5GS also integrates with legacy E-UTRAN (4G) systems.

[0003] In 5GS, a Protocol Data Unit (PDU) session defines the association between the UE and the data network providing PDU connectivity 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 can include multiple QoS flows and QoS rules. Each PDU session can be established via a 5G access network (e.g., a 3GPP radio access network (RAN) or via a non-3GPP access network). The network and / or the UE can initiate different PDU session procedures, such as PDU session establishment, PDU session modification, and PDU session release, to manage the activation, modification, and deactivation of 5GS PDU sessions. 4G EPS (EUTRAN connected to the EPC) can also be viewed as a "3GPP access" to the EPC.

[0004] Operators are seeking methods to balance data traffic between mobile networks and non-3GPP access in a way that is transparent to users and reduces mobile network congestion. A UE can simultaneously connect to 3GPP access (3GPP access for 5GS, or 3GPP access for EPC) and non-3GPP access (using NAS signalalling). 5GS can leverage these multiple accesses to improve user experience and optimize traffic allocation across various access types. Therefore, 3GPP introduced Multi-Access (MA) PDU sessions in 5GS. An MA PDU session can be configured to use one 3GPP access network or one non-3GPP access network at a time, or simultaneously use one 3GPP access network (4G or 5G) and one non-3GPP access network (5G).

[0005] In addition, ATSSS (Access Traffic Steering, Handover, Split) is an optional feature that UEs and the 5GC network can support to route data traffic across 3GPP access and non-3GPP access networks for established MA PDU sessions. UEs supporting ATSSS establish MA PDU sessions, supporting multiple access connections on both 3GPP and non-3GPP access networks. At any given time, an MA PDU session can establish user-plane resources on a 3GPP access (also known as a 3GPP tributary, such as the 3GPP 5GS tributary or the 3GPP EPS / PDN tributary), a non-3GPP access (also known as a non-3GPP tributary), or only on one access (3GPP access or non-3GPP access).

[0006] In some networks, LTE has a larger coverage area than NR, and when NR coverage is unavailable, the UE may sometimes be unable to establish 3GPP 5GS tributary user plane resources for an MA PDU session. Therefore, it is advantageous to establish a 4G EPSPDN connection as the user plane resource for the corresponding MA PDU session via 3GPP access (also known as a 3GPP PDN tributary). However, it is currently unclear how to release an MA PDU session with a 3GPP PDN tributary in 5GS. It is undefined whether a PDU session release procedure requested by the UE or network in 5GS can be used to release an MA PDU session with a 3GPP PDN tributary in 5GS. [Summary of the Invention]

[0007] The following overview is illustrative only and is not intended to be limiting in any way. That is, it is provided to introduce the concepts, key points, benefits, and advantages of the novel and progressive techniques described herein. The alternative implementations are further described in the detailed description below. Therefore, the following summary is not intended to identify essential features of the claimed subject matter, nor is it intended to define the scope of the claimed subject matter.

[0008] Based on exemplary embodiments of the present invention, the following methods and corresponding apparatus are proposed to solve the above-mentioned problems.

[0009] This invention provides a wireless communication method, comprising: maintaining a MA PDU session by a user equipment (UE) in a 5G system; triggering a first PDU session release process by sending a PDU session release request message to the network; receiving a PDU session release command message from the network in response to the PDU session release request, wherein the PDU session release command message indicates the release of the entire MA PDU session; and maintaining user plane resources for the MA PDU session on 3GPP access, wherein the UE does not release the MA PDU session in response to the received PDU session release command message indicating the release of the entire MA PDU session.

[0010] The present invention also provides a user equipment (UE), comprising: a protocol data unit (PDU) session processing circuit for maintaining a multiple access protocol data unit (MA PDU) session in a 5G system (5GS), wherein the UE also maintains a PDN connection established as user plane resources of the MA PDU session on 3GPP access; a transmitter for sending a PDU session release request message to the network and triggering a first PDU session release process; a receiver for receiving a PDU session release command message from the network in response to the PDU session release request, wherein the PDU session release command message indicates the release of the entire MA PDU session; and a control circuit for retaining the user plane resources of the MA PDU session on 3GPP access, wherein the UE does not release the MA PDU session in response to the received PDU session release command message indicating the release of the entire MA PDU session.

[0011] The present invention also provides a wireless communication method, comprising: maintaining a Multiple Access Protocol Data Unit (MAPDU) session established by a network entity and a user equipment (UE) in a 5G system (5GS), wherein a PDN connection is established as a user plane resource for the MA PDU session on 3GPP access; and triggering a network request process to release the PDN connection and user plane resources of the MAPDU session on 3GPP access.

[0012] The following embodiments will be described in detail with reference to the accompanying drawings. [Attached Image Description]

[0013] The accompanying drawings are included to provide a further understanding of this disclosure, and are incorporated in and constitute a part of this disclosure. The drawings illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure. It is understood that the drawings are not necessarily drawn to scale, as some components may be shown out of proportion to actual dimensions in order to clearly illustrate the concepts of the disclosure.

[0014] Figure 1 An exemplary 5G network supporting Multi-Access (MA) Protocol Data Unit (PDU) session management according to a novel aspect is illustrated, along with a method for releasing an MA PDU session having a PDN connection established as a user plane resource of the MA PDU.

[0015] Figure 2 A simplified block diagram of a wireless device according to an embodiment of the present invention is shown.

[0016] Figure 3 Different scenarios are illustrated for handling PDU session release commands for MA PDU sessions with non-3GPP 5GS tributaries and 3GPP PDN / 5GS tributaries.

[0017] Figure 4 It is a sequence stream of the UE and 5GS used for the UE-initiated MA PDU session release procedure based on a novel aspect.

[0018] Figure 5 It is a sequence stream between the UE and 5GS based on a novel aspect of the NW-initiated MA PDU session release procedure.

[0019] Figure 6 This is a flowchart of a method for handling the MA PDU session release process from the UE's perspective, according to a novel aspect of the present invention.

[0020] Figure 7 This is a flowchart of a method for handling the MA PDU session release process from an NW perspective according to a novel aspect of the present invention.

Detailed Implementation Methods

[0021] Reference will now be made in detail to some embodiments of the invention, examples of which are shown in the accompanying drawings.

[0022] Figure 1An exemplary 5G network 100 supporting Multi-Access (MA) Protocol Data Unit (PDU) session management according to a novel aspect is illustrated, along with a method for releasing an MA PDU session with a PDN connection established as a user plane resource of the MA PDU. The 5G New Radio (NR) network 100 includes a User Equipment (UE) 101, a 3GPP access 102 (e.g., 3GPP NR or EUTRAN radio access network (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 Interoperability Function (N3IWF) 112, a User Plane Function (UPF) 113, and a 5G Core (5GC) data network 120. The AMF 110 communicates with the base station 102, SMF 111, and UPF 113 in the 3GPP access for access and mobility management of the radio access devices in the 5G network 100. SMF 111 is primarily responsible for interacting with the decoupled data plane, creating, updating, and deleting PDU sessions, and managing session contexts with UPF 113. N3IWF 112 connects to the 5G core network control plane functions and is responsible for routing messages outside the 5G RAN.

[0023] In the Access Stratum (AS) layer, the RAN provides radio access to UE 101 via radioaccess technology (RAT). In the Non-Access Stratum (NAS) layer, AMF 110 and SMF 111 communicate with the RAN and 5GC for access and mobility management of radio access devices in the 5G network 100, as well as PDU session management. 3GPP Access 102 may include a base station (gNB or eNB) that provides radio access to UE 101 via various 3GPP RATs, including 5G, 4G, and 3G / 2G. Non-3GPP Access 103 may include an Access Point (AP) that provides radio access to UE 101 via a non-3GPP RAT, including WiFi. UE 101 can obtain access to the data network 120 through 3GPP Access 102, AMF 110, SMF 111, and UPF 113. UE 101 can obtain access to data network 120 via non-3GPP access 103, N3IWF 112, AMF110, SMF 111, and UPF 113. UE 101 can 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 can be a smartphone, wearable device, Internet of Things (IoT) device, tablet computer, etc.

[0024] In 5G, a PDU session defines the association between a UE and the data network providing PDU connectivity services. Each PDU session is identified by a PDU session ID and can include multiple QoS flows and QoS rules. Each PDU session can be established via 3GPP RAN or non-3GPP access. 5G session management (5GSM) for PDU sessions via 3GPP and non-3GPP access is managed by the AMF and SMF through NAS signaling. In 5GS, a UE can connect to both 3GPP and non-3GPP access simultaneously (using NAS signaling), thus enabling 5GS to leverage these multiple access methods to improve user experience and optimize traffic distribution among various access methods. Therefore, 3GPP introduced MA PDU sessions in 5GS. An MA PDU session uses one 3GPP access network or one non-3GPP access network at a time, or simultaneously uses one 3GPP access network and one non-3GPP access network.

[0025] For MA PDU sessions accessed via 3GPP, user plane resources need to be established on the 3GPP access (also known as the 3GPP 5GS tributary). For MA PDU sessions based on non-3GPP access, user plane resources need to be established on the non-3GPP access (also known as the non-3GPP 5GS tributary). It has been observed that 4G EPS PDN connections can be established as user plane resources for corresponding MA PDU sessions accessed via 3GPP (also known as the 3GPP PDN tributary). However, it is unclear how to deactivate or release MA PDU sessions with 3GPP PDN tributaries. Whether the UE / network-requested PDU session release procedure in 5GS can be used to release MA PDU sessions with 3GPP PDN tributaries is undefined.

[0026] Based on a novel aspect, a method for handling the deactivation of MA PDU sessions with 3GPP PDN tributaries is proposed. Figure 1In the example, UE 101 establishes and maintains an MA PDU (130) in 5GS via 3GPP access and non-3GPP access, and the MA PDU session has one 3GPP PDN tributary and one non-3GPP (WiFi) tributary. When the network or UE wants to deactivate and release the MA PDU session, it needs to send a PDU SESSION RELEASE COMMAND to the UE. For an MA PDU session, the PDU SESSION RELEASE COMMAND may contain an ACESS TYPE Information Element (IE), which indicates which tributary / access type to release for the MA PDU session. If the PDU SESSION RELEASE COMMAND message does not contain an ACESS TYPE Information Element (IE), in the original MA PDU session signaling design, this means that the network wants to release the entire MA PDU session and all (one or two) tributaries using a single PDU SESSION RELEASE COMMAND message, regardless of the message's purpose. However, 3GPP PDN tributaries are not considered purely typical / classic 5GS PDU session tributaries. Therefore, excluding ACCESS TYPE IE (which means releasing both types of access), if the 3GPP tributary is a 4G / EPS PDN tributary, UE 101 does not release the 3GPP PDN tributary, does not release the MA PDU session, but only releases the non-3GPP 5GS tributary.

[0027] To release a 5GS MA PDU session with an EPS PDN connection established as a user plane resource via 3GPP access, two actions are required. The first / second action is to release the PDN connection established as a user plane resource of the MA PDU session (131). The second / first action is to release the user plane resource (if any) established on a non-3GPP access of the MA PDU session (132). For network-triggered MA PDU release, the network initiates an EPS bearer context deactivation or deactivation procedure under the first / second action and a PDU session release procedure excluding the ACCESS TYPE IE under the second / first action. For UE-triggered MA PDU release, the UE initiates a PDN disconnection or deactivation procedure under the first / second action and a PDU session release procedure under the second / first action. Note that the UE (or network) can also initiate both the PDN disconnection / deactivation procedure and the PDU session release procedure simultaneously.

[0028] Figure 2A simplified block diagram of a wireless device, such as a UE 201 and a network entity 211, according to an embodiment of the present invention is illustrated. Network entity 211 may be a base station and / or an AMF / SMF. Network entity 211 has an antenna 215 for transmitting and receiving radio signals. An RF transceiver module 214 coupled to the antenna receives RF signals from the antenna 215, converts them into baseband signals, and sends them to a processor 213. The RF transceiver 214 also converts baseband signals received from the processor 213, converts them into RF signals, and sends them to the antenna 215. The processor 213 processes the received baseband signals and invokes different functional modules to execute features in the base station 211. Memory 212 stores program instructions and data 220 to control the operation of the base station 211. Figure 2 In one example, network entity 211 also includes a protocol stack 280 and a set of control function modules and circuits 290. Protocol stack 280 includes a Non-Access Stratum (NAS) layer to communicate with AMF / SMF / MME entities connected to the core network, a Radio Resource Control (RRC) layer for higher-layer configuration and control, a Packet Data Convergence Protocol / Radio Link Control (PDCP / RLC) layer, a Media Access Control (MAC) layer, and an entity (PHY) layer. In one example, 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 various parameters to configure and control UE-related functions, including mobility management and PDU session management.

[0029] Similarly, UE 201 has memory 202, processor 203, and radio frequency (RF) transceiver module 204. RF transceiver 204 is coupled to antenna 205, receives RF signals from antenna 205, converts them into baseband signals, and sends them to processor 203. RF transceiver 204 also converts baseband signals received from processor 203 into RF signals and sends them to antenna 205. Processor 203 processes the received baseband signals and invokes different functional modules and circuits to execute features in UE 201. Memory 202 stores data and program instructions 210 to be executed by the processor to control the operation of UE 201. Suitable processors include, for example, dedicated processors, digital signal processors (DSPs), multiple microprocessors, one or more microprocessors associated with a DSP core, controllers, microcontrollers, application-specific integrated circuits (ASICs), file-programmable gate array (FPGA) circuits, and other types of integrated circuits (ICs) and / or state machines. Software-associated processors can be used to implement and configure features of UE 201.

[0030] UE 201 also includes a protocol stack 260 and a set of control function modules and circuitry 270. Protocol stack 260 includes a NAS layer for communicating with AMF / SMF / MME entities connected to the core network, an RRC layer for higher-level configuration and control, a PDCP / RLC layer, a MAC layer, and a PHY layer. Control function modules and circuitry 270 can be implemented and configured through software, firmware, hardware, and / or a combination thereof. The control function modules and circuitry cooperate with each other when executed by the processor via program instructions contained in memory to allow UE 201 to perform implementations and functional tasks and features within the network.

[0031] In one example, the control function module and circuit 270 includes a PDU session processing circuit 271 that utilizes the network to perform MA PDU session establishment, modification, and release procedures, and a configuration and control circuit 272 that processes configuration and control parameters for mobility management and session management. When the UE receives a PDU SESSION RELEASE COMMAND message with an MA PDU session with a PDN tributary, the UE completes the PDU session release procedure for the non-3GPP tributary and simultaneously initiates a PDN disconnect or separation procedure to release the user plane resources of the 3GPP PDN tributary of the MA PDU session.

[0032] Figure 3Different scenarios are illustrated for handling PDU session release commands for MA PDU sessions with both non-3GPP 5GS tributaries and 3GPP PDN / 5GS tributaries. In the first example depicted in 310, the UE maintains an MA PDU session with both 3GPP 5GS tributaries and non-3GPP 5GS tributaries. When the UE receives a PDU SESSION RELEASECOMMAND without an ACCESS TYPE IE, this means the MA PDU should be released for both access types. As a result, the UE releases user plane resources for both 3GPP and non-3GPP access. The entire MA PDU session, including both 3GPP 5GS and non-3GPP 5GS tributaries, is then released. In the second example depicted in 320, the UE maintains an MA PDU session with both 3GPP PDN and non-3GPP 5GS tributaries. When the UE receives a PDU SESSION RELEASECOMMAND without an ACCESS TYPE IE, this means the MA PDU should be released for both access types. However, the PDN tributary is not considered a legacy / typical / classic PDU session in 5GS. Therefore, the UE retains user plane resources for 3GPP access and releases user plane resources for non-3GPP access. The MA PDU session is not released and still has the 3GPP PDN tributary. In the third example depicted in 330, the UE maintains an MA PDU session with both 3GPP PDN tributary and non-3GPP 5GS tributary. When the UE sends a PDU SESSIONRELEASE COMMAND to the network (step 1) and receives a PDU SESSION RELEASE COMMAND from the network without an ACCESS TYPE IE (step 2), this means the MA PDU should be released for both access types. However, the PDN tributary is not considered a legacy / typical / classic PDU session in 5GS. Therefore, the UE retains user plane resources for 3GPP access and releases user plane resources for non-3GPP access. The MA PDU session is not released and still has the 3GPP PDN tributary.

[0033] Figure 4This is a sequence stream of a UE-initiated MA PDU session release procedure between the UE and 5GS, based on a novel aspect. In step 411, UE 401 maintains an MA PDU session in 5GS, which has a 3GPP PDN tributary and a non-3GPP 5GS tributary. For a UE-initiated MA PDU session release procedure with a PDN tributary, the UE needs to initiate two separate procedures. In step 412, UE 401 initiates a first UE-requested PDU session release procedure in 5GS to deactivate (release) the MA PDU session by sending a PDUSESSION RELEASE REQUEST to the network. In step 413, UE 401 receives a PDU SESSION RELEASE COMMAND from the network, which does not include an ACCESS TYPE IE. In response to the PDU SESSION RELEASE COMMAND, in step 421, UE 401 releases the non-3GPP tributary but retains the 3GPP PDN tributary (because it is not considered a traditional / typical / classic 5GS PDU session). To release the entire MA PDU session, in step 431, UE 401 initiates a second procedure. If (the UE and MME support EMM-REGISTERED without a PDN connection) or (the PDN connection is not the last PDN connection), UE 401 initiates a second UE-requested PDN disconnection procedure by sending a PDN DISCONNECT REQUEST message to the network. In step 432, UE 401 receives a DEACTIVATE EPSBEARER CONTEXT REQUEST message for the default EPS bearer context of the PDN connection and then releases the PDN tributary. Otherwise, UE 401 initiates a second UE-initiated disconnection procedure by sending a DETACHREQUEST message to the network. In step 432, UE 401 receives a DETACH(ACCEPT) message from the network and releases the PDN tributary. In step 441, the entire MA PDU session is released.

[0034] Figure 5This is a sequence flow between the UE and 5GS based on a novel aspect of the NW-initiated MA PDU session release procedure. In step 511, UE 501 maintains an MA PDU session in 5GS, which has a 3GPP PDN tributary and a non-3GPP 5GS tributary. For an NW-initiated MA PDU session procedure with a PDN tributary, the network needs to initiate two separate procedures. In step 512, the network initiates a first NW-requested PDU session release procedure in 5GS to deactivate the MA PDU session by sending a PDUSESSION RELEASE COMMAND to UE 501, which does not include ACCESS TYPE IE. In response to the PDUSESSION RELEASE COMMAND, in step 521, UE 501 releases the non-3GPP tributary but retains the 3GPP PDN tributary (because it is not considered a legacy / typical / classic 5GS PDU session). To release the entire MA PDU session, in step 531, the network initiates a second procedure. If (UE and MME support EMM-REGISTERED without PDN connection) or (PDN connection is not the last PDN connection), the network initiates a second NW-requested PDN disconnection procedure (EPS deactivation procedure and release of PDN branch) by sending a DEACTIVATE EPSBEARER CONTEXT REQUEST message with the default EPS bearer context of the PDN connection to UE 501. Otherwise, the network initiates a second NW-initiated disconnection procedure by sending a DETACH REQUEST message to UE 501 and releases the PDN branch. In step 541, the entire MA PDU session is released.

[0035] Figure 6 This is a flowchart of a method for handling the MA PDU session release process from the UE's perspective according to a novel aspect of the present invention. In step 601, the UE maintains a Multiple Access Protocol Data Unit (MAPDU) session in a 5G system (5GS). The UE establishes a PDN connection as user plane resources for the MA PDU session on 3GPP access. In step 602, the UE triggers a first PDU session release process by sending a PDU session release request message to the network. In step 603, the UE receives a PDU session release command message from the network in response to the PDU session release request, wherein the PDU session release command indicates the release of the entire MA PDU session, for example, by not including an Access Type Information Element (IE). In step 604, the UE retains the user plane resources for the MAPDU session on 3GPP access, wherein the UE does not release the MA PDU session in response to the received PDU session release command message indicating the release of the MA PDU session.

[0036] Figure 7 This is a flowchart of a method for handling the MA PDU session release process from an NW perspective according to a novel aspect of the present invention. In step 701, the network entity maintains a Multiple Access Protocol Data Unit (MA PDU) session established by a User Equipment (UE) in a 5G system (5GS). A PDN connection is established as a user plane resource for the MA PDU session on 3GPP access. In step 702, the network entity triggers a network request process to release the PDN connection and user plane resources of the MA PDU session on 3GPP access.

[0037] Although the invention has been described in conjunction with specific embodiments for illustrative purposes, it is not limited thereto. Therefore, various modifications, adaptations, and combinations of the features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.

[0038] While the invention has been described by way of example and according to preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments. Rather, it is intended to cover various modifications and similar arrangements (which will be apparent to those skilled in the art). Therefore, the scope of the appended claims should be given the broadest interpretation to cover all such modifications and similar arrangements.

[0039] Although this application has been described by way of example and according to preferred embodiments, it should be understood that this application is not limited thereto. Various changes and modifications can be made by those skilled in the art without departing from the scope and spirit of this application. Therefore, the scope of this application should be defined and protected by the appended claims and their equivalents.

[0040] Some embodiments can be described in the general context of calculator executable instructions (e.g., program modules) executed by one or more calculators or other devices. Typically, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. Typically, in various embodiments, the functionality of program modules can be combined or distributed as needed.

[0041] The subjects described herein sometimes illustrate different components contained within or connected to other different components. It should be understood that the architectures depicted are merely exemplary, and many other architectures can actually be implemented to achieve the same functionality. Conceptually, any arrangement of components achieving the same function is effectively “associated” to achieve the desired function. Therefore, any two components combined in this document to obtain a particular function can be considered “associated” with each other to achieve the desired function, regardless of the architecture or intermediate components. Similarly, any two such associated components can also be considered “operably connected” or “operably coupled” with each other to achieve the desired function, and any two components that can be suchly associated can also be considered “operably coupled” with each other to achieve the desired function. Specific examples of “operably coupled” include, but are not limited to: physically connectable and / or physically interacting components, and / or wirelessly interactable and / or logically interactable components.

[0042] Furthermore, regarding the use of virtually any plural term in the text, those skilled in the art may convert plural to singular and / or singular to plural, provided that it is appropriate for the context and / or application.

[0043] Those skilled in the art will understand that, generally, the terms used herein, particularly those used in the appended claims (e.g., the subject of the appended claims), are intended as “open-ended” terms (e.g., the term “comprising” should be interpreted as “comprising but not limited to,” the term “having” should be interpreted as “at least having,” the term “comprising” should be interpreted as “comprising but not limited to,” etc.). Those skilled in the art will also understand that if a specific number of the objects of the claims is intended, such intention will be explicitly stated in the claims; in the absence of such a statement, such intention does not exist. For example, to aid understanding, the appended claims may include the use of introductory phrases such as “at least one” and “one or more” to introduce the objects of the claims. However, the use of such phrases should not be interpreted as limiting any claim containing such an indefinite article "a (a) or an" to an invention containing only one such claim, even if the same claim contains the introductory phrases "one or more" or "at least one" and indefinite articles such as "a (a)" or "an" (e.g., "a (a)" and / or "an" should generally be interpreted as meaning "at least one" or "one or more"); the same applies to the use of definite articles to introduce the claim. Furthermore, even if a specific number of the claimed claims is explicitly stated, those skilled in the art will recognize that such a statement should generally be interpreted as meaning at least the stated number (e.g., a statement containing only "two claims" without other modifiers generally means at least two claims, or two or more claims). Furthermore, when using idioms such as "at least one of A, B, and C," such a structure is generally intended to convey the meaning of the idiom as understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" would include, but is not limited to, systems having a single A, a single B, a single C, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). When using idioms such as "at least one of A, B, or C," such a structure is generally intended to convey the meaning of the idiom as understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" would include, but is not limited to, systems having a single A, a single B, a single C, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). A person skilled in the art will further understand that, whether in the specification, claims, or drawings, virtually arbitrary extractives and / or phrases representing two or more alternative terms should be understood to consider the possibility of including one, any, or all two terms.For example, the phrase “A or B” should be understood as including the possibility of “A”, “B”, or “A and B”.

[0044] Although various methods, apparatuses, and systems have been used to describe and illustrate exemplary techniques herein, those skilled in the art will understand that various other modifications and equivalent substitutions can be made without departing from the claimed subject matter. Furthermore, many modifications can be made to adapt particular situations to the teachings of the claimed subject matter without departing from the central concept described herein. Therefore, it is intended that the claimed subject matter is not limited to the specific examples disclosed, and that such claimed subject matter may also include all implementations and their equivalents falling within the scope of the appended claims.

Claims

1. A wireless communication method, comprising: In a 5G system, a user equipment maintains a multi-access protocol data unit session, wherein the user equipment has established a PDN connection as a user plane resource for the multi-access protocol data unit session on 3GPP access. The first protocol data unit session release process is triggered by sending a protocol data unit session release request message to the network; Receive from the network a Protocol Data Unit Session Release Command Message in response to the Protocol Data Unit Session Release Request, wherein the Protocol Data Unit Session Release Command Message indicates the release of the entire Multiple Access Protocol Data Unit Session; as well as The user plane resources for the Multi-Access Protocol Data Unit (MIU) session on 3GPP access are maintained, wherein the user equipment does not release the MMU session in response to a received instruction to release the entire MMU session via a MMU session release command message.

2. The wireless communication method of claim 1, wherein the release of the entire multi-access protocol data unit session is indicated by not including an access type information element in the protocol data unit session release command message.

3. The wireless communication method of claim 1, wherein the user equipment triggers a second process to release the user plane resources for the multiple access protocol data unit session on 3GPP access.

4. The wireless communication method as described in claim 3, wherein, The user equipment initiates a PDN disconnection process by sending a PDNDISCONNECT REQUEST message to the network.

5. The wireless communication method as described in claim 3, wherein, The user equipment initiates the separation process by sending a DETACHREQUEST message to the network.

6. The wireless communication method as described in claim 3, wherein, After releasing the PDN connection, the user equipment releases the entire Multi-Access Protocol Data Unit session.

7. The wireless communication method as described in claim 1, wherein, The user equipment also has user plane resources for establishing the multi-access protocol data unit session for non-3GPP access.

8. The wireless communication method of claim 7, wherein the user equipment releases the user plane resources for the Multi-Access Protocol Data Unit (MINU) session on a non-3GPP access in response to the received MINU session release command message.

9. A user equipment, comprising: Protocol data unit session processing circuitry is used to maintain multiple access protocol data unit sessions in a 5G system, wherein the user equipment also maintains PDN connections established as user plane resources for multiple access protocol data unit sessions on 3GPP access. The transmitter sends a Protocol Data Unit Session Release Request message to the network and triggers the first Protocol Data Unit Session Release process; The receiver receives from the network a Protocol Data Unit Session Release Command Message in response to the Protocol Data Unit Session Release Request, wherein the Protocol Data Unit Session Release Command Message indicates the release of the entire Multiple Access Protocol Data Unit Session. as well as The control circuit retains the user plane resources of the Multi-Access Protocol Data Unit (MINU) session on the 3GPP access, wherein the user equipment does not release the MINU session in response to a received instruction to release the entire MINU session via the MINU session release command message.

10. The user equipment of claim 9, wherein the release of the entire multi-access protocol data unit session is indicated by not including an access type information element in the protocol data unit session release command message.

11. The user equipment as claimed in claim 9, wherein, The user equipment triggers a second process to release the user plane resources used for the multi-access protocol data unit session on 3GPP access.

12. The user equipment as claimed in claim 11, wherein, The user equipment initiates a PDN disconnection process by sending a PDNDISCONNECT REQUEST message to the network.

13. The user equipment as claimed in claim 11, wherein, The user equipment initiates the separation process by sending a DETACHREQUEST message to the network.

14. The user equipment as claimed in claim 11, wherein, After releasing the PDN connection, the user equipment releases the entire Multi-Access Protocol Data Unit session.

15. The user equipment of claim 9, wherein the multi-access protocol data unit session has user plane resources established on a non-3GPP access.

16. The user equipment as claimed in claim 15, wherein, The user equipment releases the user plane resources for the Multi-Access Protocol Data Unit session used on non-3GPP access in response to the received Protocol Data Unit Session Release Command message.

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