Deregistration procedure optimization for energy sensitive user equipment

Abstract

A method performed by a user equipment (UE) is provided. The method includes sending at least one registration request to register the UE via at least one access network to the core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE. The method includes establishing, with the core network, at least one packet data unit (PDU) session across the at least one access network. And the method includes releasing the at least one PDU session across the at least one access network. Release of the at least one PDU session triggers the core network to start the at least one timer, and expiration of the at least one timer triggers the core network to implicitly deregister the UE via the at least one access network to the core network.

Description

DEREGISTRATION PROCEDURE OPTIMIZATION FOR ENERGY SENSITIVE USER EQUIPMENT TECHNOLOGICAL FIELD

[0001] The present disclosure relates generally to telecommunications and, in particular, to registration of a user equipment (UE) to a core network.BACKGROUND

[0002] A telecommunications system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations and / or other nodes by providing carriers between the various entities involved in the communications path. A telecommunications system can be provided for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, video, electronic mail (email), text message, multimedia and / or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

[0003] In a wireless telecommunications system, at least a part of a communication session between at least two stations occurs over a wireless link. Examples of wireless telecommunications systems comprise public land mobile networks (PLMN), satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). Some wireless systems can be divided into cells, and are therefore often referred to as cellular systems.

[0004] A user can access the telecommunications system by means of an appropriate communication device or terminal. A communication device of a user may be referred to as user equipment (UE) or user device. A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users. The communication device may access a carrier provided by a station, for example a base station of a cell, and transmit and / or receive communications on the carrier.

[0005] The telecommunications system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the communication system are permitted to do and how operations should be achieved. Communication protocols and / or parameters which shall be used for connection of the various entities are also typically defined. One example of a telecommunications system is the Universal Mobile Telecommunications System (UMTS). Other examples of telecommunications systems are Long-Term Evolution (LTE), LTE Advanced and the so-called 5G or New Radio (NR) networks. NR is being standardized by the 3rd Generation Partnership Project (3GPP).BRIEF SUMMARY

[0006] Example implementations of the present disclosure are directed to telecommunications and, in particular, to registration of a user equipment (UE) to a core network. The present disclosure includes, without limitation, the following example implementations.

[0007] Some example implementations provide an apparatus comprising: at least one processor; and at least one memory storing instructions of a user equipment (UE), the instructions when executed by the at least one processor causing the apparatus to perform operations, the operations comprising: registering the UE via a first access network to a core network; deciding to connect to a second access network; and sending a registration request to register the UE via the second access network to the core network, the registration request including at least one indication for at least single-access only registration that is to trigger the core network to implicitly deregister the UE via the first access network to the core network when the UE is registered via the second access network to the core network.

[0008] Some example implementations provide a method performed by a user equipment (UE), the method comprising: registering the UE via a first access network to a core network; deciding to connect to a second access network; and sending a registration request to register the UE via the second access network to the core network, the registration request including at least one indication for at least singleaccess only registration that is to trigger the core network to implicitly deregister the UE via the first access network to the core network when the UE is registered via the second access network to the core network.

[0009] Some example implementations provide an apparatus comprising: at least one processor; and at least one memory storing instructions, the instructions when executed by the at least one processor causing the apparatus to perform operations, the operations comprising: performing a registration of a user equipment (UE) via first access network to a core network; receiving a registration request to register the UE via a second access network to the core network, the registration request including at least one indication for at least single-access only registration; performing, based on the registration request, a registration of the UE via the second access network to the core network; and implicitly deregistering, when the UE is registered via the second access network to the core network, and based on the at least one indication for at least single-access only registration in the registration request, the UE via the first access network to the core network.

[0010] Some example implementations provide a method comprising: performing a registration of a user equipment (UE) via first access network to a core network; receiving a registration request to register the UE via a second access network to the core network, the registration request including at least one indication for at least single-access only registration; performing, based on the registration request, a registration of the UE via the second access network to the core network; and implicitly deregistering, when the UE is registered via the second access network to the core network, and based on the at least one indication for at least single-access only registration in the registration request, the UE via the first access network to the core network.

[0011] Some example implementations provide an apparatus comprising: at least one processor; and at least one memory storing instructions of a user equipment (UE), the instructions when executed by the at least one processor causing the apparatus to perform operations, the operations comprising: sending at least one registration request to register the UE via at least one access network to the core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE; establishing, with the core network, at least one packet data unit (PDU) session across the at least one access network; and releasing the at least one PDU session across the at least one access network, wherein release of the at least one PDU session triggers the core network to start the at least one timer, and expiration of the at least one timer triggers the core network to implicitly deregister the UE via the at least one access network to the core network.

[0012] Some example implementations provide a method performed by a user equipment (UE), the method comprising: sending at least one registration request to register the UE via at least one access network to the core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE; establishing, with the core network, at least one packet data unit (PDU) session across the at least one access network; and releasing the at least one PDU session across the at least one access network, wherein release of the at least one PDU session triggers the core network to start the at least one timer, and expiration of the at least one timer triggers the core network to implicitly deregister the UE via the at least one access network to the core network.

[0013] Some example implementations provide an apparatus comprising: at least one processor; and at least one memory storing instructions, the instructions when executed by the at least one processor causing the apparatus to perform operations, the operations comprising: receiving at least one registration request to register a user equipment (UE) via at least one access network to a core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE; receiving information that indicates release of at least one packet data unit (PDU) session of the UE across the at least one access network; starting, based on the release of the at least one PDU session, the at least one timer associated with the implicit deregistration of the UE; and implicitly deregistering the UE via the at least one access network to the core network triggered when the at least one timer expires.

[0014] Some example implementations provide a method comprising: receiving at least one registration request to register a user equipment (UE) via at least one access network to a core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE; receiving information that indicates release of at least one packet data unit (PDU) session of the UE across the at least one access network; starting, based on the release of the at least one PDU session, the at least one timer associated with the implicit deregistration of the UE; andimplicitly deregistering the UE via the at least one access network to the core network triggered when the at least one timer expires.

[0015] Some example implementations provide an apparatus comprising: at least one processor; and at least one memory storing instructions of a user equipment (UE), the instructions when executed by the at least one processor causing the apparatus to perform operations, the operations comprising: registering the UE via at least one access network to the core network; determining at least one timer associated with at least one packet data unit (PDU) session based on data to be communicated on the at least one PDU session across the at least one access network; and sending at least one PDU session establishment request to establish the at least one PDU session with the core network for the communication of the data, the request to establish the at least one PDU session including information that indicates the at least one timer which triggers the core network to start the at least one timer, and release the at least one PDU session when the at least one timer expires.

[0016] Some example implementations provide a method performed by a user equipment (UE), the method comprising: registering the UE via at least one access network to the core network; determining at least one timer associated with at least one packet data unit (PDU) session based on data to be communicated on the at least one PDU session across the at least one access network; and sending at least one PDU session establishment request to establish the at least one PDU session with the core network for the communication of the data, the request to establish the at least one PDU session including information that indicates the at least one timer which triggers the core network to start the at least one timer, and release the at least one PDU session when the at least one timer expires.

[0017] Some example implementations provide an apparatus comprising: at least one processor; and at least one memory storing instructions, the instructions when executed by the at least one processor causing the apparatus to perform operations, the operations comprising: receiving, from a user equipment (UE), at least one packet data unit (PDU) session establishment request to establish at least one PDU session, the at least one PDU session establishment request including at least one timer associated with the at least one PDU session; starting, based on establishment of the at least one PDU session, the at least one timer associated with the at least one PDU session; and releasing at least one PDU session when the at least one timer expires.

[0018] Some example implementations provide a method comprising: receiving, from a user equipment (UE), at least one packet data unit (PDU) session establishment request to establish at least one PDU session, the at least one PDU session establishment request including at least one timer associated with the at least one PDU session; starting, based on establishment of the at least one PDU session, the at least one timer associated with the at least one PDU session; and releasing at least one PDU session when the at least one timer expires.

[0019] These and other features, aspects, and advantages of the present disclosure will be apparent from a reading of the following detailed description together with the accompanying figures, which are briefly described below. The present disclosure includes any combination of two, three, four or more features or elements set forth in this disclosure, regardless of whether such features or elements are expressly combined or otherwise recited in a specific example implementation described herein. The present disclosure is intended to be read holistically such that any separable features or elements of the disclosure, in any of its aspects and example implementations, should be viewed as combinable unless the context of the disclosure clearly dictates otherwise.

[0020] It will therefore be appreciated that this Brief Summary is provided merely for purposes of summarizing some example implementations so as to provide a basic understanding of some aspects of the disclosure. Accordingly, it will be appreciated that the above described example implementations are merely examples and should not be construed to narrow the scope or spirit of the disclosure in any way. Other example implementations, aspects and advantages will become apparent from the following detailed description taken in conjunction with the accompanying figures which illustrate, by way of example, the principles of some described example implementations.BRIEF DESCRIPTION OF THE FIGURE(S)

[0021] Having thus described example implementations of the disclosure in general terms, reference will now be made to the accompanying figures, which are not necessarily drawn to scale, and wherein:

[0022] FIG. 1 illustrates a telecommunications system that includes one or more public land mobile networks (PLMNs) coupled to one or more external data networks, according to some example implementations of the present disclosure;

[0023] FIG. 2 illustrates a deployment of a PLMN, according to some example implementations;

[0024] FIG. 3 is a signaling chart of a registration procedure with single-access only registration and packet data unit (PDU) session switching, according to some example implementations;

[0025] FIG. 4 is a signaling chart of a registration procedure with a timer associated with implicit deregistration, according to some example implementations;

[0026] FIG. 5 is a signaling chart of a PDU session establishment procedure with a timer associated with at least one PDU session, according to some example implementations;

[0027] FIG. 6 is a flowchart illustrating various steps in a method performed by a user equipment (UE), according to various example implementations;

[0028] FIGS. 7A and 7B are flowcharts illustrating various steps in a method according to various example implementations;

[0029] FIGS. 8A and 8B are flowcharts illustrating various steps in a method performed by a UE, according to various example implementations;

[0030] FIGS. 9A, 9B, 9C and 9D are flowcharts illustrating various steps in a method according to various example implementations;

[0031] FIGS. 10A and 10B are flowcharts illustrating various steps in a method performed by a UE, according to various example implementations;

[0032] FIG. 11 is a flowchart illustrating various steps in a method according to various example implementations; and

[0033] FIG. 12 illustrates an apparatus according to some example implementations.DETAILED DESCRIPTION

[0034] Some implementations of the present disclosure will now be described more fully hereinafter with reference to the accompanying figures, in which some, but not all implementations of the disclosure are shown. Indeed, various implementations of the disclosure may be embodied in many different forms and should not be construed as limited to the implementations set forth herein; rather, these example implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like elements throughout.

[0035] Unless specified otherwise or clear from context, references to first, second or the like should not be construed to imply a particular order. A feature described as being above another feature (unless specified otherwise or clear from context) may instead be below, and vice versa; and similarly, features described as being to the left of another feature else may instead be to the right, and vice versa. Also, while reference may be made herein to quantitative measures, values, geometric relationships or the like, unless otherwise stated, any one or more if not all of these may be absolute or approximate to account for acceptable variations that may occur, such as those due to engineering tolerances or the like.

[0036] As used herein, unless specified otherwise or clear from context, the "or” of a set of operands is the "inclusive or” and thereby true if and only if one or more of the operands is true, as opposed to the "exclusive or” which is false when all of the operands are true. Thus, for example, "[A] or [B]” is true if [A] is true, or if [B] is true, or if both [A] and [B] are true. Further, the articles "a” and "an” mean "one or more,” unless specified otherwise or clear from context to be directed to a singular form. Furthermore, it should be understood that unless otherwise specified, the terms "data,” "content,” "digital content,” "information,” and similar terms may be at times used interchangeably. The term "network” may refer to a group of interconnected computers including clients and servers; and within a network, these computers may be interconnected directly or indirectly by various means including via one or more switches, routers, gateways, access points or the like.

[0037] The present disclosure discusses systems and architectures that, while specific terms may be used, are broadly applicable across various technologies. For instance, while the present disclosure mayreference technologies from 3GPP such as Global System for Mobile Communications (GSM), UMTS, LTE, LTE Advanced, 5G NR, 5G Advanced, and 6G, the present disclosure is equally relevant to non-3GPP technologies like IEEE 802, Bluetooth, and Bluetooth Low Energy. Example implementations of the present disclosure described herein also mention public land mobile networks (PLMNs) and mobile network operators (MNOs), but example implementations are similarly applicable to standalone non-public networks (SNPNs) and the private entities operating these networks. Furthermore, although some examples and figures focus on radio access networks (RANs) and 3GPP access, example implementations are applicable to any type of network access. This includes not only 5G or 6G 3GPP access but also non-3GPP access, such as wireline access, untrusted non-3GPP access, and trusted non-3GPP access using wireless access gateway function (W-AGF), non-3GPP interworking function (N3IWF), or trusted non-3GPP gateway function (TNGF) to connect to a 5G or 6G core network.

[0038] Further, as used in this application, the term "circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry); (b) combinations of hardware circuits and software, such as (as applicable): (I) a combination of analog and / or digital hardware circuit(s) with software / firmware and (II) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions); or (c) hardware circuit(s) and / or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0039] The above definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0040] FIG. 1 illustrates a telecommunications system 100 according to various example implementations of the present disclosure. The telecommunications system generally includes one or more telecommunications networks. As shown, for example, the system includes one or morePLMNs 102 coupled to one or more other external data networks 104 - notably including a wide area network (WAN) such as the Internet. As will be appreciated, a PLMN may be deployed in a number of different manners. Some deployments of 4G LTE and 5G NR in particular are considered standalone (SA) deployments. Other deployments combine 4G LTE and 5G technologies, and are referred to as non-standalone (NSA) deployments.

[0041] Each of the PLMNs 102 includes a core network (CN) 106 backbone, such as the Evolved Packet Core (EPC) of 4G LTE, the 5G core network (5GC) (at times referred to as the NGC) of 5G NR, and the 6G core network (6GC) of 6G; and each of the core networks and the Internet are coupled to one or more RANs 108, air interfaces or the like that implement one or more radio access technologies (RATs). Examples of these RANs include 3GPP RANS such as the evolved UMTS terrestrial radio access network (E-UTRAN) of 4G LTE, the next generation (NG) radio access network (NG-RAN) of 5G NR, and the 6G RAN. Other examples of RANs include non-3GPP RANs, including IEEE 802 RANs such as IEEE 802.11 (Wi-Fi), IEEE 802.15 (including 802.15.1 (WPAN / Bluetooth), 802.15.4 (Zigbee) and 802.15.6 (WBAN)), Bluetooth, Bluetooth Low Energy (BLE), ultra wideband (UWB). As used herein, a "network device” refers to any suitable device at a network side of a telecommunications network. Examples of suitable network devices are described in greater detail below.

[0042] Examples of RATs include 3GPP radio access technologies such as GSM, CDMA2000 1xEV-DO (HRPD), CDMA2000 1x (1xRTT), UTRA, E-UTRA, 5G NR, 5G Advanced, and 6G. Other examples of RATs include non-3GPP radio access technologies, including IEEE 802 technologies, Bluetooth, BLE, UWB, and the like. Generally, a RAT may refer to any 2G, 3G, 4G, 5G, 6G or higher generation RAT and their different versions, as well as to any other RAT that may be arranged to interwork with such a mobile communication technology to provide access to the CN 106 of a MNO.

[0043] The telecommunications system 100 also includes one or more radio units that may be varyingly known as user equipment (UE) 110, terminal device, terminal equipment, mobile station or the like. The UE is generally a device configured to communicate with a network device or a further UE in a telecommunications network. The UE may be a portable computer (e.g., laptop, notebook, tablet computer), mobile phone (e.g., cell phone, smartphone), wearable computer (e.g., smartwatch), or the like. In other examples, the UE may be an Internet of things (loT) device, an industrial loT (lloT device), a vehicle equipped with a vehicle-to-everything (V2X) communication technology, or the like. In some examples, as referenced by 3GPP, the UE may be a narrowband loT (NB-loT) device, an enhanced machine-type communication (eMTC) device, a reduced capability (RedCap) device, an ambient loT device, or the like.

[0044] In operation, these UEs 110 may connect to one or more of the RANs 108 according to their particular RATs to thereby access a particular CN 106 of a PLMN 102, or to access one or more of the external data networks 104 (e.g., the Internet). The external data network may provide Internet access, operator services, 3rd party services, etc. For example, the International Telecommunication Union (ITU) has classified 5G mobile network services into three categories: enhanced mobile broadband (eMBB), ultra-reliable and low-latency communications (URLLC), and massive machine type communications (mMTC) or massive internet of things (MIoT).

[0045] In various examples, a RAN 108 may be configured as one or more macrocells, microcells, picocells, femtocells or the like. The RAN may generally include one or more RAN nodes that interact with UEs 110. In various examples, a RAN node may be referred to as a base station (BS), access point (AP), base transceiver station (BTS), Node B (NB), evolved NB (eNB), macro BS, NB (MNB) or eNB (MeNB), home BS, NB (HNB) or eNB (HeNB), next generation NB (gNB), enhanced gNB (en-gNB), next generation eNB (ng-eNB), 6G NB (6g NB), or the like. The term 'gNB' in 5G NR may correspond to the eNB in 4G LTE. Also, a NG-RAN node may refer to a gNB or a ng-eNB. And unless otherwise specified, a gNB in 5G NR or a 6gNB in 6G may at times be more generally referred to as (6)gNB or more generally a gNB.

[0046] The RAN 108 may include some type of network controlling / governing entity responsible for control of the RAN nodes. The network controlling / governing entity and RAN node may be separate or integrated into a single apparatus. The network controlling / governing entity may include processing circuity configured to carry out various management functions, etc. The processing circuity may be associated with a memory, computer-readable storage medium or database for maintaining information required in the management functions.

[0047] FIG. 2 illustrates a deployment of a PLMN 102. As shown, a RAN 108 (e.g., 3GPP RAN, non-3GPP RAN) is configured to connect one or more UEs 110 to thereby access the CN 106. The CN may include a number of network functions (NFs) divided between the control plane (CP) and the user plane (UP). In particular, the CN may include, for example, NFs for mobility management (MM) 204 and session management (SM) 206, as well as a user plane function (UPF) 208. The MM may be, for example, an access and mobility management function (AMF) in the 5GC, or a 6G MM in the 6GC. Similarly, the SM may be, for example, a session management function (SMF) in the 5GC, or a 6G SM in the 6GC. Other examples of suitable NFs include a policy and charging function (PCF) 210, a unified data management (UDM) 212, or the like.

[0048] Although not separately shown, there are a number of network interfaces between the RAN 108 and CN 106, and between NFs in the CN. In 5G NR, for example, the network interface between a RAN node in the RAN and the MM 204 is referred to as the NG interface. The NG interface may support the exchange of signaling messages between the RAN and the MM, and these messages may be formatted according to the NG application protocol (NGAP). The NGAP supports a number of procedures, comprising elementary procedures, such as to establish, maintain or release the RAN. As another example, the network interface between the RAN node and the UPF 208 is referred to as the N3 interface. The N3 interface is primarily used for the exchange of user plane traffic between the RAN node and the UPF

[0049] As described in 3GPP TS 23.501 and TS 23.502, 5G NR supports a number of system procedures, including connection, registration and mobility management procedures, as well as session management procedures. Connection management is used to establish and release the control plane signaling connection between the UE 110 and the MM 202. Registration management is used to register orderegister a UE / user with the 5G system (5GS) and establish the user context in the 5GS. Registration management includes registration and deregistration procedures to register or deregister a UE / user with the 5GS. Mobility management is used to keep track of the current location of a UE. Session management procedures are used to handle the lifecycle of protocol data unit (PDU) sessions in the 5GS, including establishing and releasing PDU sessions.

[0050] 5G NR supports the simultaneous connection and registration of a UE 110 via multiple access networks (RANs 108) to the 5GC (CN 106). These multiple access networks are currently limited to one 3GPP access (e.g., 5G NR) plus one non-3GPP accesses (e.g., WiFi). Current discussion and study indicate that future releases (e.g., in 6G) may also support the simultaneous connection and registration via multiple 3GPP accesses (e.g., two 5G NR accesses, plus one 4G LTE access, etc.). As currently specified, a UE simultaneously connected to the same 5GC of a PLMN / SNPN over a 3GPP access and a non-3GPP access may be served by a single MM 202 (AMF) in the 5GC.

[0051] As indicated, registration management in 5G NR includes registration and deregistration procedures to register or deregister a UE 110. Registration management includes mechanisms or procedures for deregistering a UE from a specific access, which may be UE-initiated such as by a deregistration request, or network-initiated such as by an implicit deregistration via UE inactivity detection. Registration management also includes mechanisms or procedures for activating existing PDU sessions during registration, as well as switching PDU sessions from one non-3GPP access to another non-3GPP access.

[0052] A problem may be that at least some energy-sensitive UEs 110 require significant signaling for either maintaining multiple accesses or for deregistering those accesses. This signaling may in turn reduce the UE's battery lifetime since the signaling amounts for a significant part of the UE's communication with the network if the UE is otherwise used for small intermittent data exchanges (communication). The problem may be illustrated by two use cases. In a first use case, an energy-sensitive UE may have capabilities to connect to multiple accesses but prefers not to be connected to multiple accesses at any given time to conserve power / energy. In a second use case, an energy-sensitive UE may only connect to the network for a short duration to transmit / receive small amounts of data, then disconnect from the network.

[0053] Example implementations of the present disclosure provide solutions to extend the general (initial) registration procedure of a UE 110 (to a 3GPP network via a 3GPP RAN or a non-3GPP RAN), and / or PDU session establishment procedure for PDU session(s) of a UE. The solutions extend either or both procedures with triggers and consequences, with steps that enable the UE to achieve either or both of the above use cases. In this regard, the solutions may enable the UE to stay registered only to the access the UE needs and only for the time the UE needs its registration without having to perform the entire deregistration procedure (described in in 3GPP TS 23.502, clause 4.2.2.3.2). Additionally or alternatively,the solutions may enable the UE to initiate a switch PDU session(s) from one access to another access during registration of the other access itself, without having to separately perform PDU session establishment in the new access (described in TS 23.502 clause 4.9.2.1, 4.9.2.2). Even further, additionally or alternatively, the solutions may enable a UE to release PDU session(s) without external signaling.

[0054] According to some example implementations, a UE 110 may include the intelligence to determine that previously established access(es) shall not be maintained if the UE registers to a new access to perform one or more tasks. In some of these examples, the general registration procedure for registering the UE via a new access may be extended with a UE-provided indication of the above decision / determination, as well as a network-provided confirmation to the UE for the new requested functionality. The general registration procedure may also be extended to include indications and steps for switching PDU session(s) from a previously-established access to the new access being registered. Optional steps may also be provided for updating impacted SM policy association(s) instead of terminating and reestablishing the impacted SM policy association(s). Steps for releasing the network and Access Node resources of the previously established access as part / consequence of the new registration may also be provided.

[0055] According to other example implementations, a UE 110 may include the intelligence to determine that the registration to access(es) shall be terminated after one or more tasks have been performed. In some of these examples, the general registration procedure for registering the UE via the access(es) may be extended with a UE-provided indication of a timer which, upon expiration, triggers the implicit deregistration of the UE from the access(es) without further signaling to and from the UE. In this regard, as used herein, implicit deregistration refers to a deregistration of the UE without explicit signaling. This timer may therefore be associated with implicit deregistration of the UE (referred to at times as an "implicit deregister” timer) per access network. The general registration procedure in these examples may also be extended with steps for handling the implicit deregister timer in the network, which may in some cases be for multiple accesses and across multiple MMs 202 handling the accesses. Even further, in some examples, the general registration procedure may be extended with steps for releasing the network and AN resources upon expiration of the implicit deregister timer.

[0056] According to some example implementations, a UE 110 may include the intelligence to determine that specific PDU sessions shall be terminated after a specific time. These example implementations may be independent of or used in connection with other example implementations, such as those involving the implicit deregister timer. In some of these examples, the PDU session establishment procedure may be extended with a UE-provided indication of a timer which, upon expiration, triggers the release of PDU session resources without further signaling to and from the UE. This timer may therefore be associated with PDU session(s) based on data to be communicated on the PDU session(s) (referred to at times as an "implicit release” timer) per access network. In some of these examples, the PDU sessionestablishment procedure may also be extended with steps for passing the implicit release timer from the UE to the SM 204, UPF 206 and / or PCF 208. The PDU session establishment procedure may also be extended with steps for releasing the resources of the PDU session upon expiration of the implicit release timer.

[0057] FIG. 3 is a signaling chart 300 of a registration procedure with single-access only registration and PDU session switching, according to some example implementations. As shown, a UE 110 may at step 301 register via a first access network (e.g., 3GPP RAN 108A) to the CN 106 (MM 202). During registration, the UE may send a registration request to the MM, and the registration request may include information that indicates the UE supports either or both "single-access only registration” and / or "switch PDU sessions across access” features. The MM may select other NFs (e.g., SM 204, UPF 206, PCF 208) that support the same feature(s). During the registration process, the UE may request user plane activation of at least one PDU session of the UE that is across the first access network.

[0058] The UE 110 may at step 302 decide to connect to a second access network (e.g., non-3GPP RAN 108B). The UE may detect the second access network. The UE may decide to connect to the second access network because the UE cannot sustain two simultaneous connections, and the UE determines to minimize signaling and switch the PDU session(s) from being across the first access network to being across the second access network.

[0059] The UE 110 may at step 303 trigger a registration request to the MM 202, and the registration request may include information that indicates either or both "single-access only registration” and / or "switch PDU sessions across access.” The information may include an indication (e.g., a flag) for each feature; or in some examples, the information may include one indication for both features.

[0060] As shown at step 304, a number of steps 4 to 17 of the general registration procedure described in TS 23.502, clause 4.2.2.2.2 may be executed. A number of these steps are initiated by the MM 202 (AMF), and generally involve UE authentication, security establishment, UDM registration, subscription data retrieval, and optional procedures such as equipment identity check, and access and mobility (AM) policy association.

[0061] The MM 202 (AMF) may at step 305 trigger or otherwise initiate a SM policy association update procedure or a SM policy association create procedure between the SM 204 and the PCF 208. In this regard, the MM may initiate the SM policy association update procedure for updating SM policy association (s) if the same SM policy association (s) is to be maintained for the UE 110 across the first access network (e.g., 3GPP RAN 108A) and the second access network (e.g., non-3GPP RAN 108B). The MM may otherwise initiate the SM policy association create procedure for creating new SM policy association (s), and the old SM policy association(s) may be terminated.

[0062] As shown at step 306, user plane activation for the PDU session(s) may be switched from the first access network (e.g., 3GPP RAN 108A) to the second access network (e.g., non-3GPP RAN 108B).This may include execution of a number of steps 5 onward from the UE-triggered service request procedure described in TS 23.502, clause 4.2.3.2.

[0063] The MM 202 may at step 307 send a registration accept message to the UE 110, and the registration accept message may include information (e.g., a flag) indicating a status of the single-access only registration requested by the UE. In this regard, the information may indicate an unsuccessful or a successful implicit deregistration of the UE via the first access network (e.g., 3GPP RAN 108A). For example, the information (if implicit deregistration is unsuccessful) may make the UE aware that the UE's registration over the first access network is maintained, and that the UE would need to trigger or otherwise initiate an explicit deregistration if required. Alternatively, the information (if implicit deregistration is successful) make may the UE aware that the MM has implicitly deregistered the UE from the first access network which is no longer usable by the UE. In some examples, the registration accept message may omit information that indicates the status of the single-access only registration, and the UE may understand that the implicit deregistration is unsuccessful, and that the UE's registration over the first access network is maintained. In some examples, the registration accept message may also include information that indicates the successful PDU session(s) established via a PDU session status in the registration accept message.

[0064] As shown at step 308, network interface connections (e.g., NGAP, N3) for the UE 110 between the first access network (e.g., 3GPP RAN 108A) and the CN 106 (e.g., MM 202, SM 204) may be released. This may include execution of a number of steps 2 to 4 from the access network (AN) release procedure described in TS 23.502, clause 4.2.6. In examples in which new SM policy association (s) were created at step 305, then the old SM policy association(s) with the first access network may be terminated.

[0065] If the MM 202 has indicated a successful implicit deregistration in the registration accept message (at step 307), then both the UE 110 and the MM may at step 309 consider the UE implicitly deregistered from the first access network (e.g., 3GPP RAN 108A) without any signaling.

[0066] In the registration procedure shown in FIG. 3, steps 304-308 may form an extended registration procedure which, as compared to the current general registration procedure, includes additional steps for implicitly tearing down the connection to the first access network (e.g., 3GPP RAN 108A). In contrast to the current general registration procedure, the registration procedure of some example implementations supports switching PDU sessions between different access networks during initial registration to one of the access networks. The registration procedure of some example implementations may also clear the resources and implicitly deregister the UE with the first access network during the registration procedure with second access network.

[0067] As also described, the first access network may be the 3GPP RAN 108A and the second access network may be the non-3GPP RAN 108B. In other examples, however, the first access network may be the non-3GPP RAN and the second access network may be the 3GPP RAN. And in yet further examples, both the first access network and the second access network may be 3GPP RANs or non-3GPPRANs. The registration procedure may be further extended to more than two access networks in which the UE may also be implicitly deregistered from additional access network(s) (3GPP RAN, non-3GPP RAN) when the UE is registered via the second access network.

[0068] FIG. 4 is a signaling chart 400 of a registration procedure with a timer associated with implicit deregistration, according to some example implementations. As shown, a UE 110 in a deregistered state may at step 401 decide to connect to the network for a short duration for communication (exchange) of data for a transaction; and based on estimated data to be communicated or an estimated time to complete the transaction, the UE may set an "implicit deregister” timer per access network (e.g., 3GPP RAN 108A, non-3GPP RAN 108B). In this regard, the UE may register via one or more access networks to the CN 106. In examples in which the UE registers via multiple access networks, the UE may set the same timer or different timers per access network. The remaining steps of the procedure are described for the UE registering via at least one access network, but may be easily extended to multiple access networks.

[0069] The UE 110 may at step 402 send a registration request to the MM 202 for registration of the UE via the access network (e.g., 3GPP RAN 108A, non-3GPP RAN 108B) to the CN 106, and the registration request may include the implicit deregister timer. As shown at step 403, a number of steps 4 to 20 of the general registration procedure described in TS 23.502, clause 4.2.2.2.2 may be executed. The MM may at step 404 send registration accept message to the UE, and the registration accept message may include information that indicates the (negotiated) implicit deregister timer per access.

[0070] The UE 110 may at step 405 trigger or otherwise initiate a PDU session establishment procedure to establish PDU session(s) for the transaction, such as that described in TS 23.502, clause 4.3.2.2. The UE may communicate (exchange) data for the transaction over the PDU session(s). The UE may then at step 406 release the established PDU session(s), such as according to the UE or network requested PDU session release procedure described in TS 23.502, clause 4.3.4.2.

[0071] When the PDU session(s) are released (or the last of the PDU session(s) is released), the MM 202 may at step 407 start the implicit deregister timer. In some examples (case A), the MM may at step 408 initiate an implicit deregistration procedure to implicitly deregister the UE via the access network to the CN when the implicit deregister timer expires.

[0072] In other examples (case B), the UE 110 at step 409 may trigger or otherwise initiate a mobility registration update (MRU) or a PDU session establishment procedure for new PDU session(s) after the earlier PDU session(s) are released (and the implicit deregister timer started). The UE may send the MM 202 a registration request to initiate the MRU procedure; and in some examples, the registration request may include a timer value related to the implicit deregister timer. The MM may then perform an update or renegotiation of the implicit deregister timer based on the timer value. In case the registration request does not include a timer value, the MM may simply stop the implicit deregister timer. When the UE initiates a PDU establishment procedure, the MM may receive information that indicates the establishment of the newPDU session(s). The MM may then in response stop and reset the implicit deregister timer (and restart the timer when the last of the new PDU session(s) is released).

[0073] Relative to the current (de)registration procedure that supports network-initiated implicit deregistration without involvement of the UE 110, the registration procedure shown in FIG. 4 enables a UE-initiated or UE-requested implicit deregistration. In some examples, artificial intelligence (AI) / machine learning (ML) may also be used to provide the UE with increased intelligence to make predictions, and these may include implicit deregistration for energy conservation when the UE can predict estimated data to be communicated (exchanged) or an estimated time to complete a transaction at step 401.

[0074] FIG. 5 is a signaling chart 500 of a PDU session establishment procedure with a timer associated with at least one PDU session, according to some example implementations. As shown, a UE 110 in a deregistered state may at step 501 register via one or more access networks (e.g., 3GPP RAN 108A, non-3GPP RAN 108B) to the CN 106. The UE may at step 502 decide to communicate (exchange) data for a period of time, and set an "implicit release” timer for PDU session(s) to be established per access network. In this regard, the UE may register via one or more access networks to the CN 106. In examples in which the UE registers via multiple access networks, the UE may set the same timer or different timers for PDU session(s) per access network. The UE may further set the same timer or different timers per PDU session per access network. The remaining steps of the procedure are described for the UE registering via at least one access network and setting a timer for PDU session(s) established across the access network, but may be easily extended to multiple access networks.

[0075] The UE 110 may at step 503 trigger or otherwise initiate a PDU session establishment procedure to establish PDU session(s) for the communication (exchange) of data, such as that described in TS 23.502, clause 4.3.2.2. In this regard, the UE may send the SM 204 a PDU session establishment request to establish the PDU session(s). The PDU session establishment request may include information that indicates the implicit release timer.

[0076] In some examples, the SM 204 may send the information that indicates the (negotiated) implicit release timer to the PCF 208 (optionally, if indicated by the UE 110) during SM policy association establishment I modification for the PDU session(s) (at step 7 of the PDU establishment procedure). The PCF may later use the implicit release timer for termination of the SM policy association(s) when the PDU session(s) are released. Likewise, the SM may send the information that indicates the (negotiated) implicit release timer to the UPF 206 during an N4 session establishment procedure (at step 10 of the PDU establishment procedure). The UPF may later use the implicit release timer for an N3 connection user plane deactivation. The SMF may sand a PDU session establishment accept message to the UE that includes information indicating the (negotiated) "implicit release” timer (at step 13 of the PDU establishment procedure).

[0077] As shown at step 504, one or more of the UE 110, SM 204, UPF 206 or PCF 208 start the implicit release timer. When the implicit release timer expires, at step 505, the PDU session(s) may be released. In particular, the UE, SM, UPF and PCF may release or deactivate resources, the N3 connection and SM policy association (s) for the PDU session(s), when the implicit release timer expires. Relative to the current PDU session establishment procedure, the PDU session establishment procedure of example implementations may perform a PDU session release / AN release I user plane deactivation and SM policy termination without explicit signaling.

[0078] According to some example implementations of the procedures described above, different MFs 202 may handle the different radio network accesses to which the UE 110 is registered. In some examples, then, the MM may store the UE-provided information regarding single-access only registration or implicit deregister timer into the UDM 210 (e.g., using the Nudm_UECM service). The UE-provided information may from there be notified to the MMs handing the accesses without the need to be implicitly deregistered. The steps for implicit deregistration may then be triggered for each access by the MM that is handling the access.

[0079] FIG. 6 is a flowchart illustrating various steps in a method 600 performed by a user equipment (UE), according to various example implementations. The method includes registering the UE via a first access network to a core network, as shown at block 602. The method includes deciding to connect to a second access network, as shown at block 604. And the method includes sending a registration request to register the UE via the second access network to the core network, the registration request including at least one indication for at least single-access only registration that is to trigger the core network to implicitly deregister the UE via the first access network to the core network when the UE is registered via the second access network to the core network, as shown at block 606.

[0080] In some examples, the method 600 further includes receiving a registration accept message that includes information indicating a status of the single-access only registration.

[0081] In some examples, the status of the single-access only registration includes information that indicates a successful implicit deregistration of the UE via the first access to the core network.

[0082] In some examples, the status of the single-access only registration includes information that indicates an unsuccessful implicit deregistration of the UE via the first access to the core network, and In some of these examples, the unsuccessful implicit deregistration indicates registration of the UE via the first access network is maintained.

[0083] In some examples, registering at block 602 the UE further comprises registering the UE via at least one additional access network to the core network. In some of these examples, the at least one indication for at least the single-access only registration is also to trigger the core network to implicitly deregister the UE via the at least one additional access network to the core network.

[0084] In some examples, registering at block 602 the UE via the first access network to the core network comprises requesting activation of at least one packet data unit (PDU) session of the UE that is across the first access network. In some of these examples, the at least one indication for at least singleaccess only registration is also to trigger the core network to switch the at least one PDU session from across the first access network to across the second access network.

[0085] FIGS. 7A and 7B are flowcharts illustrating various steps in a method 700 according to various example implementations. The method includes performing a registration of a user equipment (UE) via first access network to a core network, as shown at block 702 of FIG. 7A. The method includes receiving a registration request to register the UE via a second access network to the core network, the registration request including at least one indication for at least single-access only registration, as shown at block 704.The method includes performing, based on the registration request, a registration of the UE via the second access network to the core network, as shown at block 706. And the method includes implicitly deregistering, when the UE is registered via the second access network to the core network, and based on the at least one indication for at least single-access only registration in the registration request, the UE via the first access network to the core network, as shown at block 708.

[0086] In some examples, the method 700 further includes sending to the UE a registration accept message that includes information indicating a status of the single-access only registration.

[0087] In some examples, the status of the single-access only registration includes information that indicates a successful implicit deregistration of the UE via the first access to the core network.

[0088] In some examples, performing the registration of the UE at block 702 further comprises performing a registration of the UE via at least one additional access network to the core network. In some of these examples, implicitly deregistering the UE at block 708 further comprises implicitly deregistering the UE via the at least one additional access network to the core network.

[0089] In some examples, performing the registration of the UE via the first access network to the core network at block 702 comprises activating at least one packet data unit (PDU) session across the first access network, as shown at block 710 of FIG. 7B. In some of these examples, the method 700 further includes switching the at least one PDU session from being across the first access network to being across the second access network, as shown at block 712.

[0090] In some examples, the switching of the at least one PDU session at block 712 is based on the at least one indication for at least single-access only registration in the registration request.

[0091] In some examples, the method 700 further includes initiating a session management (SM) policy association update procedure or a SM policy association create procedure for the at least one PDU session based on the switching of the at least one PDU session.

[0092] In some examples, the SM policy association update procedure is for updating at least one policy association for the at least one PDU session from being across the first access network to being across the second access network.

[0093] In some examples, the SM policy association create procedure is for creating at least one policy association for the at least one PDU session across the second access network, and for terminating at least one policy association for the at least one PDU session across the first access network.

[0094] In some examples, the method 700 further includes storing, in a unified data management network function, the at least one indication for at least single-access only registration in association with registration of the UE via the first access network, and in association with registration of the UE via the second access network.

[0095] FIGS. 8A and 8B are flowcharts illustrating various steps in a method 800 performed by a user equipment (UE), according to various example implementations. The method includes sending at least one registration request to register the UE via at least one access network to the core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE, as shown at block 802 of FIG. 8A. The method includes establishing, with the core network, at least one packet data unit (PDU) session across the at least one access network, as shown at block 804. And the method includes releasing the at least one PDU session across the at least one access network, wherein release of the at least one PDU session triggers the core network to start the at least one timer, and expiration of the at least one timer triggers the core network to implicitly deregister the UE via the at least one access network to the core network, as shown at block 806.

[0096] In some examples, the method 800 further includes starting the at least one timer when the at least one PDU session is released, as shown at block 808 of FIG. 8B. In some of these examples, the method also includes considering the UE implicitly deregistered via the at least one access network to the core network when the at least one timer expires, as shown at block 810.

[0097] In some examples, the method 800 further includes determining the at least one timer associated with the implicit deregistration of the UE based on data to be communicated on the at least one PDU session across the at least one access network.

[0098] In some examples, the method 800 further includes receiving at least one registration accept message that includes information indicating the at least one timer associated with the implicit deregistration of the UE.

[0099] In some examples, the method 800 further includes initiating a mobility registration update with the core network, the mobility registration update including a timer value for the core network to update or renegotiate the at least one timer associated with the implicit deregistration of the UE based on the timer value.

[0100] In some examples, the method 800 further includes initiating a mobility registration update with the core network, the mobility registration update triggering the core network to stop the at least one timer associated with the implicit deregistration of the UE.

[0101] In some examples, the method 800 further includes establishing a PDU session after the at least one PDU session is released and the at least one timer is started, In some of these examples, establishing the PDU session triggers the core network to stop and reset the at least one timer associated with the implicit deregistration of the UE.

[0102] FIGS. 9A - 9D are flowcharts illustrating various steps in a method 900 according to various example implementations. The method includes receiving at least one registration request to register a user equipment (UE) via at least one access network to a core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE, as shown at block 902 of FIG. 9A. The method includes receiving information that indicates release of at least one packet data unit (PDU) session of the UE across the at least one access network, as shown at block 904. The method includes starting, based on the release of the at least one PDU session, the at least one timer associated with the implicit deregistration of the UE, as shown at block 906. And the method includes implicitly deregistering the UE via the at least one access network to the core network triggered when the at least one timer expires, as shown at block 908.

[0103] In some examples, the method 900 further includes sending to the UE at least one registration accept message that includes information indicating the at least one timer associated with the implicit deregistration of the UE.

[0104] In some examples, the method 900 further includes receiving a registration request from the UE to trigger a mobility registration update with the core network, the registration request including a timer value related to the at least one timer associated with the implicit deregistration of the UE, as shown at block 910 of FIG. 9B. In some of these examples, the method also includes performing an update or renegotiation of the at least one timer associated with the implicit deregistration of the UE based on the timer value, as shown at block 912.

[0105] In some examples, the method 900 further includes receiving a registration request from the UE to trigger a mobility registration update with the core network, as shown at block 914 of FIG. 9C. in some of these examples, the method also includes stopping, based on the mobility registration update, the at least one timer associated with the implicit deregistration of the UE, as shown at block 916.

[0106] In some examples, the method 900 further includes receiving information that indicates establishment of a PDU session after the at least one PDU session is released, as shown at block 918 of FIG. 9D. i n some of these examples, the method also includes stopping and resetting, based on the establishment of the PDU session, the at least one timer associated with the implicit deregistration of the UE, as shown at block 920.

[0107] In some examples, the method 900 further includes storing, in a unified data management network function, the at least one timer associated with the implicit deregistration of the UE in association with registration of the UE via the at least one access network to the core network.

[0108] FIGS. 10A and 10B are flowcharts illustrating various steps in a method 1000 performed by a user equipment (UE), according to various example implementations. The method includes registering the UE via at least one access network to the core network, as shown at block 1002 of FIG. 10A. The method includes determining at least one timer associated with at least one packet data unit (PDU) session based on data to be communicated on the at least one PDU session across the at least one access network, as shown at block 1004. And the method includes sending at least one PDU session establishment request to establish the at least one PDU session with the core network for the communication of the data, the request to establish the at least one PDU session including information that indicates the at least one timer which triggers the core network to start the at least one timer, and release the at least one PDU session when the at least one timer expires, as shown at block 1006.

[0109] In some examples, the method 1000 further includes starting the at least one timer when the at least one PDU session is established, as shown at block 1008 of FIG. 10B. In some of these examples, the method also includes considering the at least one PDU session released when the at least one timer expires, as shown at block 1010.

[0110] In some examples, the method 1000 further includes receiving at least one PDU session establishment accept message that includes information indicating the at least one timer associated with the at least one PDU session.

[0111] In some examples, the at least one PDU session is multiple PDU sessions, and determining the at least one timer at block 1004 comprises determining multiple timers for the multiple PDU sessions. In some of these examples, the at least one PDU session establishment request triggers the core network to start a timer of the multiple timers for each PDU session of the multiple PDU sessions, and release the PDU session when the timer expires.

[0112] In some examples, a timer of the multiple timers for one of the multiple PDU sessions has a timer value that is different from another timer of the multiple timers for another of the multiple PDU sessions.

[0113] In some examples, registering the UE at block 1002 comprises sending at least one registration request to register the UE via the at least one access network to the core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE. In some of these examples, the release of the at least one PDU session triggers the core network to start the at least one timer associated with the implicit deregistration of the UE, and expiration of the at least one timer associated with implicit deregistration of the UE triggers the core network to implicitly deregister the UE.

[0114] FIG. 11 is a flowchart illustrating various steps in a method 1100 according to various example implementations. The method includes receiving, from a user equipment (U E), at least one packet data unit (PDU) session establishment request to establish at least one PDU session, the at least one PDU session establishment request including at least one timer associated with the at least one PDU session, as shown at block 1102. The method includes starting, based on establishment of the at least one PDU session, the at least one timer associated with the at least one PDU session, as shown at block 1104. And the method includes releasing at least one PDU session when the at least one timer expires, as shown at block 1106.

[0115] In some examples, the method 1100 further includes sending to the UE at least one PDU session establishment accept message that includes information indicating the at least one timer associated with the at least one PDU session.

[0116] In some examples, the at least one PDU session is multiple PDU sessions, and the at least one timer comprises multiple timers for the multiple PDU sessions. In some of these examples, starting the at least one timer at block 1104 comprises starting a timer of the multiple timers for each PDU session of the multiple PDU sessions. And releasing the at least one PDU session at block 1106 comprises releasing the PDU session when the timer expires.

[0117] In some examples, a timer of the multiple timers for one of the multiple PDU sessions has a timer value that is different from another timer of the multiple timers for another of the multiple PDU sessions.

[0118] In some examples, the method 1100 further includes sending information that indicates the at least one timer to a policy control function (PCF). In some of these examples, the information that indicates the at least one timer triggers the PCF to start the at least one timer, and terminate at least one session management (SM) policy association for the at least one PDU session when the at least one timer expires.

[0119] In some examples, the method 1100 further includes sending information that indicates the at least one timer to a user plane function (UPF). In some of these examples, the information that indicates the at least one timer triggers the UPF to start the at least one timer, and release user plane resources for the at least one PDU session when the at least one timer expires.

[0120] According to example implementations of the present disclosure, a telecommunications system 100 or PLMN 102, and its components such as a CN 106, RAN 108, UE, MM 202, SM 204, UPF 206, PCF 208 and / or UDM 210, may be implemented by various means. Means for implementing the system and its components may include hardware, firmware, software, or combinations thereof. In some examples, one or more apparatuses may be configured to function as or otherwise implement the system and its components shown and described herein. In examples involving more than one apparatus, the respective apparatuses may be connected to or otherwise in communication with one another in a number of different manners, such as directly or indirectly via a wired or wireless network or the like.

[0121] According to some example implementations, at least some of the methods 600 and 700 described with respect to FIG. 6 and FIGS. 7A and 7B may be carried out by respective apparatuses comprising means for performing functions corresponding steps of the methods. Similarly, at least some of the methods 800 and 900 described with respect to FIGS. 8A and 8B and FIGS. 9A-9D may be carried out by respective apparatuses comprising means for performing functions corresponding steps of the methods. At least some of the methods 1000 and 1100 described with respect to FIGS. 10A and 10B and FIG. 11 may be carried out by respective apparatuses comprising means for performing functions corresponding steps of the methods. Examples of a suitable apparatus may include a user equipment, user device, user terminal or the like. Other examples of a suitable apparatus may include a network function (e.g., MM, SM, etc.) or any suitable apparatus, such as a server, host or node.

[0122] FIG. 12 illustrates an apparatus 1200 in which means for performing various functions includes hardware, alone or under direction of one or more computer programs from a computer-readable storage medium or other memory, such as computer memory, according to some example implementations of the present disclosure. The apparatus may include one or more of each of a number of components such as, for example, processing circuitry 1202 connected to computer-readable storage medium or other memory 1204.

[0123] The processing circuitry 1202 may be composed of one or more processors alone or in combination with one or more computer-readable storage media. The processing circuitry is generally any piece of computer hardware that is capable of processing information such as, for example, data, computer programs and / or other suitable electronic information. The processing circuitry is composed of a collection of electronic circuits some of which may be packaged as an integrated circuit or multiple interconnected integrated circuits (an integrated circuit at times more commonly referred to as a "chip”). The processing circuitry may be configured to execute computer programs, which may be stored onboard the processing circuitry or otherwise stored in the memory 1204 (of the same or another apparatus).

[0124] The processing circuitry 1202 may be a number of processors, a multi-core processor or some other type of processor, depending on the particular implementation. Further, the processing circuitry may be implemented using a number of heterogeneous processor systems in which a main processor is present with one or more secondary processors on a single chip. As another illustrative example, the processing circuitry may be a symmetric multi-processor system containing multiple processors of the same type. In yet another example, the processing circuitry may be embodied as or otherwise include one or more ASICs, FPGAs or the like. Thus, although the processing circuitry may be capable of executing a computer program to perform one or more functions, the processing circuitry of various examples may be capable of performing one or more functions without the aid of a computer program. In either instance, the processing circuitry may be appropriately programmed to perform functions or operations according to example implementations of the present disclosure.

[0125] The memory 1204 is generally any piece of computer hardware that is capable of storing information such as, for example, data, computer programs, instructions 1206 (e.g., computer-readable program code) and / or other suitable information either on a temporary basis and / or a permanent basis. The memory may include volatile and / or non-volatile memory, and may be fixed or removable. Examples of suitable memory include recording media, random access memory (RAM), read-only memory (ROM), a hard drive, a flash memory, a thumb drive, a removable computer diskette, an optical disk or some combination thereof.

[0126] The memory 1204 is a non-transitory device capable of storing information. One example of a suitable memory is a computer-readable storage medium, which is distinguishable from a computer-readable transmission medium capable of carrying information from one location to another. Examples of suitable computer-readable transmission media comprise electronic carrier signals, telecommunications signals, or some combination thereof. As used herein, the term "non-transitory” is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM versus ROM). A computer-readable medium as described herein generally refers to a computer-readable storage medium or computer-readable transmission medium. A computer-readable medium is any entity or device capable in which information, such as one or more computer programs or portions thereof, may be stored and carried.

[0127] In addition to the memory 1204 (e.g., computer-readable storage medium), the processing circuitry 1202 may also be connected to one or more interfaces for displaying, transmitting and / or receiving information. The interfaces may include a communications interface 1208 and / or one or more user interfaces. The communications interface may be configured to transmit and / or receive information, such as to and / or from other apparatus(es), network(s) or the like. The communications interface may be configured to transmit and / or receive information by physical (wired) and / or wireless communications links. Examples of suitable communication interfaces include a network interface controller (NIC), wireless NIC (WNIC) or the like.

[0128] The user interfaces may include a display 1210 and / or one or more user input interfaces 1212.The display may be configured to present or otherwise display information to a user, suitable examples of which include a liquid crystal display (LCD), light-emitting diode (LED) display, organic LED (OLED) display, active-matrix OLED (AMOLED) or the like. The user input interfaces may be wired or wireless, and may be configured to receive information from a user into the apparatus, such as for processing, storage and / or display. Suitable examples of user input interfaces include a microphone, image or video capture device, keyboard or keypad, joystick, touch-sensitive surface (separate from or integrated into a touchscreen), biometric sensor or the like. The user interfaces may further include one or more interfaces for communicating with peripherals such as printers, scanners or the like.

[0129] Execution of the instructions 1206 by the processing circuitry 1202, or storage of the instructions in the memory 1204, supports combinations of operations for implementing example implementations of the present disclosure. In this manner, an apparatus 1200 may comprise at least one processing circuitry and at least one memory coupled to the at least one processing circuitry, where the at least one processing circuitry is configured to execute instructions stored in the at least one memory. It will also be understood that one or more functions, and combinations of functions, may be implemented by special purpose hardware-based computer systems and / or processing circuitry which perform the specified functions, or combinations of special purpose hardware and program code instructions.

[0130] Some example implementations of the present disclosure may also be carried out in the form of a computer process defined by one or more computer programs or portions thereof. Example implementations of the present disclosure may be carried out by executing at least one portion of a computer program comprising instructions. The computer program may be in source code form, object code form, or in some intermediate form. The computer program may be stored in a computer-readable medium that is readable by a computer, processing circuitry or other suitable apparatus. As indicated above, for example, the computer program may be stored in a memory, such as a computer-readable storage medium. Additionally or alternatively, for example, the computer program may be stored in a computer-readable transmission medium. The coding of software for carrying out example implementations of the present disclosure is well within the scope of a person of ordinary skill in the art.

[0131] As will be appreciated, any suitable instructions may be loaded onto a computer, a processing circuitry or other programmable apparatus from a memory or a computer-readable medium (e.g., computer- readable storage medium, computer-readable transmission medium) to produce a particular machine, such that the particular machine becomes a means for implementing the functions specified herein. The instructions may also be stored in a computer-readable medium that can direct a computer, a processing circuitry or other programmable apparatus to function in a particular manner to thereby generate a particular machine or particular article of manufacture. In some examples, the instructions stored in the computer-readable medium may produce an article of manufacture, where the article of manufacture becomes a means for implementing functions described herein. The instructions may be retrieved from a computer-readable medium and loaded into a computer, processing circuitry or other programmable apparatus to configure the computer, processing circuitry or other programmable apparatus to execute operations to be performed on or by the computer, processing circuitry or other programmable apparatus.

[0132] Retrieval, loading and execution of instructions comprising program code instructions may be performed sequentially such that one instruction is retrieved, loaded and executed at a time. In some example implementations, retrieval, loading and / or execution may be performed in parallel such that multiple instructions are retrieved, loaded, and / or executed together. Execution of the program code instructions may produce a computer-implemented process such that the instructions executed by thecomputer, processing circuitry or other programmable apparatus provide operations for implementing functions described herein.

[0133] As explained above and reiterated below, the present disclosure includes, without limitation, the following example implementations.

[0134] Clause 1. A method performed by a user equipment (UE), the method comprising: registering the UE via a first access network to a core network; deciding to connect to a second access network; and sending a registration request to register the UE via the second access network to the core network, the registration request including at least one indication for at least single-access only registration that is to trigger the core network to implicitly deregister the UE via the first access network to the core network when the UE is registered via the second access network to the core network.

[0135] Clause 2. The method of ciause 1 further comprising receiving a registration accept message that includes information indicating a status of the single-access only registration.

[0136] Ciause 3, The method of ciause 2, wherein the status of the single-access only registration includes information that indicates a successful implicit deregistration of the UE via the first access to the core network.

[0137] Clause 4. The method of clause 2 or ciause 3, wherein the status of the single-access only registration includes information that indicates an unsuccessful implicit deregistration of the UE via the first access to the core network, and wherein the unsuccessful implicit deregistration indicates registration of the UE via the first access network is maintained.

[0138] Clause 5. The method of any of clauses 1 to 4, wherein registering the UE further comprises registering the UE via at least one additional access network to the core network, and wherein the at least one indication for at least the single-access only registration is also to trigger the core network to implicitly deregister the UE via the at least one additional access network to the core network.

[0139] Clause 6. The method of any of clauses 1 to 5, wherein registering the UE via the first access network to the core network comprises requesting activation of at least one packet data unit (PDU) session of the UE that is across the first access network, and wherein the at least one indication for at least single¬ access only registration is also to trigger the core network to switch the at least one PDU session from across the first access network to across the second access network.

[0140] Clause 7. An apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to perform the method of any of clauses 1 to 6.

[0141] Clause 8. An apparatus comprising means for performing the method of any of clauses 1 to 6.

[0142] Clause 9. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 1 to 6.

[0143] Clause 10. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 1 to 6.

[0144] Clause 11. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 1 to 6.

[0145] Clause 12. A method comprising: performing a registration of a user equipment (UE) via first access network to a core network; receiving a registration request to register the UE via a second access network to the core network, the registration request including at ieast one indication for at least single¬ access only registration; performing, based on the registration request, a registration of the UE via the second access network to the core network; and implicitly deregistering, when the UE is registered via the second access network to the core network, and based on the at least one indication for at least single¬ access only registration in the registration request, the UE via the first access network to the core network.

[0146] Clause 13. The method of clause 12 further comprising sending to the UE a registration accept message that includes information indicating a status of the single-access only registration.

[0147] Clause 14. The method of clause 13, wherein the status of the single-access only registration includes information that indicates a successful implicit deregistration of the UE via the first access to the core network.

[0148] Clause 15. The method of any of clauses 12 to 14, wherein performing the registration of the UE further comprises performing a registration of the UE via at least one additional access network to the core network, and wherein implicitly deregistering the UE further comprises implicitly deregistering the UE via the at least one additional access network to the core network.

[0149] Clause 16. I he method of any of clauses 12 to 15, wherein performing the registration of the UE via the first access network to the core network comprises activating at least one packet data unit (PDU) session across the first access network, and wherein the method further comprises switching the at least one PDU session from being across the first access network to being across the second access network.[01 SO] Clause 17. The method of clause 16, wherein the switching of the at least one PDU session is based on the at least one indication for at least singie-access only registration in the registration request.

[0151] Clause 18. The method of clause 16 or clause 17. wherein the method further comprises initiating a session management (SM) policy association update procedure or a SM policy association create procedure for the at least one PDU session based on the switching of the at least one PDU session.

[0152] Clause 19. The method of clause 18, wherein the SM policy association update procedure is for updating at least one policy association for the at least one PDU session from being across the first access network to being across the second access network.

[0153] Clause 20. The method of clause 18 or clause 19, wherein the SM policy association create procedure is for creating at least one policy association for the at least one PDU session across the second access network, and for terminating at least one policy association for the at least one PDU session across the first access network,

[0154] Clause 21. The method of any of clauses 12 to 20 further comprising storing, in a unified data management network function, the at least one indication for at least single-access only registration in association with registration of the UE via the first access network, and in association with registration of the UE via the second access network.

[0155] Clause 22. An apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to perform the method of any of clauses 12 to 21.

[0156] Clause 23. An apparatus comprising means for performing the method of any of clauses 12 to

[0157] Clause 24. A computer-readable medium comprising instructions that, in response to execution by at ieast one processing circuitry, causes an apparatus to perform the method of any of clauses 12 to 21.

[0158] Clause 25. A computer-readable storage medium comprising instructions that, in response to execution by at ieast one processing circuitry, causes an apparatus to perform the method of any of clauses 12 to 21.

[0159] Clause 26. A computer program comprising instructions that, in response to execution by at ieast one processing circuitry, causes an apparatus to perform the method of any of clauses 12 to 21.

[0160] Clause 27. A method performed by a user equipment (UE), the method comprising: sending at ieast one registration request to register the UE via at ieast one access network to the core network, the at ieast one registration request including information that indicates at least one timer associated with implicit deregistration of the UE; establishing, with the core network, at least one packet data unit (PDU) session across the at least one access network: and releasing the at ieast one PDU session across the at least one access network, wherein release of the at least one PDU session triggers the core network to start the at least one timer, and expiration of the at least one timer triggers the core network to implicitly deregister the UE via the at least one access network to the core network.

[0161] Clause 28. The method of clause 27 further comprising: starting the at least one timer when the at least one PDU session is released; and considering the UE implicitly deregistered via the at least one access network to the core network when the at least one timer expires.

[0162] Clause 29. The method of clause 27 or clause 28 further comprising determining the at least one timer associated with the implicit deregistration of the UE based on data to be communicated on the at least one PDU session across the at least one access network.

[0163] Clause 30. The method of any of clauses 27 to 29 further comprising receiving at least one registration accept message that includes information indicating the at least one timer associated with the implicit deregistration of the UE.

[0164] Clause 31. The method of any of clauses 27 to 30 further comprising initiating a mobility registration update with the core network, the mobility registration update including a timer value for the core network to update or renegotiate the at least one timer associated with the implicit deregistration of the UE based on the timer value.

[0165] Clause 32. The method of any of clauses 27 to 31 further comprising initiating a mobility registration update with the core network, the mobility registration update triggering the core network to stop the at least one timer associated with the implicit deregistration of the UE.

[0166] Clause 33. The method of any of clauses 27 to 32 further comprising establishing a PDU session after the at least one PDU session is released and the at least one timer is started, wherein establishing the PDU session triggers the core network to stop and reset the at least one timer associated with the implicit deregistration of the UE.

[0167] Clause 34. An apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to perform the method of any of clauses 27 to 33.

[0168] Clause 35. An apparatus comprising means for performing the method of any of clauses 27 to 33.

[0169] Clause 36. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 27 to 33.

[0170] Clause 37. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 27 to 33.

[0171] Clause 38. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 27 to 33.

[0172] Clause 39. A method comprising: receiving at least one registration request to register a user equipment (UE) via at least one access network to a core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE; receiving information that indicates release of at least one packet data unit (PDU) session of the UE across the at least one access network; starting, based on the release of the at least one PDU session, the at least one timer associated with the implicit deregistration of the UE; and implicitly deregistering the UE via the at least one access network to the core network triggered when the at least one timer expires.

[0173] Clause 40. The method of clause 39 further comprising sending to the UE at least one registration accept message that includes information indicating the at least one timer associated with the implicit deregistration of the UE.

[0174] Clause 41. The method of clause 39 or clause 40 further comprising: receiving a registration request from the UE to trigger a mobility registration update with the core network, the registration request including a timer value related to the at least one timer associated with the implicit deregistration of the UE: and performing an update or renegotiation of the at least one timer associated with the implicit deregistration of the UE based on the timer value.

[0175] Clause 42. The method of any of clauses 39 to 41 further comprising: receiving a registration request from the UE to trigger a mobility registration update with the core network; and stopping, based on the mobility registration update, the at least one timer associated with the implicit deregistration of the UE.

[0176] Clause 43. The method of any of clauses 39 to 42 further comprising: receiving information that indicates establishment of a PDU session after the at ieast one PDU session is released; and stopping and resetting, based on the establishment of the PDU session, the at least one timer associated with the implicit deregistration of the UE.

[0177] Clause 44. The method of any of clauses 39 to 43 further comprising storing, in a unified data management network function, the at ieast one timer associated with the implicit deregistration of the UE in association with registration of the UE via the at ieast one access network to the core network.

[0178] Clause 45. An apparatus comprising: at least one memory configured to store instructions; and at ieast one processing circuitry configured to access the at ieast one memory, and execute the instructions to cause the apparatus to perform the method of any of clauses 39 to 44.

[0179] Clause 46. An apparatus comprising means for performing the method of any of clauses 39 to 44.

[0180] Clause 47. A computer-readable medium comprising instructions that, in response to execution by at ieast one processing circuitry, causes an apparatus to perform the method of any of clauses 39 to 44.

[0181] Clause 48. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 39 to 44.

[0182] Clause 49. A computer program comprising instructions that, in response to execution by at ieast one processing circuitry, causes an apparatus to perform the method of any of clauses 39 to 44.

[0183] Clause 50. A method performed by a user equipment (UE), the method comprising: registering the UE via at ieast one access network to the core network; determining at ieast one timer associated with at ieast one packet data unit (PDU) session based on data to be communicated on the at least one PDU session across the at least one access network; and sending at least one PDU session establishment request to establish the at ieast one PDU session with the core network for the communication of the data,the request to establish the at feast one PDU session including information that indicates the at least one timer which triggers the core network to start the at least one timer, and release the at least one PDU session when the at least one timer expires.

[0184] Clause 51. The method of clause 50 further comprising: starting the at least one timer when the at least one PDU session is established; and considering the at least one PDU session released when the at least one timer expires.

[0185] Clause 52. The method of clause 50 or clause 51 further comprising receiving at least one PDU session establishment accept message that includes information indicating the at feast one timer associated with the at least one PDU session.

[0186] Clause 53. The method of any of clauses 50 to 52, wherein the at least one PDU session is multiple PDU sessions, and determining the at least one timer comprises determining multiple timers for the multiple PDU sessions, and wherein the at least one PDU session establishment request triggers the core network to start a timer of the multiple timers for each PDU session of the multiple PDU sessions, and release the PDU session when the timer expires.

[0187] Clause 54. The method of clause 53, wherein a timer of the multiple timers for one of the multiple PDU sessions has a timer value that is different from another timer of the multiple timers for another of the multiple PDU sessions.

[0188] Clause 55. The method of any of clauses 50 to 54, wherein registering the UE comprises sending at feast one registration request to register the UE via the at least one access network to the core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE, and wherein the release of the at least one PDU session triggers the core network to start the at least one timer associated with the implicit deregistration of the UE, and expiration of the at least one timer associated with implicit deregistration of the UE triggers the core network to implicitly deregister the UE.

[0189] Clause 56. An apparatus comprising: at least one memory configured to store instructions: and at feast one processing circuitry configured to access the at feast one memory, and execute the instructions to cause the apparatus to perform the method of any of clauses 50 to 55.

[0190] Clause 57. An apparatus comprising means for performing the method of any of clauses 50 to 55.

[0191] Clause 58. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 50 to 55.

[0192] Clause 59. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 50 to 55.

[0193] Clause 60. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 50 to 55.

[0194] Clause 61. A method comprising: receiving, from a user equipment (UE), at least one packet data unit (PDU) session establishment request to establish at least one PDU session, the at least one PDU session establishment request including at least one timer associated with the at least one PDU session; starting, based on establishment of the at least one PDU session, the at least one timer associated with the at least one PDU session; and releasing at least one PDU session when the at least one timer expires.

[0195] Clause 62. The method of clause 61 further comprising sending to the UE at least one PDU session establishment accept message that includes information indicating the at least one timer associated with the at least one PDU session.

[0196] Clause 63. The method of clause 61 or clause 62, wherein the at least one PDU session is multiple PDU sessions, and the at least one timer comprises multiple timers for the multiple PDU sessions, and wherein starting the at least one timer comprises starting a timer of the multiple timers for each PDU session of the multiple PDU sessions, and releasing the at least one PDU session comprises releasing the PDU session when the timer expires.

[0197] Clause 64. The method of clause 63, wherein a timer of the multiple timers for one of the multiple PDU sessions has a timer value that is different from another timer of the multiple timers for another of the multiple PDU sessions.

[0198] Clause 65. The method of any of clauses 61 to 64 further comprising sending information that indicates the at least one timer to a policy control function (PCF), wherein the information that indicates the at least one timer triggers the PCF to start the at least one timer, and terminate at least one session management (SM) policy association for the at least one PDU session when the at least one timer expires.

[0199] Clause 66. The method of any of clauses 61 to 65 further comprising sending information that indicates the at least one timer to a user plane function (UPF), wherein the information that indicates the at least one timer triggers the UPF to start the at least one timer, and release user plane resources for the at least one PDU session when the at least one timer expires.

[0200] Clause 67. An apparatus comprising: at least one memory configured to store instructions; and at least one processing circuitry configured to access the at least one memory, and execute the instructions to cause the apparatus to perform the method of any of clauses 61 to 66.

[0201] Clause 68. An apparatus comprising means for performing the method of any of clauses 61 to 66.

[0202] Clause 69. A computer-readable medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 61 to 66.

[0203] Clause 70. A computer-readable storage medium comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 61 to 66.

[0204] Clause 71. A computer program comprising instructions that, in response to execution by at least one processing circuitry, causes an apparatus to perform the method of any of clauses 61 to 66.

[0205] Many modifications and other implementations of the disclosure set forth herein will come to mind to one skilled in the art to which the disclosure pertains having the benefit of the teachings presented in the foregoing description and the associated figures. Therefore, it is to be understood that the disclosure is not to be limited to the specific implementations disclosed and that modifications and other implementations are intended to be included within the scope of the appended claims. Moreover, although the foregoing description and the associated figures describe example implementations in the context of certain example combinations of elements and / or functions, it should be appreciated that different combinations of elements and / or functions may be provided by alternative implementations without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and / or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

WHAT IS CLAIMED IS:

1. An apparatus comprising:at least one processor; andat least one memory storing instructions of a user equipment (UE), the instructions when executed by the at least one processor causing the apparatus to perform operations, the operations comprising: sending at least one registration request to register the UE via at least one access network to the core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE;establishing, with the core network, at least one packet data unit (PDU) session across the at least one access network; andreleasing the at least one PDU session across the at least one access network, wherein release of the at least one PDU session triggers the core network to start the at least one timer, and expiration of the at least one timer triggers the core network to implicitly deregister the UE via the at least one access network to the core network.

2. The apparatus of claim 1, wherein the operations further comprise:starting the at least one timer when the at least one PDU session is released; and considering the UE implicitly deregistered via the at least one access network to the core network when the at least one timer expires.

3. The apparatus of claim 1 or claim 2, wherein the operations further comprise determining the at least one timer associated with the implicit deregistration of the UE based on data to be communicated on the at least one PDU session across the at least one access network.

4. The apparatus of any of claims 1 to 3, wherein the operations further comprise receiving at least one registration accept message that includes information indicating the at least one timer associated with the implicit deregistration of the UE.

5. The apparatus of any of claims 1 to 4, wherein the operations further comprise initiating a mobility registration update with the core network, the mobility registration update including a timer value for the core network to update or renegotiate the at least one timer associated with the implicit deregistration of the UE based on the timer value.

6. The apparatus of any of claims 1 to 5, wherein the operations further comprise initiating a mobility registration update with the core network, the mobility registration update triggering the core network to stop the at least one timer associated with the implicit deregistration of the UE.

7. The apparatus of any of claims 1 to 6, wherein the operations further comprise establishing a PDU session after the at least one PDU session is released and the at least one timer is started, wherein establishing the PDU session triggers the core network to stop and reset the at least one timer associated with the implicit deregistration of the UE.

8. A method performed by a user equipment (UE), the method comprising:sending at least one registration request to register the UE via at least one access network to the core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE;establishing, with the core network, at least one packet data unit (PDU) session across the at least one access network; andreleasing the at least one PDU session across the at least one access network, wherein release of the at least one PDU session triggers the core network to start the at least one timer, and expiration of the at least one timer triggers the core network to implicitly deregister the UE via the at least one access network to the core network.

9. The method of claim 8 further comprising:starting the at least one timer when the at least one PDU session is released; and considering the UE implicitly deregistered via the at least one access network to the core network when the at least one timer expires.

10. The method of claim 8 or claim 9 further comprising determining the at least one timer associated with the implicit deregistration of the UE based on data to be communicated on the at least one PDU session across the at least one access network.

11. The method of any of claims 8 to 10 further comprising receiving at least one registration accept message that includes information indicating the at least one timer associated with the implicit deregistration of the UE.

12. The method of any of claims 8 to 11 further comprising initiating a mobility registration update with the core network, the mobility registration update including a timer value for the core network toupdate or renegotiate the at least one timer associated with the implicit deregistration of the UE based on the timer value.

13. The method of any of claims 8 to 12 further comprising initiating a mobility registration update with the core network, the mobility registration update triggering the core network to stop the at least one timer associated with the implicit deregistration of the UE.

14. The method of any of claims 8 to 13 further comprising establishing a PDU session after the at least one PDU session is released and the at least one timer is started, wherein establishing the PDU session triggers the core network to stop and reset the at least one timer associated with the implicit deregistration of the UE.

15. An apparatus comprising:at least one processor; andat least one memory storing instructions, the instructions when executed by the at least one processor causing the apparatus to perform operations, the operations comprising:receiving at least one registration request to register a user equipment (UE) via at least one access network to a core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE;receiving information that indicates release of at least one packet data unit (PDU) session of the UE across the at least one access network;starting, based on the release of the at least one PDU session, the at least one timer associated with the implicit deregistration of the UE; andimplicitly deregistering the UE via the at least one access network to the core network triggered when the at least one timer expires.

16. The apparatus of claim 15, wherein the operations further comprise sending to the UE at least one registration accept message that includes information indicating the at least one timer associated with the implicit deregistration of the UE.

17. The apparatus of claim 15 or claim 16, wherein the operations further comprise: receiving a registration request from the UE to trigger a mobility registration update with the core network, the registration request including a timer value related to the at least one timer associated with the implicit deregistration of the UE; andperforming an update or renegotiation of the at least one timer associated with the implicit deregistration of the UE based on the timer value.

18. The apparatus of any of claims 15 to 17, wherein the operations further comprise: receiving a registration request from the UE to trigger a mobility registration update with the core network; andstopping, based on the mobility registration update, the at least one timer associated with the implicit deregistration of the UE.

19. The apparatus of any of claims 15 to 18, wherein the operations further comprise: receiving information that indicates establishment of a PDU session after the at least one PDU session is released; andstopping and resetting, based on the establishment of the PDU session, the at least one timer associated with the implicit deregistration of the UE.

20. The apparatus of any of claims 15 to 19, wherein the operations further comprise storing, in a unified data management network function, the at least one timer associated with the implicit deregistration of the UE in association with registration of the UE via the at least one access network to the core network.

21. A method comprising:receiving at least one registration request to register a user equipment (UE) via at least one access network to a core network, the at least one registration request including information that indicates at least one timer associated with implicit deregistration of the UE;receiving information that indicates release of at least one packet data unit (PDU) session of the UE across the at least one access network;starting, based on the release of the at least one PDU session, the at least one timer associated with the implicit deregistration of the UE; andimplicitly deregistering the UE via the at least one access network to the core network triggered when the at least one timer expires.

22. The method of claim 21 further comprising sending to the UE at least one registration accept message that includes information indicating the at least one timer associated with the implicit deregistration of the UE.

23. The method of claim 21 or claim 22 further comprising:receiving a registration request from the UE to trigger a mobility registration update with the core network, the registration request including a timer value related to the at least one timer associated with the implicit deregistration of the UE; andperforming an update or renegotiation of the at least one timer associated with the implicit deregistration of the UE based on the timer value.

24. The method of any of claims 21 to 23 further comprising:receiving a registration request from the UE to trigger a mobility registration update with the core network; andstopping, based on the mobility registration update, the at least one timer associated with the implicit deregistration of the UE.

25. The method of any of claims 21 to 24 further comprising:receiving information that indicates establishment of a PDU session after the at least one PDU session is released; andstopping and resetting, based on the establishment of the PDU session, the at least one timer associated with the implicit deregistration of the UE.

26. The method of any of claims 21 to 25 further comprising storing, in a unified data management network function, the at least one timer associated with the implicit deregistration of the UE in association with registration of the UE via the at least one access network to the core network.

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