Method for inter-plmn cell reselection in rrcinactive reselection without transition to rrcconnected or rrcidle

Abstract

An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: receive an indication from a network cell, the indication comprising: at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection; and reselecting another network cell while in the radio resource control inactive state and not transitioning to the radio resource control idle state, the other network cell is among the indicated at least one public land mobile network cell that supports inter-public land mobile network radio resource control inactive state cell reselection.

Description

Technical Field

[0001] The exemplary and non-limiting exemplary embodiments relate generally to communications and, more particularly, to methods for inter-PLMN cell reselection in RRC_INACTIVE without transitioning to RRC_CONNECTED or RRC_IDLE. Background Art

[0002] It is well known for user equipment to connect to non-terrestrial networks and terrestrial networks. Summary of the invention

[0003] According to one aspect, a device includes: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the device to at least: receive an indication from a network cell, the indication including: at least one public land mobile network cell that supports reselection of radio resource control inactive state cells between public land mobile networks; and while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, reselect another network cell, the other network cell being among the indicated at least one public land mobile network cell that supports reselection of radio resource control inactive state cells between public land mobile networks.

[0004] According to one aspect, an apparatus comprises: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a cause value from a terminal device, the cause value being configured to be used for a registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; store the cause value within a resume request; retain the terminal device in a radio resource control inactive state using an updated pause configuration; and send a physical downlink shared channel transmission including a registration acceptance message to the terminal device.

[0005] According to one aspect, a device comprises: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the device to at least: receive a non-access stratum registration message from a terminal device using a network node, the network node providing access to a network cell; and send an indication to the terminal device, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive state cells between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state, the other network cell being among at least one public land mobile network cell that supports reselection of radio resource control inactive state cells between public land mobile networks.

[0006] According to one aspect, an apparatus comprises: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a registration request from a network node providing access to a network cell; and send an indication to a terminal device directly or through the network node, the indication comprising: at least one public land mobile network cell supporting reselection of radio resource control inactive state cells between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, the other network cell being among at least one public land mobile network cell supporting reselection of radio resource control inactive state cells between public land mobile networks.

[0007] According to one aspect, a device comprises: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the device to at least: receive a path switching request from a network node that provides access to another network cell while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from the network cell while being in the radio resource control inactive state and not transitioning to a radio resource control idle state; receive a next generation application protocol uplink non-access stratum transmission message including a mobility registration update non-access stratum message from the network node that provides access to another network cell; based on the mobility registration update non-access stratum message, retain at least one protocol data unit session and at least one data radio bearer setting before transitioning the terminal device to an inactive state without performing radio resource control reconstruction; and send a registration acceptance message to the terminal device directly or through a network node that provides access to another network cell.

[0008] According to one aspect, an apparatus comprises: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive an indication from a network cell that signals support for reselection of a radio resource control inactive state cell between public land mobile networks; and based on the indication, reselect another network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state.

[0009] According to one aspect, an apparatus comprises: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a cause value from a terminal device, the cause value being configured to be used for a registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; store the cause value within a recovery request; retain the terminal device in a radio resource control inactive state; and send a physical downlink shared channel transmission including a registration acceptance message to the terminal device.

[0010] According to one aspect, an apparatus comprises: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a registration message from a terminal device using a network node, the network node providing access to a network cell; and send indication signaling to the terminal device, the indication signaling support for reselection of a radio resource control inactive state cell between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state.

[0011] According to one aspect, an apparatus comprises: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a registration request from a network node providing access to a network cell; and send an indication to a terminal device directly or through the network node, the indication signaling support for reselection of a radio resource control inactive state cell between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while in a radio resource control inactive state and without transitioning to a radio resource control idle state.

[0012] According to one aspect, a device comprises: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the device to at least: receive a path switching request from a network node that provides access to another network cell while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from a network cell while being in the radio resource control inactive state and not transitioning to a radio resource control idle state; receive a mobility registration update message from the network node that provides access to another network cell; based on the mobility registration update message, retain at least one protocol data unit session and at least one data radio bearer setting before transitioning the terminal device to an inactive state without performing radio resource control reconstruction; and send a registration acceptance message to the terminal device directly or through a network node that provides access to another network cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above aspects and other features are explained in the following description in conjunction with the accompanying drawings.

[0014] Figure 1 is a block diagram of one possible and non-limiting system in which example embodiments may be practiced.

[0015] Figure 2 Depicted is the NR RRC state machine with RRC state transitions.

[0016] Figure 3 A signalling diagram for a first embodiment is depicted.

[0017] Figure 4 A signaling diagram for an alternative embodiment is depicted.

[0018] Figure 5 is an example apparatus configured to implement the examples described herein.

[0019] Figure 6 A representation of an example of a non-volatile storage medium is shown.

[0020] Figure 7 It is an example method performed by a terminal device to implement the examples described in this article.

[0021] Figure 8 An example method performed using a network node to implement the examples described herein is provided.

[0022] Fig. 9 An example method performed using a network node to implement the examples described herein is provided.

[0023] Fig.10 An example method of implementing the examples described herein is performed using access and mobility management functions.

[0024] Fig.11 An example method of implementing the examples described herein is performed using access and mobility management functions.

[0025] Fig.12 It is an example method performed by a terminal device to implement the examples described in this article.

[0026] Fig.13 An example method performed using a network node to implement the examples described herein is provided.

[0027] Fig.14 An example method performed using a network node to implement the examples described herein is provided.

[0028] Fig.15 An example method of implementing the examples described herein is performed using access and mobility management functions.

[0029] Fig.16 An example method of implementing the examples described herein is performed using access and mobility management functions. DETAILED DESCRIPTION

[0030] Go to Figure 1 , which shows a block diagram of one possible and non-limiting example in which the examples may be practiced. A user equipment (UE) 110, a radio access network (RAN) node 170 and (multiple) network elements 190 are shown. Figure 1In the example of , a user equipment (UE) 110 wirelessly communicates with a wireless network 100. A UE is a wireless device that can access the wireless network 100. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected by one or more buses 127. Each transceiver in the one or more transceivers 130 includes a receiver Rx 132 and a transmitter Tx 133. The one or more buses 127 can be address, data, or control buses, and can include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, optical fiber or other optical communication devices, etc. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a module 140, including one or both of the parts 140-1 and / or 140-2, which can be implemented in a variety of ways. The module 140 can be implemented in hardware as the module 140-1, such as as part of the one or more processors 120. Module 140-1 may also be implemented as an integrated circuit or by other hardware (such as a programmable gate array). In another example, module 140 may be implemented as module 140-2, which is implemented as computer program code 123 and executed by one or more processors 120. For example, one or more memories 125 and computer program code 123 may be configured to perform one or more operations as described herein with one or more processors 120 using user equipment 110. UE 110 communicates with RAN node 170 via wireless link 111.

[0031] The RAN node 170 in this example is a base station that provides access to the wireless network 100 to wireless devices such as UE 110. The RAN node 170 may be, for example, a base station for 5G, also known as New Radio (NR). In 5G, the RAN node 170 may be a NG-RAN node, which is defined as a gNB or ng-eNB. A gNB is a node that provides NR user plane and control plane protocol termination to a UE and is connected to a 5GC such as, for example, network element(s) 190 via an NG interface such as connection 131. An ng-eNB is a node that provides E-UTRA user plane and control plane protocol termination to a UE and is connected to a 5GC via an NG interface such as connection 131. An NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU) 196 and (multiple) distributed units (DU) (gNB-DU), of which DU 195 is shown. Note that DU 195 may include or be coupled to and control a radio unit (RU). The gNB-CU 196 is a logical node that hosts the radio resource control (RRC), SDAP and PDCP protocols of the gNB or the RRC and PDCP protocols of the en-gNB, and controls the operation of one or more gNB-DUs. The gNB-CU 196 terminates the F1 interface connected to the gNB-DU 195. The F1 interface is shown as reference 198, although reference 198 also shows a link between a remote element of the RAN node 170 and a centralized element of the RAN node 170, such as a link between the gNB-CU 196 and the gNB-DU 195. The gNB-DU 195 is a logical node that hosts the RLC, MAC, and PHY layers of the gNB or en-gNB, and its operation is controlled in part by the gNB-CU 196. One gNB-CU 196 supports one or more cells. One cell can be supported by one gNB-DU 195, or one cell can be supported / shared by multiple DUs under RAN sharing. The gNB-DU 195 terminates the F1 interface 198 connected to the gNB-CU 196. Note that the DU 195 is considered to include the transceiver 160, for example as part of the RU, but some examples may include the transceiver 160 as part of a separate RU, for example under the control of the DU 195 and connected to the DU 195. The RAN node 170 may also be an eNB (evolved NodeB) base station for LTE (Long Term Evolution), or any other suitable base station or node. The examples described herein are considered to be for intra-RAT environment scenarios.

[0032] The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces ((multiple) N / WI / F) 161, and one or more transceivers 160 interconnected by one or more buses 157. Each of the one or more transceivers 160 includes a receiver Rx 162 and a transmitter Tx 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include (multiple) processors 152, (multiple) memories 155, and a network interface 161. Note that the DU 195 may also contain its own memory and (multiple) processors and / or other hardware, but these are not shown.

[0033] The RAN node 170 includes a module 150, which includes one or both of the parts 150-1 and / or 150-2, which can be implemented in a variety of ways. The module 150 can be implemented in hardware as the module 150-1, such as as part of one or more processors 152. The module 150-1 can also be implemented as an integrated circuit or by other hardware (such as a programmable gate array). In another example, the module 150 can be implemented as a module 150-2, which is implemented as a computer program code 153 and executed by one or more processors 152. For example, one or more memories 155 and computer program code 153 are configured to, together with one or more processors 152, cause the RAN node 170 to perform one or more operations as described herein. Note that the functionality of the module 150 can be distributed, such as distributed between the DU 195 and the CU 196, or implemented only in the DU 195.

[0034] One or more network interfaces 161 communicate over a network, such as via links 176 and 131. Two or more gNBs 170 may communicate using, for example, link 176. Link 176 may be wired or wireless or both, and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interfaces for other standards.

[0035] The one or more buses 157 may be an address bus, a data bus, or a control bus, and may include any interconnection mechanism, such as a series of wires on a motherboard or integrated circuit, an optical fiber or other optical communication device, a wireless channel, etc. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for a gNB implementation for 5G, where other elements of the RAN node 170 may be physically located in a different location from the RRH / DU 195, and the one or more buses 157 may be partially implemented as, for example, a fiber optic cable or other suitable network connection to connect other elements of the RAN node 170 (e.g., a central unit (CU), gNB-CU 196) to the RRH / DU 195. Reference numeral 198 also indicates those suitable network links (multiple).

[0036] The RAN node / gNB may include one or more TRPs, and the methods described in this document may be applied to these TRPs. Figure 1 RAN node 170 is shown to include two TRPs, namely TRP 51 and TRP 52. RAN node 170 may host or include Figure 1 Other TRPs not shown in .

[0037] It should be noted that the description herein indicates that a "cell" performs functions, but it should be clear that the devices that form the cells can perform these functions. A cell constitutes part of a base station. That is, each base station can have multiple cells. For example, for a single carrier frequency and associated bandwidth, there can be three cells, each covering one-third of a 360-degree area, so that the coverage area of ​​a single base station covers an approximate ellipse or circle. In addition, each cell can correspond to a single carrier, and a base station can use multiple carriers. Therefore, if there are three 120-degree cells and two carriers per carrier, the base station has a total of 6 cells.

[0038] The wireless network 100 may include one or more network elements 190, which may include core network functions and provide connectivity to another network, such as a telephone network and / or a data communication network (e.g., the Internet), via one or more links 181. Such core network functions for 5G may include location management functions ((multiple) LMFs) and / or (multiple) access and mobility management functions ((multiple) AMFs) and / or user plane functions (multiple) (UPFs) and / or (multiple) session management functions ((multiple) SMFs). Such core network functions for LTE may include MME (mobility management entity) / SGW (serving gateway) functions. Such core network functions may include SON (self-organizing / optimized network) functions. These are merely example functions that may be supported by (multiple) network elements 190, and it is noted that both 5G and LTE functions may be supported. The RAN node 170 is coupled to the network element 190 via a link 131. The link 131 may be implemented, for example, as an NG interface for 5G, an S1 interface for LTE, or other suitable interfaces for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N / WI / F) 180 interconnected by one or more buses 185. The one or more memories 171 include computer program code 173. The computer program code 173 may include SON and / or MRO functionality 172.

[0039] The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functions into a single software-based management entity (virtual network). Network virtualization involves platform virtualization, usually combined with resource virtualization. Network virtualization is divided into external virtualization and internal virtualization, where external virtualization combines many networks or parts of networks into a pseudo-unit, and internal virtualization provides network-like functions to software containers on a single system. Note that the virtualized entities produced by network virtualization are still implemented using hardware (such as processors 152 or 175 and memories 155 and 171) at some level, and such virtualized entities produce technical effects.

[0040] Computer readable memories 125, 155, and 171 may be of any type suitable for the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, non-transitory memory, transient memory, fixed memory, and removable memory. Computer readable memories 125, 155, and 171 may be components for performing storage functions. Processors 120, 152, and 175 may be of any type suitable for the local technical environment and may include, as non-limiting examples, one or more of a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Processors 120, 152, and 175 may be components for performing functions, such as controlling UE 110, RAN node 170, (multiple) network elements 190, and other functions as described herein.

[0041] In general, various example embodiments of user equipment 110 may include, but are not limited to, a cellular phone, such as a smartphone, a tablet computer, a personal digital assistant (PDA) with wireless communication capabilities, a portable computer with wireless communication capabilities, an image capture device (such as a digital camera with wireless communication capabilities), a gaming device with wireless communication capabilities, a music storage and playback device with wireless communication capabilities, an Internet device that allows wireless Internet access and browsing, a tablet computer with wireless communication capabilities, a head-mounted display (such as a head-mounted display that implements virtual / augmented / mixed reality), and a portable unit or terminal that combines these functions. UE 110 may also be a vehicle (such as a car), or a UE installed in a vehicle, a UAV (such as, for example, a drone), or a UE installed in a UAV.

[0042] UE 110, RAN node 170 and / or network element(s) 190 (and associated memory, computer program code and modules) may be configured to (e.g., in part) implement the methods described herein, including methods for inter-PLMN cell reselection in RRC_INACTIVE without transitioning to RRC_CONNECTED or RRC_IDLE. Thus, computer program code 123, modules 140-1, modules 140-2 and Figure 1 The other elements / features shown in the figure may implement the user equipment related aspects of the examples described herein. Similarly, the computer program code 153 of the RAN node 170, the module 150-1, the module 150-2 and Figure 1 Other elements / features shown in the figure may implement the example gNB / TRP related aspects described herein. Computer program code 173 and (multiple) network elements 190 Figure 1Other elements / features shown in may implement network element related aspects of the examples described herein.

[0043] Having thus introduced a suitable but non-limiting technical context for practicing example embodiments, example embodiments are now more particularly described.

[0044] The examples described in this article relate to enhancements to the connection recovery procedure in 5G NR in the context of the NTN mobility use case.

[0045] Figure 2 The NR RRC state machine with RRC state transitions is depicted. The RRC_INACTIVE state (206) was introduced in 3GPP NR Rel-15 to complement the existing states RRC_CONNECTED (202) and RRC_IDLE (212) with the goal of streamlining signaling and saving energy to support NR services and use cases.

[0046] The RRC_INACTIVE state (206) enables the network to quickly resume a suspended RRC connection (see 204) and start transmission of small or sporadic data with much lower initial access delay and associated signaling overhead compared to the RRC_IDLE state (212).

[0047] like Figure 2 Also shown, UE 110 transitions from NR RRC_INACTIVE state (206) to NR RRC_IDLE state (212) during release (208), and UE 110 transitions between NR RRC_CONNECTED state (202) and NR RRC_IDLE state (212) during connection, establishment, release, or rejection (210).

[0048] Compared to the UE 110 in the RRC_CONNECTED state (202), the RRC_INACTIVE state (206) minimizes mobility signaling to both the RAN and the core network because the UE is still in the CM-CONNECTED state. A UE in the RRC_INACTIVE state (206) can move within an area configured by the RAN, referred to as the RAN Notification Area (RNA), without any notification to the network, using a unique identifier "Inactive-RNTI (I-RNTI) when accessing the network. The RNA can be configured to cover a single or multiple cells and is contained within a Registration Area (RA) configured by the AMF.

[0049] When moving the UE from RRC_CONNECTED (202) to RRC_INACTIVE state (206), the serving gNB (e.g., 170) allocates an I-RNTI as part of the suspendConfig in the RRC release message to UE 110. The I-RNTI is used by the network side to identify both UE 110 and the gNB 170 (last serving gNB) hosting the UE context.

[0050] The I-RNTI can be 40 bits long (full I-RNTI) or 24 bits long (short I-RNTI). The UE reads the information in SIB1 to decide whether to use the short I-RNTI or the full I-RNTI when resuming the connection.

[0051] The UE 110 initiates a RAN Notification Area Update (RNAU) periodically (as configured) and when it reselects a cell that is not part of the configured RAN Notification Area (RNA). The RNA must be configured within the CN Registration Area (RA). When the UE 110 moves out of the configured Registration Area (RA), the UE 110 initiates a Mobility Registration Area Update (RAU) to inform the AMF that it has entered a new RA.

[0052] In 3GPP TR 38.821 – “Solutions for NR to support NTN”, the idle / inactive mode UE procedures specified for TN systems are considered as the baseline for NTN; however, enhancements are not excluded.

[0053] One of the objectives of Rel-18 NR NTN Enhancement (NR_NTN_enh) WI [Ref: RP-222654] is to support service continuity or seamless UE mobility between NTN and TN, which includes UE mobility in RRC_INACTIVE state.

[0054] 4.1.4 NTN-TN and NTN-NTN mobility and service continuity enhancements. This work considers the existing approaches for NR TN and the results of Rel-17 NR NTN WI results as a baseline for NTN-TN mobility. This includes specifying NTN-TN and NTN-NTN measurement / mobility and service continuity enhancements [RAN2, RAN3, RAN4]. For NTN-NTN mobility, this includes specifying cell reselection enhancements for geo-mobile cells, where the timing-based and location-based cell reselection for quasi-geo-fixed cells in Rel-17 can be considered as a starting point. [RAN2, RAN3, RAN4]. This work also includes specifying NTN-NTN handover enhancements for RRC_CONNECTED UEs in quasi-geo-fixed cells and geo-mobile cells to reduce signaling overhead. [RAN2, RAN3]. This work also includes specifying cell reselection enhancements for RRC_IDLE / INACTIVE UEs to reduce UE power consumption (NTN-TN mobility is prioritized). [RAN2, RAN3, RAN4]. This work also includes studying and (if needed) specifying enhancements to Xn[ / NG] signalling to support feeder link handover, CHO, e.g. to exchange the necessary information between gNBs. [RAN3].

[0055] 3GPP SA Working Group 2 (SA2) has reached the following agreement on NTN. NTN satellite types GEO, MEO, LEO and TN are considered different RAT types. Each RAT type must be configured with non-overlapping Registration Area (RA) or Tracking Area (TA). The above means that for NTN and TN overlapping scenarios, the RA or TA of NTN and TN must be clearly defined. However, from the RAN2 perspective, NR NTN GEO, MEO, LEO cells and NR TN cells are considered intra-RAT cells.

[0056] Furthermore, deployment options for the NTN as identified in 3GPP TR 38.821 include the following: NTN deployed with a different PLMN than the TN, NTN and TN deployed with an equivalent PLMN (EPLMN), and NTN and TN deployed with a common PLMN.

[0057] However, the inventors of the examples described herein have identified that there are some limitations to supporting UE mobility in the RRC_INACTIVE state for all possible deployment scenarios, the details of which are listed below.

[0058] The example described in this article considers the scenario where a UE in RRC_INACTIVE state (connected to NTN) reselects a TN cell. Assume that both NTN and TN are NR RAT type and connected via Xn interface. Further assume that the networks belong to different PLMNs, which is a possible NTN-TN deployment scenario.

[0059] According to the SA2 protocol listed earlier, NTN and TN cells are expected to be part of different Registration Areas (RAs); this means that the reselected TN cell will not be part of the RNA configured by the last serving gNB. This means that the current UE will need to initiate both the RAN Notification Area Update procedure (RNAU) and the Mobile Registration Update procedure (MRU) when reselecting a TN cell of the same PLMN as the NTN cell. The MRU is a NAS procedure used to notify the AMF that it has entered a new RA.

[0060] According to the existing specifications (see clause 4.1 in TS 38.304), if the registration update procedure is triggered by a UE in RRC_INACTIVE state due to cell reselection to an inter-PLMN cell, the UE first transitions to RRC_IDLE and then re-establishes the RRC connection; a registration request (NAS message) is then initiated by the UE as part of the RRCSetupComplete message, which is forwarded to the AMF within the NGAP Initial UE Message message.

[0061] As stated in clause 4.1 in TS 38.304, "When the UE selects a new PLMN or SNPN, the UE transitions from RRC_INACTIVE to RRC_IDLE as described in TS 24.501".

[0062] Therefore, in the hypothetical different PLMN scenario, whenever a TN cell of a new PLMN is reselected, the current UE has to discard the stored RRC inactive context assigned by the NTN network and re-establish it from scratch in the new TN cell.

[0063] This document describes a solution that enables: a) RNAU and MRU procedures due to reselection to an inter-PLMN (intra-RAT) cell of a different RA / TA to be successfully performed in the RRC Inactive state without transitioning to RRC Idle or RRC Connected, while also preserving the PDU sessions and configured DRBs, and b) the network indicates support for such inter-PLMN connection recovery to the UE, enabling the UE to attempt inter-PLMN connection recovery when it is supported. It should be noted that such procedures apply to related capabilities and procedures within the network, which may not always be present. For example, the following will be implemented on the network side: obtaining AS Inactive UE context from a neighboring gNB belonging to a different PLMN, switching core network C-plane and U-plane paths between different AMFs serving different PLMNs, transferring NAS UE context when the new and old AMFs are different, etc.

[0064] The above lists the core enhancements solved by the examples described in this article. The solutions described in this article can reduce the power consumption of UE and network, signaling overhead and latency. Such support can make the transition between NTN and TN more efficient and smoother, where such transition may occur frequently for NTN UE.

[0065] The RNAU and NAS registration procedures can be combined jointly in the RRC inactivity resumption procedure in order to optimize the synchronization process. However, these procedures do not address how to handle RNAU and RAU procedures by avoiding unnecessary RRC_CONNECTED state transitions.

[0066] One of the differences between the examples described herein and previous developments is that what is described herein is a method of reselecting a cell belonging to a different RA / TA, RNA and a different PLMN in the RRC_INACTIVE state without transitioning to RRC_CONNECTED. The previously developed methods cannot implement this solution. In addition, the methods described herein enable the network to indicate support for inter-PLMN recovery so that the UE attempts inter-PLMN connection recovery when it is supported by the network. The examples described herein are applicable to intra-RAT scenarios.

[0067] The method described herein is intended to solve the aforementioned problems and enables a UE in RRC_INACTIVE state to reselect an inter-PLMN NR (TN) cell while connected to an NR (NTN) cell without transitioning to RRC_IDLE or RRC_CONNECTED, while retaining the PDU session and DRB configured in the NTN PLMN to continue after the cell is reselected to the TN cell. This embodiment is also applicable to TN to NTN cell reselection in RRC_INACTIVE state, NTN to NTN cell reselection in RRC_INACTIVE state, and TN to TN cell reselection in RRC_INACTIVE state, and generally reselection from a first network cell to a second network cell in RRC_INACTIVE state. In addition, the examples described herein are applicable to intra-RAT scenarios.

[0068] The following are example steps for implementing an example solution embodiment:

[0069] 1. For UEs capable of NTN and TN connectivity, as part of the attach or initial registration procedure, the serving AMF (home PLMN) may indicate to the UE that inter-PLMN RRC_INACTIVE state cell reselection is supported, including a list of supported PLMNs. This indication, together with the list of supported PLMNs, may be provided in a NAS Registration Accept message carried on an existing NGAP message (such as an Initial Context Setup Request message or a DL NAS transmission). This enables the UE to attempt to resume connectivity after inter-PLMN cell reselection when the core network has indicated that it is supported, otherwise the UE will transition to RRC Idle (as per legacy behavior). It should be noted that inter-PLMN RRC_INACTIVE state cell reselection may be configured or enabled for other inter-PLMN mobility use cases in addition to NTN.

[0070] 2. The serving cell may broadcast support for inter-PLMN RRC_INACTIVE state mobility in SIB1 or SIB19 (NTN specific) or any other suitable SIB. This enables the UE to attempt to resume the connection after inter-PLMN cell reselection when both the RAN and the core network support it, otherwise the UE will transition to RRC idle state. Alternatively, the NW may inform entities (e.g. UE) of support for inter-PLMN RRC_INACTIVE state mobility in the RRC release message with suspension configuration (i.e. in RRC_CONNECTED to RRC_INACTIVE transition) (e.g. Figure 2In another example, the NW configures (via dedicated and / or broadcast signaling) the UE to perform an RRC recovery procedure in case of inter-PLMN cell reselection.

[0071] 3. When reselecting a new cell as part of inter-PLMN cell reselection, the UE may decide to reselect a cell based on its support for the inter-PLMN RRC-INACTIVE state.

[0072] 4. After a UE in RRC_INACTIVE state reselects inter-PLMN to a PLMN belonging to the supported PLMN list as signaled by the network, it may initiate an SDT procedure for MRU if the SRB is configured for SDT (i.e. the NW allows the UE to initiate an SDT procedure for NAS signaling). The UE may use the existing RRCResumeRequest message with a new cause value (e.g. ra-Update) as a trigger for the gNB of the new serving cell to perform an XnAP UE context acquisition from the last serving gNB of a different PLMN (if the new gNB and the last serving gNB are different).

[0073] The new cause value in the RRC RESUME REQUEST message shall be an indication to the network node of the reselected cell that the NAS REGISTRATION UPDATE procedure is expected to be followed. The network node of the reselected cell shall then store the new cause value based at least in part on the cause value and leave the UE in the RRC INACTIVE state with the updated suspension configuration. Figure 3 Items 330 and 335 of Figure 4 Examples of items 434 and 440 in FIG.

[0074] If msg3 size is enough to accommodate the NAS message, the UE includes a "Registration Request with Mobility Update" NAS message in Msg3 for 4-step RACH based SDT, otherwise it sends a BSR in msg3 to request an additional UL grant.

[0075] As an alternative, for this MRU use case, the PRACH resources (preamble, RO) dedicated to the SDT procedure can be configured by the cell so that the UE can indicate to the network that a Msg3 size of 4-step RACH is required, which can fit in the NAS message.

[0076] Alternatively, a new resumption cause is provided in the RRC resumption request using an LCID dedicated for this purpose. For example, a dedicated (multiple) CCCH SDU LCID for this purpose may be used, i.e. the LCID used to indicate a CCCH SDU (in this case RRCResumeRequest).

[0077] 5. The gNB of the new serving cell (TN cell), upon receiving the "NAS Registration Update" message as SDT payload, extracts the NAS message and forwards it to the new AMF using the NGAP "UPLINK NAS TRANSPORT" message after the PATH SWITCH REQUEST procedure. Therefore, for a UE in RRC_INACTIVE state, the NAS mobility registration update procedure due to inter-PLMN cell reselection is performed without RRC state transition while the UE remains in RRC_INACTIVE state.

[0078] 6. In the case that the AMF serving the new serving TN gNB is different from the old serving AMF, the new AMF requests UE context transfer from the old AMF (serving the last serving NTN gNB).

[0079] 7. The above mechanism enables the new network to preserve the PDU Session / DRB associated with the UE even in the case of a different AMF serving the new serving gNB (TN in this case), potentially avoiding RRC connection re-establishment.

[0080] 8.NGAP Downlink NAS Transfer and DL SDT can be used to forward the Registration Accept NAS message from the AMF to the UE. Currently in Rel-17 SDT, NAS message transfer is only supported in UL.

[0081] In summary, this document describes a method for enabling continuation of the RRC_INACTIVE state in the inter-PLMN cell change scenario "from AMF during the registration procedure" or "from RAN during the UE transition to RRC_INACTIVE state". The list of PLMNs where this feature is activated is signaled. This document also describes a method for continuing in the RRC_INACTIVE state when the UE is in the process of reselecting to a cell of another PLMN configured to support inter-PLMN RRC_INACTIVE mobility. This document also describes a method for the UE to trigger the inter-PLMN mobility update procedure for context transfer from the old RAN node to the new RAN node and context transfer from the old AMF to the new AMF to resume the RRC connection and bearers. This document also describes a method for the UE to trigger the SDT procedure for the inter-PLMN mobility update procedure when it is in the RRC_INACTIVE state.

[0082] The signaling diagram for the first embodiment is as follows Figure 3Key aspects include item 308 (“Inter-PLMN RRC_INACTIVE state mobility is enabled (PLMN list)”), item 310 (“Inter-PLMN RRC_INACTIVE state mobility is enabled (PLMN list)”), item 312 (“The serving network may broadcast support for inter-PLMN connection resumption in the serving cell in SIB1 or network-specific SIB19”), item 330 (“(New cause)”), item 340 (“UE in RRC_INACTIVE CM-CONNECTED”), item 342 (“Based on the previously stored cause, the gNB treats the subsequent SDT message content as NAS and initiates PATH SWITCH PROCEDURE”), item 358 (“UE RRC_INACTIVE state inter-PLMN connection resumption while preserving the PDU session and DRB setup prior to moving the UE to RRC_INACTIVE state, thereby avoiding RRC_Reestablishment”), and item 362 (“(Registration Accepted)”).

[0083] At 302, the UE 110 sends an RRC Setup Request to the last serving gNB 170-2 (e.g., NTN gNB 170-2). The last serving gNB 170-2 may also be referred to as a serving network node, which becomes the last serving network node after the UE 110 reselects to another cell to which another network node (e.g., gNB 170-1) provides access. At 304, the last serving gNB 170-2 sends an RRC Setup message to the UE 110. At 306, the UE 110 sends an RRC Setup Complete and a NAS Registration message to the last serving gNB 170-2. At 307, the last serving gNB 170-2 sends an NGAP Initial UE message and a Registration Request to the old AMF 190-1. At 308, the old AMF 190-1 sends a NGAP Initial Context Setup Request and Registration Accept message with an indication that Inter-PLMN RRC_INACTIVE state mobility is enabled including a list of PLMNs to the last serving gNB 170-2. At 310, the last serving gNB 170-2 sends an RRC Connection Reconfiguration SRB2, DRB and Registration Accept message including an indication that Inter-PLMN RRC_INACTIVE state mobility is enabled message (list of PLMNs) to the UE 110. At 312, the serving network may broadcast support for inter-PLMN connection resumption in SIB1 or network (e.g., NTN) specific SIB19 in the serving cell, as performed by the last serving gNB 170-2.

[0084] At 314, the last serving gNB 170-2 sends an NGAP Initial Context Setup Response message to the old AMF 190-1. At 316, the UE 110 sends a NAS Registration Complete message to the last serving gNB 170-2. At 318, the last serving gNB 170-2 sends an NGAP Registration Complete message to the old AMF 190-1. At 320, the UE 110 is in RRC_CONNCTED CM-CONNECTED state. At 322, as it relates to gNB 170-1 (e.g., TN gNB 170-1), last serving gNB 170-2, and old AMF 190-1, gNB 170-1 (PLMN 1) and gNB 170-2 (PLMN 2) have Xn connectivity, gNB 170-2 and gNB 170-1 are 5G NR RATs, and PLMN 1 and PLMN 2 may be configured as EPLMNs. At 324, last serving gNB 170-2 sends an RRC Release message (with SuspendConfig) to UE 110. At 326, UE 110 is in RRC_INACTIVE CM-CONNECTED state. At 328, as it relates to UE 110 and gNB 170-1, UE 110 reselects to a network cell (e.g., a TN network cell to which gNB 170-1 provides access).

[0085] At 330, UE 110 sends a RRCResumeRequest message (new cause) to gNB 170-1. At 332, gNB 170-1 sends a Get UE Context Request (RNAU) message to the last serving gNB 170-2. At 334, the last serving gNB 170-2 sends a Get UE Context Response message to gNB 170-1. At 335, gNB 170-1 stores the new cause in the resume request and leaves UE 110 in the RRC_INACTIVE state with the updated suspendConfig. At 336, gNB 170-1 sends an UL grant to UE 110. At 338, gNB 170-1 sends a RRCRelease message with the updated suspendconfig to UE 110. At 340, UE 110 is in the RRC_INACTIVE CM-CONNECTED state. At 342, gNB 170-1 treats the subsequent SDT message content as NAS based on the previously stored reason and initiates the path switching procedure. At 344, UE 110 sends a PUSCH transmission including a "Registration Request NAS message" to gNB 170-1.

[0086] At 346, gNB 170-1 sends a Data Forwarding Address Indication to the last serving gNB 170-2. At 348, gNB 170-1 sends a Path Switch Request to the new AMF 190-2. At 350, the new AMF 190-1 sends a Path Switch Request Response to gNB 170-1. At 352, gNB 170-1 sends a UE Context Release message to the last serving gNB 170-2. At 354, gNB 170-1 sends a NGAP Uplink NAS Transfer (Registration Request (Mobility Update)) message to the new AMF 190-2. At 356, upon receipt of the Registration Request, the UE context is transferred from the old AMF 190-1 to the new AMF 190-2 as per conventional procedures. At 358, UE 110 is in RRC_INACTIVE state inter-PLMN connection recovery with respect to old AMF 190-1 and new AMF 190-2, while preserving PDU session and DRB setup before moving UE 110 to RRC_INACTIVE state, thereby avoiding RRC_Reestablishment. At 360, new AMF 190-2 sends NGAP downlink NAS transfer (Registration Accept) message to gNB 170-1. At 362, gNB 170-1 sends a PDSCH transmission including the "Registration Accept" message to UE 110.

[0087] The signaling diagram for an alternative embodiment is as follows Figure 4 Key aspects include item 414 (“In case the gNB is pre-configured with a list of PLMNs supporting inter-PLMN RRC_INACTIVE state mobility”), item 416 (“The serving network may broadcast support for inter-PLMN connection resumption in the serving cell in SIB1 or network-specific SIB19 or any other SIB”), item 428 (“inter-PLMN_RRC_INACTIVE_state_mobility_enable+PLMN list”), item 434 (“(new cause)”), item 446 (“UE in RRC_INACTIVE CM-CONNECTED”), item 448 (“gNB treats subsequent SDT message content as NAS based on previously stored cause and initiates PATH SWITCH PROCEDURE”), item 464 (“UE RRC_INACTIVE state inter-PLMN connection resumption before moving the UE to RRC_INACTIVE while preserving PDU session and DRB setup, thereby avoiding RRC_Reestablishment”), and item 468 (“(“Registration Accepted”)”).

[0088] At 402, the UE 110 sends an RRC setup request to the last serving gNB 170-2 (e.g., NTN gNB 170-2). The last serving gNB 170-2 may also be referred to as a serving network node, which becomes the last serving network node after the UE 110 reselects to another cell to which another network node (e.g., gNB 170-1) provides access. At 404, the last serving gNB 170-2 sends an RRC setup message to the UE 110. At 406, the UE 110 sends an RRC setup complete and NAS registration message to the last serving gNB 170-2. At 408, the last serving gNB 170-2 sends an NGAP initial UE message and a registration request to the old AMF 190-1. At 410, the old AMF 190-1 sends an NGAP initial context setup request and a registration accept message to the last serving gNB 170-2. At 412, the last serving gNB 170-2 sends an RRC connection reconfiguration SRB2, DRB, and registration accept message to UE 110. At 414, in the event that gNB 170-2 is preconfigured with a list of PLMNs that support inter-PLMN RRC_INACTIVE state mobility, as performed by the last serving gNB 170-2, then at 416, the serving network may broadcast support for inter-PLMN connection resumption in SIB1 or network (e.g., NTN) specific SIB19 or any other SIB in the serving cell.

[0089] At 418, the last serving gNB 170-2 sends a NGAP Initial Context Setup Response message to the old AMF 190-1. At 420, the UE 110 sends a NAS Registration Complete message to the last serving gNB 170-2. At 422, the last serving gNB 170-2 sends a NGAP Registration Complete message to the old AMF 190-1. At 424, the UE 110 is in RRC_CONNCTED CM-CONNECTED state. At 426, since it is associated with gNB 170-1 (e.g., TN gNB 170-1), the last serving gNB 170-2, and the old AMF 190-1, gNB 170-1 (PLMN 1) and gNB 170-2 (PLMN 2) have Xn connectivity. gNB 170-2 and gNB 170-1 are 5G NR RAT. PLMN 1 and PLMN 2 may be configured as EPLMNs. At 428, finally serving gNB 170-2 sends an RRC Release message (with SuspendConfig and inter-PLMN_RRC_INATIVE_state_mobility_enable and the PLMN list) to UE 110. At 430, UE 110 is in an RRC_INACTIVE CM-CONNECTED state. At 432, associated with UE 110 and gNB 170-1 (e.g., TN gNB 170-1), UE 110 reselects to a network cell (e.g., a TN network cell or a network cell to which gNB 170-1 provides access).

[0090] At 434, UE 110 sends a RRCResumeRequest message (new cause) to gNB 170-1. At 436, gNB 170-1 sends a Get UE Context Request (RNAU) message to the last serving gNB 170-2. At 438, the last serving gNB 170-2 sends a Get UE Context Response message to gNB 170-1. At 440, gNB 170-1 stores the new cause in the Resume Request and retains UE 110 in the RRC_INACTIVE state with the updated suspendConfig. At 442, gNB 170-1 sends an UL Grant to UE 110. At 444, gNB 170-1 sends a RRCRelease message with the updated suspendConfig to UE 110. At 446, UE 110 is in the RRC_INACTIVE CM-CONNECTED state. At 448, gNB 170-1 treats the subsequent SDT message content as NAS based on the previously stored reason and initiates a path switching procedure. At 450, UE 110 sends a PUSCH transmission including a "Registration Request NAS message" to gNB 170-1.

[0091] At 452, the gNB 170-1 sends a Data Forwarding Address Indication to the last serving gNB 170-2. At 454, the gNB 170-1 sends a Path Switch Request to the new AMF 190-2. At 456, the new AMF 190-1 sends a Path Switch Request Response to the gNB 170-1. At 458, the gNB 170-1 sends a UE Context Release message to the last serving gNB 170-2. At 460, the gNB 170-1 sends a NGAP Uplink NAS Transfer (Registration Request (Mobility Update)) message to the new AMF 190-2. At 462, upon receipt of the Registration Request, the UE context is transferred from the old AMF 190-1 to the new AMF 190-2 as per conventional procedures. At 464, UE 110 is in RRC_INACTIVE state inter-PLMN connection recovery with respect to old AMF 190-1 and new AMF 190-2, while preserving PDU session and DRB setup before moving UE 110 to RRC_INACTIVE state, thereby avoiding RRC_Reestablishment. At 466, new AMF 190-2 sends NGAP downlink NAS transfer (Registration Accept) message to gNB 170-1. At 468, gNB 170-1 sends a PDSCH transmission including the "Registration Accept" message to UE 110.

[0092] The examples described herein have multiple advantages and technical effects. The examples described herein enable inter-PLMN connection recovery in networks and network nodes (such as NTN and TN), and the NTN and TN are configured in different CN registration areas. Inter-PLMN cell reselection for UE is performed in the RRC_INACTIVE state without transitioning to RRC_IDLE and / or RRC_CONNECTED. The method described herein allows the UE to perform mobility registration updates in the RRC_INACTIVE state without RRC state transitions, thereby reducing signaling overhead, latency, and UE and network power consumption. The method described herein enables the retention of PDU sessions / DRBs associated with the UE, and all of them must be reestablished due to the transition via RRC_IDLE. The method described herein enables smooth service continuity and network reselection without RRC connection release or unwanted transitions to the RRC_CONNECTED state or RRC_IDLE. The method described herein provides additional criteria for cell reselection in the RRC_INACTIVE state.

[0093] Figure 5 5 is an example apparatus 500, which can be implemented in hardware and is configured to implement the examples described herein. The apparatus 500 includes at least one processor 502 (e.g., FPGA and / or CPU), at least one memory 504 including computer program code 505, wherein the at least one memory 504 and the computer program code 505 are configured to, together with the at least one processor 502, cause the apparatus 500 to implement circuit systems, processes, components, modules or functions (collectively referred to as control 506) to implement the examples described herein, including multiple random access responses.

[0094] The memory 504 may be a non-transitory memory, a transient memory, a volatile memory (such as RAM), or a non-volatile memory (such as ROM).

[0095] The device 500 optionally includes a display and / or I / O interface 508, which can be used to display aspects or states of the methods described herein (e.g., while one of the methods is being executed or at a subsequent time), or to receive input from a user, such as by using a keyboard, camera, touch screen, touch area, microphone, biometrics, one or more sensors, etc. The device 500 includes one or more communication interfaces (e.g., network (N / W) interface (I / F) 510. The (multiple) communication I / F 510 can be wired and / or wireless, and communicate over the Internet / (multiple) other networks via any communication technology. The (multiple) communication I / F 510 can include one or more transmitters and one or more receivers. The (multiple) communication I / F 510 can include standard well-known components such as amplifiers, filters, frequency converters, modems / modulators, encoder / decoder circuit systems, and one or more antennas.

[0096] The apparatus 500 implementing the functionality of the control 506 may be a UE 110, a RAN node 170 (e.g., a gNB), or a (multiple) network element 190. Thus, the processor 502 may correspond to the (multiple) processors 120, the (multiple) processors 152, and / or the (multiple) processors 175, the memory 504 may correspond to the (multiple) memories 125, the (multiple) memories 155, and / or the (multiple) memories 171, the computer program code 505 may correspond to the computer program code 123, the module 140-1, the module 140-2, and / or the computer program code 153, the module 150-1, the module 150-2, and / or the computer program code 173, and the (multiple) communication I / F 510 may correspond to the transceiver 130, the (multiple) antenna 128, the transceiver 160, the (multiple) antenna 158, the (multiple) N / WI / F 161, and / or the (multiple) N / WI / F 180. Alternatively, apparatus 500 may not correspond to UE 110, RAN node 170, or network element(s) 190, as apparatus 500 may be part of a Self-Organizing / Optimizing Network (SON) node, such as in the cloud.

[0097] The device 500 may also be distributed throughout a network (e.g., 100), including within the device 500 and, for example, any network node or network element (such as, for example, a network control element (NCE) 190 and / or a RAN node 170 and / or a UE 110), and between the device 500 and any network node or network element.

[0098] Interface 512 enables data communication between various items of device 500, such as Figure 5As shown. For example, interface 512 may be one or more buses, such as an address bus, a data bus, or a control bus, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, an optical fiber or other optical communication device, etc. Computer program code 505, including control 506, may include object-oriented software configured to pass data or messages between objects within computer program code 505. Apparatus 500 need not include each of the features mentioned, or may also include other features.

[0099] Figure 6 A schematic diagram of a non-volatile memory medium 600a (e.g., a computer compact disc (CD) or digital versatile disc (DVD)) and 600b (e.g., a universal serial bus (USB) memory stick) is shown, storing instructions and / or parameters 602 that, when executed by a processor, allow the processor to perform one or more of the steps of the method described herein.

[0100] Figure 7 The present invention is an example method 700 for implementing the example embodiments described herein. At 710, the method includes: receiving an indication from a network cell, the indication including: at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection. At 720, the method includes: while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, reselecting another network cell, the other network cell being among the indicated at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection. The method 700 may be implemented using the UE 110 or the apparatus 500.

[0101] Figure 8 is an example method 800 for implementing the example embodiments described herein. At 810, the method includes: receiving a cause value from a terminal device, the cause value being configured to be used for a non-access layer registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state. At 820, the method includes: storing the cause value within a resume request. At 830, the method includes: retaining the terminal device in a radio resource control inactive state using an updated pause configuration. At 840, the method includes: sending a physical downlink shared channel transmission including a registration accept message to the terminal device. The method 800 may be implemented using a RAN node 170, a network node 170-1, a network node 170-2, or an apparatus 500.

[0102] Fig. 9is an example method 900 for implementing the examples described herein. At 910, the method includes: receiving a non-access stratum registration message from a terminal device using a network node, the network node providing access to a network cell. At 920, the method includes: sending an indication to the terminal device, the indication including: at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection. At 930, the method includes: wherein the indication is configured to be used with the terminal device to reselect another network cell, the other network cell being among at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection, while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state. The method 900 may be implemented using the RAN node 170, the network node 170-1, the network node 170-2, or the apparatus 500.

[0103] Fig.10 is an example method 1000 for implementing the examples described herein. At 1010, the method includes: receiving a registration request from a network node providing access to a network cell. At 1020, the method includes: sending an indication to a terminal device directly or through a network node, the indication including: at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection. At 1030, the method includes: wherein the indication is configured to be used with the terminal device to reselect another network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, the other network cell being among the at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection. The method 1000 may be performed using the network element 190, the network element 190-1, or the apparatus 500.

[0104] Fig.11The present invention is an example method 1100 for implementing the examples described herein. At 1110, the method includes: receiving a path switch request from a network node providing access to another network cell while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from the network cell while being in the radio resource control inactive state and not transitioning to a radio resource control idle state. At 1120, the method includes: receiving a next generation application protocol uplink non-access stratum transmission message including a mobility registration update non-access stratum message from a network node providing access to another network cell. At 1130, the method includes: retaining at least one protocol data unit session and at least one data radio bearer setup before transitioning the terminal device to the inactive state based on the mobility registration update non-access stratum message without performing radio resource control reestablishment. At 1140, the method includes: sending a registration accept message to the terminal device directly or through a network node providing access to another network cell. The method 1100 may be performed using the network element 190, the network element 190-2, or the apparatus 500.

[0105] Fig.12 An example method 1200 for implementing the examples described herein is provided. At 1210, the method includes receiving an indication from a network cell that signals support for inter-public land mobile network radio resource control inactive state cell reselection. At 1220, the method includes reselecting another network cell while in a radio resource control inactive state and not transitioning to a radio resource control idle state based on the indication. The method 1200 may be performed using the UE 110 or the apparatus 500.

[0106] Fig.13 is an example method 1300 for implementing the examples described herein. At 1310, the method includes: receiving a cause value from a terminal device, the cause value being configured to be used for a registration update procedure when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state. At 1320, the method includes: storing the cause value within a resume request. At 1330, the method includes: retaining the terminal device in the radio resource control inactive state. At 1340, the method includes: sending a physical downlink shared channel transmission including a registration accept message to the terminal device. The method 1300 may be implemented using the RAN node 170, the network node 170-1, the network node 170-2, or the apparatus 500.

[0107] Fig.14An example method 1400 for implementing the examples described herein is provided. At 1410, the method includes: receiving a registration message from a terminal device using a network node, the network node providing access to a network cell. At 1420, the method includes: sending an indication to the terminal device, the indication signaling support for inter-public land mobile network radio resource control inactive state cell reselection. At 1430, the method includes: wherein the indication is configured to be used with the terminal device to reselect another network cell when the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state. The method 1400 may be implemented using the RAN node 170, the network node 170-1, the network node 170-2, or the apparatus 500.

[0108] Fig.15 is an example method 1500 for implementing the examples described herein. At 1510, the method includes: receiving a registration request from a network node providing access to a network cell. At 1520, the method includes: sending an indication to a terminal device directly or through a network node, the indication signaling support for inter-public land mobile network radio resource control inactive state cell reselection. At 1530, the method includes: wherein the indication is configured to be used with the terminal device to reselect another network cell while in a radio resource control inactive state and not transitioning to a radio resource control idle state. The method 1500 may be performed using the network element 190, the network element 190-1, or the apparatus 500.

[0109] Fig.16 is an example method 1600 for implementing the examples described herein. At 1610, the method includes: receiving a path switch request from a network node providing access to another network cell while the terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from the network cell while being in the radio resource control inactive state and not transitioning to a radio resource control idle state. At 1620, the method includes: receiving a mobility registration update message from the network node providing access to another network cell; based on the mobility registration update message, retaining at least one protocol data unit session and at least one data radio bearer setup before transitioning the terminal device to the inactive state without performing radio resource control reestablishment. At 1630, the method includes: sending a registration accept message to the terminal device directly or through the network node providing access to another network cell. The method 1600 may be performed using the network element 190, the network element 190-2, or the apparatus 500.

[0110] The following examples are described and provided herein.

[0111] Example 1. A device comprising: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the device to at least: receive an indication from a network cell, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive state cells between public land mobile networks; and while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, reselect another network cell, the other network cell being among the indicated at least one public land mobile network cell that supports reselection of radio resource control inactive state cells between public land mobile networks.

[0112] Example 2. An apparatus according to Example 1, wherein the apparatus comprises a terminal device or a user equipment.

[0113] Example 3. The apparatus of any one of Examples 1 to 2, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: reselect another network cell without transitioning to a radio resource control connected state.

[0114] Example 4. An apparatus according to any one of Examples 1 to 3, wherein the instruction, when executed by the at least one processor, causes the apparatus to at least: receive an indication from an access and mobility management function of a core network via a network cell.

[0115] Example 5. An apparatus according to any one of Examples 1 to 4, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: receive an indication while in a radio resource control inactive state.

[0116] Example 6. The apparatus of Example 5, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: receive an indication within a system information block message.

[0117] Example 7. An apparatus according to any one of Examples 1 to 6, wherein the instruction, when executed by the at least one processor, causes the apparatus to at least: receive the indication from a serving network node that provides access to a network cell, wherein the network cell comprises a non-terrestrial network cell or a terrestrial network cell.

[0118] Example 8. The apparatus of Example 7, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: receive the indication from the serving network node while in a radio resource control connected state and before transitioning to a radio resource control inactive state.

[0119] Example 9. An apparatus according to any of Examples 7 to 8, wherein the serving network node becomes the last serving network node after reselecting another network cell while the terminal device is in a radio resource control inactive state.

[0120] Example 10. The apparatus of any one of Examples 7 to 9, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: receive an indication as part of a registration accept message from a serving network node providing access to a network cell.

[0121] Example 11. An apparatus according to any one of Examples 7 to 10, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: receive an indication from a serving network node providing access to a network cell as part of a radio resource control release message with a pause configuration.

[0122] Example 12. An apparatus according to any one of Examples 7 to 11, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: receive an indication as part of broadcast signaling from a serving network node providing access to a network cell.

[0123] Example 13. The apparatus of Example 12, wherein the broadcast signaling comprises one of: a system information block type 1 message, or a network specific system information block type 19 message.

[0124] Example 14. An apparatus according to any one of Examples 1 to 13, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: receive the indication using dedicated signaling, the dedicated signaling comprising a radio resource control connection reconfiguration message.

[0125] Example 15. An apparatus according to any one of Examples 1 to 14, wherein the instruction, when executed by at least one processor, causes the apparatus to at least: send a cause value to a network node providing access to another network cell when the network node providing access to the other network cell is different from the serving network node providing access to the network cell.

[0126] Example 16. The apparatus of Example 15, wherein the cause value is configured to be used for a non-access stratum registration update procedure.

[0127] Example 17. The apparatus of any one of Examples 15 to 16, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: send a cause value within a radio resource control recovery request message.

[0128] Example 18. The apparatus of Example 17, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: send a cause value within a radio resource control recovery request message using a dedicated logical channel identifier.

[0129] Example 19. An apparatus according to any one of Examples 1 to 18, wherein the instruction, when executed by at least one processor, causes the apparatus to at least: initiate a small data transmission procedure for mobility registration update using a network node that provides access to another network cell while in a radio resource control inactive state.

[0130] Example 20. An apparatus according to Example 19, wherein the instruction, when executed by at least one processor, causes the apparatus to at least: send a registration request with a mobility update non-access stratum message as message 3 to a network node that provides access to another network cell during a mobility registration update based on the size of message 3 of a 4-step random access channel process being sufficient to accommodate a non-access stratum message; and send a cache status report in message 3 to request an additional uplink authorization to a network node that provides access to another network cell based on the size of message 3 being insufficient to accommodate a non-access stratum message.

[0131] Example 21. An apparatus according to any one of Examples 19 to 20, wherein the instruction, when executed by at least one processor, causes the apparatus to at least: indicate to the network node providing access to another network cell during a mobility registration update: the size of message 3 for a 4-step random access channel procedure for accommodating a registration request with a mobility update non-access stratum message.

[0132] Example 22. The apparatus of any one of Examples 1 to 21, wherein at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection is received within the list.

[0133] Example 23. An apparatus according to any one of Examples 1 to 23, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: receive a registration accept message from a network node providing access to another network cell using a physical downlink shared channel transmission.

[0134] Example 24. An apparatus according to any one of Examples 1 to 23, wherein the instruction, when executed by at least one processor, causes the apparatus to at least: receive a registration acceptance message from an access and mobility management function based on reselection of another network cell while in a radio resource control inactive state.

[0135] Example 25. The apparatus of any one of Examples 1 to 24, wherein the network cell comprises a non-terrestrial network cell and the other network cell comprises a terrestrial network cell.

[0136] Example 26. The apparatus of any one of Examples 1 to 25, wherein the network cell comprises a terrestrial network cell and the other network cell comprises a non-terrestrial network cell.

[0137] Example 27. The apparatus of any of Examples 1 to 26, wherein the network cell comprises a non-terrestrial network cell and the another network cell comprises a non-terrestrial network cell.

[0138] Example 28. The apparatus of any one of Examples 1 to 27, wherein the network cell comprises a terrestrial network cell and the another network cell comprises a terrestrial network cell.

[0139] Example 29. An apparatus comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a cause value from a terminal device, the cause value being configured to be used for a registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; store the cause value within a resume request; retain the terminal device in a radio resource control inactive state using an updated pause configuration; and send a physical downlink shared channel transmission including a registration acceptance message to the terminal device.

[0140] Example 30. An apparatus according to Example 29, wherein: the network node providing access to another network cell is different from the network node providing access to the network cell, the apparatus includes the network node providing access to the other network cell, and while the terminal device is in a radio resource control inactive state, the network node providing access to the network cell becomes the last serving network node after reselection of the other network cell

[0141] Example 31. An apparatus according to any one of Examples 29 to 30, wherein the instruction, when executed by at least one processor, causes the apparatus to at least: receive a mobility registration update non-access layer message from a terminal device during a small data transmission process; initiate a path switching process based on stored reasons using an access and mobility management function while keeping the terminal device in a radio resource control inactive state; and send a next generation application protocol uplink non-access layer transmission message including a mobility registration update non-access layer message to the access and mobility management function while keeping the terminal device in a radio resource control inactive state.

[0142] Example 32. A device comprising: at least one processor; and at least one memory storing instructions, which, when executed by the at least one processor, cause the device to at least: receive a non-access stratum registration message from a terminal device using a network node, the network node providing access to a network cell; and send an indication to the terminal device, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state, the other network cell being among at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks.

[0143] Example 33. An apparatus according to Example 32, wherein the instruction, when executed by at least one processor, causes the apparatus to at least: receive an initial indication from an access and mobility management function, the initial indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks; wherein the indication sent to the terminal device comprises: the initial indication received from the access and mobility management function.

[0144] Example 34. An apparatus according to any one of Examples 32 to 33, wherein the apparatus comprises a network node, and the network node becomes the last serving network node after reselecting another network cell while the terminal device is in a radio resource control inactive state.

[0145] Example 35. An apparatus according to any one of Examples 32 to 34, wherein the instruction, when executed by at least one processor, causes the apparatus to perform at least one of the following: sending an indication as part of a registration acceptance message from a network node that provides access to a network cell; sending an indication as part of a radio resource control release message with a pause configuration from a network node that provides access to a network cell; sending the indication using broadcast signaling; or sending the indication using dedicated signaling, the dedicated signaling including a radio resource control connection reconfiguration message.

[0146] Example 36. The apparatus of Example 35, wherein the broadcast signaling comprises one of: a system information block type 1 message, or a network-specific system information block type 19 message.

[0147] Example 37. An apparatus according to any one of Examples 32 to 36, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: send the indication while the terminal device is in a radio resource control inactive state.

[0148] Example 38. The apparatus of Example 37, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: send the indication within a system information block message.

[0149] Example 39. An apparatus comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a registration request from a network node that provides access to a network cell; and send an indication to a terminal device directly or through the network node, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, the other network cell being among at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks.

[0150] Example 40. According to the apparatus of Example 39, at least one memory stores instructions which, when executed by at least one processor, cause the apparatus to at least: retain at least one protocol data unit session and at least one data radio bearer setup before transitioning the terminal device to an inactive state without performing radio resource control reconstruction.

[0151] Example 41. An apparatus according to any one of Examples 39 to 40, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: send the indication while the terminal device is in a radio resource control inactive state.

[0152] Example 42. The apparatus of Example 41, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: send the indication within a system information block message.

[0153] Example 43. An apparatus comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a path switching request from a network node providing access to another network cell while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from the network cell while being in the radio resource control inactive state and not transitioning to a radio resource control idle state; receive a next generation application protocol uplink non-access stratum transmission message including a mobility registration update non-access stratum message from the network node providing access to another network cell; based on the mobility registration update non-access stratum message, retain at least one protocol data unit session and at least one data radio bearer setting before transitioning the terminal device to an inactive state without performing radio resource control reconstruction; and send a registration acceptance message to the terminal device directly or through a network node providing access to another network cell.

[0154] Example 44. The apparatus of Example 43, at least one memory storing instructions which, when executed by at least one processor, cause the apparatus to at least: perform a context transfer from a previous access and mobility management function to a new access and mobility management function.

[0155] Example 45. A device comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the device to at least: receive an indication from a network cell that signals support for reselection of a radio resource control inactive state cell between public land mobile networks; and based on the indication, reselect another network cell while being in a radio resource control inactive state and without transitioning to a radio resource control idle state.

[0156] Example 46. The apparatus of Example 45, wherein the indication comprises: at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection.

[0157] Example 47. The apparatus of Example 46, wherein the another network cell is among at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection.

[0158] Example 48. An apparatus according to any one of Examples 45 to 47, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: receive the indication while in a radio resource control inactive state.

[0159] Example 49. The apparatus of Example 48, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: receive the indication within a system information block message.

[0160] Example 50. An apparatus comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a cause value from a terminal device, the cause value being configured to be used for a registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; store the cause value within a recovery request; retain the terminal device in a radio resource control inactive state; and send a physical downlink shared channel transmission including a registration acceptance message to the terminal device.

[0161] Example 51. The apparatus of Example 50, wherein the registration update procedure comprises a non-access stratum registration update procedure.

[0162] Example 52. An apparatus according to any one of Examples 50 to 51, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: retain the terminal device in a radio resource control inactive state using the updated pause configuration.

[0163] Example 53. An apparatus comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a registration message from a terminal device using a network node that provides access to a network cell; and send an indication to the terminal device, the instruction signaling support for reselection of a radio resource control inactive state cell between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state.

[0164] Example 54. The apparatus of Example 53, wherein the registration message comprises a non-access stratum registration message.

[0165] Example 55. An apparatus according to any one of Examples 53 to 54, wherein the indication includes: at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection.

[0166] Example 56. The apparatus of Example 55, wherein the another network cell is between at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection.

[0167] Example 57. An apparatus according to any one of Examples 53 to 56, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: send the indication while the terminal device is in a radio resource control inactive state.

[0168] Example 58. The apparatus of Example 57, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: send the indication within a system information block message.

[0169] Example 59. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: receive a registration request from a network node that provides access to a network cell; and send an indication to a terminal device directly or through the network node, the indication signaling support for reselection of a radio resource control inactive state cell between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while in a radio resource control inactive state and without transitioning to a radio resource control idle state.

[0170] Example 60. The apparatus of Example 59, wherein the indication comprises: at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection.

[0171] Example 61. The apparatus of Example 60, wherein the another network cell is among at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection.

[0172] Example 62. An apparatus according to any one of Examples 59 to 61, wherein the instructions, when executed by at least one processor, cause the apparatus to at least: send the indication while the terminal device is in a radio resource control inactive state.

[0173] Example 63. An apparatus comprising: at least one processor; and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus to at least: receive a path switching request from a network node that provides access to another network cell while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from the network cell while the terminal device is in the radio resource control inactive state and does not transition to a radio resource control idle state; receive a mobility registration update message from the network node that provides access to another network cell; based on the mobility registration update message, retain at least one protocol data unit session and at least one data radio bearer setting before transitioning the terminal device to an inactive state without performing radio resource control reconstruction; and send a registration acceptance message to the terminal device directly or through a network node that provides access to another network cell.

[0174] Example 64. The apparatus of Example 63, wherein the mobility registration update message is received as part of a Next Generation Application Protocol Uplink Non-Access Stratum Transmit message.

[0175] Example 65. The apparatus of any of Examples 63 to 64, wherein the mobility registration update message comprises a non-access stratum message.

[0176] Example 66. A method comprising: receiving an indication from a network cell, the indication comprising: at least one public land mobile network cell that supports inter-public land mobile network radio resource control inactive state cell reselection; and while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, reselecting another network cell, the other network cell being among the indicated at least one public land mobile network cell that supports inter-public land mobile network radio resource control inactive state cell reselection.

[0177] Example 67. A method comprising: receiving a cause value from a terminal device, the cause value being configured to be used for a registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; storing the cause value within a resume request; retaining the terminal device in the radio resource control inactive state using an updated pause configuration; and sending a physical downlink shared channel transmission including a registration acceptance message to the terminal device.

[0178] Example 68. A method, comprising: receiving a non-access stratum registration message from a terminal device using a network node, the network node providing access to a network cell; and sending an indication to the terminal device, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell among at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state.

[0179] Example 69. A method, comprising: receiving a registration request from a network node that provides access to a network cell; and sending an indication to a terminal device directly or through the network node, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive state cells between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, the other network cell being among at least one public land mobile network cell that supports reselection of radio resource control inactive state cells between public land mobile networks.

[0180] Example 70. A method, comprising: receiving a path switching request from a network node that provides access to another network cell while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from the network cell while being in the radio resource control inactive state and not transitioning to a radio resource control idle state; receiving a next generation application protocol uplink non-access stratum transmission message including a mobility registration update non-access stratum message from the network node that provides access to another network cell; retaining at least one protocol data unit session and at least one data radio bearer setting before transitioning the terminal device to an inactive state based on the mobility registration update non-access stratum message without performing radio resource control reconstruction; and sending a registration acceptance message to the terminal device directly or through a network node that provides access to another network cell.

[0181] Example 71. An apparatus comprising: a component for receiving an indication from a network cell, the indication comprising: at least one public land mobile network cell that supports inter-public land mobile network radio resource control inactive state cell reselection; and a component for reselecting another network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, the other network cell being among the indicated at least one public land mobile network cell that supports inter-public land mobile network radio resource control inactive state cell reselection.

[0182] Example 72. An apparatus comprising: a component for receiving a cause value from a terminal device, the cause value being configured to be used for a registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; a component for storing the cause value within a recovery request; a component for retaining the terminal device in the radio resource control inactive state using an updated pause configuration; and a component for sending a physical downlink shared channel transmission including a registration acceptance message to the terminal device.

[0183] Example 73. An apparatus comprising: a component for receiving a non-access stratum registration message from a terminal device using a network node, the network node providing access to a network cell; and a component for sending an indication to the terminal device, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state, the other network cell being among at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks.

[0184] Example 74. An apparatus comprising: a component for receiving a registration message from a terminal device using a network node, the network node providing access to a network cell; and a component for sending an indication to the terminal device directly or through the network node, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, the other network cell being among at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks.

[0185] Example 75. An apparatus comprising: a component for receiving a path switching request from a network node that provides access to another network cell while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from the network cell while being in the radio resource control inactive state and not transitioning to a radio resource control idle state; a component for receiving a next generation application protocol uplink non-access stratum transmission message including a mobility registration update non-access stratum message from a network node that provides access to another network cell; a component for retaining at least one protocol data unit session and at least one data radio bearer setting before transitioning the terminal device to an inactive state based on the mobility registration update non-access stratum message without performing radio resource control reconstruction; and a component for sending a registration acceptance message to the terminal device directly or via a network node that provides access to another network cell.

[0186] Example 76. A non-transitory program storage device readable by a machine, tangibly embodying an instruction program executable by the machine for performing operations, the operations comprising: receiving an indication from a network cell, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks; and while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, reselecting another network cell, the other network cell being among the indicated at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks.

[0187] Example 77. A non-transitory program storage device readable by a machine, tangibly embodying an instruction program executable by the machine for performing operations, the operations comprising: receiving a cause value from a terminal device, the cause value being configured to be used for a registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; storing the cause value within a resume request; retaining the terminal device in the radio resource control inactive state using an updated pause configuration; and sending a physical downlink shared channel transmission including a registration acceptance message to the terminal device.

[0188] Example 78. A non-transitory program storage device readable by a machine, tangibly embodying an instruction program executable by the machine for performing operations, the operations comprising: receiving a non-access stratum registration message from a terminal device using a network node, the network node providing access to a network cell; and sending an indication to the terminal device, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell, the other network cell being among at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks, while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state.

[0189] Example 79. A non-transitory program storage device readable by a machine, tangibly embodying an instruction program executable by the machine for performing operations, the operations comprising: receiving a registration request from a network node that provides access to a network cell; and sending an indication to a terminal device directly or through the network node, the indication comprising: at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, the other network cell being among at least one public land mobile network cell that supports reselection of radio resource control inactive cells between public land mobile networks.

[0190] Example 80. A non-transitory program storage device readable by a machine, tangibly embodying an instruction program executable by the machine for performing operations, the operations comprising: receiving a path switching request from a network node that provides access to another network cell while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell while being in the radio resource control inactive state and not transitioning from the network cell to the radio resource control idle state; receiving a next generation application protocol uplink non-access stratum transmission message including a mobility registration update non-access stratum message from a network node that provides access to another network cell; based on the mobility registration update non-access stratum message, retaining at least one protocol data unit session and at least one data radio bearer setting before transitioning the terminal device to an inactive state without performing radio resource control reconstruction; and sending a registration acceptance message to the terminal device directly or through a network node that provides access to another network cell.

[0191] Example 81. A method comprising: receiving an indication from a network cell that signals support for reselection of a radio resource control inactive state cell between public land mobile networks; and based on the indication, reselecting another network cell while in a radio resource control inactive state and without transitioning to a radio resource control idle state.

[0192] Example 82. A method comprising: receiving a cause value from a terminal device, the cause value being configured to be used for a registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; storing the cause value within a recovery request; retaining the terminal device in the radio resource control inactive state; and sending a physical downlink shared channel transmission including a registration acceptance message to the terminal device.

[0193] Example 83. A method comprising: receiving a registration message from a terminal device using a network node that provides access to a network cell; and sending an indication to the terminal device that signals support for reselection of a radio resource control inactive state cell between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state.

[0194] Example 84. A method comprising: receiving a registration request from a network node providing access to a network cell; and sending an indication to a terminal device directly or via the network node, the indication signaling support for reselection of a radio resource control inactive state cell between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while in a radio resource control inactive state and without transitioning to a radio resource control idle state.

[0195] Example 85. A method, comprising: receiving a path switching request from a network node that provides access to another network cell while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from the network cell while the terminal device is in the radio resource control inactive state and does not transition to a radio resource control idle state; receiving a mobility registration update message from the network node that provides access to another network cell; based on the mobility registration update message, retaining at least one protocol data unit session and at least one data radio bearer setting before transitioning the terminal device to an inactive state without performing radio resource control reconstruction; and sending a registration acceptance message to the terminal device directly or through a network node that provides access to another network cell.

[0196] Example 86. An apparatus comprising: a component for receiving an indication from a network cell that signals support for reselection of a radio resource control inactive state cell between public land mobile networks; and a component for reselecting another network cell based on the indication while in a radio resource control inactive state and without transitioning to a radio resource control idle state.

[0197] Example 87. An apparatus comprising: a component for receiving a cause value from a terminal device, the cause value being configured to be used for a registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; a component for storing the cause value within a recovery request; a component for retaining the terminal device in the radio resource control inactive state; and a component for sending a physical downlink shared channel transmission including a registration acceptance message to the terminal device.

[0198] Example 88. An apparatus comprising: a component for receiving a registration message from a terminal device using a network node that provides access to a network cell; and a component for sending an indication to the terminal device that signals support for reselection of a radio resource control inactive state cell between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state.

[0199] Example 89. An apparatus comprising: a component for receiving a registration request from a network node providing access to a network cell; and a component for sending an indication to a terminal device directly or through the network node, the indication signaling support for reselection of a radio resource control inactive state cell between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while in a radio resource control inactive state and without transitioning to a radio resource control idle state.

[0200] Example 90. An apparatus comprising: a component for receiving a path switching request from a network node that provides access to another network cell while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from the network cell while being in the radio resource control inactive state and not transitioning to a radio resource control idle state; a component for receiving a mobility registration update message from a network node that provides access to another network cell; a component for retaining at least one protocol data unit session and at least one data radio bearer setting before transitioning the terminal device to an inactive state based on the mobility registration update message without performing radio resource control reconstruction; and a component for sending a registration acceptance message to the terminal device directly or via a network node that provides access to another network cell.

[0201] Example 91. A non-transitory program storage device readable by a machine, tangibly embodying an instruction program executable by the machine for performing operations, the operations comprising: receiving an indication from a network cell that signals support for reselection of a radio resource control inactive state cell between public land mobile networks; and based on the indication, reselecting another network cell while in a radio resource control inactive state and without transitioning to a radio resource control idle state.

[0202] Example 92. A non-transitory program storage device readable by a machine, tangibly embodying an instruction program executable by the machine for performing operations, the operations comprising: receiving a cause value from a terminal device, the cause value being configured to be used for a registration update process when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; storing the cause value within a recovery request; retaining the terminal device in the radio resource control inactive state; and sending a physical downlink shared channel transmission including a registration acceptance message to the terminal device.

[0203] Example 93. A non-transitory program storage device readable by a machine, tangibly embodying an instruction program executable by the machine for performing operations, the operations comprising: receiving a registration message from a terminal device using a network node, the network node providing access to a network cell; and sending an indication to the terminal device, the indication signaling support for reselection of a radio resource control inactive state cell between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state.

[0204] Example 94. A non-transitory program storage device readable by a machine, tangibly embodying an instruction program executable by the machine for performing operations, the operations comprising: receiving a registration request from a network node providing access to a network cell; and sending an indication to a terminal device directly or through the network node, the indication signaling support for reselection of a radio resource control inactive state cell between public land mobile networks; wherein the indication is configured to be used with the terminal device to reselect another network cell while in a radio resource control inactive state and without transitioning to a radio resource control idle state.

[0205] Example 95. A non-transitory program storage device readable by a machine, tangibly embodying an instruction program executable by the machine for performing operations, the operations comprising: receiving a path switching request from a network node that provides access to another network element while a terminal device is in a radio resource control inactive state, the terminal device reselecting another network cell from a network cell while being in the radio resource control inactive state and not transitioning to a radio resource control idle state; receiving a mobility registration update message from a network node that provides access to another network cell; based on the mobility registration update message, retaining at least one protocol data unit session and at least one data radio bearer setting before transitioning the terminal device to an inactive state without performing radio resource control reconstruction; and sending a registration acceptance message to the terminal device directly or through a network node that provides access to another network cell.

[0206] It should be understood that references to "computers," "processors," and the like include not only computers having different architectures (such as single / multi-processor architectures and sequential or parallel architectures), but also special-purpose circuits (such as field programmable gate arrays (FPGAs), application-specific circuits (ASICs), signal processing devices, and other processing circuit systems. It should be understood that references to computer programs, instructions, codes, and the like include software or firmware for programmable processors, such as, for example, programmable content of hardware devices, whether instructions for a processor, or configuration settings for a fixed-function device, gate array, or programmable logic device, and the like.

[0207] The memory(s) as described herein may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, non-transitory memory, transient memory, fixed memory, and removable memory. The memory(s) may include a database for storing data.

[0208] As used herein, the term "circuitry" may refer to the following: (a) hardware circuit implementations, such as implementations in analog and / or digital circuitry, and (b) combinations of circuitry and software (and / or firmware), such as, as applicable: (i) combinations of processors or (ii) portions of processors / software, including digital signal processors, software, and memory(s), which work together to enable the device to perform various functions, and (c) circuitry, such as microprocessors or portions of microprocessors, which require software or firmware to operate, even if the software or firmware is not physically present. As a further example, as used herein, the term "circuitry" would also cover implementations of only a processor (or processors) or portions of a processor and its (or their) accompanying software and / or firmware. For example, if applicable to the particular element, the term "circuitry" would also cover a baseband integrated circuit or application processor integrated circuit for a mobile phone, or a similar integrated circuit in a server, cellular network device, or other network device.

[0209] In the figure, the arrows between the blocks indicate the operational couplings between them and the direction of data flow over these couplings.

[0210] It should be understood that the above description is illustrative only. Various alternatives and modifications can be designed by those skilled in the art. For example, the features described in each dependent claim can be combined with each other in any suitable (multiple) combination. In addition, the features in the above different example embodiments can be selectively combined into new example embodiments. Therefore, this description is intended to cover all such alternatives, modifications and variations that fall within the scope of the appended claims.

[0211] The following acronyms and abbreviations that may be found in the specification and / or drawings are defined as follows (these abbreviations and acronyms may be attached to each other or to other characters, such as using dashes, hyphens or numbers):

[0212] 3GPP Third Generation Partnership Project

[0213] 4G Fourth Generation

[0214] 5G Fifth Generation

[0215] 5GC 5G Core Network

[0216] AMF Access and Mobility Management Function

[0217] AS Access Layer

[0218] ASIC Application-Specific Integrated Circuit

[0219] BSR Cache Status Report

[0220] CCCH Common Control Channel

[0221] CHO Condition Switch

[0222] CM Connection Management

[0223] CN Core Network

[0224] C-plane

[0225] CPU Central Processing Unit

[0226] CT1 Core Network and Termination Conference

[0227] CU Central Unit or Centralized Unit

[0228] DL Downlink

[0229] DRB Data Radio Bearer

[0230] DSP Digital Signal Processor

[0231] eNB Evolved Node B (e.g. LTE base station)

[0232] EN-DC E-UTRAN New Radio - Dual Connectivity

[0233] en-gNB provides the NR user plane and control plane protocol termination node to the UE and acts as a secondary node in EN-DC

[0234] enh Enhanced

[0235] EPLMN Equivalent PLMN

[0236] E-UTRA Evolved Universal Terrestrial Radio Access, also known as LTE radio access technology

[0237] E-UTRAN E-UTRA Network

[0238] F1 Interface between CU and DU

[0239] FPGA Field Programmable Gate Array

[0240] GEO Geosynchronous Orbit

[0241] gNB is a base station for 5G / NR, which is a node that provides NR user plane and control plane protocol termination to UE and is connected to 5GC via NG interface.

[0242] I / F Interface

[0243] I / O Input / Output

[0244] I-RNTI Inactive RNTI

[0245] LCID Logical Channel Identifier

[0246] LMF Location Management Function

[0247] LEO Low Earth Orbit

[0248] LTE Long Term Evolution (4G)

[0249] MAC Media Access Control

[0250] MEO Medium Earth Orbit

[0251] MME Mobility Management Entity

[0252] MRO Mobility Robustness Optimization

[0253] MRU Mobility Registration Update

[0254] msg3 or Msg3 Message 3 in the 4-step random access process

[0255] NAS Non-Access Stratum

[0256] NCE Network Control Element

[0257] ng or NG new generation

[0258] NGAP Next Generation Applications Part

[0259] ng-eNB Next Generation eNB

[0260] NG-RAN Next Generation Radio Access Network

[0261] NR New Radio (5G)

[0262] NTN Non-Terrestrial Network

[0263] NW or N / W Network

[0264] PDA Personal Digital Assistant

[0265] PDCP Packet Data Convergence Protocol

[0266] PDSCH Physical Downlink Shared Channel

[0267] PDU Protocol Data Unit

[0268] PHY Physical Layer

[0269] PLMN Public Land Mobile Network

[0270] PRACH Physical Random Access Channel

[0271] PUSCH Physical Uplink Shared Channel

[0272] RA Registration Area

[0273] RACH Random Access Channel

[0274] RAM Random Access Memory

[0275] RAN Radio Access Network

[0276] RAN2 Radio Layer 2

[0277] RAN3 Radio Layer 3

[0278] RAN4 Radio Layer 4

[0279] RAT Radio Access Technology

[0280] RAU Registration Area Update

[0281] Rel- version

[0282] RLC Radio Link Control

[0283] RNA RAN Notification Area

[0284] RNAU RAN Notification Regional Update

[0285] RNTI Radio Network Temporary Identifier

[0286] RO RACH Timing

[0287] ROM Read Only Memory

[0288] RNAU RAN Notification Regional Update

[0289] RP-RAN Meeting

[0290] RRC Radio Resource Control (protocol)

[0291] RU Radio Unit

[0292] Rx Receiver or Receiver

[0293] SA system aspects

[0294] SDT Small Data Transfer

[0295] SDU Service Data Unit

[0296] SGW Service Gateway

[0297] SI Research Projects

[0298] SIB System Information Block

[0299] SMF session management functions

[0300] SON self-organizing / optimizing network

[0301] SNPN Standalone Non Public Network

[0302] SRB Signalling Radio Bearer

[0303] TA Tracking Area

[0304] TN Terrestrial Network

[0305] TR Technical Report

[0306] TRP Transmission Reception Point

[0307] TS Technical Specifications

[0308] Tx Transmitter or Transmit

[0309] UAV

[0310] UE User Equipment (e.g., wireless, usually mobile)

[0311] UL Uplink

[0312] UPF User Plane Function

[0313] U-plane User plane

[0314] WI Work Items

[0315] X2 Network interface between RAN nodes and between RAN and core network

[0316] Xn Network interface between NG-RAN nodes

[0317] XnAP Xn Application Protocol

Claims

1. A device comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: receiving an indication from a network cell, the indication comprising: at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection; as well as While being in a radio resource control inactive state and not transitioning to a radio resource control idle state, reselecting another network cell, the another network cell being among the at least one public land mobile network cell indicated to support inter-public land mobile network radio resource control inactive state cell reselection.

2. The apparatus according to claim 1, wherein the apparatus comprises a terminal device or a user equipment.

3. The apparatus according to any one of claims 1 to 2, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The another network cell is reselected without transitioning to a radio resource control connected state.

4. The apparatus according to any one of claims 1 to 3, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The indication is received from an access and mobility management function of a core network via the network cell.

5. The apparatus according to any one of claims 1 to 4, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The indication is received within a system information block message.

6. The apparatus of any one of claims 1 to 5, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The indication is received from a serving network node providing access to the network cell.

7. The apparatus of any one of claims 6, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The indication is received from the serving network node while in a radio resource control connected state and prior to transitioning to the radio resource control inactive state.

8. The apparatus of any one of claims 6 to 7, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The indication is received as part of a registration accept message from the serving network node providing access to the network cell.

9. The apparatus of any one of claims 6 to 8, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The indication is received as part of a radio resource control release message with a suspension configuration from the serving network node providing access to the network cell.

10. The apparatus of any one of claims 6 to 9, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The indication is received as part of broadcast signaling from the serving network node providing access to the network cell.

11. The apparatus of claim 10, wherein the broadcast signaling comprises one of: a system information block type 1 message, or a network specific system information block type 19 message.

12. The apparatus of any one of claims 1 to 11, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The indication is received using dedicated signaling, the dedicated signaling comprising a radio resource control connection reconfiguration message.

13. The apparatus of any one of claims 1 to 12, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: When the network node providing access to the another network cell is different from a serving network node providing access to the network cell, a cause value is sent to the network node providing access to the another network cell.

14. The apparatus of claim 13, wherein the cause value is configured to be used for a non-access stratum registration update procedure.

15. The apparatus of any one of claims 13 to 14, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The cause value is sent within a radio resource control resumption request message.

16. The apparatus of claim 15, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The cause value is sent within the radio resource control resumption request message using a dedicated logical channel identifier.

17. The apparatus of any one of claims 1 to 16, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: While in the radio resource control inactive state, a small data transfer procedure for a mobility registration update is initiated with a network node providing access to the another network cell.

18. The apparatus of claim 17, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: The size of message 3 based on the 4-step random access channel procedure is sufficient to accommodate the non-access stratum message, sending a registration request with a mobility update non-access stratum message as the message 3 to the network node providing access to the another network cell during the mobility registration update; and Based on the size of the message 3 being insufficient to accommodate the non-access stratum message, a buffer status report is sent in the message 3 to the network node providing access to the another network cell to request an additional uplink grant.

19. The apparatus of any one of claims 17 to 18, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: indicating to the network node providing access to the another network cell during the mobility registration update a size of message 3 for a 4-step random access channel procedure for accommodating a registration request with a mobility update non-access stratum message.

20. The apparatus of any one of claims 1 to 19, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: A registration accept message is received from a network node providing access to the another network cell using a physical downlink shared channel transmission.

21. The apparatus of any one of claims 1 to 20, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: Based on the reselection of the another network cell while in a radio resource control inactive state, a registration accept message is received from an access and mobility management function.

22. An apparatus comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: receiving a registration message from a terminal device using a network node, the network node providing access to a network cell; as well as sending an indication to the terminal device, the indication comprising: at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection; The indication is configured to be used together with the terminal device to reselect another network cell while the terminal device is in a radio resource control inactive state and does not transition to a radio resource control idle state, the other network cell being among at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection.

23. The apparatus of claim 22, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: Receiving an initial indication from an access and mobility management function, the initial indication comprising: the at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection; The indication sent to the terminal device comprises: the initial indication received from the access and mobility management function.

24. An apparatus comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: receiving a registration request from a network node providing access to a network cell; as well as sending an indication to the terminal device directly or through the network node, the indication comprising: at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection; The indication is configured to be used together with the terminal device to reselect another network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state, the other network cell being among at least one public land mobile network cell supporting inter-public land mobile network radio resource control inactive state cell reselection.

25. The apparatus of claim 24, at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: Prior to transitioning the terminal device to an inactive state, at least one protocol data unit session and at least one data radio bearer setup are retained without performing a radio resource control reestablishment.

26. An apparatus comprising: at least one processor; as well as at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least: receiving a cause value from a terminal device, the cause value being configured to be used for a registration update procedure when the terminal device reselects another network cell from a network cell while being in a radio resource control inactive state and not transitioning to a radio resource control idle state; storing the cause value in a resume request; maintaining the terminal device in the radio resource control inactive state using an updated suspension configuration; as well as A physical downlink shared channel transmission including a registration accept message is sent to the terminal device.

27. The apparatus of claim 26, wherein the instructions, when executed by the at least one processor, cause the apparatus to at least: receiving a mobility registration update non-access stratum message from a terminal device during a small data transmission process; initiating a path switching procedure using an access and mobility management function based on said stored reasons while maintaining said terminal device in a radio resource control inactive state; and A Next Generation Application Protocol Uplink Non-Access Stratum Transfer message including the Mobility Registration Update Non-Access Stratum message is sent to the Access and Mobility Management Function while maintaining the terminal device in a Radio Resource Control Inactive State.

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