Selective secondary cell group (SCG) operations during master cell group (MCG) mobility

Abstract

Embodiments include methods for a user equipment (UE). Such methods include receiving the following from a master node (MN) that provides the UE's master cell group (MCG): one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE's secondary cell group (SCG) should be maintained; and for each MCG mobility configuration, one or more associated SCG configurations. Such methods include subsequently initiating the MCG mobility procedure to the candidate cell, in accordance with a first one of the MCG mobility configurations. Such methods include selectively performing one or more SCG- related operations in conjunction with the MCG mobility procedure, based on one or more of: the one or more SCG configurations associated with the first MCG mobility configuration, whether one or more MCG-related operations need to be performed by the UE, and information received with a command to initiate the MCG mobility procedure.

Description

[0001] SELECTIVE SECONDARY CELL GROUP (SCG) OPERATIONS DURING MASTER CELL GROUP (MCG) MOBILITY TECHNICAL FIELD

[0002] The present disclosure relates generally to wireless networks, and more specifically to techniques for managing a user equipment’s (UE’s) secondary cell group (SCG) that should be maintained during a mobility operation in which the UE’s master cell group (MCG) is changed.

[0003] BACKGROUND

[0004] The fifth generation (5G) of cellular systems has been standardized within the Third-Generation Partnership Project (3GPP). 5G was developed for maximum flexibility to support various use cases including enhanced mobile broadband (eMBB), machine type communications (MTC), ultra-reliable low latency communications (URLLC), side-link device-to-device (D2D), and several others. 5G was initially specified in Release 15 (Rel-15) and continues to evolve through subsequent releases.

[0005] Figure 1 illustrates a high-level view of an exemplary 5G network architecture, consisting of a Next Generation Radio Access Network (NG-RAN, 199) and a 5G Core (5GC, 198). The NG-RAN can include one or more gNodeB’s (gNBs) connected to the 5GC via one or more NG interfaces, such as gNBs (100, 150) connected via respective interfaces (102, 152). More specifically, the gNBs can be connected to one or more Access and Mobility Management Functions (AMFs) in the 5GC via respective NG-C interfaces and to one or more User Plane Functions (UPFs) in 5GC via respective NG-U interfaces. The 5GC can include various other network functions (NFs), such as Session Management Function(s) (SMF).

[0006] In addition, the gNBs can be connected to each other via one or more Xn interfaces, such as Xn interface (140) between gNBs (100, 150). The radio interface technology for the NG-RAN is often referred to as New Radio (NR) and utilizes frequency division duplexing (FDD), time division duplexing (TDD), or a combination thereof. Each of the gNBs serves a geographic coverage area including one or more cells and, in some cases, uses various directional beams to provide coverage in the respective cells. In general, a DL “beam” is a coverage area of a network-transmitted reference signal (RS) that may be measured or monitored by a UE.

[0007] NG RAN logical nodes (e.g., gNB 100) include a Central Unit (CU or gNB-CU, e.g., 110) and one or more Distributed Units (DU or gNB-DU, e.g., 120, 130) connected via respective Fl logical interfaces (e.g., 122, 132). CUs are logical nodes that host higher-layer protocols and perform various gNB functions such controlling the operation of DUs. DUs are decentralized logical nodes that host lower layer protocols and can include, depending on the functional split option, various subsets of the gNB functions. Each CU and DU can include various circuitryneeded to perform their respective functions, including processing circuitry, communication interface circuitry (e.g., transceivers), and power supply circuitry.

[0008] Access stratum (AS) security in the 5G network includes integrity protection and ciphering of radio resource control (RRC) signaling radio bearers (SRBs) and user data radio bearers (DRBs). Each gNB applies four different AS security keys: one for integrity protection of RRC signaling (KRRCint), one for ciphering of RRC signaling (KRRCenc), one for integrity protection of user data (Kupint) and one for ciphering of user data (Kupenc).

[0009] As described in 3GPP TS 38.501 (vl 8.4.0), whenever an initial AS security context needs to be established between a UE and a gNB, both the AMF and the UE derive the K§NB key of the gNB and a Next Hop parameter (NH), based on the KAMF key provided by the AMF. The UE and the gNB use K§NB to secure the communication between each other, including derivation of the four AS security keys mentioned above. A NH Chaining Counter (NCC) is associated with each KgNB and NH parameter, and each K§NB is associated with the NCC corresponding to the NH value from which the KgNB was derived.

[0010] 3GPP Release 12 (Rel-12) introduced Long-Term Evolution (LTE) dual connectivity (DC), whereby a UE can be connected to two network nodes simultaneously, thereby improving connection robustness and / or capacity. In particular, a master node (MN) provides a master cell group (MCG) for the UE and a secondary node (SN) provides a secondary cell group (SCG). Each cell group includes a primary cell (PCell) and may include one or more secondary cells (S Cells).

[0011] 5G also supports DC, including NR-DC that is similar to LTE-DC except that both the MN and SN use the NR radio interface to communicate with the UE, with AS security in the SCG being based on a separate key of the SN (i.e., S-K§NB). In addition, 5G supports various multi-RAT DC (MR-DC) scenarios in one of the MN and SN uses the NR radio interface and the other uses the LTE radio interface to communicate with the UE.

[0012] Seamless mobility is a key feature of 3GPP radio access technologies (RATs). In general, a RAN (e.g., NG-RAN) configures a UE to perform and report radio resource management (RRM) measurements to assist network-controlled mobility decisions, such as for handover from a serving cell to a neighbor cell. Seamless handovers ensure that the UE moves around in the coverage area of different cells without excessive interruption to data transmission.

[0013] Conventionally, serving cell change is triggered by layer 3 (L3, e.g., RRC) measurements and involves RRC signaling to change PCell and PSCell (e.g., when DC is configured) and to release / add SCells. L3 serving cell change - also referred to as handover (HO) - also involves layer 1 (LI) and layer 2 (L2) resets, leading to longer latency, increased signaling overhead, and longer interruptions than for intra-cell beam switching.Certain L3 mobility operations may also involve changes to integrity protection and ciphering algorithms as well the four AS keys. For example, during handovers, the basis for K§NB used between the UE and the target RAN node (e.g., gNB) - called KNG-RAN* - is derived from the currently active K§NB or from the NH parameter. Deriving KNG-RAN* from the currently active KgNB is referred to as a “horizontal key derivation” while deriving KNG-RAN* from the NH parameter is referred to as “vertical key derivation.” To facilitate horizontal key derivation, the UE must receive an indication of the NH value currently being used by the source RAN node (e.g., gNB). This indication is an NCC value (e.g., eight bits) that points to an NH value, and is secured by the source RAN node using one or more of the existing AS keys.

[0014] 3GPP Rel-18 includes new mobility procedures that facilitate serving cell changes via L1 / L2 signaling to address these problems and / or difficulties. These new procedures are often referred to as L1 / L2 based inter-cell mobility or L1 / L2 triggered mobility (LTM). In LTM, a UE is pre-configured by its serving RAN node with one RRC configuration per LTM candidate cell, sometimes referred to as an “LTM candidate cell configuration.” The UE performs lower-layer measurements on its configured LTM candidate cells and transmits corresponding measurement reports to the RAN node, based on which the RAN node triggers execution of a LTM cell switch procedure by the UE to one of the configured LTM candidate cells. The RAN node may trigger the LTM cell switch procedure by sending the UE an LTM cell switch command, which is a lower-layer message (e.g., MAC CE).

[0015] According to 3GPP agreements, a UE may perform multiple LTM cell switch procedures without being reconfigured by the RAN. For example, after the UE has performed an LTM cell switch from a serving cell to a first target cell (e.g., a first LTM candidate cell), the UE may perform another LTM cell switch from the first target cell to a second target cell (e.g., a second LTM candidate cell) without receiving another RRCReconflguration message in the first target cell. This second LTM cell switch is often referred to as “subsequent LTM.”

[0016] The Rel-18 mobility enhancements also support the split CU / DU architecture of Figure 1, including intra-DU and inter-DU / intra-CU LTM cell switches. In the first scenario, the candidate cell is served by the same DU that currently provides the UE’s PCell (or PSCell, for SCG change in DC). In the second scenario, the candidate cell is served by a neighbor DU to the (serving or source) DU that currently provides the UE’s PCell. In both scenarios, LTM candidate cell configurations and other LTM-related configurations (e.g., measurement and reporting, early UL / DL synchronization configuration, etc.) are only used within a single CU.SUMMARY

[0017] 3GPP Rel-19 will support inter-CU LTM between source and candidate cells associated with different CUs (or gNBs). In contrast to intra-CU LTM cell switches, an inter-CU LTM cell switch requires a change in the UE’s AS keys, since K§NB is associated with a particular CU / gNB. If a UE is in NR-DC at execution of an inter-CU LTM cell switch in the MCG (which may be referred to as “inter-MN LTM cell switch”), there is then also a need to update the AS keys for UE’s SCG, since these are based on the AS keys for the UE’s MCG / MN.

[0018] According to 3GPP agreements, the Rel-15 RRC reconfiguration with sync procedure will be used to update the AS keys for UE’s SCG in conjunction with an inter-MN LTM cell switch. Even so, there are some problems, issues, and / or difficulties. For example, an LTM cell switch to a particular candidate cell may be inter-MN or intra-MN, such that the need to update the AS keys for UE’s SCG when executing an LTM cell switch to the particular candidate cell varies. There may be other conditions where it is unclear to the UE whether to update the AS keys for UE’s SCG in conjunction with an LTM cell switch in the MCG.

[0019] An object of embodiments of the present disclosure is to provide flexible techniques for selectively updating SCG AS keys (as well as other SCG-related operations) in conjunction with an LTM cell switch in the MCG, such as by enabling and / or facilitating solutions to exemplary problems summarized above and described in more detail below.

[0020] Embodiments include methods (e.g., procedures) for a UE configured for dual connectivity in a RAN.

[0021] These exemplary methods include receiving the following from an MN that provides the UE’s MCG: one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE’s SCG should be maintained; and for each of the one or more MCG mobility configurations, one or more associated SCG configurations. These exemplary methods also include subsequently initiating the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations. These exemplary methods also include selectively performing one or more SCG-related operations in conjunction with the MCG mobility procedure, based on one or more of the following:

[0022] • the one or more SCG configurations associated with the first MCG mobility configuration, • whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, and

[0023] • information received with a command to initiate the MCG mobility procedure.

[0024] In some embodiments, each of the one or more MCG mobility configurations includes the associated one or more SCG configurations. In some embodiments, the one or more MCG mobility configurations are respective LTM candidate cell configurations and the MCG mobilityprocedure is an LTM cell switch of the primary cell (PCell) of the MCG to the candidate cell, as the target cell.

[0025] In some embodiments, initiating the MCG mobility procedure is responsive receiving the command to initiate the MCG mobility procedure. In some of these embodiments, the information received with the command, on which selectively performing one or more SCG-related operations is based, includes one or more of the following:

[0026] • an indication of whether all of the one or more SCG-related operations should be performed;

[0027] • respective indications of whether the one or more SCG-related operations should be performed;

[0028] • an indication of the first MCG mobility configuration;

[0029] • a first one of the SCG configurations associated with the first MCG mobility configuration, that should be used when performing the one or more SCG-related operations; and

[0030] • an indication of the first SCG configuration, which was received prior to the command.

[0031] In some of these embodiments, the one or more MCG mobility configurations include only the first MCG mobility configuration and the first MCG mobility configuration includes only a first SCG configuration. In other of these embodiments, the one or more MCG mobility configurations include the first MCG mobility configuration and a second MCG mobility configuration, and / or the first MCG mobility configuration includes first and second SCG configurations. In some variants of these embodiments, selectively performing the one or more SCG-related operations includes the following operations:

[0032] • selecting between the first and second SCG configurations based on whether the one or more MCG-related operations are performed during the MCG mobility procedure; and • performing the one or more SCG-related operations in accordance with the selected first or second SCG configuration.

[0033] In a variant of different embodiments described above, the first MCG mobility configuration or the first SCG configuration indicates which of the SCG-related operations should be performed in conjunction with the MCG mobility procedure. In such case, selectively performing the one or more SCG-related operations includes performing the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration. In some further variants, the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration are performed only when the one or more MCG-related operations are performed during the MCG mobility procedure.

[0034] In other embodiments, initiating the MCG mobility procedure to the candidate cell is responsive to determining that one or more radio-related conditions are fulfilled.In some embodiments, the one or more SCG-related operations include one or more of the following: SCG security key change, reconfiguration with sync in the SCG, and random access (RA) to a primary SCG cell (PSCell). In some embodiments, the one or more MCG-related operations include one or more of the following: MCG security key change, RA to the target cell, MCG radio bearer change, and MCG radio bearer termination point change.

[0035] In some of these embodiments, selectively performing the one or more SCG-related operations in conjunction with the MCG mobility procedure includes the following operations:

[0036] • performing at least a portion of the one or more SCG-related operations when MCG security key change is performed during the MCG mobility procedure; and

[0037] • refraining from performing at least a portion of the one or more SCG-related operations when MCG security key change is not performed during the MCG mobility procedure. In some of these embodiments, the one or more MCG-related operations are performed only when the current MN does not provide the target cell (i. e. , inter-MN mobility procedure).

[0038] In some embodiments, each of the SCG configurations includes one or more of the following:

[0039] • one or more indications of whether to perform the following SCG-related operations in conjunction with the MCG mobility procedure: security key change, reconfiguration with sync, packet data convergence protocol (PDCP) re-establishment, radio link control (RLC) re-establishment, and random access (RA); and

[0040] • any of the following information: an MCG security key, an SCG security key, one or more security counters, a timing advance (TA) value, and a time alignment timer (TAT) value. Other embodiments include exemplary methods (e.g., procedures) for a RAN node configured to operate as an MN that provides an MCG for a UE. In general, these exemplary methods may be complementary to the exemplary methods for a UE summarized above.

[0041] These exemplary methods include sending the following to the UE: one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE’s SCG should be maintained; and for each of the one or more MCG mobility configurations, one or more associated SCG configurations. These exemplary methods also include subsequently sending to the UE a command to initiate the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations. One or more of the following information configures the UE to selectively perform one or more SCG-related operations in conjunction with the MCG mobility procedure:

[0042] • the one or more SCG configurations associated with the first MCG mobility configuration, • whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, and• information sent with the command.

[0043] In various embodiments, the one or more MCG mobility configurations, the one or more SCG configurations associated with each MCG mobility configuration, the one or more SCG-related operations, and the one or more MCG-related operations may be the same as the corresponding features summarized above in relation to UE embodiments.

[0044] Other embodiments, variants, and features of the exemplary methods summarized above are described herein. Other embodiments include UEs (e.g., wireless devices) and RAN nodes (e.g., base stations, eNBs, gNBs, ng-eNBs, etc.) configured to perform operations corresponding to any of the exemplary methods described herein. Other embodiments include non-transitory, computer-readable media storing program instructions that, when executed by processing circuitry, configure such UEs and RAN nodes to perform operations corresponding to any of the exemplary methods described herein.

[0045] These and other embodiments described herein can provide various advantages, benefits, and / or solutions to problems. For example, by providing a candidate cell configuration that is usable for both inter- and intra-MN mobility operations (e.g., LTM cell switches) where the UE’s SCG is maintained, embodiments may facilitate efficient and correct UE operations in the SCG for both types of MCG mobility operations. As a more specific example, the UE may only perform RA, reconfiguration with sync, and security key change for the SCG when there is an MCG security key change in conjunction with execution of the MCG mobility operation. In this manner, embodiments may avoid interruptions and latency associated with unnecessary operations for an SCG that is maintained after an MCG mobility operation.

[0046] These and other objects, features, and advantages of embodiments of the present disclosure will become apparent upon reading the following Detailed Description in view of the Drawings briefly described below.

[0047] BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 shows a high-level view of an exemplary 5G / NR network architecture.

[0049] Figure 2 shows a logical architecture for an NG-RAN node arranged in a split CU / DU architecture.

[0050] Figure 3 shows exemplary NR user plane (UP) and control plane (CP) protocol stacks. Figure 4 illustrates security key derivation for handover and other UE mobility procedures. Figure 5 shows a signaling diagram for an exemplary two-stage L3 handover for a UE. Figure 6 illustrates a system structure in which some embodiments of the present disclosure may be implemented.Figure 7 shows a flow diagram of an exemplary procedure for a UE, according to various embodiments of the present disclosure.

[0051] Figure 8 shows a flow diagram of an exemplary method for a UE (e.g., wireless device), according to various embodiments of the present disclosure.

[0052] Figure 9 shows a flow diagram of an exemplary method for a RAN node (e.g., base station, eNB, gNB, DU, etc.), according to various embodiments of the present disclosure.

[0053] Figures 10-11 show two example communication systems according to some embodiments of the present disclosure.

[0054] Figure 12 shows an example wireless device according to some embodiments of the present disclosure.

[0055] Figure 13 shows an example network node according to some embodiments of the present disclosure.

[0056] Figure 14 shows an example virtualization environment in which some embodiments of the present disclosure may be virtualized.

[0057] DETAILED DESCRIPTION

[0058] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided as examples to convey the scope of the subject matter to those skilled in the art.

[0059] In general, all terms used herein are to be interpreted according to their ordinary meaning to a person of ordinary skill in the relevant technical field, unless a different meaning is expressly defined and / or implied from the context of use. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise or clearly implied from the context of use. The operations of any methods and / or procedures disclosed herein do not have to be performed in the exact order disclosed, unless an operation is explicitly described as following or preceding another operation and / or where it is implicit that an operation must follow or precede another operation. Any feature of any embodiment disclosed herein can apply to any other disclosed embodiment, as appropriate. Likewise, any advantage of any embodiment described herein can apply to any other disclosed embodiment, as appropriate.

[0060] Furthermore, the following terms are used throughout the description given below:

[0061] • Radio Access Node: As used herein, a “radio access node” (or equivalently “radio network node,” “radio access network node,” or “RAN node”) can be any node in a radio accessnetwork (RAN) that operates to wirelessly transmit and / or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., gNB in a 3GPP 5G / NR network or an enhanced or eNB in a 3GPP LTE network), base station distributed components (e.g., CU and DU), a high-power or macro base station, a low-power base station (e.g., micro, pi co, femto, or home base station, or the like), an integrated access backhaul (IAB) node, a transmission point (TP), a transmission reception point (TRP), a remote radio unit (RRU or RRH), and a relay node.

[0062] • Core Network Node: As used herein, a “core network node” is any type of node in a core network. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a serving gateway (SGW), aPDN Gateway (P-GW), a Policy and Charging Rules Function (PCRF), an access and mobility management function (AMF), a session management function (SMF), a user plane function (UPF), a Charging Function (CHF), a Policy Control Function (PCF), an Authentication Server Function (AUSF), a location management function (LMF), or the like.

[0063] • Wireless Device: As used herein, a “wireless device” (or “WD” for short) is any type of device that is capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other wireless devices. Communicating wirelessly can involve transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information through air. Unless otherwise noted, the term “wireless device” is used interchangeably herein with the term “user equipment” (or “UE” for short), with both of these terms having a different meaning than the term “network node”.

[0064] • Radio Node: As used herein, a “radio node” can be either a “radio access node” (or equivalent term) or a “wireless device.”

[0065] • Network Node: As used herein, a “network node” is any node that is either part of the radio access network (e.g., a radio access node or equivalent term) or of the core network (e.g., a core network node discussed above) of a cellular communications network. Functionally, a network node is equipment capable, configured, arranged, and / or operable to communicate directly or indirectly with a wireless device and / or with other network nodes or equipment in the cellular communications network, to enable and / or provide wireless access to the wireless device, and / or to perform other functions (e.g., administration) in the cellular communications network.

[0066] • Node: As used herein, the term “node” (without prefix) can be any type of node that can in or with a wireless network (including RAN and / or core network), including a radio access node (or equivalent term), core network node, or wireless device. However, theterm “node” may be limited to a particular type (e.g., radio access node, IAB node) based on its specific characteristics in any given context.

[0067] The above definitions are not meant to be exclusive. In other words, various ones of the above terms may be explained and / or described elsewhere in the present disclosure using the same or similar terminology. Nevertheless, to the extent that such other explanations and / or descriptions conflict with the above definitions, the above definitions should control.

[0068] Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system and can be applied to any communication system that may benefit from them.

[0069] Figure 2 shows a logical architecture for an NG-RAN node (e.g., gNB or ng-eNB) arranged in the split CU / DU architecture, such as gNB 100 in Figure 1. This logical architecture separates the CU into control plane (CP) and user plane (UP) functionality, called CU-C (or CU-CP) and CU-U (or CU-UP) respectively. Furthermore, each of the NG, Xn, and Fl interfaces is split into a CP interface (e.g., NG-C) and a UP interface (e.g., NG-U). Moreover, the CU-U and CU-C can communicate via an El interface. Each DU may be connected to only one CU-C, and each CU-U may be connected to only one CU-C. However, a single DU may be connected to multiple CU-Us under the control of the same CU-C, or a single CU-U may be connected to multiple DUs under the control of the same CU-C. Note that the terms “Central Entity” and “Distributed Entity” in Figure 2 refer to physical network nodes.

[0070] Figure 3 shows an exemplary configuration of NR UP and CP protocol stacks between a UE (310), a gNB (320), and an AMF (330). Physical (PHY), Medium Access Control (MAC), Radio Link Control (RLC), and Packet Data Convergence Protocol (PDCP) layers between UE and gNB are common to UP and CP. PDCP provides ciphering / deciphering, integrity protection, sequence numbering, reordering, and duplicate detection for both CP and UP, as well as header compression and retransmission for UP data.

[0071] On the UP side, Internet protocol (IP) packets arrive to PDCP as service data units (SDUs), and PDCP creates protocol data units (PDUs) to deliver to RLC. The Service Data Adaptation Protocol (SDAP) layer handles quality-of-service (QoS) including mapping between QoS flows and Data Radio Bearers (DRBs) and marking QoS flow identifiers (QFI) in UL and DL packets. RLC transfers PDCP PDUs to MAC through logical channels (LCH). RLC provides error detection / correction, concatenation, segmentation / reassembly, sequence numbering, reordering of data transferred to / from the upper layers. MAC provides mapping between LCHs and PHY transport channels, LCH prioritization, multiplexing into or demultiplexing from transport blocks (TBs), hybrid ARQ (HARQ) error correction, and dynamic scheduling (in gNB). PHY providestransport channel services to MAC and manages transfer over the NR radio interface, e.g., via modulation, coding, antenna mapping, and beam forming.

[0072] On the CP side, the non-access stratum (NAS) layer between UE and AMF handles UE / gNB authentication, mobility management, and security control. RRC sits below NAS in the UE but terminates in the gNB rather than the AMF. RRC controls communications between UE and gNB at the radio interface as well as the mobility of a UE between cells in the NG-RAN. RRC also broadcasts system information (SI) and performs establishment, configuration, maintenance, and release of DRBs and Signaling Radio Bearers (SRBs) and used by UEs. Additionally, RRC controls addition, modification, and release of carrier aggregation (CA) and dual-connectivity (DC) configurations for UEs, and performs various security functions such as key management.

[0073] After a UE is powered ON it will be in the RRC IDLE state until an RRC connection is established with the network, at which time the UE will transition to RRC CONNECTED state (e.g., where data transfer can occur). The UE returns to RRC ..IDLE after the connection with the network is released. In RRC IDLE state, the UE’s radio is active on a discontinuous reception (DRX) schedule configured by upper layers. During DRX active periods (also referred to as “DRX On durations”), an RRC IDLE UE receives SI broadcast in the cell where the UE is camping, performs measurements of neighbor cells to support cell reselection, and monitors a paging channel on PDCCH for pages from 5GC via gNB. An NR UE in RRC IDLE state is not known to the gNB serving the cell where the UE is camping. However, NR RRC includes an RRC_INACTIVE state in which a UE is known (e.g., via UE context) by the serving gNB.

[0074] As mentioned above, RRC manages configuration of AS security parameters such as integrity protection and ciphering algorithms and parameters keySetChangelndicator and nextHopChainingCount used by the UE to determine its AS security keys during various RRC procedures. The integrity protection algorithm is common for SRB1, SRB2, SRB3 (if configured), SRB4 (if configured) and DRBs configured with integrity protection, with the same keyToUse value. The ciphering algorithm is common for SRB1, SRB2, SRB3 (if configured), SRB4 (if configured) and DRBs configured with the same keyToUse value. Neither integrity protection nor ciphering is used for SRBO.

[0075] RRC integrity protection and ciphering are always activated together, i.e., in one message / procedure. RRC integrity protection and ciphering for SRBs are never de-activated. However, it is possible to switch to a 'NULL' ciphering algorithm (neaO). The 'NULL' integrity protection algorithm (niaO) is used only for SRBs and for the UE in limited service mode, as specified in 3GPP TS 33.501 (V18.0.0). When used for SRBs, integrity protection is disabled for DRBs. In case the ’NULL' integrity protection algorithm is used, 'NULL' ciphering algorithm isalso used. Additionally, lower layers discard RRC messages for which the integrity protection check has failed and indicate the integrity protection check failure to RRC.

[0076] The AS applies four different security keys: one for integrity protection of RRC signaling (KRRCint), one for ciphering of RRC signaling (KRRCCIIC), one for integrity protection of user data (Kupint) and one for ciphering of user data (Kupenc). All four AS keys are derived from the K§NB key of the gNB, which is based on the KAMF key managed by upper layers as specified in 3GPP TS 33.501 (vl8.0.0). The integrity protection and ciphering algorithms can only change upon reconfiguration with sync. The four AS keys change upon reconfiguration with sync (if masterKeyUpdate is included), RRC connection re-establishment, and RRC connection resume.

[0077] For each DRB or SRB an independent counter (COUNT) is maintained for each direction and is used in an initialization vector (IV) input to ciphering and integrity protection algorithms applied to each data packet. Specifically, COUNT ensures fresh IVs when other, semi-stable parameters remain the same. However, the same COUNT value may not be used more than once for a given security key. To avoid such re-use, the network may use different RB identities for RB establishment, change of AS security key, or cause the UE to perform an RRC_CONNECTED to RRC IDLE / RRC INACTIVE transition and then return to RRC CONNECTED state. The network must ensure that DL IVs are fresh and that the UE can generate fresh UL IVs. For example, since the UE cannot change DRB IDs or initiate re-keying, the gNB must ensure that such actions are taken when the UL COUNT for a DRB approaches wrap-around.

[0078] In order to limit the signaling overhead, individual messages / packets include a short PDCP sequence number (PDCP-SN). In addition, the hyper frame number (HFN) is used as an overflow counter mechanism. HFN needs to be synchronized between the UE and the network. Further details are specified in 3GPP TS 38.323 (v!8.0.0). For each SRB, the value provided by RRC to lower layers to derive the 5 -bit BEARER parameter used as input for ciphering and for integrity protection is the value of the corresponding srb-Identity with the MSBs padded with zeroes.

[0079] As described in 3GPP TS 38.501 (vl 8.4.0), whenever an initial AS security context needs to be established between a UE and a gNB, the AMF and the UE derive K§NB and a Next Hop parameter (NH) from KAMF provided by the AMF. A NH Chaining Counter (NCC) is associated with each K§NB and NH parameter, and each K§NB is associated with the NCC corresponding to the NH value from which the K§NB was derived. At initial setup, K§NB is derived directly from KAMF, and is then considered to be associated with a virtual NH parameter with NCC value equal to zero. At initial setup, the derived NH value is associated with the NCC value one. The UE and the gNB use K§NB to secure the communication between each other, including derivation of the four keys mentioned above.For DC, when the MN establishes security context between an SN and the UE for the first time for a given AS security context shared between the MN and the UE, the MN generates the security key KSN for the SN and sends it to the SN over the Xn-C interface. When the SN is a gNB, its security key may also be referred to as S-K§NB. TO generate KSN, the MN associates a counter (SN Counter) with the current AS security context. The SN Counter is used as freshness input into KSN derivations as described in the 3GPP TS 38.501 (vl8.4.0) section 6.10.3.2.

[0080] The MN maintains the value of SN Counter for a duration of the current 5G AS security context between UE and MN. The MN sends the SN Counter value the to the UE via RRC signaling when the UE is required to generate anew KSN, which is then used to derive further keys that are used between the UE and SN for ciphering and integrity protection of user data and signaling, as discussed above. The UE does not need to maintain SN Counter after it has computed KSN since the MN provides the UE with the current SN Counter value when the UE needs to compute a new KSN.

[0081] Seamless mobility is a key feature of 3GPP radio access technologies (RATs). When the UE moves between the coverage areas of two cells, a serving cell change needs to be performed at some point. Currently, serving cell change is triggered by L3 (e.g., RSRP) measurements and involves RRC signaling to change PCell and PSCell (e.g., when dual connectivity is configured), as well as release / add SCells (e.g., when CA is configured).

[0082] In general, a RAN (e.g., NG-RAN) configures a UE in RRC_CONNECTED state to perform and report radio resource management (RRM) measurements to assist network-controlled mobility decisions, such as for handover from a serving cell to a target cell (e.g., PCell change). Upon the reported measurements meeting a certain condition or threshold, the serving RAN node may send a handover command to the UE, indicating a target cell for the handover. In NR, the handover command is an RRCReconflguration message with a reconflgurationWithSync field. The procedure to perform a handover is sometimes also referred to as “L3 mobility”, as it is controlled by layer 3 (L3, i.e., RRC) and the messages exchanged are part of L3.

[0083] These reconfigurations are prepared in advance by a target RAN node serving the target cell, upon a request from the UE’s serving RAN node. This request is transmitted over the Xn interface when the serving and target RAN nodes are part of the NG-RAN. The reconfiguration provided by the target RAN node contains all information the UE needs to access the target cell, e.g., random access configuration, a new cell radio network temporary identifier (C-RNTI) assigned to the UE in the target cell, and parameters enabling the UE to calculate security keys that it can use when communicating with the target cell (including sending a handover complete message).On UE handovers and transitions from RRC INACTIVE to RRC CONNECTED, the basis for K§NB used between the UE and the target RAN node (e.g., gNB) - called KNG-RAN* - is derived from either the currently active K§NB or from the NH parameter. Deriving KNG-RAN* from the currently active K§NB this is referred to as a “horizontal key derivation” while deriving KNG-RAN* from the NH parameter is referred to as “vertical key derivation.” To facilitate horizontal key derivation, the UE must receive an indication of the NH value currently being used by the source RAN node. This indication is an NCC value (e.g., eight bits) that points to an NH value, and is secured by the source RAN node using one or more of the existing AS keys.

[0084] These horizontal and vertical key derivations are illustrated by Figure 4, which shows exemplary security key derivation for HO and other UE mobility procedures. Since NH parameters are only computable by the UE and the AMF, the AMF provides NH parameters to RAN nodes in a way that forward security can be achieved. On handovers with vertical key derivation, the NH is further bound to the target PCI and its DL frequency (ARFCN-DL) before it is used for KgNB in the target RAN node. On handovers with horizontal key derivation, the currently active K§NB is further bound to the target PCI and its frequency ARFCN-DL before it is used for K§NB in the target RAN node.

[0085] In some cases, however, the RAN may use both horizontal and vertical key derivation to achieve desired “key separation” between source and target RAN nodes for a UE handover. Figure 5 shows a signaling diagram for an exemplary two-stage L3 handover for a UE from a source cell provided by a source RAN node (gNB#l) to a target cell provided by a target RAN node (gNB#2). The first and target RAN nodes are connected via an Xn interface and both are coupled to an AMF and a UPF in the 5GC.

[0086] Initially, the source RAN node triggers inter-cell, Xn-based L3 handover of the UE to the target cell provided by the target RAN node. The source RAN node includes a masterKeyUpdate information element (IE) in the handover command to trigger security key update by the UE. During this procedure, the UE and the target RAN node perform horizontal key derivation, which facilitates initial secure communication between UE and target RAN node in the target cell. Subsequently, the target RAN sends a path switch request to AMF / UPF and receives in response a new {NH, NCC} pair for the UE. The target RAN node informs the source RAN node to release its context for the UE and then triggers an intra-cell L3 handover for the UE, during which the UE and the target RAN node perform vertical key derivation based on the new {NH, NCC} pair.

[0087] 3GPP Rel-18 also includes an NR mobility enhancement known as L1 / L2 based intercell mobility or L1 / L2 triggered mobility (LTM). Conventional L3-based inter-cell mobility (e.g., handover) involves complete LI and L2 resets, leading to longer latency, increasedsignaling overhead, and longer interruptions than for intra-cell beam switching. Thus, Rel-18 LTM is intended to facilitate serving cell changes via L1 / L2 signaling that reduces latency, signaling overhead, and interruptions.

[0088] In LTM, a UE is pre-configured by its serving RAN with one RRC configuration per LTM candidate cell, sometimes referred to as an “LTM candidate cell configuration,” which may be part of an “LTM configuration” with additional information. Each LTM candidate cell configuration may be an RRCReconflguration message or a portion thereof, such as one or more lEs / fields / parameters. For example, when the UE is in DC, the configuration includes a CellGroupConfig IE for the SCG.

[0089] The UE performs measurements on configured LTM candidate cells and transmits corresponding measurement reports to the RAN, which triggers the execution of a LTM cell switch procedure by the UE to one of the configured LTM candidate cells. This triggering is done by transmitting an LTM cell switch command to the UE in lower layer signaling (e.g., MAC CE). Based on this command, the UE connects to the associated LTM candidate cell and uses the previously received RRC configuration for this cell.

[0090] According to 3GPP agreements, a UE may perform multiple LTM cell switch procedures without being reconfigured by the RAN. For example, after the UE has performed an LTM cell switch from a serving cell to a first target cell (e.g., a first LTM candidate cell), the UE may perform another LTM cell switch from the first target cell to a second target cell (e.g., a second LTM candidate cell) without receiving another RRCReconflguration message in the first target cell. This second LTM cell switch and any further LTM cell switches performed without being reconfigured are often referred to as “subsequent LTM.”

[0091] Since a goal of LTM is to reduce interruption time for UE data transmissions, the UE needs to be ready to communicate with an LTM candidate cell upon (or shortly after) receiving the L1 / L2 signaling for mobility execution from the source cell. For example, the UE must be able to transmit UL data or a scheduling request (SR) to the LTM candidate cell and / or monitor a DL control channel (e.g., PDCCH) from the LTM candidate cell. In other words, UE needs to know the cell that it is moving to so it can apply the corresponding configuration, including the correct timing alignment and / or transmission configuration indicator (TCI) state for the cell. Likewise, in the case of inter-DU LTM, when the source DU transmits the L1 / L2 signaling for mobility execution, the target DU needs to be prepared for scheduling UL and DL transmissions for the UE in the target cell, and for receiving SR from the UE.

[0092] Accordingly, before receiving an LTM cell switch command, the UE performs early UL and DL synchronization with its configured LTM candidate cells. For early UL synchronization, the UE transmits a contention-free random access (CFRA) preamble towards an LTM candidatecell in response to a physical DL control channel (PDCCH) order received via the source cell. In order to minimize the data interruption of the source cell due to CFRA towards the LTM candidate cell, the UE doesn’t receive a RA response (with TA) from the LTM candidate cell. Instead, the TA for the LTM candidate cell is indicated in a subsequent LTM cell switch command.

[0093] As mentioned above, the LTM cell switch command from the source RAN node (or DU) may be a MAC control element (CE) that includes an identifier (e.g., index) of the corresponding LTM candidate cell configuration previously provided to the UE. The MAC CE may also include an identifier of a beam by which the UE should access the target cell. For example, the beam indication is given as a TCI state identifier (ID) associated with the LTM candidate cell. Upon receiving the LTM cell switch command, the UE monitors PDCCH on the indicated beam of the target cell. In other words, the UE considers the TCI state for the indicated beam / TCI state to be “activated” when performing the LTM cell switch. The UE also applies the LTM candidate cell configuration identified in the MAC CE. Note that since the UE previously performed early UL synchronization, it does not need to perform RA at LTM cell switch.

[0094] Note the MAC layer does not include security mechanisms similar to the AS security keys and algorithms used for RRC-layer signaling. Thus, the LTM cell switch command MAC CE transmitted by the source RAN node is neither encrypted nor integrity protected. Although other layers (e.g., PHY) may try to detect and recover bit and block errors, it is still possible that information in the MAC CE may be corrupted or changed without detection by the MAC layer.

[0095] The split CU / DU architecture shown in Figure 1 also supports Rel-18 LTM, including intra-DU and inter-DU / intra-CU cell switches. In the inter-DU / intra-CU scenario, the candidate cell for LTM is served by a neighbor DU to the (serving or source) DU that currently provides the UE’s primary cell (PCell). In the intra-DU scenario, the candidate cell for LTM is served by the same DU that currently provides the UE’s PCell.

[0096] 3GPP Rel-19 will support inter-CU LTM between source and candidate cells associated with different CUs (or gNBs). In contrast to intra-CU LTM cell switches, an inter-CU LTM cell switch necessitates a change in the UE’s AS keys, since K§NB is associated with a particular CU / gNB. As such, an inter-CU LTM configuration (or LTM candidate cell configuration) may include the same information as an intra-CU LTM configuration (or LTM candidate cell configuration) as well as one or more of the following:

[0097] • Information needed to perform security key update, e.g., MasterKeyUpdate IE or a RadioBearerConflg IE that includes SecurityConflg with SecurityAlgorithmConfig', • Indication to perform L2 / PDCP re-establishment; and

[0098] • Indication to perform a full configuration, e.g., RRC field fullConfig.If a UE is in NR-DC at execution of an inter-CU LTM cell switch in the MCG (which may be referred to as “inter-MN LTM cell switch”), there is then also a need to update the AS keys for UE’s SCG, since these are based on KSN generated by the (new) MN and provided to the SN over the Xn-C interface.

[0099] According to 3 GPP agreements, upon execution of a Rel-19 inter-MN LTM cell switch, the UE must perform refresh of AS keys, re-establishment of RLC and PDCP layers, and reset of MAC layer for both MN and SN. In particular, the Rel-15 L3 reconfiguration with sync procedure will be used to update AS keys for UE’s SCG in conjunction with an Rel-19 inter-MN LTM cell switch. In more detail, when a UE is in DC and the UE’s SCG should be maintained upon execution of an inter-MN LTM cell switch to an LTM candidate cell, the configuration for the LTM candidate cell includes an SCG configuration (i.e., CellGroupConflg IE in RRCReconflguratiori) to be applied and executed at the inter-MN LTM cell switch. When the AS keys for UE’s SCG should be updated, the SCG configuration includes an spCellConflg IE with reconflgurationWithSync field, the application of which causes the UE to the SCG key update.

[0100] Even so, there are some problems, issues, and / or difficulties. For example, when the LTM candidate cell configuration includes this SCG information, the UE must perform the reconfiguration with sync (and AS key update for SCG) for every LTM cell switch to this LTM candidate cell. While this is appropriate for inter-MN LTM cell switches, it is also possible that the same LTM candidate cell may be used for an intra-LTM cell switch. For example, the inter-LTM cell switch may be initial LTM while the intra-LTM cell switch may be subsequent LTM, or vice versa. Such SCG AS key updates for intra-LTM cell switches are unnecessary and cause undesirable latency and interruption in the UE’s SCG connection due to the MAC reset and RA that the UE must perform as part of the reconfiguration with sync procedure.

[0101] Another problem is that it is unclear how the UE determines whether to change the security key for the SCG / SN at the execution of an LTM cell switch in the MCG (i.e., to an PCell that is an LTM candidate cell) when the SCG is maintained. If the RRCReconflguratiori for the LTM candidate cell includes an sk-counter value, currently the UE would generate anew secondary key (i.e., security key towards the SN) when it apples the RRCReconflguration during LTM cell switch. While this may be appropriate for inter-MN LTM cell switches where AS keys for the MCG must change, this is unnecessary for intra-MN LTM cell switches that do not involve any AS key change for the MCG.

[0102] Accordingly, embodiments of the present disclosure address these problems and / or issues by flexible techniques for managing a UE’s SCG to be maintained after an LTM cell switch in the UE’s MCG. For example, when a UE in DC receives an LTM candidate cell configuration that includes an SCG configuration, the UE may flexibly and correctly use this LTM candidatecell configuration for both intra- and inter-MN LTM cell switches in which the SCG is maintained. In other words, the same LTM candidate cell configuration may be used for cases when AS key update is necessary (e.g., inter-MN LTM) and unnecessary (e.g., intra-MN LTM).

[0103] In some embodiments, the UE may perform a reconfiguration with sync procedure, RA procedure, and / or AS security key change for the SCG when an LTM cell switch in the MCG (e.g., inter-MN) necessitates an AS security key change for the MCG, but refrain from performing such operations when an LTM cell switch in the MCG (e.g., intra-MN) does not necessitate an AS security key change for the MCG.

[0104] Embodiments of the present disclosure may provide various advantages and / or benefits. For example, by providing a candidate cell configuration that is usable for both inter- and intra-MN mobility operations (e.g., LTM cell switches) where the UE’s SCG is maintained, embodiments facilitate efficient and correct UE operations in the SCG for both types of mobility operations in the MCG. For example, the UE may only perform RA, reconfiguration with sync, and security key change for the SCG when there is an MCG security key change in conjunction with execution of the MCG mobility operation. In this manner, embodiments may avoid interruptions and latency associated with unnecessary operations for an SCG that is maintained after the MCG mobility operation.

[0105] In the present disclosure, the following terms may be used interchangeably: “L1 / L2 based inter-cell mobility”, “L1 / L2 mobility,” “LI -mobility,” “LI based mobility,” “Ll / L2-centric inter-cell mobility,” “L1 / L2 inter-cell mobility,” “inter-cell beam management,” “inter-DU L1 / L2 based inter-cell mobility”, and “L1 / L2 triggered mobility” (or LTM). These terms refer to a scenario in which a UE receives lower layer (i.e., below RRC, such as MAC or PHY) signaling from a network indicating for the UE to change of its serving cell (e.g., PCell) from a source cell to a target cell.

[0106] The content of the lower layer signaling may be referred to as “LTM cell switch command”. Exemplary lower layer signaling includes LI DL control information (DCI) and L2 MAC control element (CE). Compared to conventional RRC signaling, lower layer signaling reduces processing time and interruption time during mobility and may also increase mobility robustness since the network can respond more quickly to changes in the UE’s channel conditions.

[0107] The term “LTM candidate cell” refers to a cell for which the UE is configured for LTM, specifically a cell the UE can move to in a LTM cell switch procedure in response to receiving an LTM cell switch command. An LTM candidate cell may also be referred to herein as “candidate cell”, “(LTM) candidate, “mobility candidate”, “non-serving cell”, “additional cell”, “(LTM) target candidate cell”, “(LTM) target candidate”, and comparable terms. A UE may perform and report measurements (e.g., CSI measurements) on an LTM candidate cell, based on which theUE’s serving RAN node may make an informed decision about which beam (or TCI state) and / or cell to switch the UE. An LTM candidate cell may be a candidate to be a target PCell or PSCell, or an SCell of a cell group (e.g., MCG SCell). In the case of LTM fast recovery, when a failure is detected and the UE selects an LTM candidate cell, the UE performs an LTM cell switch towards the selected LTM candidate cell (e.g., by applying the associated LTM candidate cell configuration) rather than performing RRC re-establishment.

[0108] The change of serving cell (e.g., PCell) may also lead to a change in SCell(s) of the same cell group, e.g., in case an LTM cell switch command triggers the UE to change to another cell group configuration of the same type (e.g., another MCG configuration). For example, an LTM cell switch may include a change in SpCell (e.g., PCell for MCG, PSCell for SCG) and a change (e.g., addition, modification and / or release) in SCells of the same cell group. This may happen when the command triggers the UE to change to another cell group configuration of the same type (e.g., another SCG configuration).

[0109] Before the UE receives the LTM cell switch command, the UE is configured by the network with one or more “LTM candidate cell configurations” via an RRCReconflguration message. The terms “(LTM) candidate configuration”, “(LTM) candidate target cell configuration”, and “(LTM) target candidate (cell) configuration” may be used interchangeably with LTM candidate cell configuration.

[0110] The lower layer signaling from the RAN may include an identifier (or index) associated with an LTM candidate cell configuration. The identifier may be sent together with an LTM cell switch command, indicating for the UE to perform an LTM cell switch to the associated LTM candidate cell.

[0111] The term “LTM configuration” (or more generically “mobility configuration”) refers to a data structure that is used for or related to UE mobility procedures such as LTM, and may include one or more of the following elements (non-exclusive):

[0112] • a candidate cell configuration, such as one or more of the following for a mobility (e.g., LTM) candidate cell:

[0113] o lower layer information, such as Ll / PHY configuration, L2 / MAC / RLC configuration, cell group configuration, serving cell configuration, etc.; and

[0114] o higher layer information, such as L3 / RRC parameter and / or timer values, PDCP configuration, radio bearer configuration, L3 / RRC measurement configuration, etc.;

[0115] • a measurement configuration, e.g., measurements for LTM, measurement reports for LTM, CSI resource configuration for LTM, CSI report configuration for LTM, etc.; • a configuration for early DL synchronization, e.g., for early TCI state activation;• a configuration for early UL synchronization, e.g., for transmission of PDCCH ordered preamble transmission and reception of timing advance (TA);

[0116] • a configuration for execution of an LTM cell switch procedure according to a given LTM candidate cell configuration (e.g., whether to perform RA, RLC reestablishment, MAC reset, PDCP recovery, etc.).;

[0117] • indication of whether to perform a full and / or complete configuration, e.g., RRC fullConfig field;

[0118] • information needed to perform security key refresh, e.g., RRC MasterKeyUpdate IE or RadioBearerConflg IE including SecurityConflg with Security AlgorithmConfig; and • additional information needed for an inter-CU / gNB LTM cell switch procedure, such as examples mentioned above.

[0119] The term “part of a mobility configuration” may refer to a subset of the elements in the above list, and / or a subset of items comprising any of the elements present (e.g., subset of configurations for DL pre-sync).

[0120] For example, an LTM candidate cell configuration may be included in an RRC IE such as CellGroupConflg, SpCellConflg, or SCellConflg and / or an embedded RRCReconflguration message for an LTM candidate cell. As mentioned above, an LTM candidate cell configuration includes configuration parameters the UE needs to operate in that LTM candidate cell when it performs an LTM cell switch procedure, e.g., upon reception of the LTM cell switch command. As some more specific examples, an LTM candidate cell configuration can include a PCell configuration and one or more SCell configurations of an MCG, or a PSCell configuration and one or more SCell configurations of an SCG. The exact content and / or structure of the IE and / or embedded message for an LTM candidate cell configuration may be called “RRC model for the candidate configuration” or more simply “RRC model”.

[0121] A UE may receive an LTM candidate cell configuration in a complete form or as a delta (or difference) relative to a reference configuration (which may be signaled separately). In the latter case, the actual LTM candidate configuration is a combination of the delta configuration and the reference configuration.

[0122] In some embodiments described herein, a UE configured for DC may be provided with an MCG mobility configuration that includes an SCG configuration and / or an SCG indication. For example, an MCG mobility configuration may be an LTM candidate cell configuration for LTM cell switch of the UE’s MCG PCell, with the LTM candidate cell configuration including an SCG configuration for use after execution of the corresponding LTM cell switch in the MCG. However, the SCG configuration may be the same or different before and after the LTM cell switch in the MCG. For example, the security key for the SCG may change after the LTM cell switch in theMCG (e.g., inter-MN LTM). MCG mobility configurations may be associated with other MCG mobility procedures such as HO (e.g., inter- or intra-RAT, inter- or intra-system, conditional or non-conditional, etc.), PCell change, conditional LTM, PSCell change, conditional PSCell change, etc.

[0123] An SCG indication may be included in or external to the SCG configuration, such as the RRC IE mrdc-SecondaryCellGroupConflg or an Xn-AP IE used in communication between RAN nodes. This indication may be used by the UE or a RAN node to determine how to manage the UE’s SCG during an MCG mobility procedure associated with the MCG mobility configuration, such as whether to perform RA, MAC reset, security key change, etc. in the SCG in conjunction with the MCG mobility procedure. Alternately, the SCG indication may be external to the MCG mobility configuration, such as a field (e.g., bit) in a mobility command (e.g., LTM cell switch MAC CE) indicating whether the UE should perform RA, MAC reset, security key change, etc. in the SCG in conjunction with the MCG mobility procedure.

[0124] As an example, the MCG mobility configuration may have two alternative SCG configurations, and the corresponding mobility command (e.g., LTM cell switch MAC CE) may include an SCG indication that indicates which of the alternative SCG configurations to apply during the MCG mobility procedure (e.g., inter-MN LTM cell switch). For example, one of the alternative SCG configurations may involve perform RA, MAC reset, security key change, etc. in the SCG in conjunction with the MCG mobility procedure, while the other does not involve such operations. As another example, the SCG indication may be or include a criterion or a condition that the UE evaluates to determine which of the alternative SCG configurations to apply during the MCG mobility procedure. As a specific example, the condition may be security key change for MCG, such that the UE applies the SCG configuration that involves performing RA, MAC reset, security key change, etc. in the SCG when there is an MCG security key change in conjunction with the MG mobility procedure.

[0125] The phrase “execute (execution of) a mobility configuration” refers to a UE applying a mobility configuration (e.g., LTM candidate cell configuration) and executing an associated mobility (e.g., LTM cell switch) procedure. For example, execution of a mobility configuration may be performed conditionally (e.g., for conditional L3 HO or conditional LTM) or non-conditionally (e.g., based on an L3 HO command or a MAC CE). More generally, “execution of a mobility configuration” may be synonymous with “execution of a mobility procedure” since when the UE perform the mobility procedure, the UE applies or executes the associated mobility configuration. Alternately, this may be referred to as the UE “executing a mobility procedure according to a mobility configuration.”The phrase “LTM cell switch procedure” refers to the process of a UE switching (or changing) from a source cell to a target cell (i.e. , an LTM candidate cell) using LTM. An LTM cell switch procedure may also be referred to as “L1 / L2 based inter-cell mobility execution”, “LTM execution”, “dynamic switch”, “LTM switch”, “(LTM) cell switch”, “(LTM) serving cell change”, or “(LTM) cell change”. Similarly, the phrase “switching to an LTM candidate cell configuration” means that the UE applies an LTM candidate cell configuration such that the associated LTM candidate cell becomes its new special cell (SpCell, e.g., PCell for LTM in MCG or PSCell for LTM in SCG) or its new secondary cell (SCell). In other words, an LTM candidate cell can be a candidate for the UE’s PCell, PSCell, or SCell.

[0126] Furthermore, an LTM cell switch may involve a UE switching (or changing) from a source cell group to a target cell group using LTM. For example, this may involve a change in the SpCell for a cell group (e.g., PCell for MCG, PSCell for SCG), a change in SCells of the cell group (e.g., addition, modification, and / or release of one or more SCells), and / or a swap between SpCell and SCell roles for two cells in the same cell group.

[0127] The term “security key” may refer to an integrity protection key for CP, an integrity protection key for UP, an encryption key for CP, an encryption key for UP, or an intermediate key used for derivation of any of these key (e.g., K§NB). The term “security configuration” refers to one or more parameters used to control security key derivation performed by a UE, and may include one or more of the following:

[0128] • a first identifier associated to a candidate cell;

[0129] • a second identifier associated to a source cell the UE is connected to when the mobility procedure is executed;

[0130] • a key set change indicator;

[0131] • a next hop chaining counter (NCC);

[0132] • a non-access stratum (NAS) container (NASC);

[0133] • an indication, indicating that mobility from current serving cell to a certain candidate target cell requires security key refresh;

[0134] • an indication, indicating that mobility towards a certain target cell requires security key refresh (or does not require security key refresh);

[0135] • an indication, indicating that security key refresh is required (or is not required) for subsequent mobility towards a certain cell; and

[0136] • an indication that security key refresh is to be performed without RA.

[0137] An example security configuration is the masterKeyUpdate IE.

[0138] The terms “security key refresh,” “security key update,” “AS key refresh,” “AS key update,” or similar terms refer to a procedure by which a UE changes or updates one or more ASsecurity keys, including during a mobility procedure such as an LTM cell switch procedure. A security key refresh may include at least one of the following operations:

[0139] • UE receives a masterKeyUpdate IE included in a mobility configuration, e.g., in the candidate cell configuration;

[0140] • When a NAS indication (e.g., NASC) is received masterKeyUpdate IE, the UE forwards the NAS indication to UE NAS layer and updates its NAS security context according to 3GPP TS 33.501 clause 6.9.2.3.4;

[0141] • When a key set change indication (e.g., keySetChangelndicator) is received and / or is set to ‘true’ (e.g., within masterKeyUpdate IE), the UE derives or updates KgNB based on KAMF, as specified in 3GPP TS 33.501;

[0142] • UE derives or updates K§NB for the candidate cell configuration based on the current K§NB or the NH, using the NCC value indicated in the received masterKeyUpdate IE, as specified in 3GPP TS 33.501;

[0143] • UE derives KRRCCIIC and Kupenc associated with a ciphering algorithm (e.g., cipheringAlgorithm indicated in securityAlgorithmConflg), as specified in 3GPP TS 33.501;

[0144] • UE derives KRRCint and Kupint associated with an integrity protection algorithm (e.g., integrityProtAlgorithm indicated in securityAlgorithmConflg), as specified in 3GPP TS 33.501;

[0145] • UE receives a security algorithm configuration included in a mobility configuration, based on which the UE derives UP security keys (e.g., Kupenc and Kupint) and / or CP security keys (e.g., KpRCenc and KRRCint) for encryption and / or integrity protection;

[0146] • UE uses its current security algorithm configuration, based on which the UE derives UP security keys (e.g., Kupenc and Kupint) and / or CP security keys (e.g., KpRCenc and KRRCint) for encryption and / or integrity protection;

[0147] • UE applies the provided ciphering algorithm and associated security key during a PDCP entity re-establishment procedure; and

[0148] • UE applies the provided integrity protection algorithm and associated security key during a PDCP entity re-establishment procedure;

[0149] • UE derives the security key(s) when it receives a mobility configuration, which it may user for a subsequent mobility procedure.

[0150] Figure 6 illustrates a system structure in which some embodiments of the present disclosure may be implemented. User equipment (UE) 601 is a wireless device, such as a cellular smartphone, sometimes connected to the first RAN node 602 over a wireless interface 604 andsometimes connected to a second RAN node 603, to which the UE 601 is connected over a wireless interface 605.

[0151] First RAN node 602 provides a first cell 607, which may be referred to as the UE’s source cell in the context of mobility (e.g., LTM or L3 HO), or the UE’s serving cell, SpCell, PCell, or PSCell in the context of CA and / or DC. The second RAN node 603 provides a second cell 608, which may be referred to as neighbor cell to the serving cell or, in the context of mobility, as target cell, candidate cell, LTM candidate cell, or inter-CU LTM candidate cell for the UE.

[0152] First RAN node 602 and second RAN node 603 may be gNBs of an NG-RAN, and may be interconnected via an interface 606, which may be an Xn or Xn-C type of interface. However, the first RAN node and the second RAN node are not necessarily interconnected.

[0153] In the context of mobility, first RAN node 602 may be referred to as source RAN node since it provides a source cell for UE mobility. Likewise, second RAN node 603 may be referred to as target or candidate RAN node since it provides the target or candidate cell for UE mobility. In some cases, such as during intra-gNB or intra-CU mobility, the first RAN node and the second RAN node may be a single RAN node.

[0154] In case of the distributed CU / DU architecture, each of the first RAN node 602 and / or the second RAN node 603 may be divided into a CU and one or more DUs. In the example shown in Figure 6, first RAN node 602 includes CU 609 and DU 610, which may be referred to as the UE’s serving or source CU / DU. Likewise, second RAN node 603 includes CU 612 and DU 610, which may be referred to as the UE’s target or candidate CU / DU. In some cases, such as during intra-gNB or intra-CU mobility, source CU 609 and target CU 612 may be a single CU.

[0155] CU 609 and DU 610 are connected over an interface 611, which may be an Fl type of interface in case of NG-RAN. Likewise, CU 612 and DU 613 are connected over an interface 614, which may also be an Fl type of interface in case of NG-RAN.

[0156] First RAN node 602 and second RAN node 603 may be connected to a third network node 615 over interfaces 616 and 617, respectively. In some embodiments, third network node 615 may be a core network node, such as a UPF or an AMF. In the latter case, interfaces 616 and 617 are both an NG type of interface or an N2 reference point. Sometimes the third network node may comprise two different network nodes, such as a source AMF connected with the first RAN node and a target AMF connected with the second RAN node. These two network nodes are interconnected over an interface, such as an N14 reference point or an Namf type of service-based interface.

[0157] In some embodiments, such as when UE 601 is configured for NR-DC, first RAN node 602 may be an MN that provides an MCG for UE 601 while third network node 615 may be a RAN node operating as an SN to provide an SCG for UE 601. Moreover, the MCG provided byfirst RAN node 602 may be a source MCG and second RAN node 603 may configured to operate as an MN that provides a target (or candidate) MCG for UE 601. In the context of embodiments related to UE MCG mobility with SCG maintained (e.g., inter-MN LTM), first RAN node 602 may be referred to as source or serving MN while second RAN node 603 may be referred to as target or candidate MN.

[0158] Some embodiments include methods for a UE configured for dual connectivity (e.g., NR-DC) with an MN that provides an MCG and an SN that provides an SCG. The UE receives from the MN an MCG mobility configuration associated with an MCG mobility procedure (e.g., LTM cell switch of PCell) during which the SCG should be maintained by the UE. The MCG mobility configuration may include an SCG configuration or alternative SCG configurations. In some embodiments, the handling of the SCG in conjunction with the MCG mobility procedure is dependent on whether the MCG mobility procedure involves an MCG security key change. The SCG configuration (or alternative SCG configurations) facilitate use of the same MCG mobility configuration for both inter-MN mobility operations (e.g., initial LTM) that involve MCG security key change and intra-MN mobility operations (e.g., subsequent LTM) that do not involve MCG security key change.

[0159] In the context of LTM, the MCG mobility configuration may be an LTM candidate cell configuration, and the UE may be configured with one or more LTM candidate cell configurations for respective LTM candidate cells in relation to the MCG PCell. Each LTM candidate cell configuration may include a corresponding SCG configuration (or alternatives), as noted above. Further, when the UE performs an LTM cell switch of the MCG PCell to one of the configured LTM candidate cells, the UE applies the corresponding LTM candidate cell configuration including the SCG configuration (or one of the alternatives) when executing the LTM cell switch.

[0160] In some embodiments, the UE selectively performs one or more actions towards the SN / SCG in conjunction with the MCG mobility procedure. For example, the UE selectively performs a security key update, reconfiguration with sync, and RA in the SCG during execution of the MCG mobility procedure (e.g., LTM cell switch of PCell). These selective operations may be referred to as “handling of SCG” or “SCG handling”, and may be dependent on various information and / or conditions, as described in more detail below.

[0161] In some embodiments, the UE may be configured with an LTM candidate cell configuration for respective LTM candidate cells in relation to the MCG PCell, with change of MCG security keys such as for inter-MN LTM cell switch. In some variants, the SCG configuration includes or indicates an SCG security key change for the SCG in relation to an LTM cell switch. In some variants, the SCG configuration includes or indicates a reconfiguration with sync for the SCG, such as a reconflgurationWithSync sub-field in spCellConflg field withinCellGroupConflg IE of the RRCReconflguration message that acts as the LTM candidate cell configuration. The reconfiguration with sync may also involve a RA towards the SCG, or the SCG configuration may separately indicate an RA towards the SCG in conjunction with the LTM cell switch of the PCell.

[0162] In some embodiments, the UE selectively performs these SCG-related operations included or indicated by the SCG configuration depending on whether the UE also performs an MCG security key change in conjunction with the LTM cell switch of the PCell. For example, if the LTM cell switch is intra-MN and does not involve an MCG security key change, the UE does not perform the SCG-related operations included or indicated by the SCG configuration. As a more specific example, even if the SCG configuration indicates a reconfiguration with sync towards the SCG, the UE refrains from this operation when the LTM cell switch of the PCell is intra-MN and / or does not include an MCG security key change. As another more specific example, even if the SCG configuration includes a configuration for SCG security key change (e.g., sk-counter value), the UE refrains from this operation when the LTM cell switch of the PCell is intra-MN and / or does not include an MCG security key change.

[0163] In other embodiments, whether the UE selectively performs these SCG-related operations included or indicated by the SCG configuration may be based on an explicit indication in the LTM candidate cell configuration (or elsewhere, as discussed below). For example, when this indication is present or has a first value, the UE selectively performs these SCG-related operations depending on whether the UE also performs an MCG security key change in conjunction with the LTM cell switch of the PCell, as discussed above. In contrast, when this indication is absent or has a second value, the UE non-selectively performs these SCG-related operations in conjunction with the LTM cell switch of the PCell. In different variants, this indication may be included in any of the following fields or IES:

[0164] • LTM-Candidate IE that includes an LTM candidate cell configuration for an LTM candidate cell for the MCG PCell;

[0165] • LTM-Config IE common to all LTM candidate cell configurations for MCG mobility with SCG maintained; or

[0166] • Separate from and / or outside of LTM-Config.

[0167] In other embodiments, the UE selectively performs these SCG-related operations included or indicated by the SCG configuration depending on explicit indications in the LTM candidate cell configuration (or elsewhere, as discussed below). For example, when this indication is present or has a first value, the UE performs these SCG-related operations in conjunction with the LTM cell switch of the PCell, as discussed above. In contrast, when this indication is absent or has a second value, the UE does not perform these SCG-related operations in conjunction with the LTMcell switch of the PCell. In some variants, there may be separate indications for different ones of the SCG-related operations, such as a first indication for reconfiguration with sync, a second indication for SCG security key change, a third indication for RA, etc. In other variants, a single indication may apply to a combination of SCG-related operations. In different variants, this indication (or these indications) may be included in any of the following fields or IES:

[0168] • LTM-Candidate IE that includes an LTM candidate cell configuration for an LTM candidate cell for the MCG PCell;

[0169] • LTM-Config IE common to all LTM candidate cell configurations for MCG mobility with SCG maintained; or

[0170] • Separate from and / or outside of LTM-Config.

[0171] In other embodiments, the UE performs SCG-related operations based on the actions performed on the MCG in conjunction with the LTM cell switch of the PCell, regardless of information included in the SCG configuration. For example, if the LTM candidate configuration indicates to perform an MCG security key change, the UE performs various SCG-related operations (e.g., reconfiguration with sync) regardless of whether these are indicated in the SCG configuration. For example, these UE operations toward the SCG would be part of a 3GPP specification rather than being depending on contents of the SCG configuration.

[0172] In some embodiments, the UE determines whether there is an MCG security key change in conjunction with the LTM cell switch of the PCell. For example, this may be based on identities of the current serving PCell and the LTM candidate cell (i.e. , target cell for LTM cell switch). If the identities are the same, the UE determines that an MCG security key change is not needed. If the identities are not the same, the UE determines that an MCG security key change is needed. Based on this determination, the UE may selectively perform various SCG-related operations in conjunction with the LTM cell switch of the PCell, as discussed above.

[0173] In other embodiments, the UE may selectively perform one or more first SCG-related operations in conjunction with the LTM cell switch of the PCell, depending on whether one or more second SCG-related operations were performed in conjunction with the LTM cell switch of the PCell. For example, the UE may condition the performance of RA and / or reconfiguration with sync towards the SCG on whether an SCG security key change was also performed in conjunction with the LTM cell switch of the PCell. As a more specific example, when no SCG security key change was performed, the UE may refrain from performing RA and / or reconfiguration with sync towards the SCG, even if such operations are indicated in the SCG configuration that is part of the LTM candidate cell configuration.

[0174] In some variants of these embodiments, the UE’s selective performance of the one or more first SCG-related operations in conjunction with the LTM cell switch of the PCell may be furtherdependent on one or more explicit indications in the LTM candidate cell configuration (or elsewhere, as discussed below). For example, when this indication is present or has a first value, the UE selectively performs these first SCG-related operations depending on whether the second SCG-related operations (e.g., SCG security key change) were also performed in conjunction with the LTM cell switch of the PCell. In contrast, when this indication is absent or has a second value, the UE does not perform these first SCG-related operations in conjunction with the LTM cell switch of the PCell, regardless of whether the second SCG-related operations were performed. In some variants, there may be separate indications for different ones of the SCG-related operations, such as a first indication for reconfiguration with sync, a second indication for RA, etc. In different variants, this indication (or these indications) may be included in any of the following fields or IES:

[0175] • LTM-Candidate IE that includes an LTM candidate cell configuration for an LTM candidate cell for the MCG PCell;

[0176] • LTM-Config IE common to all LTM candidate cell configurations for MCG mobility with SCG maintained; or

[0177] • Separate from and / or outside of LTM-Config.

[0178] In other embodiments, the UE receives from its serving RAN node (e.g., MN) a mobility command that triggers the MCG mobility procedure associated with the previously received MCG mobility configuration that includes the SCG configuration, as discussed above. For example, the mobility command may be an LTM cell switch MAC CE. In these embodiments, the mobility command includes an indication of whether the UE should perform one or more SCG-related operations in conjunction with the LTM cell switch (or other mobility operation) of the PCell. In some variants, a single indication may apply to all relevant SCG-related operations, such as SCG security change, RA, reconfiguration with sync, etc. In other variants, there may be separate indications for different ones of the SCG-related operations, such as a first indication for reconfiguration with sync, a second indication for SCG security key change, a third indication for RA, etc. In other variants, a single indication may apply to multiple - but less than all - of the SCG-related operations. In any case, a first value (or presence) of an indication may indicate that the UE should perform the relevant SCG-related operation(s), while a second value (or absence) of the indication may indicate that the UE should not perform the relevant SCG-related operation(s).

[0179] In some variants, such indications in the mobility command may override other information about the SCG-related operations in the SCG configuration of the MCG mobility configuration associated with the mobility command. For example, if the indication indicates thatthe UE should not perform the relevant SCG-related operation(s), the UE does not perform such operations even if they are configured in the SCG configuration.

[0180] In other variants, such indications may take the place of information about the SCG-related operations that is missing from the SCG configuration of the MCG mobility configuration associated with the mobility command. For example, if the SCG configuration does not indicate SCG security key change, reconfiguration with sync, and / or RA in conjunction with an LTM cell switch for the PCell, the UE nevertheless performs such SCG-related operations when indicated by the indication(s) received with the LTM cell switch MAC CE.

[0181] In some further variants, the mobility command may also include or indicate configurations for performing the SCG-related operations in conjunction with the MCG mobility operation (e.g., LTM cell switch of PCell). These configurations may override corresponding configurations included in the SCG configuration or may be used when the SCG configuration does not include such information, as discussed above. For example, the mobility command may include one or more of the following configuration information for the SCG-related operations:

[0182] • For SCG security key change: a security key associated with the MCG, one or more security counters, a security key associated with the SCG, an indication to perform horizontal or vertical key derivation, an indication to perform security key change, etc.

[0183] • For reconfiguration with sync: an indication to perform reconfiguration with sync, an indication to perform PDCP re-establishment, an indication to perform RLC reestablishment, etc.

[0184] • For RA: a TA value, a time alignment timer value, an indication to perform RA, etc. The UE then applies this configuration information when performing the SCG-related operations in conjunction with the MCG mobility operation.

[0185] In other embodiments, a UE receives multiple LTM candidate cell configurations for a single LTM candidate cell for the UE’s PCell. At least one of these includes an SCG configuration indicating one or more SCG-related operations in conjunction with LTM cell switch of the UE’s PCell. for At least one other of these includes an SCG configuration indicating no SCG-related operations in conjunction with LTM cell switch of the UE’s PCell. The SCG-related operations may be any of those discussed above in relation to other embodiments.

[0186] In some of these embodiments, the multiple LTM candidate cell configurations are received as respective Itm-CandidateConflg fields within a single LTM-Candidate IE for the LTM candidate cell. In other of these embodiments, the multiple LTM candidate cell configurations are received as respective LTM-Candidate IES for the same LTM candidate PCell, i.e., the same Itm-CandidatePCI . In one option, the different LTM candidate cell configurations for the same LTM candidate PCell may specify different MCG-related operations in conjunction with an LTM cellswitch of the PCell. For example, one of the LTM candidate cell configurations may specify no MCG security key change (e.g., for intra-MN LTM cell switch) and accordingly does not include or indicate SCG-related operations such as SCG security key change, reconfiguration with sync, and / or RA. In contrast, another of the LTM candidate cell configurations may specify MCG security key change (e.g., for inter-MN LTM cell switch) and accordingly includes or indicates SCG-related operations such as SCG security key change, reconfiguration with sync, and / or RA.

[0187] In some of these embodiments, the UE receives from its serving MN an LTM cell switch command (e.g., MAC CE) that indicates one of the previously received multiple LTM candidate cell configurations for the same LTM candidate cell. The UE selectively performs SCG-related operations in conjunction with the LTM cell switch of the PCell, depending on whether these SCG-related operations are specified by the indicated LTM candidate cell configuration.

[0188] In other embodiments, a UE receives an LTM candidate cell configuration that includes multiple SCG configurations. At least one of these SCG configurations indicates one or more SCG-related operations in conjunction with LTM cell switch of the UE’s PCell. At least one other of these SCG configurations indicates no SCG-related operations in conjunction with LTM cell switch of the UE’s PCell. The SCG-related operations may be any of those discussed above in relation to other embodiments.

[0189] In some of these embodiments, the multiple SCG configurations are received within a single LTM-Candidate IE for the LTM candidate cell. In other of these embodiments, one of the multiple SCG configurations is included within the LTM candidate cell configuration for the MCG LTM cell switch (e.g., Itm-CandidateConflg IE) while the other SCG configuration(s) is / are received in the same message (e.g., RRCReconflguratiori) but outside the LTM candidate cell configuration.

[0190] In some of these embodiments, the UE receives from its serving MN an LTM cell switch command (e.g., MAC CE) that indicates the LTM candidate cell configuration as well as one of the multiple SCG configurations included in the LTM candidate cell configuration. The UE selectively performs SCG-related operations in conjunction with the LTM cell switch of the PCell, depending on whether these SCG-related operations are specified by the indicated SCG configuration.

[0191] In some embodiments, the SCG configuration may include additional fields to indicate the SCG-related operations to be performed in conjunction with the LTM cell switch of the PCell, thereby providing different configurations to be used depending on actions for the MCG. For example, the SCG configuration may include separate (different) configurations for when an MCG security key change is performed and when no MCG security key change is performed. In some embodiments, the MCG part of an LTM candidate configuration (i.e., generated by the candidateMN) may include separate (different) SCG-related fields or configurations (e.g., sk-counter values) to be used depending on whether an MCG security key change is performed in conjunction with the LTM cell switch of the UE’s PCell.

[0192] In some of these embodiments, the UE determines which of the SCG configurations for the LTM candidate cell to apply based on whether an MCG security key change is performed in conjunction with the LTM cell switch. If there is an MCG security key change, the UE selects one of the SCG configurations that includes or indicates SCG-related operations such as SCG security key change, a reconfiguration with sync, and RA. If there is no MCG security key change, the UE selects one of the SCG configurations that does not include or indicate such SCG-related operations.

[0193] Although certain embodiments described above involve a UE determining whether to perform certain SCG-related operations based on whether an MCG security key change was performed in conjunction with an LTM cell switch of the PCell, the UE may base this determination on other aspects such as whether there is any change of radio bearers (e.g., DRBs) and / or termination points for radio bearers in the MCG.

[0194] Although certain embodiments described above involve UE operations responsive to a mobility command (e.g., LTM cell switch MAC CE), these operations may also be responsive to a UE determination that one or more conditions are fulfilled, such as in conditional L3 mobility and conditional LTM.

[0195] Figure 7 shows an exemplary method for a UE, according to some embodiments of the present disclosure. The UE is configured for dual connectivity (e.g., NR-DC) with an MN that provides an MCG and an SN that provides an SCG. In block 701, the UE receives from the MN an MCG mobility configuration (e.g., LTM candidate cell configuration) associated with an MCG mobility procedure (e.g., LTM cell switch of PCell) during which the SCG should be maintained by the UE. As mentioned above, the MCG mobility configuration may include an SCG configuration or alternative SCG configurations.

[0196] In block 702, the UE initiates execution of the MCG procedure according to the MCG mobility configuration. In some embodiments, this execution may be initiated by a mobility command from the MN, such as an LTM cell switch MAC CE. In other embodiments, this execution may be initiated based UE determination that one or more conditions are fulfilled, such as in conditional LTM and conditional L3 mobility.

[0197] In blocks 703-704, the UE determines whether an MCG security key change is needed in conjunction with the MCG mobility procedure. For example, if the MCG mobility configuration indicates an intra-MN LTM cell switch, the UE determines that no MCG security key change isneeded. In contrast, if the MCG mobility configuration indicates an inter-MN LTM cell switch, the UE determines that an MCG security key change is needed.

[0198] When the UE determines that an MCG security key change is needed in conjunction with the MCG mobility procedure, operation proceeds to block 705 where the UE performs SCG-related operations such as SCG security key change, reconfiguration with sync, RA, etc., such as discussed above. In contrast, when the UE determines that no MCG security key change is needed in conjunction with the MCG mobility procedure, operation proceeds to block 706 where the UE refrains from performing such SCG-related operations in conjunction with the MCG mobility procedure.

[0199] In some variants, certain SCG-related operations may be performed independently of other SCG-related operations in block 705. For example, the UE may perform an SCG security key change but refrain from performing RA towards the PSCell of the SCG. This behavior may be controlled and / or specified in various ways, such as described above.

[0200] Other embodiments include complementary methods for a RAN node (e.g., MN) configured to provide an MCG for a UE configured for DC with an SN that provides an SCG. The MN sends to the UE an MCG mobility configuration (e.g., LTM candidate cell configuration) associated with an MCG mobility procedure (e.g., LTM cell switch of PCell) during which the SCG should be maintained by the UE. As mentioned above, the MCG mobility configuration may include an SCG configuration or alternative SCG configurations. In some variants, each of the SCG configurations may include or indicate certain SCG-related operations to be performed (or not) in conjunction with the MCG mobility procedure.

[0201] In some embodiments, the MN subsequently sends to the UE a mobility command (e.g., LTM cell switch MAC CE), which triggers execution of the MCG mobility procedure by the UE. The MCG mobility procedure may involve an MCG security key change, which may be indicated by the MCG mobility configuration and / or the mobility command. Moreover, whether the MCG mobility procedure involves an MCG security key change may depend on the source cell (e.g., PCell) in which the UE applies the MCG mobility configuration and executes the MCG mobility procedure.

[0202] For example, if the MCG mobility configuration or the mobility command indicates an intra-MN LTM cell switch of the PCell, no MCG security key change is needed. In contrast, if the MCG mobility configuration or the mobility command indicates an inter-MN LTM cell switch of the PCell, an MCG security key change is needed. In some variants, the mobility command may include or indicate certain SCG-related operations to be performed (or not) in conjunction with the MCG mobility procedure.

[0203] Various features of the embodiments summarized above correspond to various operationsillustrated in Figures 8-9, which show exemplary methods (e.g., procedures) for a UE and a RAN node, respectively. In other words, various features of the operations described below correspond to various embodiments described above. Furthermore, the exemplary methods shown in Figures 8-9 can be used cooperatively to provide various benefits, advantages, and / or solutions to problems described herein. Although Figures 7-9 show specific blocks in particular orders, the operations of the exemplary methods can be performed in different orders than shown and can be combined and / or divided into blocks having different functionality than shown. Optional blocks or operations are indicated by dashed lines.

[0204] In particular, Figure 8 shows an exemplary method (e.g., procedure) for a UE configured for dual connectivity in a RAN, according to various embodiments of the present disclosure. The exemplary method can be performed by any appropriate UE (e.g., wireless device) such as described elsewhere herein.

[0205] The exemplary method includes the operations of block 810, where the UE receives the following from an MN that provides the UE’s MCG: one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE’s SCG should be maintained; and for each of the one or more MCG mobility configurations, one or more associated SCG configurations. The exemplary method also includes the operations of block 840, where the UE subsequently initiates the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations. The exemplary method also includes the operations of block 850, where the UE selectively performs one or more SCG-related operations in conjunction with the MCG mobility procedure, based on one or more of the following:

[0206] • the one or more SCG configurations associated with the first MCG mobility configuration, • whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, and

[0207] • information received with a command to initiate the MCG mobility procedure.

[0208] In some embodiments, each of the one or more MCG mobility configurations includes the associated one or more SCG configurations. In some embodiments, the one or more MCG mobility configurations are respective LTM candidate cell configurations and the MCG mobility procedure is an LTM cell switch of the primary cell (PCell) of the MCG to the candidate cell, as the target cell.

[0209] In some embodiments, initiating the MCG mobility procedure in block 840 is responsive to the operations of block 820, where the UE receives the command to initiate the MCG mobility procedure. For example, the command may be a medium access control (MAC) control element (CE) or a radio resource control (RRC) message. In some of these embodiments, the informationreceived with the command, on which selectively performing one or more SCG-related operations in block 850 is based, includes one or more of the following:

[0210] • an indication of whether all of the one or more SCG-related operations should be performed;

[0211] • respective indications of whether the one or more SCG-related operations should be performed;

[0212] • an indication of the first MCG mobility configuration;

[0213] • a first one of the SCG configurations associated with the first MCG mobility configuration, that should be used when performing the one or more SCG-related operations; and

[0214] • an indication of the first SCG configuration, which was received prior to the command.

[0215] In some of these embodiments, the one or more MCG mobility configurations include only the first MCG mobility configuration and the first MCG mobility configuration includes only a first SCG configuration. In other of these embodiments, the one or more MCG mobility configurations include the first MCG mobility configuration and a second MCG mobility configuration, and / or the first MCG mobility configuration includes first and second SCG configurations. In some variants of these embodiments, selectively performing the one or more SCG-related operations in block 850 includes the following operations, labelled with corresponding sub-block numbers:

[0216] • (851) selecting between the first and second SCG configurations based on whether the one or more MCG-related operations are performed during the MCG mobility procedure; and • (852) performing the one or more SCG-related operations in accordance with the selected first or second SCG configuration.

[0217] In a variant of different embodiments described above, the first MCG mobility configuration or the first SCG configuration indicates which of the SCG-related operations should be performed in conjunction with the MCG mobility procedure. In such case, selectively performing the one or more SCG-related operations in block 850 includes the operations of subblock 853, where the UE perform the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration. In some further variants, the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration are performed only when the one or more MCG-related operations are performed during the MCG mobility procedure.

[0218] In other embodiments, initiating the MCG mobility procedure to the candidate cell in block 840 is responsive to the operations of block 830, where the UE determines that one or more radiorelated conditions are fulfilled. For example, these radio-related conditions may be part of the MCG mobility configuration, such as a conditional LTM candidate cell configuration.In some embodiments, the one or more SCG-related operations include one or more of the following: SCG security key change, reconfiguration with sync in the SCG, and random access (RA) to a primary SCG cell (PSCell). In some embodiments, the one or more MCG-related operations include one or more of the following: MCG security key change, RA to the target cell, MCG radio bearer change, and MCG radio bearer termination point change.

[0219] In some of these embodiments, selectively performing the one or more SCG-related operations in conjunction with the MCG mobility procedure in block 850 includes the following operations, labelled with corresponding sub-block numbers:

[0220] • (854) performing at least a portion of the one or more SCG-related operations when MCG security key change is performed during the MCG mobility procedure; and

[0221] • (855) refraining from performing at least a portion of the one or more SCG-related operations when MCG security key change is not performed during the MCG mobility procedure.

[0222] In some of these embodiments, the one or more MCG-related operations are performed only when the current MN does not provide the target cell (i.e., inter-MN mobility procedure).

[0223] In some embodiments, each of the SCG configurations includes one or more of the following:

[0224] • one or more indications of whether to perform the following SCG-related operations in conjunction with the MCG mobility procedure: security key change, reconfiguration with sync, packet data convergence protocol (PDCP) re-establishment, radio link control (RLC) re-establishment, and random access (RA); and

[0225] • any of the following information: an MCG security key, an SCG security key, one or more security counters, a timing advance (TA) value, and a time alignment timer (TAT) value. In addition, Figure 9 shows an exemplary method (e.g., procedure) for a RAN node configured to operate as an MN that provides an MCG for a UE, according to various embodiments of the present disclosure. The exemplary method can be performed by any appropriate RAN node (e.g., base station, eNB, gNB, ng-eNB, DU, etc.) such as described elsewhere herein.

[0226] The exemplary method includes the operations of block 910, where the RAN node sends the following to the UE: one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE’s SCG should be maintained; and one or more SCG configurations associated with each of the one or more MCG mobility configurations. The exemplary method also includes the operations of block 920, where the RAN node subsequently sends to the UE a command to initiate the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations. One or more of thefollowing information configures the UE to selectively perform one or more SCG-related operations in conjunction with the MCG mobility procedure:

[0227] • the one or more SCG configurations associated with the first MCG mobility configuration, • whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, and

[0228] • information sent with the command.

[0229] In some embodiments, each of the one or more MCG mobility configurations includes the associated one or more SCG configurations. In some embodiments, the one or more MCG mobility configurations are respective LTM candidate cell configurations and the MCG mobility procedure is an LTM cell switch of the primary cell (PCell) of the MCG to the candidate cell, as the target cell. In some embodiments, the command is a MAC CE or an RRC message. In various embodiments, the information sent with the command may include any of the corresponding information received with the command, as described above in relation to UE embodiments.

[0230] In some embodiments, the one or more MCG mobility configurations include only the first MCG mobility configuration and the first MCG mobility configuration includes only a first SCG configuration. In other embodiments, the one or more MCG mobility configurations include the first MCG mobility configuration and a second MCG mobility configuration, and / or the first MCG mobility configuration includes first and second SCG configurations. In some of these embodiments, the information configures the UE to select between the first and second SCG configurations based on whether the one or more MCG-related operations are performed during the MCG mobility procedure, and to perform the one or more SCG-related operations in accordance with the selected first or second SCG configuration, such as described above in relation to UE embodiments.

[0231] In a variant of different embodiments described above, the first MCG mobility configuration or the first SCG configuration indicates which of the SCG-related operations should be performed in conjunction with the MCG mobility procedure. In such case, the information configures the UE to perform the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration. In some further variants, the information configures the UE to perform the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration only when the one or more MCG-related operations need to be performed during the MCG mobility procedure.

[0232] In some embodiments, the one or more SCG-related operations include one or more of the following: SCG security key change, reconfiguration with sync in the SCG, and RA to a primary SCG cell (PSCell). In some embodiments, the one or more MCG-related operations include one or more of the following: MCG security key change, RA to the target cell, MCG radio bearerchange, and MCG radio bearer termination point change. In some of these embodiments, the information configures the UE to perform at least a portion of the one or more SCG-related operations when MCG security key change is performed during the MCG mobility procedure, and to refrain from performing at least a portion of the one or more SCG-related operations when MCG security key change is not performed during the MCG mobility procedure. In some of these embodiments, the one or more MCG-related operations need to be performed only when the MN does not provide the target cell.

[0233] In various embodiments, each of the SCG configurations may include any of the corresponding information described above in relation to UE embodiments.

[0234] Although various embodiments are described above in terms of methods, techniques, and / or procedures, the person of ordinary skill will readily comprehend that such methods, techniques, and / or procedures can be embodied by various combinations of hardware and software in various systems, communication devices, computing devices, control devices, apparatuses, non-transitory computer-readable media, computer program products, etc.

[0235] Figure 10 shows an example communication system 1000 according to some embodiments. In this example, communication system 1000 includes a telecommunication network 1002 that includes an access network 1004 (e.g., RAN) and a core network 1006, which includes one or more core network nodes 1008. Access network 1004 includes one or more access network nodes, such as access network nodes lOlOa-b (one or more of which may be referred to as network nodes 1010), or any other similar 3GPP access nodes ornon-3GPP access points (APs). Some embodiments of the access network 1004 may include more than one access network technology. Access network nodes 1010 of access network 1004 facilitate direct or indirect connection of wireless devices, to the core network 1006 over one or more wireless connections. Such wireless devices may also referred to as user equipment (UEs), with UEs 1012A-D (one or more of which may be referred to as UEs 1012) shown by way of example.

[0236] Moreover, such network nodes are not necessarily limited to implementations in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Rather, the network nodes may include disaggregated implementations. For example, in some embodiments, telecommunication network 1002 includes one or more Open-RAN (ORAN) network nodes. An ORAN network node is a node in telecommunication network 1002 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in telecommunication network 1002, including one or more access network nodes 1010 and / or core network nodes 1008.Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU-CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e. g. , r App), or any combination thereof (the adj ective “open” designating support of an ORAN specification). The network node may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an 0-2 interface defined by the 0-RAN Alliance or comparable technologies.

[0237] Access network nodes 1010 facilitate direct or indirect connection of UEs, such as by connecting UEs 1012, to core network 1006 over one or more wireless connections. Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, communication system 1000 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. Communication system 1000 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0238] UEs 1012 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with access network nodes 1010 and other communication devices. Similarly, access network nodes 1010 are arranged, capable, configured, and / or operable to communicate directly or indirectly with UEs 1012 and / or with other network nodes or equipment in telecommunication network 1002 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in telecommunication network 1002.

[0239] More specifically, UEs 1012 may send messages, data, and / or other signals to network nodes 1008, 1010 or other elements of the telecommunications network 1002 by transmitting such signals to the relevant device directly without the signals passing through any intervening devicesor by transmitting such signals to the relevant device indirectly through an intervening device (or multiple intervening devices) that then transmit the signal to the relevant device. Similarly, network nodes 1008, 1010 may send messages, data, and other signals to UEs 10122, other network nodes 1008, 1010, and other devices in telecommunications network 1002 directly or indirectly. As one specific example, core network node 108 may transmit a particular message to a UE 1012 by transmitting the message to an access network node 1010, which will then transmit the message to the UE 1012. Similarly, core network node 108 may receive a particular message from a UE 1012 by receiving the message from an access network node 1010 that itself received the message from the UE 1012.

[0240] As shown in Figure 10, core network 1006 connects elements of access network 1004 (e.g., one or more of access network nodes 1010) to one or more host computing systems, such as host 1016. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. Core network 1006 may include one or more core network nodes (e.g., 1008) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of core network node 1008. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0241] Host 1016 may be under the ownership or control of a service provider other than an operator or provider of access network 1004 and / or telecommunication network 1002, and may be operated by the service provider or on behalf of the service provider. Host 1016 may host a variety of applications to provide one or more service. Examples of such applications include live and pre-recorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0242] As a whole, communication system 1000 of Figure 10 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal MobileTelecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0243] Moreover, communication system 1000 may be configured to support multiple different standards, protocols, or other rule sets, with individual components supporting all of the relevant rule sets or with different components or sub-systems within the communication system 1000 supporting different standards, protocols, or rule sets. As one example, access network 1004 may contain some access network nodes 1010 that support 3GPP radio access technologies (RAT), such as LTE or NR, while the same (or other) access network nodes 1010 (non-3GPP RATs, such as Wi-Fi or a proprietary RAT. As another example, telecommunications network 1002 may support multiple generations of related communication standards (e.g., 3 GPP 4G and 5G standards) and, as a result, access network 1004 and / or core network 1006 may support multiple generations of related communication standards. Alternately, telecommunications network 1002 may include multiple access networks 1004 and / or multiple core networks 1006, which support respective generations of standards.

[0244] In some embodiments, telecommunications network 1002 may support network slicing to provide different logical networks to different devices that are connected to the telecommunications network 1002. For example, the telecommunications network 1002 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive loT services to yet further UEs.

[0245] In some examples, one or more of UEs 1012 may be configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to access network 1004 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from access network 1004. Additionally, a UE may be configured for operating in single- or multi-RAT or multi-standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e., being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN / NR dual connectivity (EN-DC).

[0246] According to the example shown in Figure 10, hub 1014 communicates with access network 1004 to facilitate indirect communication between one or more UEs (e.g., 1012C and / or1012D) and network nodes (e.g., network node 1010b). In some examples, hub 1014 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, hub 1014 may be a broadband router enabling access to core network 1006 for the UEs. As another example, hub 1014 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, access network nodes 1010, or by executable code, script, process, or other instructions in hub 1014.

[0247] As another example, hub 1014 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, hub 1014 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, hub 1014 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which hub 1014 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, hub 1014 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0248] Hub 1014 may have a constant / persistent or intermittent connection to network node 1010b. Hub 1014 may also allow for a different communication scheme and / or schedule between hub 1014 and UEs (e.g., 1012C and / or 1012D), and between hub 1014 and core network 1006. In other examples, hub 1014 is connected to core network 1006 and / or one or more UEs via a wired connection. Moreover, hub 1014 may be configured to connect to an M2M service provider over access network 1004 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with access network nodes 1010 while still connected via hub 1014 via a wired or wireless connection. In some embodiments, hub 1014 may be a dedicated hub -that is, a hub whose primary function is to route communications to / from the UEs from / to network node 1010b. In other embodiments, hub 1014 may be anon-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 1010b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0249] In some embodiments, any of UEs 1012 may be configured to perform operations attributed to a UE in various methods or procedures described above, including the exemplary method shown in Figures 7-8. In some embodiments, any of access network nodes 1010 may be configured to perform operations attributed to a RAN node in various methods or procedures described above, including the exemplary method shown in Figure 9.

[0250] Figure 11 shows another example communication system 1100 according to some embodiments. In this example, communication system 1100 includes multiple access points (APs)(e.g., APs 1110A-D) and multiple wireless devices 1112A-E, which may also be referred to in this context as stations (STAs) 1112A-E (or collectively as STAs 1112).

[0251] Each STA 1112A-E connect through a radio link to one of APs 1110. For example, depending on location or channel conditions experienced by a particular STA, the STA may select an appropriate AP and basic service set (BSS) for establishing the radio link. The radio link may be based on one or more orthogonal frequency-division multiplexing (OFDM) carriers from a frequency spectrum that is shared on the basis of a contention-based mechanism, e.g., an unlicensed or license exempt band like 2.4 GHz Industrial, Scientific, and Medical (ISM) band, 5-GHz band, 6-GHz band, 60-GHz band, etc. In the specific example shown, STA 1112A is served by AP 1110A in a first BSS 1120A, STA 1110B-C are served by AP 1110B in a second BSS 1120B, STA 1112D is served by AP 1110C in a third BSS 1120C, and STA 1112E is served by AP 1110D in a fourth BSS 1120D.

[0252] STAs 1112 may be non-AP STAs and correspond to various kinds of wireless devices such as user terminals, mobile or stationary computing devices, smartphones, laptop computers, desktop computers, tablet computers, gaming devices, head-mounted displays (HMDs) for Augmented Reality (AR) or Virtual Reality (VR), smart home devices, printers, multimedia devices, data storage devices, etc.

[0253] As illustrated, APs 1110 may be connected to a data network 1130, enabling each AP to provide data connectivity between STAs 1112 and other entities in data network 1130 (e.g., servers, service providers, data sources, data sinks, user terminals, etc.). Accordingly, a radio link established between a particular STA 1112 and its serving AP 1110 may be used for providing various kinds of services to STA 1112, such as voice, multimedia, data, etc. Such services may be based on applications that are executed on STA 1112 and / or on a device linked to STA 1112.

[0254] In the example shown in Figure 11, data network 1130 includes application service platform 1132, with which application(s) executed on any of STAs 1112 (and / or on one or more other devices linked to STAs 1112) may communicate via the respective radio links between STAs 1112 and their respective serving APs 1110. Such communication may facilitate efficient utilization of the corresponding service(s) at STA 1112.

[0255] In some embodiments, any of STAs 1112 may be configured to perform operations attributed to a UE in various methods or procedures described above, including the exemplary method shown in Figures 7-8. In some embodiments, any of APs 1010 may be configured to perform operations attributed to a RAN node in various methods or procedures described above, including the exemplary method shown in Figure 9.

[0256] Figure 12 shows an example wireless device 1200 according to some embodiments. Wireless device 1200 may represent any of various examples including, but not limited to, smartphones, mobile phones, cellular phones, voice over IP (VoIP) phones, wireless local loop phones, desktop computers, personal digital assistants (PDAs), wireless cameras, gaming consoles or devices, music storage devices, playback appliances, wearable devices, wireless endpoints, mobile stations, tablets, laptops, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart devices, wireless customer-premise equipment (CPE), vehicles, vehicle-mounted or vehicle embedded / integrated wireless devices, etc. Other examples include any user equipment (UE) identified by 3GPP, including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0257] A wireless device may support device-to-device (D2D) communication, for example by implementing a 3 GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, a wireless device may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a wireless device may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a wireless device may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0258] Wireless device 1200 includes processing circuitry 1202 that is operatively coupled via a bus 1204 to an input / output interface 1206, a power source 1208, a memory 1210, a communication interface 1212, and / or one or more other components not explicitly shown. Moreover, certain wireless devices may utilize all or a subset of the components shown in Figure 12. The level of integration between the components may vary from one wireless device to another wireless device, and one or more of the components explicitly shown in Figure 12 may be integrated wholly or partially with other components not explicitly shown. Further, certain wireless devices may contain multiple instances of a particular component (e.g., processors, memories, transceivers, transmitters, receivers, etc.).

[0259] Processing circuitry 1202 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in memory 1210. Processing circuitry 1202 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general-purpose processors, such as a microprocessor or digital signal processor (DSP), togetherwith appropriate software; or any combination of the above. For example, processing circuitry 1202 may include multiple central processing units (CPUs).

[0260] In the example shown in Figure 12, input / output interface 1206 may be configured to provide interface(s) to input device(s), output device(s), or some combination thereof. Example output devices include speakers, sound cards, video cards, displays, monitors, printers, actuators, emitters, smartcards, etc., or some combination thereof. Example input devices include atouch-(or presence-) sensitive displays, cameras (e.g., digital camera, video camera, web camera, etc.), microphones, sensors, mice, trackballs, directional pads, trackpads, scroll wheels, smartcards, etc., or some combination thereof.

[0261] As a more specific example, presence-sensitive displays may include a capacitive or resistive touch sensor to sense input from a user. As other more specific examples, sensors may include an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or some combination thereof. In some variants, an output device may use the same interface port (or same port type) as an input device. As an example of these variants, a Universal Serial Bus (USB) port may be used as an input device and an output device.

[0262] In some embodiments, power source 1208 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. Power source 1208 may further include power circuitry for delivering power from power source 1208 itself, and / or an external power source, to the various parts of wireless device 1200 via input circuitry or an interface such as an electrical power cable. Power circuitry may perform any formatting, converting, or other modification to the power from power source 1208 to make the power suitable for the respective components of wireless device 1200 to which power is supplied.

[0263] Memory 1210 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, memory 1210 includes one or more programs 1214, such as an operating system, web browser application, widgets, a gadget engine, etc. and corresponding data 1216. Memory 1210 may store, for use by wireless device 1200, one or more specific operating systems or combinations thereof.

[0264] Memory 1210 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical discdrive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ Memory 1210 may allow wireless device 1200 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in memory 1210, which may be or comprise a device-readable storage medium.

[0265] Processing circuitry 1202 may be configured to communicate with an access network or other network using communication interface 1212. Communication interface 1212 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1222. Communication interface 1212 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another wireless device or a network node in an access network). Each transceiver may include a transmitter 1218 and / or a receiver 1220 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, transmitter 1218 and receiver 1220 may be coupled to one or more antennas (e.g., antenna 1222) and may share circuit components, software, or firmware, or alternatively be implemented separately.

[0266] In the example shown in Figure 12, communication interface 1212 may support and / or provide cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communication (e.g., Bluetooth, near-field communication), location-based communication (e.g., use of the global navigation satellite system, GNSS, to determine location), etc., or any combination thereof. Communications may be implemented according to one or more protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), orthogonal frequency division multiplexing or multiple access (OFDM / OFDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / intemet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0267] In some embodiments, wireless device 1200 may output data captured by its sensors through its communication interface 1212 to a network node via a wireless connection, such asshown in Figures 10-11. In some variants, the wireless connection may be through another wireless device of similar or different type. Output of the captured sensor data may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., an alert is sent when moisture is detected), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0268] In some embodiments, wireless device 1200 may include an actuator, a motor, or a switch related to a communication interface configured to receive wireless input from a network node via a wireless connection. In some variants, the states of the actuator, motor, or switch may change in response to the received wireless input. For example, the UE may include a motor that adjusts control surfaces or rotors of a unmanned aerial vehicle (UAV, e.g., drone) in flight according to the received input, or adjusts a robotic arm performing a medical procedure according to the received input.

[0269] When in the form of an Internet of Things (loT) device, wireless device 1200 may be used in one or more application domains such as wearable technology, extended industrial application, and healthcare. As some non-limiting example, such an loT device may include (or be embedded in) a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a headmounted display for Augmented Reality (AR) or Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, a UAV, and a medical device (e.g., heart rate monitor, remote controlled surgical robot, etc.). When arranged as an loT device, wireless device 1200 may include circuitry and / or software associated with its intended application as well as other components such as described above for more generic embodiments of wireless device 1200.

[0270] As another example loT-related application, wireless device 1200 may include (or be embedded in) a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to other wireless devices and / or to network nodes in a communication network. As a more specific example, wireless device 300 may be an M2M device, which may also be referred to as a machine-type communication (MTC) device in 3GPP vocabulary. Such an M2M device may implement the 3GPP NB-IoT standard. Asanother example loT-related application, wireless device 1200 may be embedded in a vehicle (e.g., passenger car, motorcycle, bus, truck, ship, airplane, etc.) or in other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0271] In practice, any number of wireless devices (e.g., 1200) may be used together in a single use case. For example, a first wireless device may be or be integrated in a UAV and provide the UAV’s speed information (e.g., obtained through a speed sensor) to a second wireless device that is a remote controller operating the UAV. When the user makes changes from the remote controller, the first wireless device may adjust the throttle on the UAV (e.g., by controlling an actuator) to increase or decrease the UAV’s speed. The first and / or the second wireless devices may include more than the specific functionalities described above. For example, a wireless device may include a sensor and an actuator, and handle communication of data for both the sensor and the actuator.

[0272] In some embodiments, wireless device 1200 may be configured to perform operations attributed to a UE in various methods or procedures described above, including the exemplary method shown in Figures 7-8.

[0273] Figure 13 shows an example network node 1300 according to some embodiments. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (e.g., radio base stations, Node Bs, eNBs, gNBs), and O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU). Network node 1300 may be considered as a type of network equipment (in contrast to user equipment, UE).

[0274] Network nodes may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. Network node 1300 may be a relay node or a relay donor node controlling a relay. Network node 1300 may include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0275] Other examples of network nodes (such as 1300) include multiple transmission point (multi-TRP) 5G access nodes, multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell / multicastcoordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0276] Network node 1300 includes processing circuitry 1302, memory 1304, communication interface 1306, and power source 1308. Network node 1300 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. For example, the specific components shown in Figure 13 may represent or include physical components common to or shared by one or more of the other elements of network node 1300.

[0277] In certain scenarios in which network node 1300 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, network node 1300 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memories 1304 for different RATs) and some components may be reused (e.g., one antenna 1310 may be shared by different RATs). Network node 1300 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1300, e.g., GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID), Bluetooth, etc. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1300.

[0278] Processing circuitry 1302 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other components (e.g., memory 1304) to provide the functionality of network node 1300.

[0279] In some embodiments, processing circuitry 1302 may include a system on a chip (SOC). In some embodiments, processing circuitry 1302 includes radio frequency (RF) transceiver circuitry 1312 and / or baseband processing circuitry 1314. In some embodiments, RF transceiver circuitry 1312 and / or baseband processing circuitry 1314 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1312 and / or baseband processing circuitry 1314 may be on the same chip or set of chips, boards, or units.Memory 1304 may include any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non-transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by processing circuitry 1302. Memory 1304 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions (collectively denoted computer program 1304A, which may be in the form of a computer program product) capable of being executed by processing circuitry 1302 and utilized by network node 1300. Memory 1304 may be used to store any calculations made by processing circuitry 1302 and / or any data received via communication interface 1306. In some embodiments, processing circuitry 1302 and memory 1304 is integrated.

[0280] Communication interface 1306 may be used for wired or wireless communication of signaling and / or data between network node 1300, an access network, a core network, and / or wireless device(s). As illustrated, communication interface 1306 comprises port(s) / terminal(s) 1316 to send and receive data, for example to and from a network over a wired connection. Communication interface 1306 also includes radio front-end circuitry 1318 that may be coupled to, or in certain embodiments a part of, antenna 1310. Radio front-end circuitry 1318 comprises filters 1320 and amplifiers 1322. Radio front-end circuitry 1318 may be connected to an antenna 1310 and processing circuitry 1302. The radio front-end circuitry may be configured to condition signals communicated between antenna 1310 and processing circuitry 1302. Radio front-end circuitry 1318 may receive digital data that is to be sent out to other network nodes or wireless devices via a wireless connection. Radio front-end circuitry 1318 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1320 and / or amplifiers 1322. The radio signal may then be transmitted via antenna 1310. Similarly, when receiving data, antenna 1310 may collect radio signals which are then converted into digital data by radio front-end circuitry 1318. The digital data may be passed to processing circuitry 1302. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0281] In certain alternative embodiments, network node 1300 does not include separate radio front-end circuitry 1318, instead, processing circuitry 1302 includes radio front-end circuitry and is connected to antenna 1310. Similarly, in some embodiments, all or some of RF transceiver circuitry 1312 is part of communication interface 1306. In still other embodiments,communication interface 1306 includes one or more ports or terminals 1316, radio front-end circuitry 1318, and RF transceiver circuitry 1312, as part of a radio unit (not shown), and communication interface 1306 communicates with baseband processing circuitry 1314, which is part of a digital unit (not shown).

[0282] Antenna 1310 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. Antenna 1310 may be coupled to radio front-end circuitry 1318 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, antenna 1310 is separate from network node 1300 and connectable to network node 1300 through one or more interfaces or ports.

[0283] Antenna 1310, communication interface 1306, and / or processing circuitry 1302 may be configured to perform various receiving and / or obtaining operations described herein as being performed by a network node. Any information, data and / or signals may be received from a wireless device, another network node, and / or any other network equipment. Similarly, antenna 1310, communication interface 1306, and / or processing circuitry 1302 may be configured to perform any transmitting operations described herein as being performed by a network node. Any information, data and / or signals may be transmitted to a wireless device, another network node, and / or any other network equipment.

[0284] Power source 1308 provides power to the various components of network node 1300 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). Power source 1308 may further comprise, or be coupled to, power management circuitry to supply the components of network node 1300 with power for performing the functionality described herein. For example, network node 1300 may be connectable to an external power source (e.g., generator, power grid, electrical outlet, etc.) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of power source 1308. As another example, power source 1308 may include a battery or battery pack that is connected to, or integrated with, power circuitry. Such a battery or battery pack may provide backup power should the external power source fail.

[0285] Embodiments of network node 1300 may include additional components beyond those shown in Figure 13 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, network node 1300 may include user interface equipment to allow input of information into network node 1300 and to allow output of information from network node 1300. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for network node 1300.In some embodiments, network node 1300 may be configured to perform operations attributed to a RAN node in various methods or procedures described above, including the exemplary method shown in Figure 9.

[0286] Figure 14 shows an example virtualization environment 1400 in which some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 1400 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized. In some embodiments, the virtualization environment 1400 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface.

[0287] Applications 1402 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 1400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein. For example, one or more virtual nodes 1402 may be configured to perform operations attributed to a RAN node in various methods or procedures described above, including the exemplary method shown in Figure 9.

[0288] Hardware 1404 may include processing circuitry, memory that stores software and / or instructions (collectively denoted computer program 1404A, which may be in the form of a computer program product) executable by the processing circuitry, and other hardware devices such as a network interface, input / output interface, etc. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1406 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1408A-B (one or more of which may be referred to as VMs 1408), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. Virtualization layer 1406 may present a virtual operating platform that appears like networking hardware to the VMs 1408.

[0289] VMs 1408 may include virtual processing resources, virtual memory and / or storage, virtual networking and / or communication interfaces, etc., and may be run by a corresponding virtualization layer 1406. Different instances of a virtual appliance 1402 may be implemented onone or more VMs 1408, in various ways. In this context, hardware virtualization may also be referred to as network function virtualization (NFV), which may be used to consolidate many network equipment types onto commercial off-the-shelf (COTS) hardware such as server hardware, physical switches, physical storage, etc.. Such equipment may be located in data centers, customer premises, etc.

[0290] In the context of NFV, each VM 1408 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each VM 1408, and that part of hardware 1404 which executes the particular VM (e.g., VM-dedicated hardware or hardware shared with other VMs), forms a separate virtual network element. Further in the context of NFV, a virtual network function (NF) may be responsible for handling specific NFs that run in one or more VMs 1408 on top of hardware 1404 and that corresponds to a particular application 1402.

[0291] Hardware 1404 may be implemented in a standalone network node with generic or specific components. Hardware 1404 may implement some functions via virtualization. Alternatively, hardware 1404 may be part of a larger cluster of hardware (e.g., in a data center or customer premises) where many hardware nodes are managed cooperatively by a management and orchestration function 1410, which may oversee lifecycle management (LCM) of applications 1402. In some embodiments, hardware 1404 may be coupled to one or more radio units, each of which may include one or more transmitters and / or one or more receivers and may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1412 which may alternatively be used for communication between hardware nodes and radio units.

[0292] The foregoing merely illustrates the principles of the disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures that, although not explicitly shown or described herein, embody the principles of the disclosure and can be thus within the spirit and scope of the disclosure. Various embodiments can be used together with one another, as well as interchangeably therewith, as should be understood by those having ordinary skill in the art.

[0293] The term unit, as used herein, can have conventional meaning in the field of electronics, electrical devices and / or electronic devices and can include, for example, electrical and / or electronic circuitry, devices, modules, processors, memories, logic solid state and / or discretedevices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and / or displaying functions, and so on, as such as those that are described herein.

[0294] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for performing one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according to one or more embodiments of the present disclosure.

[0295] As described herein, device and / or apparatus can be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of a device or apparatus, instead of being hardware implemented, be implemented as a software module such as a computer program or a computer program product comprising executable software code portions for execution or being run on a processor. Furthermore, functionality of a device or apparatus can be implemented by any combination of hardware and software. A device or apparatus can also be regarded as an assembly of multiple devices and / or apparatuses, whether functionally in cooperation with or independently of each other. Moreover, devices and apparatuses can be implemented in a distributed fashion throughout a system, so long as the functionality of the device or apparatus is preserved. Such and similar principles are considered as known to a skilled person.

[0296] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0297] In addition, certain terms used in the present disclosure, including the specification and drawings, may be used synonymously in certain instances (e.g., “data” and “information”). Itshould be understood that although such terms may be used synonymously herein, there may be instances when such terms are not intended to be used synonymously.

[0298] Embodiments of the techniques and apparatus described herein also include, but are not limited to, the following enumerated examples:

[0299] Al. A method for a user equipment (UE) configured for dual connectivity (DC) with a master node (MN) that provides a master cell group (MCG) and a secondary node (SN) that provides a secondary cell group (SCG), the method comprising:

[0300] receiving the following from the MN:

[0301] one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the SCG should be maintained; and one or more SCG configurations associated with each of the one or more MCG mobility configurations;

[0302] subsequently initiating the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations; and selectively performing one or more SCG-related operations in conjunction with the MCG mobility procedure, based on one or more of the following:

[0303] the one or more SCG configurations associated with the first MCG mobility configuration,

[0304] whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, and

[0305] information received with a command to initiate the MCG mobility procedure.

[0306] Ala. The method of embodiment Al, wherein each of the one or more MCG mobility configurations includes the associated one or more SCG configurations.

[0307] A2. The method of any of embodiments Al -Al a, wherein:

[0308] the one or more MCG mobility configurations are respective layer-l / layer-2 triggered inter-cell mobility (LTM) candidate cell configurations; and

[0309] the MCG mobility procedure is an LTM cell switch of the primary cell (PCell) of the MCG to the candidate cell, as the target cell.

[0310] A3. The method of any of embodiments A1-A2, wherein:

[0311] initiating the MCG mobility procedure is responsive to receiving the command to initiate the MCG mobility procedure; andthe command is a medium access control (MAC) control element (CE) or a radio resource control (RRC) message.

[0312] A3a. The method of embodiment A3, wherein the information received with the command, on which selectively performing one or more SCG-related operations is based, includes one or more of the following:

[0313] an indication of whether all of the one or more SCG-related operations should be performed;

[0314] respective indications of whether the one or more SCG-related operations should be performed;

[0315] an indication of the first MCG mobility configuration;

[0316] a first one of the SCG configurations associated with the first MCG mobility configuration, that should be used when performing the one or more SCG-related operations; and

[0317] an indication of the first SCG configuration, which was received prior to the command.

[0318] A3b. The method of any of embodiments A3-A3a, wherein the one or more MCG mobility configurations include only the first MCG mobility configuration and the first MCG mobility configuration includes only a first SCG configuration.

[0319] A3c. The method of any of embodiments A3-A3a, wherein one or more of the following applies:

[0320] the one or more MCG mobility configurations include the first MCG mobility configuration and a second MCG mobility configuration; and

[0321] the first MCG mobility configuration includes first and second SCG configurations.

[0322] A3d. The method of embodiment A3c, wherein selectively performing the one or more SCG-related operations comprises:

[0323] selecting between the first and second SCG configurations based on whether the one or more MCG-related operations are performed during the MCG mobility procedure; and

[0324] performing the one or more SCG-related operations in accordance with the selected first or second SCG configuration.

[0325] A3e. The method of any of embodiments A3a-A3c, wherein:the first MCG mobility configuration or the first SCG configuration indicates which of the SCG-related operations should be performed in conjunction with the MCG mobility procedure, and

[0326] selectively performing the one or more SCG-related operations comprises performing the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration.

[0327] A3f. The method of embodiment A3e, wherein the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration are performed only when the one or more MCG-related operations are performed during the MCG mobility procedure.

[0328] A4. The method of any of embodiments A1-A2, wherein initiating the MCG mobility procedure to the candidate cell is responsive to determining that one or more radio-related conditions are fulfilled.

[0329] A5. The method of any of embodiments A1-A4, wherein the one or more SCG-related operations include one or more of the following: SCG security key change, reconfiguration with sync in the SCG, and random access (RA) to a primary SCG cell (PSCell).

[0330] A6. The method of any of embodiments A1-A5, wherein the one or more MCG-related operations include one or more of the following: MCG security key change, random access (RA) to the target cell, MCG radio bearer change, and MCG radio bearer termination point change.

[0331] A6a. The method of embodiment A6, wherein selectively performing the one or more SCG-related operations in conjunction with the MCG mobility procedure comprises:

[0332] performing at least a portion of the one or more SCG-related operations when MCG security key change is performed during the MCG mobility procedure; and refraining from performing at least a portion of the one or more SCG-related operations when MCG security key change is not performed during the MCG mobility procedure.

[0333] A6b. The method of embodiments A6-A6a, wherein the one or more MCG-related operations are performed only when the target cell is not provided by the MN.

[0334] A7. The method of any of embodiments Al-A6b, wherein each of the SCG configurationsincludes one or more of the following:

[0335] one or more indications of whether to perform the following SCG-related operations in conjunction with the MCG mobility procedure: security key change, reconfiguration with sync, packet data convergence protocol (PDCP) reestablishment, radio link control (RLC) re-establishment, and random access (RA); and

[0336] any of the following information: an MCG security key, an SCG security key, one or more security counters, a timing advance (TA) value, and a time alignment timer (TAT) value.

[0337] Bl . A method for a radio access network (RAN) node configured to operate as a master node (MN) that provides a master cell group (MCG) for a user equipment (UE) configured for dual connectivity with a secondary node (SN) that provides a secondary cell group (SCG) for the UE, the method comprising:

[0338] sending the following to the UE:

[0339] one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the SCG should be maintained; and one or more SCG configurations associated with each of the one or more MCG mobility configurations; and

[0340] subsequently sending to the UE a command to initiate the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations,

[0341] wherein one or more of the following information configures the UE to selectively perform one or more SCG-related operations in conjunction with the MCG mobility procedure:

[0342] the one or more SCG configurations associated with the first MCG mobility configuration,

[0343] whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, and

[0344] information sent with the command.

[0345] Bia. The method of embodiment Bl, wherein each of the one or more MCG mobility configurations includes the associated one or more SCG configurations.

[0346] B2. The method of any of embodiments Bl -Bl a, wherein:the one or more MCG mobility configurations are respective layer-l / layer-2 triggered inter-cell mobility (LTM) candidate cell configurations; and

[0347] the MCG mobility procedure is an LTM cell switch of the primary cell (PCell) of the MCG to the candidate cell, as the target cell.

[0348] B3. The method of any of embodiments B1-B2, wherein the command is a medium access control (MAC) control element (CE) or a radio resource control (RRC) message.

[0349] B3a. The method of embodiment B3, wherein the information sent with the command includes one or more of the following:

[0350] an indication of whether all of the one or more SCG-related operations should be performed;

[0351] respective indications of whether the one or more SCG-related operations should be performed;

[0352] an indication of the first MCG mobility configuration;

[0353] a first one of the SCG configurations associated with the first MCG mobility configuration, that should be used when performing the one or more SCG-related operations; and

[0354] an indication of the first SCG configuration, which was received prior to the command.

[0355] B3b. The method of any of embodiments B3-B3a, wherein the one or more MCG mobility configurations include only the first MCG mobility configuration and the first MCG mobility configuration includes only a first SCG configurations.

[0356] B3c. The method of any of embodiments B3-B3a, wherein one or more of the following applies:

[0357] the one or more MCG mobility configurations include the first MCG mobility configuration and a second MCG mobility configuration; and

[0358] the first MCG mobility configuration includes first and second SCG configurations.

[0359] B3d. The method of embodiment B3c, wherein the information configures the UE to select between the first and second SCG configurations based on whether the one or more MCG-related operations are performed during the MCG mobility procedure, and to perform the one or more SCG-related operations in accordance with the selected first or second SCG configuration.B3e. The method of any of embodiments B3a-B3c, wherein:

[0360] the first MCG mobility configuration or the first SCG configuration indicates which of the SCG-related operations should be performed in conjunction with the MCG mobility procedure, and

[0361] the information configures the UE to perform the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration.

[0362] B3f The method of embodiment B3e, wherein the information configures the UE to perform the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration only when the one or more MCG-related operations need to be performed during the MCG mobility procedure.

[0363] B4. The method of any of embodiments Bl-B3f, wherein the one or more SCG-related operations include one or more of the following: SCG security key change, reconfiguration with sync in the SCG, and random access (RA) to a primary SCG cell (PSCell).

[0364] B5. The method of any of embodiments B1-B4, wherein the one or more MCG-related operations include one or more of the following: MCG security key change, random access (RA) to the target cell, MCG radio bearer change, and MCG radio bearer termination point change.

[0365] B5a. The method of embodiment B5, wherein the information configures the UE to:

[0366] perform at least a portion of the one or more SCG-related operations when MCG security key change is performed during the MCG mobility procedure; and refrain from performing at least a portion of the one or more SCG-related operations when MCG security key change is not performed during the MCG mobility procedure.

[0367] B5b. The method of embodiments B5-B5a, wherein the one or more MCG-related operations need to be performed only when the target cell is not provided by the MN.

[0368] B6. The method of any of embodiments Bl-B5b, wherein each of the SCG configurations includes one or more of the following:

[0369] one or more indications of whether to perform the following SCG-related operations in conjunction with the MCG mobility procedure: security key change, reconfiguration with sync, packet data convergence protocol (PDCP) re-establishment, radio link control (RLC) re-establishment, and random access (RA); and

[0370] any of the following information: an MCG security key, an SCG security key, one or more security counters, a timing advance (TA) value, and a time alignment timer (TAT) value.

[0371] Cl . User equipment (UE) configured for dual connectivity (DC) with a master node (MN) that provides a master cell group (MCG) and a secondary node (SN) that provides a secondary cell group (SCG), the UE comprising:

[0372] communication interface circuitry configured to communicate with the MN and the SN;

[0373] and

[0374] processing circuitry operatively coupled to the communication interface circuitry, wherein the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to the methods of any of embodiments A1-A7.

[0375] C2. User equipment (UE) configured for dual connectivity (DC) with a master node (MN) that provides a master cell group (MCG) and a secondary node (SN) that provides a secondary cell group (SCG), the UE being further configured to perform operations corresponding to the methods of any of embodiments A1-A7.

[0376] C3. Non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of user configured for dual connectivity (DC) with a master node (MN) that provides a master cell group (MCG) and a secondary node (SN) that provides a secondary cell group (SCG), configure the UE to perform operations corresponding to the methods of any of embodiments A1-A7.

[0377] C4. Computer program product comprising computer-executable instructions that, when executed by processing circuitry of user configured for dual connectivity (DC) with a master node (MN) that provides a master cell group (MCG) and a secondary node (SN) that provides a secondary cell group (SCG), configure the UE to perform operations corresponding to the methods of any of embodiments A1-A7.

[0378] DI. Radio access network (RAN) node configured to operate as a master node (MN) that provides a master cell group (MCG) for a user equipment (UE) configured for dual connectivitywith a secondary node (SN) that provides a secondary cell group (SCG) for the UE, the RAN node comprising:

[0379] communication interface circuitry configured to communicate with the UE and with the SN; and

[0380] processing circuitry operatively coupled to the communication interface circuitry, wherein the processing circuitry and the communication interface circuitry are configured to perform operations corresponding to the methods of any of embodiments B1-B6.

[0381] D2. Radio access network (RAN) node configured to operate as a master node (MN) that provides a master cell group (MCG) for a user equipment (UE) configured for dual connectivity with a secondary node (SN) that provides a secondary cell group (SCG) for the UE, the RAN node being further configured to perform operations corresponding to the methods of any of embodiments B1-B6.

[0382] D3. Non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a radio access network (RAN) node configured to operate as a master node (MN) that provides a master cell group (MCG) for a user equipment (UE) configured for dual connectivity with a secondary node (SN) that provides a secondary cell group (SCG) for the UE, configure the RAN node to perform operations corresponding to the methods of any of embodiments B1-B6.

[0383] D4. Computer program product comprising computer-executable instructions that, when executed by processing circuitry of a radio access network (RAN) node configured to operate as a master node (MN) that provides a master cell group (MCG) for a user equipment (UE) configured for dual connectivity with a secondary node (SN) that provides a secondary cell group (SCG) for the UE, configure the RAN node to perform operations corresponding to the methods of any of embodiments B1-B6.

Claims

CLAIMS1. A method for a user equipment, UE, configured for dual connectivity in a radio access network, RAN, the method comprising:receiving (810) the following from a master node, MN, that provides the UE’s master cell group, MCG:one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE’s secondary cell group, SCG, should be maintained; andfor each of the one or more MCG mobility configurations, one or more associated SCG configurations;subsequently initiating (840) the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations; andselectively performing (850) one or more SCG-related operations in conjunction with the MCG mobility procedure, based on one or more of the following: the one or more SCG configurations associated with the first MCG mobility configuration,whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, andinformation received with a command to initiate the MCG mobility procedure.

2. The method of claim 1, wherein each of the one or more MCG mobility configurations includes the associated one or more SCG configurations.

3. The method of any of claims 1-2, wherein:the one or more MCG mobility configurations are respective layer-l / layer-2 triggered inter-cell mobility, LTM, candidate cell configurations; andthe MCG mobility procedure is an LTM cell switch of the primary cell, PCell, of the MCG to the candidate cell, as the target cell.

4. The method of any of claims 1-3, wherein:initiating (840) the MCG mobility procedure is responsive to receiving (820) the command to initiate the MCG mobility procedure; andthe command is a medium access control, MAC, control element, CE, or a radio resource control, RRC, message.

5. The method of claim 4, wherein the information received with the command, on which selectively performing (850) the one or more SCG-related operations is based, includes one or more of the following:an indication of whether all of the one or more SCG-related operations should be performed;respective indications of whether the one or more SCG-related operations should be performed;an indication of the first MCG mobility configuration;a first one of the SCG configurations associated with the first MCG mobility configuration, that should be used when performing the one or more SCG-related operations; andan indication of the first SCG configuration, which was received prior to the command.

6. The method of any of claims 4-5, wherein the one or more MCG mobility configurations include only the first MCG mobility configuration and the first MCG mobility configuration includes only a first SCG configuration.

7. The method of any of claims 4-5, wherein one or more of the following applies:the one or more MCG mobility configurations include the first MCG mobility configuration and a second MCG mobility configuration; andthe first MCG mobility configuration includes first and second SCG configurations.

8. The method of claim 7, wherein selectively performing (850) the one or more SCG-related operations comprises:selecting (851) between the first and second SCG configurations based on whether the one or more MCG-related operations are performed during the MCG mobility procedure; andperforming (852) the one or more SCG-related operations in accordance with the selected first or second SCG configuration.

9. The method of any of claims 5-7, wherein:the first MCG mobility configuration or the first SCG configuration indicates which of the SCG-related operations should be performed in conjunction with the MCG mobility procedure, andselectively performing (850) the one or more SCG-related operations comprises performing (853) the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration.

10. The method of claim 9, wherein the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration are performed only when the one or more MCG-related operations are performed during the MCG mobility procedure.

11. The method of any of claims 1-3, wherein initiating (840) the MCG mobility procedure to the candidate cell is responsive to determining (830) that one or more radio-related conditions are fulfilled.

12. The method of any of claims 1-11, wherein the one or more SCG-related operations include one or more of the following: SCG security key change; reconfiguration with sync in the SCG; and random access, RA, to a primary SCG cell, PSCell.

13. The method of any of claims 1-12, wherein the one or more MCG-related operations include one or more of the following: MCG security key change; random access, RA, to the target cell; MCG radio bearer change; and MCG radio bearer termination point change.

14. The method of claim 13, wherein selectively performing (850) the one or more SCG-related operations in conjunction with the MCG mobility procedure comprises:performing (854) at least a portion of the one or more SCG-related operations when MCG security key change is performed during the MCG mobility procedure; and refraining from performing (855) at least a portion of the one or more SCG-related operations when MCG security key change is not performed during the MCG mobility procedure.

15. The method of claims 13-14, wherein the one or more MCG-related operations are performed only when the target cell is not provided by the MN.

16. The method of any of claims 1-15, wherein each of the SCG configurations includes one or more of the following:one or more indications of whether to perform the following SCG-related operations in conjunction with the MCG mobility procedure: security key change; reconfiguration with sync; packet data convergence protocol, PDCP, reestablishment; radio link control, RLC, re-establishment; and random access, RA; andany of the following information: an MCG security key; an SCG security key; one or more security counters; a timing advance, TA, value; and a time alignment timer, TAT, value.

17. A method for a radio access network, RAN, node configured to operate as a master node, MN, that provides a master cell group, MCG, for a user equipment, UE, the method comprising:sending (910) the following to the UE:one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE’s secondary cell group, SCG, should be maintained; andfor each of the one or more MCG mobility configurations, one or more associated SCG configurations; andsubsequently sending (920) to the UE a command to initiate the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations,wherein one or more of the following information configures the UE to selectively perform one or more SCG-related operations in conjunction with the MCG mobility procedure:the one or more SCG configurations associated with the first MCG mobility configuration,whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, andinformation sent with the command.

18. The method of claim 17, wherein each of the one or more MCG mobility configurations includes the associated one or more SCG configurations.

19. The method of any of claims 17-18, wherein:the one or more MCG mobility configurations are respective layer-l / layer-2 triggered inter-cell mobility, LTM, candidate cell configurations; andthe MCG mobility procedure is an LTM cell switch of the primary cell, PCell, of the MCG to the candidate cell, as the target cell.

20. The method of any of claims 17-19, wherein the command is a medium access control, MAC, control element, CE, or a radio resource control, RRC, message.

21. The method of claim 20, wherein the information sent with the command includes one or more of the following:an indication of whether all of the one or more SCG-related operations should be performed;respective indications of whether the one or more SCG-related operations should be performed;an indication of the first MCG mobility configuration;a first one of the SCG configurations associated with the first MCG mobility configuration, that should be used when performing the one or more SCG-related operations; andan indication of the first SCG configuration, which was received prior to the command.

22. The method of any of claims 20-21, wherein the one or more MCG mobility configurations include only the first MCG mobility configuration and the first MCG mobility configuration includes only a first SCG configurations.

23. The method of any of claims 20-21, wherein one or more of the following applies:the one or more MCG mobility configurations include the first MCG mobility configuration and a second MCG mobility configuration; andthe first MCG mobility configuration includes first and second SCG configurations.

24. The method of claim 23, wherein the information configures the UE to select between the first and second SCG configurations based on whether the one or more MCG-related operations are performed during the MCG mobility procedure, and to perform the one or more SCG-related operations in accordance with the selected first or second SCG configuration.

25. The method of any of claims 21-23, wherein:the first MCG mobility configuration or the first SCG configuration indicates which of the SCG-related operations should be performed in conjunction with the MCG mobility procedure, andthe information configures the UE to perform the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration.

26. The method of claim 25, wherein the information configures the UE to perform the SCG-related operations indicated by the first MCG mobility configuration or the first SCG configuration only when the one or more MCG-related operations need to be performed during the MCG mobility procedure.

27. The method of any of claims 17-26, wherein the one or more SCG-related operations include one or more of the following: SCG security key change; reconfiguration with sync in the SCG; and random access, RA, to a primary SCG cell, PSCell.

28. The method of any of claims 17-27, wherein the one or more MCG-related operations include one or more of the following: MCG security key change; random access, RA, to the target cell; MCG radio bearer change; and MCG radio bearer termination point change.

29. The method of claim 28, wherein the information configures the UE to:perform at least a portion of the one or more SCG-related operations when MCG security key change is performed during the MCG mobility procedure; and refrain from performing at least a portion of the one or more SCG-related operations when MCG security key change is not performed during the MCG mobility procedure.

30. The method of claims 28-29, wherein the one or more MCG-related operations need to be performed only when the target cell is not provided by the MN.

31. The method of any of claims 17-30, wherein each of the SCG configurations includes one or more of the following:one or more indications of whether to perform the following SCG-related operations in conjunction with the MCG mobility procedure: security key change; reconfiguration with sync; packet data convergence protocol, PDCP, re-establishment; radio link control, RLC, re-establishment; and random access, RA; andany of the following information: an MCG security key; an SCG security key; one or more security counters; a timing advance, TA, value; and a time alignment timer, TAT, value.

32. User equipment, UE (310, 601, 1012, 1112, 1200) configured for dual connectivity in a radio access network, RAN (199, 1004), the UE comprising communication interface circuitry (1212) and processing circuitry (1202) that are operatively coupled and are configured to:receive the following from a master node, MN (100, 320, 602, 1010, 1110, 1300, 1402) that provides the UE’s master cell group, MCG:one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE’s secondary cell group, SCG should be maintained; andfor each of the one or more MCG mobility configurations, one or more associated SCG configurations;subsequently initiate the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations; and selectively perform one or more SCG-related operations in conjunction with the MCG mobility procedure, based on one or more of the following:the one or more SCG configurations associated with the first MCG mobility configuration,whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, andinformation received with a command to initiate the MCG mobility procedure.

33. The UE of claim 32, wherein the processing circuitry and the communication interface circuitry are further configured to perform operations corresponding to the methods of any of claims 2-16.

34. User equipment, UE (310, 601, 1012, 1112, 1200) configured for dual connectivity in a radio access network, RAN (199, 1004), the UE being further configured to:receive the following from a master node, MN (100, 320, 602, 1010, 1110, 1300, 1402) that provides the UE’s master cell group, MCG:one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE’s secondary cell group, SCG should be maintained; andfor each of the one or more MCG mobility configurations, one or more associated SCG configurations;subsequently initiate the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations; and selectively perform one or more SCG-related operations in conjunction with the MCG mobility procedure, based on one or more of the following:the one or more SCG configurations associated with the first MCG mobility configuration,whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, andinformation received with a command to initiate the MCG mobility procedure.

35. The UE of claim 34, being further configured to perform operations corresponding to the methods of any of claims 2-16.

36. Non-transitory, computer-readable medium (1210) storing computer-executable instructions that, when executed by processing circuitry (1202), cause the method of any of claims 1-16 to be performed by the UE (310, 601, 1012, 1112, 1200) configured for dual connectivity with the MN (100, 320, 602, 1010, 1110, 1300, 1402) that provides the MCG and the SN (100, 320, 615, 1010, 1110, 1300, 1402) that provides the SCG.

37. Computer program product (1214) comprising computer-executable instructions that, when executed by processing circuitry (1202), cause the method of any of claims 1-16 to be performed by the UE (310, 601, 1012, 1112, 1200) configured for dual connectivity with the MN (100, 320, 602, 1010, 1110, 1300, 1402) that provides the MCG and the SN (100, 320, 615, 1010, 1110, 1300, 1402) that provides the SCG.

38. Radio access network, RAN, node (100, 320, 1010, 1110, 1300, 1402) arranged to operate as a master node, MN (602) that provides a master cell group, MCG, for a user equipment, UE (310, 601, 1012, 1112, 1200) configured for dual connectivity with a secondary node, SN (603) that provides a secondary cell group, SCG, the RAN node comprisingcommunication interface circuitry (1306, 1404) and processing circuitry (1302, 1404) that are operatively coupled and are configured to:send the following to the UE:one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE’s SCG should be maintained; and one or more SCG configurations associated with each of the one or more MCG mobility configurations; andsubsequently send to the UE a command to initiate the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations,wherein one or more of the following information configures the UE to selectively perform one or more SCG-related operations in conjunction with the MCG mobility procedure:the one or more SCG configurations associated with the first MCG mobility configuration,whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, andinformation sent with the command.

39. The RAN node of claim 38, wherein the processing circuitry and the communication interface circuitry are further configured to perform operations corresponding to the methods of any of claims 18-31.

40. Radio access network, RAN, node (100, 320, 1010, 1110, 1300, 1402) arranged to operate as a master node, MN (602) that provides a master cell group, MCG, for a user equipment, UE (310, 601, 1012, 1112, 1200) configured for dual connectivity with a secondary node, SN (603) that provides a secondary cell group, SCG, the RAN node being configured to:send the following to the UE:one or more MCG mobility configuration for an MCG mobility procedure to a candidate cell, during which the UE’s SCG should be maintained; and one or more SCG configurations associated with each of the one or more MCG mobility configurations; andsubsequently send to the UE a command to initiate the MCG mobility procedure to the candidate cell as a target cell, in accordance with a first one of the MCG mobility configurations,wherein one or more of the following information configures the UE to selectively perform one or more SCG-related operations in conjunction with the MCG mobility procedure:the one or more SCG configurations associated with the first MCG mobility configuration,whether one or more MCG-related operations need to be performed by the UE during the MCG mobility procedure, andinformation sent with the command.

41. The RAN node of claim 40, being further configured to perform operations corresponding to the methods of any of claims 18-31.

42. Non-transitory, computer-readable medium (1304, 1404) storing computer-executable instructions that, when executed by processing circuitry (1302, 1404), cause the method of any of claims 17-31 to be performed by the RAN node (100, 320, 1010, 1110, 1300, 1402) configured to operate as the MN (602) that provides the MCG for the UE (310, 601, 1012, 1112, 1200).

43. Computer program product (1304a, 1404a) comprising computer-executable instructions that, when executed by processing circuitry (1302, 1404), cause the method of any of claims 17-31 to be performed by the RAN node (100, 320, 1010, 1110, 1300, 1402) configured to operate as the MN (602) that provides the MCG for the UE (310, 601, 1012, 1112, 1200).

Images