Transparent transfer of LTM information between sns via mn

Abstract

Techniques for handling mobility-related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between a first network node and a second network node An example method, in the first network node, includes the steps of determining a need to communicate mobility-related information to the second network node and transmitting, to a third network node acting as a master node (MN) for the UE, a message including mobility-related information to be relayed by the third network node to the second network node. The message may include any of a number of different parameters that facilitate smooth and efficient execution of inter-SN mobility, such as an indication of the second network node (which may be a SN for the UE), or an indication of the target cell for mobility, or an indication of a UE context.

Description

[0001] TRANSPARENT TRANSFER OF LTM INFORMATION BETWEEN SNs VIA MN

[0002] TECHNICAL FIELD

[0003] The present disclosure relates generally to wireless networks, and more specifically to techniques for improving mobility of user equipment (UEs) across multiple cells in a radio access network (RAN), specifically in relation to the handling of mobility-related information during an intersecondary node (inter-SN) mobility procedure for a UE.

[0004] BACKGROUND

[0005] Currently the fifth generation (5G) of cellular systems is being standardized within the Third- Generation Partnership Project (3GPP). 5G is developed for maximum flexibility to support many different 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 other use cases.

[0006] 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).

[0007] 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 technology for the NG-RAN is often referred to as “New Radio” (NR). With respect to the NR interface to UEs, each of the gNBs can support frequency division duplexing (FDD), time division duplexing (TDD), or a combination thereof. Each of the gNBs can serve a geographic coverage area including one or more cells and, in some cases, can also use various directional beams to provide coverage in the respective cells. In general, a downlink (DL) “beam” is a coverage area of a network-transmitted reference signal (RS) that may be measured or monitored by a UE. 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). 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 circuitry needed to perform their respective functions, including processing circuitry, communication interface circuitry (e.g., transceivers), and power supply circuitry. A gNB-CU connects to one or more gNB-DUs over respective F1 logical interfaces (e.g., 122 and 132 shown in Figure 1).

[0008] 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.

[0009] Even so, handover and other mobility procedures can have various problems related to robustness. For example, a HO command is normally sent when the radio conditions for the UE are already quite bad, such as at or near cell borders. As such, the HO command may need to be segmented (e.g., to allow for redundancy to protect against errors) and / or retransmitted one or more times before it reaches the UE. In such case, the HO command may not reach the UE in time (or at all) before the degraded connection with the source node (e.g., the node hosting the UE’s current serving cell) is dropped. Failure of handover to a target cell may lead to the UE declaring radio link failure (RLF) in the source cell.

[0010] To address various difficulties with handovers and other mobility procedures, 3GPP Rel-16 includes support for conditional handover (CHO) and SN-initiated intra-SN conditional PSCell change (CPC) procedures, while Rel-17 includes support for various other conditional mobility procedures. A main principle of conditional mobility is separation of transmission and execution of a mobility (e.g., handover) command. This allows the mobility command to be sent earlier to the UE, when the radio conditions are still good, thus increasing the likelihood that it is successfully transferred. The execution of the mobility command is done at later point in time based on an associated execution condition. Conditional mobility procedures are based on a conditional reconfiguration framework in which the network provides a UE with one or more reconfigurations, each with associated execution condition(s). Each reconfiguration can be provided in an RRCReconfiguration message (in NR) or an RRCConnectionReconfiguration message (in LTE). When the UE later detects the execution condition(s) associated with one of the earlier-received reconfigurations, the UE executes the associated reconfiguration to perform the mobility procedure (e.g., HO, PSCell change, PSCell addition, etc.).

[0011] Even so, conditional (e.g., CHO) and non-conditional (e.g., HO) mobility operations are triggered by layer 3 (L3) measurements and involve radio resource control (RRC) signaling to change primary cells as well as to release / add secondary cells as needed. Moreover, conventional inter-cell mobility involves complete layer 2 (L2) and layer 1 (L1) resets, leading to longer latency, increased signaling overhead, and longer interruptions than for intra-cell beam switching.

[0012] 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.” Each LTM candidate cell configuration may be accompanied by a MAC CE that triggers early TCI state activation for the LTM candidate cell, whereby the UE acquires early DL synchronization. The UE performs measurements on configured LTM candidate cells and transmits corresponding measurement reports to the RAN node, based on which the RAN node triggers execution of an LTM cell switch procedure by the UE to one of the configured LTM candidate cells. The RAN node may trigger the LTM cell switch by sending the UE an LTM cell switch command, including an identifier of an earlier-activated TCI state that the UE should use after the cell switch.

[0013] There are some notable differences between Rel-18 LTM and conditional L3 mobility. For example, unlike conditional L3 mobility in which the UE initiates execution, LTM is initiated by a UE’s serving RAN node based on measurements reported by the UE. This introduces some amount of delay in an LTM cell switch. To capture advantages of both LTM and conditional L3 mobility, 3GPP Rel-19 will introduce conditional LTM (CLTM). Much like conditional L3 mobility, when a UE detects the execution condition(s) associated with an earlier-received LTM candidate cell configuration, the UE executes an LTM cell switch to the candidate cell.

[0014] The standardization of LTM in 3GPP Release 18 is part of a work item known as Further NR mobility enhancements, a technical area entitled L1 / L2 based inter-cell mobility is included. According to an applicable 3GPP work item description, the goal of L1 / L2 based inter-cell mobility (also known as L1 / L2 Triggered Mobility) is to enable a serving cell change, sometimes also known as an LTM cell switch or an LTM cell switch procedure, via L1 / L2 signalling, in order to reduce the latency, overhead and interruption time.

[0015] A basic principle with L1 / L2 triggered mobility is that the UE is pre-configured, by the network, with an LTM configuration that includes information such as measurement configuration and an RRC configuration per LTM candidate cell, sometimes also known as a LTM candidate cell configuration. Such a LTM candidate cell configuration may be sent to the UE in the form of a RRCReconfiguration message or one or more IEs / fields / parameters such as CellGroupConfig. The UE performs measurements on LTM candidate cells and beams in those cells, according to the measurement configuration included in the LTM configuration received by the network. The UE transmits L1 measurement reports for LTM including L1-RSRP measurements for up to four LTM candidate cells and up to four beams in in each cell. When the network (e.g. a gNB or a gNB-DU), receives the L1 measurement report for LTM, it may use the content of this report to trigger an LTM cell switch towards one of the LTM candidate cells.

[0016] The network triggers the execution of a LTM cell switch procedure in the UE to one of these LTM candidate cells by transmitting a LTM cell switch command MAC Control Element, MAC CE, to the UE. The LTM cell switch command includes information such as a reference to a LTM candidate cell configuration and an indication of a target beam in the LTM candidate cell. The UE then connects to the beam and switches to the LTM candidate cell configuration.

[0017] The overall procedures for LTM in Rel-18 are described in 3GPP TS 38.300, subclause 9.2.3.5, and for the gNB-CU / gNB-DU Architecture in 3GPP TS 38.401 , subclauses 8.2.1 .4-8.2.1 .6.

[0018] LTM in Rel-18 is limited to intra-gNB (including intra-CU intra-DU and intra-CU inter-DU) mobility. In 3GPP Rel-19, a work item on NR Mobility enhancements Phase 4 has started, which aims to enhance mobility features, including introducing support for inter-CU LTM according to the objective below:

[0019] • Specify support for inter-CU Layerl / Layer 2 Triggered Mobility (LTM) [RAN2, RAN3] o Prioritize the case when CU is acting as MN when DC is not configured o As secondary priority, support the case when NR-DC is configured and CU is acting as SN and MCG is unchanged o As secondary priority, support the case when NR-DC is configured, CU is acting as MN and SCG is unchanged or SCG is released

[0020] ■ Note: The case that LTM is configured in both MCG and SCG is excluded o Specify support for subsequent LTM mobility procedures aiming to avoid RRC configuration between cell switches as per Rel-18 LTM

[0021] ■ Coordination with SA3 needed with respect to security key handling

[0022] The description of the work item notes that Release 18 intra-CU LTM procedure is considered as baseline for adding inter-CU support.

[0023] In 3GPP Release 12, an LTE feature Dual Connectivity (DC) was introduced, to enable a UE to be connected in two cell groups, each controlled by an LTE access node, eNBs, labelled as the Master eNB (MeNB) and the Secondary eNB (SeNB). The UE still only has one Radio Resource Control (RRC) connection with the network. In 3GPP, the Dual Connectivity (DC) solution has since then been evolved and is now also specified for NR as well as between LTE and NR. Multi-connectivity (MC) is the case when there are more than two nodes involved. With the introduction of 5G, the term Multi-Radio Dual Connectivity (MR-DC), see also 3GPP TS 37.340, was defined as a generic term for all dual connectivity options that include at least one NR access node. Using the MR-DC generalized terminology, the UE is connected in a Master Cell Group (MCG), controlled by the Master Node (MN), and in a Secondary Cell Group (SCG) controlled by a Secondary Node (SN).

[0024] Further, in MR-DC, when dual connectivity is configured for the UE, within each of the two cell groups, MCG and SCG, carrier aggregation may be used as well. In this case, within the MCG controlled by the MN, the UE may use one Primary Cell (Pcell) and one or more Secondary Cell(s) (SCell(s)). And within the SCG, controlled by an SN, the UE may use one Primary SCell (PSCell), also known as the primary SCG cell in NR, and one or more SCell(s). This combined case is illustrated in Figure 2, which illustrates dual connectivity combined with carrier aggregation in MR- DC. In NR, the primary cell of a master or secondary cell group is sometimes also referred to as the Special Cell (SpCell). Hence, the SpCell in the MCG is the PCell and the SpCell in the SCG is the PSCell.

[0025] In NR-DC, NR dual connectivity, both the MN, controlling the MCG, and the SN, controlling the SCG, use NR as the radio access technology.

[0026] SUMMARY

[0027] A work item on NR Mobility Enhancements Phase 4 is currently underway in Rel-19, aiming to introduce support for inter-CU LTM, including scenarios where NR-DC is configured for the UE. One scenario to consider is inter-SN LTM, where two secondary NG-RAN nodes connect to the same MN and the LTM cell switch occurs from a cell of the source SN to a cell of the target SN and the network handling of the LTM cell switch goes through the MN.

[0028] There are some procedures for LTM that require signalling between two different cells in Secondary Nodes for a UE, the serving cell (which would be the source cell of an LTM cell switch) and a candidate LTM cell that the UE is configured with for SCG mobility. This includes, e.g., signaling for early uplink synchronization, where the source cell / node triggers the UE to send a PRACH preamble to the LTM candidate target cell / node and the candidate target cell / node then determines a Timing Advance (TA) value and sends it back to the source cell / node, and the indication from the source cell / node to the candidate target node that a LTM Cell Switch Command MAC CE has been sent to the UE triggering an LTM cell switch to the LTM candidate cell.

[0029] In the case of inter-SN LTM, the serving / source node and the candidate target node would be different Secondary Nodes (SNs) for the UE in NR-DC, one acting as the current serving SN and one acting as a candidate SN for LTM. Given the system specifications that currently exist, it is not clear how the corresponding signalling between these different SNs would be performed, since there is no direct signaling exchange between the two SNs due to the design used for DC, where the node acting as anchor towards CN (MN) should be always involved in a procedure aiming to change the SN.

[0030] 3GPP’s work on Rel-19 Inter-CU LTM should specify support for subsequent LTM mobility procedures aiming to avoid RRC configuration between cell switches. For example, the information related to cell switch, e.g., TCI configurations, TA values, etc., should be transferred to the target SN in the above case. But, current solutions do not specify how the source SN signals to the target SN with all the necessary information to configure and / or execute LTM.

[0031] The techniques and apparatuses described herein address these problems. These techniques include methods to ensure that the required information and configurations for the LTM cell switch of a UE in dual connectivity during inter-SN LTM is synchronized between the source and target SNs involved in LTM preparation.

[0032] In some methods, a first network node, such as an NG-RAN node in the role of Secondary Node (SN) for a Dual-Connectivity, or the gNB-CU of an NG-RAN node in the role of SN for DualConnectivity, sends a new message (or a new piece of information extending an existing message) to a third network node, such as a Master Node (MN) or the gNB-CU of the MN, with a container that is transparent for the third network node. The third network node sends a message to a second network node, such as, e.g., another NG-RAN node in the role of SN, or the gNB-CU or the second network node acting as SN for the same UE, including the container that is transparent for the third network node. The container is then addressed to the second network node, which handles the content of it. The characteristic of a container or message (or new piece of information) of being transparent indicates that the third network node receiving it from the first network node is not required to (or even not supposed to, i.e., it shall not) comprehend the content of the new container or message (or new piece of information), and / or does not modify the content of the new container or message (or new piece of information).

[0033] The gNB-CU of the SN acting as first (or source) network node is also described below as first (or source) secondary gNB-CU. The gNB-CU of the SN acting as second (or target) network node is also described below as second (or target) secondary gNB-CU.

[0034] In some of the methods described herein, the first network node, such as a first (or source) secondary NG-RAN node or first (or source) secondary gNB-CU, transmits a message to a third network node, such as a MN or a master gNB-CU, to indicate that a mobility procedure is triggered / executed towards a second network node, such as a target SN.

[0035] New messages (or new pieces of information) described below can be sent from a first network node (source SN) to a second network node (target SN) via the third network node (MN), or vice versa, from the second network node (target SN) to the first network node (source SN) via the third network node (MN).

[0036] The proposed solution enables a source secondary network to transfer LTM-related configurations to the target secondary nodes in an efficient way and to maintain consistent LTM configurations in the network and in the UE. This avoids sending the information in multiple procedures over network interfaces, which will cause signaling overhead and extra latency.

[0037] BRIEF DESCRIPTION OFTHE FIGURES

[0038] Figure 1 shows a high-level view of an exemplary 5G / NR network architecture.

[0039] Figure 2 illustrates dual-connectivity combined with carrier aggregation in MR-DC.

[0040] Figure 3 is a block diagram illustrating components of a system in which the presently disclosed techniques may be carried out.

[0041] Figures 4, 5, 6, and 7 are signaling diagrams illustrating the signaling for each of several embodiments of the techniques described herein.

[0042] Figures 8, 9, and 10 are each process flow diagrams illustrating an example method as implemented in each of several network nodes, according to some embodiments.

[0043] Figure 11 is a process flow diagram illustrating an example method as implemented in a user equipment (UE).

[0044] Figure 12 is a block diagram of an example network, according to some embodiments.

[0045] Figure 13 is a block diagram of an example UE, or wireless device, according to some embodiments.

[0046] Figure 14 is a block diagram of an example network node, according to some embodiments.

[0047] Figure 15 illustrates an example of a virtualization environment, according to some embodiments.

[0048] Figure 16 illustrates the LTM Transparent Information Transfer procedure, as might be shown in 3GPP specifications, for a successful procedure. DETAILED DESCRIPTION

[0049] 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.

[0050] In general, all terms used herein are to be interpreted accordingto 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.

[0051] Furthermore, the following terms are used throughout the description given below:

[0052] • 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 access network (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, pico, 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.

[0053] • 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), a PDN 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.

[0054] • 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”.

[0055] • Radio Node: As used herein, a “radio node” can be either a “radio access node” (or equivalent term) or a “wireless device.”

[0056] • 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.

[0057] • 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, the term “node” may be limited to a particular type (e.g., radio access node, IAB node) based on its specific characteristics in any given context.

[0058] 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.

[0059] 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.

[0060] The text refers to the term “L1 / L2 based inter-cell mobility” as used in the Work Item Description [Error! Reference source not found.] in 3GPP, though it interchangeably also uses the terms L1 / L2 mobility, L1-mobility, L1 based mobility, L1 / L2-centric inter-cell mobility, L1 / L2 inter-cell mobility L1 / L2 Triggered Mobility, Lower-layer triggered Mobility or LTM. The basic principle is that the UE receives a lower layer signaling (e.g. a MAC CE) from the network indicating to the UE a change (or switch or activation) of its serving cell (e.g. change of PCell, from a source to a target PCell), wherein a lower layer signaling is a message / signaling of a lower layer protocol, which may be referred as a L1 / L2 inter-cell mobility execution command or LTM cell switch command. The change of serving cell (e.g. change of PCell) may also lead to a change in Scell(s) for the same cell group e.g. in case the command triggers the UE to change to another cell group configuration of the same type (e.g. another MCG configuration). Before the UE receives the LTM cell switch command, the UE is configured by the network with one or more LTM candidate cells (e.g. reception of an RRC Reconfiguration message, with at least one LTM candidate cell configuration) A candidate cell configuration may include parameters in the IE CellGroupConfig per candidate cell and / or an embedded RRC Reconfiguration per candidate cell.

[0061] The term LTM cell switch procedure refers to the process of a UE changing its cell from a source cell to a target cell (which may be called here a candidate cell or a neighbour cell), using L1 / L2 triggered mobility (LTM). In the context of L1 / L2 triggered mobility (LTM), an LTM cell switch procedure may sometimes also be known as dynamic switch, LTM switch, (LTM) cell switch, (LTM) serving cell change or (LTM) cell change. Even if the term change of cell is used, that may comprise a change of a whole cell group configuration, which includes a change in the SpCell (e.g. change of PCell, or change of PSCell) and a change in SCells of the cell group (e.g. addition, modification and / or release of one or more SCells). The LTM cell switch procedure may be triggered by the UE receiving an LTM cell switch command from the network. The source and target cells in a LTM cell switch procedure may be controlled by the same gNB, which sometimes is referred to as the intra-gNB case, or when the gNB uses a distributed CU / DU RAN architecture, the intra-CU inter-DU case or the intra-CU intra-DU case (depending on whether the cells are controlled by the same DU or different DUs). When the source and target cells in a LTM cell switch procedure are controlled by different gNBs, this is sometimes referred to as the inter-gNB case, or inter-CU case, or sometimes known as an inter-CU LTM cell switch procedure.

[0062] The text refers to at least one LTM candidate cell configuration. This is also sometimes referred to as a configuration of a LTM candidate cell, which may be an RRC configuration, such as encapsulated in an RRC Reconfiguration message, that the UE receives when being configured with L1 / L2 Triggered Mobility. A LTM candidate cell configuration comprises the configuration which the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to that LTM candidate cell e.g. upon reception of the LTM cell switch command indicating the UE to perform a LTM cell switch procedure to that LTM candidate cell, which becomes the target cell and the current (new) SpCell, or an SCell in a serving frequency. The LTM candidate cell configuration comprises parameters of a serving cell (or multiple serving cells, such as a cell group), comprising one or more of the groups of parameters, such as an RRCReconfiguration message, an IE CellGroupConfig or an IE SpCellConfig (or the IE SCellConfig, in the case of a Secondary Cell).

[0063] An LTM candidate cell configuration is associated with an identifier which is used in the signaling when referring to a certain LTM candidate cell configuration, such as when the UE receives the LTM candidate cell configuration and when the UE receives an LTM cell switch command indicating the UE to perform a LTM cell switch procedure to that LTM candidate cell. This identifier is sometimes known as the LTM candidate cell configuration identity or LTM candidate configuration index (or similar).

[0064] An inter-CU LTM cell switch procedure, sometimes also referred to as inter-CU LTM or inter-gNB LTM, is an LTM cell switch procedure resulting in a change of serving cell, e.g. change of SpCell, PCell, PSCell, to an LTM candidate cell controlled by a different gNB than the source gNB or serving gNB of the UE when the execution LTM cell switch procedure was triggered (e.g. upon reception of the LTM cell switch command). From UE point of view, the actions performed during an inter-CU LTM cell switch procedure may be the same type of actions of an LTM cell switch procedure, but may also include additional actions, such as change of security key(s). The text refers to inter Master Node L1 / L2 Triggered Mobility, inter-MN LTM, configuration of inter- MN LTM, execution of inter-MN LTM and an inter-MN LTM cell switch procedure. In the context of this disclosure, inter-MN LTM refers to inter-CU LTM, sometimes also referred to as inter-gNB LTM, handover or MCG mobility, when the UE is configured with dual connectivity, such as NR-DC, and where the source cell and target cell are both part of the source and target MCG, respectively, and controlled by different CUs or different gNBs.

[0065] The term conditional LTM refers to L1 / L2 Triggered Mobility where the execution of the LTM cell switch is triggered by the UE when an execution condition, such as a layer 1 , layer 2 or a layer 3 event, criterion or condition related to, for example, a radio measurement, is fulfilled. Upon the cell switch the UE applies a stored LTM candidate cell configuration.

[0066] The text refers to an inter-CU LTM candidate cell configuration. An inter-CU LTM candidate cell configuration is an LTM candidate cell configuration which contains the configuration which the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to an LTM candidate cell which is controlled by a different base station, e.g. gNB, from the current source base station e.g. serving gNB of the UE. In some cases, the UE may receive an inter-CU LTM candidate cell configuration during configuration of inter-MN LTM. In some cases, the UE may apply an inter-CU LTM candidate cell configuration during execution of inter-MN LTM.

[0067] An inter-CU LTM candidate cell configuration, sometimes referred to as inter-MN LTM configuration, may be the same as an LTM candidate cell configuration but it may also include additional information than what is included in the LTM candidate cell configuration used for inter- CU cell switch. This additional information may be, for example:

[0068] • Information to perform security key refresh, e.g. the RRC IE MasterKeyUpdate or a RRC IE RadioBearerConfig that includes SecurityConfig with SecurityAlgorithmConfig

[0069] • Indication to perform PDCP re-establishment

[0070] • Indication to perform a full configuration, e.g. the RRC field fullConfig

[0071] The text refers to a mobility procedure, configuration of a mobility procedure or execution of a mobility procedure. In the context of this disclosure, a mobility procedure may be L1 / L2 Triggered Mobility, LTM, inter-CU LTM, inter-MN LTM, L3 handover, PCell handover, conditional handover (CHO), conditional LTM, PSCell change or conditional PSCell Addition or Change (CPAC). The solutions described in the invention sometimes uses the inter-MN LTM as the example. However, many of the examples may also be applied for other mobility procedures, for example, LTM, inter- CU LTM, conditional LTM or CHO.

[0072] The text refers to a mobility configuration. When the UE has been configured with a mobility configuration, it may use the mobility configuration during preparation of a mobility procedure, including measurements (such as RSRP measurements on neighbor or serving cells), triggering and transmission of measurement reports, synchronization towards neighbor cells, evaluation of conditions (for conditional mobility, e.g. CHO), and during the execution of a mobility procedure (e.g. execution of an LTM cell switch procedure, execution of an inter-MN LTM cell switch procedure or execution of handover).

[0073] A mobility configuration may include one or multiple of the following type of elements where each element contains a configuration of one aspect of LTM, for example as follows:

[0074] • LTM candidate cell configuration(s),

[0075] • inter-CU LTM candidate cell configuration(s),

[0076] • inter-MN LTM configuration(s)

[0077] • reference configuration(s)

[0078] • lower layer information, such as physical layer configuration, MAC layer configuration or RLC layer configuration, Cell Group configuration, serving cell configuration

[0079] • higher layer information, such as RRC protocol parameters, such as timer values, PDCP layer configuration, radio bearer configuration or measurement configuration

[0080] • Configuration of measurements for LTM

[0081] • Configuration for measurement reports for LTM

[0082] • CSI resource configuration(s) for LTM

[0083] • CSI report configuration for LTM

[0084] Configurations of early synchronization procedures, such as o Configurations for DL pre-sync for LTM, such as configurations for early TCI state activation o Configurations for UL pre-sync for LTM, such as configurations for reception of PDCCH ordered triggered preamble transmission and reception of TA

[0085] • Configurations for the execution of an LTM cell switch procedure for a given LTM candidate cell configuration or inter-CU LTM candidate cell configuration (e.g., whether to perform random access procedure, whether to perform RLC reestablishment, or MAC reset, or PDCP recovery), a timer value, configured UL grants, dedicated RA preambles .

[0086] • A configuration which the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to an LTM candidate cell which is controlled by a different base station, e.g. gNB, from the current source base station e.g. serving gNB of the UE.

[0087] • Information to perform security key refresh, e.g. the RRC IE MasterKeyUpdate or a RRC IE RadioBearerConfig that includes SecurityConfig with SecurityAlgorithmConfig.

[0088] • Indication to perform a complete configuration

[0089] • Indication to perform a full configuration, e.g. the RRC field fullConfig.

[0090] • Indication to perform L2 reset or re-establishment, such as an indication to perform MAC reset, RLC re-establishment, PDCP recovery, PDCP re-establishment for one or multiple bearers.

[0091] The term “subsequent LTM”, sometimes also referred to a “subsequent LTM cell switch (procedures)” refers to that the UE performs a first LTM cell switch procedure from a source cell to a first target cell, then performs a second LTM cell switch procedure from the first target cell (which is now the new source cell) to a second target cell, and between the first and second LTM cell switch procedures there is no RRC reconfiguration of the UE. This implies also that the network does not add / remove / modify the LTM candidate cell configuration(s) or inter-CU LTM candidate cell configuration(s) in the UE between the two LTM cell switch procedures.

[0092] The text uses the term “cell” to identify a location (or coverage) on which the UE is located. However, the term “cell” can also be exchanged without any loss of meaning with the terms “radio resources”, “beams”, “TCI state”, or “TRS”. This is just to clarify that this invention does not target specifically a scenario where there is a cell, but rather when a UE uses a set of source radio resources and need to switch to a target set of radio resources. In such a case, radio resource can also identify a set of configurations, field, parameters, or ASN.1 structures or lEs.

[0093] The text further uses the term MCG to identify a first network node that provides a first connectivity linkto the UE and SCG to identify e second network node that provides a second connectivity link to the UE. However, the terms “MCG” and “MN” can be exchanged without any loss of meaning as well as the terms “SCG” and “SN”.

[0094] Figure 3 illustrates a system structure including the entities involved in the invention. The first network node 1002, controls a first cell 1007. The second network node 1003 controls a second cell 1008. The UE 1001 , which may be a wireless terminal, such as a smartphone, may sometimes be connected with the first network node over a wireless interface 1004 (in the first cell) and with the second network node over a wireless interface 1005 (in the second cell). The UE 1001 may also be connected with the third network node over a wireless interface 1006 at the same time as being connected over a wireless interface with the first network node or the second network node.

[0095] Each of first network node 1002 and the second network node 1003 may be a base station such as, when they are part of NG-RAN, for example, a gNB. In case of a distributed CU / DU RAN architecture, each of the first network node 1002 and / or the second network node 1003 may be divided into a distributed unit, sometimes known as gNB-DU or DU, and a central unit, CU, sometimes referred to as gNB-CU, CU, gNB-CU-CP or gNB-CU-UP. Thus, in such a case the first network node 1002 may be divided into a first central unit, CU 1009, and a first distributed unit, DU, 1010, and second network node 1003 may be divided into a second central unit, CU 1012, and a second distributed unit, DU, 1013. Sometimes the first central unit, CU, is referred to as the first network node and the second central unit, CU, is referred to as the second network node.

[0096] The first CU 1009 and the first DU 1010 are connected over an interface 1011 , which may be an F1 type of interface in case of NG-RAN. Correspondingly, the second CU 1012 and the second DU 1013 are connected over an interface 1014, which may be an F1 type of interface in case of NG- RAN.

[0097] The first network node 1002 and the second network node 1003 may be connected to a third network node 1015 over interfaces 1016 and 1017, respectively. The third network node 1015 may be a base station such as, when it is e.g. are part of NG-RAN, e.g. a gNB. In the latter case the interfaces 1016 and 1017 may both be an Xn or Xn-C type of interface. The UE may sometimes be connected to the third network node over a wireless interface 1006.

[0098] Sometimes the UE is configured with dual connectivity, such as NR-DC. In this case the UE may be configured with a master cell group (MCG), and a secondary cell group (SCG). The first network node controls an SCG, sometimes called first SCG, which includes the first cell. In this case, the second network node controls also an SCG, sometimes known as second SCG, which includes the second cell. In this case, including in the context of mobility for the SCG, such as inter-SN LTM, when controlling an SCG, either of the first network node or the second network node may be referred to as source Secondary Node, source SN, serving SN or as target Secondary Node, candidate SN or second SN.

[0099] When the UE is configured with dual connectivity, such as NR-DC, the third network node controls a master cell group, MCG, including a third cell, which sometimes may be referred to as a PCell (not illustrated in the figure). In this case the third network node may be referred to as a Master Node (MN).

[0100] Figure 4 illustrates a message sequence chart corresponding to an example implementation of the techniques described herein. In this example, the information transparent transferring, from one secondary node to another, is used during execution of inter-SN LTM.

[0101] The steps illustrated in Figure 4 include:

[0102] • Step 1 . The UE is configured for inter-SN LTM and transmits, to the source SN, lower-layer measurement reports with measurements on LTM candidate cells and serving cells.

[0103] • Step 2. The source SN decides to trigger an inter-SN LTM cell switch procedure towards an LTM candidate cell controlled by the target SN.

[0104] • Step 3. The source SN transmits, to the UE, an LTM cell switch command, indicating an LTM candidate cell configuration, to trigger the inter-SN LTM cell switch procedure towards the indicated LTM candidate cell.

[0105] • Step 4. The source SN transmits, to the MN, a transparent information transfer message, including information, which may be another message, indicating execution of the inter-SN LTM cell switch. The message may include an indication of a target SN, a target cell ID, and / or an identity of an LTM candidate cell configuration. The information may be transparent for the MN, which is to say that the MN does not need to read or parse the content of the information.

[0106] • Step 5 The MN if applicable, triggers an Xn-U Address Indication procedure to inform the source SN the address of the target SN to start late data forwarding.

[0107] • Step 6. The MN transmits, to the target SN, a transparent information transfer message, including the previously received information in the transparent information message received in the previous step. The information may be transparent for the MN, i.e., the MN does not need to read or parse the content of the information. The MN in this step is effectively relaying the information included in the transparent information message, which may be referred to generally as mobility-related information, to the target SN. Thus, the mobility-related information is transferred from one SN (the source SN) to another (the target SN) via the MN, where in at least some examples all or part of the mobility-related information relayed from the first SN to the other is in a transparent container, i.e., a container that the MN does not need to parse or read.

[0108] • Step 7. If needed, the source SN sends the SN Status Transfer message, which the MN sends then to the target SN. If applicable, data forwarding from the source SN takes place. It may be initiated as early as the source SN receives the data forwarding address related information from the MN in step 5. In one example, the exchanged information (e.g., an SN STATUS TRANSFER message) may be sent using a transparent transfer procedure, similar to steps 4-5. The source SN may forward downlink data packets to the target SN (possibly via the MN), which buffers those packets until they are sent to the UE.

[0109] • Steps 8-10. The UE executes the inter-SN LTM cell switch procedure. UE transmits the first UL data (e.g., a scheduling request, a buffer status report or a CSI report) to the target SN using the new configuration. The UE may also perform a random access procedure before sending the data if needed. The target SN detects the UE access.

[0110] • Steps 11-12. The UE also transmits an RRCReconfigurationComplete message to the target SN, via the MN, to indicate that the cell switch has been successfully completed.

[0111] Figure 5 illustrates a message sequence chart corresponding to another example implementation of the techniques described herein. In this example, the information transparent transferring is again used during execution of inter-SN LTM.

[0112] The steps illustrated in Figure 5 include: • Steps 1-3. Same as the corresponding steps in Figure 4, as described above.

[0113] • Steps 4-8. Same as steps 8-12 in Figure 4, as described above.

[0114] • Step 9. Same as step 5 in Figure 4, as described above.

[0115] • Step 10. The target SN transmits, to the MN, a transparent information transfer message, including information, which may be another message, indicating that the UE has successfully accessed the target cell after an inter-SN LTM cell switch. The message may include an indication of a source SN, a target cell ID, and / or an identity of an LTM candidate cell configuration. The information may be transparent for the MN, e.g. the MN does not need to read or parse the content of the information.

[0116] • Step 11 . The MN transmits, to the source SN, a transparent information transfer message, including the previously received information in the transparent information message received in the previous step. The information may be transparent for the MN, e.g. the MN does not need to read or parse the content of the information. Thus, the mobility-related information is transferred from one SN (the target SN) to another (the source SN) via the MN, where in at least some examples all or part of the mobility-related information relayed from one SN to the other is in a transparent container, i.e. , a container that the MN does not need to parse or read.

[0117] • Steps 12-13. Triggered by the received information, the source SN may exchange information with the target SN to initiate data forwarding, such as an SN STATUS TRANSFER message sent from the source SN to the target SN via the MN. It may be initiated as early as the source SN receives the data forwarding address related information from the MN in step 5. In one example, the exchanged information (e.g., an SN STATUS TRANSFER message) may be sent using a transparent transfer procedure, similar to steps 10-11.

[0118] Figure 6 illustrates a message sequence chart corresponding to another example implementation of the techniques described herein. In this example, the information transparent transferring is used during timing advance (TA) acquisition for inter-SN LTM.

[0119] The steps illustrated in Figure 6 include:

[0120] Step 1 . The UE is configured with inter-SN LTM and the source SN determines to initiate TA acquisition for the UE of an LTM candidate cell controlled by the target SN. • Step 2. The source SN transmits a PDCCH order to the UE indicating the LTM candidate cell and a random access preamble index to use for the random access.

[0121] • Step 3. The UE transmits a random access preamble in the indicated an LTM candidate cell controlled by the target SN using the indicated random access preamble index.

[0122] • Step 4. The target SN receives the random access preamble and determines Timing Advance information, such as a TA value.

[0123] • Steps 5-6. The target SN transmits the determined Timing Advance information to the source SN via the MN using a transparent information transfer procedure. The information may be carried in another message inside the transparent information transfer message, such as TA INFORMATION TRANSFER message or similar.

[0124] • Step 7. If early data forwarding is applied, the source SN, if applicable, together with the Early Status Transfer procedure, starts early data forwarding.

[0125] • Steps 8-15. Same as the steps 1-8. In step 10, the source SN includes the Timing Advance information received in step 6.

[0126] Figure 7 illustrates another message sequence chart corresponding to another example implementation of the techniques described herein. In this example, the information transparent transferring is again used during timing advance (TA) acquisition for inter-SN LTM, as well as for the transfer of LTM-related mobility information during the SN change procedure.

[0127] The steps illustrated in Figure 7 include:

[0128] • Step 1 . The UE is configured with inter-SN LTM and the source SN determines to initiate TA acquisition for the UE of an LTM candidate cell controlled by the target SN.

[0129] • Step 2. The source SN transmits a PDCCH order to the UE indicating the LTM candidate cell and a random access preamble index to use for the random access.

[0130] • Step 3. The UE transmits a random access preamble in the indicated an LTM candidate cell controlled by the target SN using the indicated random access preamble index.

[0131] • Step 4. The target SN receives the random access preamble and determines Timing Advance information, such as a TA value.

[0132] • Steps 5-6. The target SN transmits the determined Timing Advance information to the source SN via the MN using a transparent information transfer procedure. The information may be carried in another message inside the transparent information transfer message, such as TA INFORMATION TRANSFER message or similar.

[0133] • Steps 7-10. L1 or L3 measurement report is received, based on which the source SN decides to execute LTM, and sends an LTM cell switch command to the UE. The UE applies the target configuration and performs SCG security key refresh.

[0134] • Step 11. The source SN initiates the change of SN due to LTM mobility, e.g., sending an S- NODE CHANGE REQUIRED to the MN. The message sent to the MN includes LTM related information in a container transparent to the MN, to be transferred to the target SN. Step 11 can precede step 9.

[0135] • Steps 12-13. The MN initiates the addition of the target SN due to LTM mobility, and forwards to the target SN the container including LTM related information received by the source SN. The target SN acknowledges the request to be added. For example, the S-NODE ADDITION REQUEST XnAP message is extended to transfer LTM related information as described in the invention.

[0136] • Steps 14-15. The UE sends first UL data to the target SN which detects UE access.

[0137] • Steps 16-17. The UE sends an RRCReconfigurationComplete to the MN including the SCG RRCReconfigurationComplete, and the MN forwards the SCG RRCReconfigurationComplete to the target SN (e.g., reusing the S-NODE RECONFIGURATION COMPLETE XnAP message)

[0138] • Steps 18-19. The target SN sends to the MN the indication that UE has accessed the target cell at the target SN in a transparent container (e.g. using a new XnAP message such as LTM Information TransparentTransfer message). The MN forwards the information received in the transparent container to the source SN, e.g., in an SN Change Confirm procedure (e.g., in a S-NODE CHANGE CONFIRM XnAP message).

[0139] Various embodiments of the presently disclosed techniques thus involve the transfer of mobility- related information from one SN to another, e.g., in the context of inter-SN mobility, where that mobility-related information is transferred via an MN, which may be viewed as relaying the mobility- related information, in some cases using a transparent container or transparent message, i.e., a container of information or a message that the MN need not interpret or be able to interpret. The mobility-related information may be, in several embodiments, LTM-related information, such as a request for early UL synch information from source SN to target SN via the MN, a notification of early UL synch information from target SN to source SN via the MN, etc.. In some embodiments, this LTM-related information is, at least in part, transferred from source SN to target SN via MN (or vice versa), by reusing existing dual connectivity procedures and extending messages included in those procedures by using containers (e.g., encoded as OCTET STRING) to request or notify LMT related information in a way that is transparent for the MN. For instance, the source SN sends to the MN an S-NODE MODIFICATION REQUIRED XnAP message containing a request for early UL synch that the MN should forward to the candidate target SN. The MN then sends an XnAP message to the candidate SN (e.g., a new XnAP LTM Information Transparent Transfer message) and the candidate SN returns to the source SN (via the MN) the requested information (e.g., the early UL synch information). The MN can for example include the information provided by the target candidate SN in the S-NODE MODIFICATION CONFIRM XnAP message. Later, when the source SN triggers the LTM execution, it sends to the MN another message (e.g., an S-NODE CHANGE REQUIRED), indicating that LTM execution has been initiated towards the candidate target SN. The MN, upon receiving the message, triggers the addition of the target SN (e.g., reusing the S-NODE ADDITION PREPARATION REQUEST XnAP message). The target SN, in the response message to the MN associated to the SN Addition preparation (e.g., in an S-NODE ADDITION PREPARATION ACKNOWLEDGE), can send to the MN an indication, indicating that the UE has accessed the target SN. The MN then forwards this information to the source SN. Alternatively, the target SN may send another message, such as an LTM Information Transparent Transfer message, to let the MN know that UE has accessed the target SN.

[0140] In some embodiments, the source SN sends to the MN a message containing a container, transparent for the MN, including a request to the candidate SN for LTM-related information of the candidate SN, as described herein (e.g., the source SN sends an S-NODE MODIFICATION REQUIRED XnAP message to request the candidate SN information for early UL synch). The MN initiates a procedure to add the candidate target SN (e.g., it sends an S-NODE ADDITION PREPARATION REQUEST) and includes the container received by the source SN. The candidate target SN returns to the source SN (via the MN) the requested information (e.g., the early UL synch information). For example, the candidate target SN sends to the MN a container, transparent for the MN, and carrying LTM related information, in an S-NODE ADDITION PREPARATION ACKNOWLEDGE message. The MN, upon receiving this message from the candidate target SN, forwards the container to the source SN, e.g., it includes the container provided by the target candidate SN in the S-NODE MODIFICATION CONFIRM XnAP message. Later, when the source SN triggers the LTM execution, the source SN sends to the MN another message (e.g., an S-NODE CHANGE REQUIRED), indicating that LTM execution has been initiated towards the candidate target SN. The MN, upon receiving this message, initiates an MN initiated procedure to modify the dual connectivity configuration prepared towards the candidate target SN (e.g., reusing the S-NODE MODIFICATION REQUEST XnAP message). The target SN, in the response message to the MN associated to the latter MN initiated procedure to modify the dual connectivity (e.g., in an S-NODE MODIFICATION REQUEST ACKNOWLEDGE), sends to the MN an indication, indicatingthat the UE has accessed the target SN. The MN then forwards this information to the source SN.

[0141] In another option, the source SN may send another message, such as an LTM Information Transparent Transfer message, to the MN, which the MN forwards to the candidate target SN, to request the candidate target SN for LTM related information or to inform the candidate target SN of LTM related information. In another option, the candidate target SN may send another message to the MN, such as an LTM Information Transparent Transfer message, which the MN forwards to the source SN, to let the MN and / or the source SN know that UE has accessed the target SN.

[0142] Embodiments of the presently disclosed techniques may be understood as including various methods for a first network node, acting as a Secondary Node for a UE configured with NR-DC, to handle the network signaling for the transfer of mobility related information during an inter-SN mobility procedure for the UE between the first network node and a second network node, where these methods comprise transmitting, to a third network node, such as a node acting as a Master Node for the UE, a message including mobility-related information, for subsequent transfer to the second network node.

[0143] In various embodiments, the transmitted message may include one or more of:

[0144] • an indication of the second network node, such as a node acting as a Secondary Node for the UE;

[0145] • an indication of a target cell; and

[0146] • an indication of a UE context.

[0147] As discussed in the several examples detailed above, the transmitted mobility-related information may be transparent for the third network node, e.g., in a transparent container or transparent message that the third network node relays to the second network node, without reading or interpreting the information. In various examples, the transmitted mobility related information includes one or more of:

[0148] • an indication of a second network node, such as a Secondary Node, a Secondary gNB-DU or a Secondary gNB-CU;

[0149] • an indication of a target cell;

[0150] • a mobility related request to the second network node;

[0151] • a response of the previously transmitted mobility related request;

[0152] • a request to prepare a mobility configuration for the UE;

[0153] • a response including a mobility configuration for the UE;

[0154] • an indication of execution of a mobility procedure for the UE;

[0155] • LTM-related information;

[0156] • information related to subsequent mobility; and

[0157] • early sync information, such as random access preamble(s) or Timing Advance (TA) information, beam-related information such as TCI state information for an candidate cell.

[0158] In some embodiments or instances, the first network node is acting as the serving Secondary Node for the UE. In others, the first network node may be acting as a candidate Secondary Node for the UE. The candidate Secondary Node may control an LTM candidate cell for the UE, for example.

[0159] Various embodiments may include information transfers in both directions, such that, for example, the serving Secondary Node and the candidate Secondary Node play both roles (the first network node and the second network node), for different information transfers.

[0160] In some embodiments, the mobility-related information comprises or consists of LTM-related information, which may include at least one of:

[0161] • LTM candidate cell configuration(s);

[0162] • inter-CU LTM candidate cell configuration(s);

[0163] • inter-MN LTM configuration(s);

[0164] • reference configuration(s);

[0165] • lower layer information;

[0166] • higher layer information;

[0167] • configuration of measurements for LTM;

[0168] • configuration for measurement reports for LTM; • CSI resource configuration(s) for LTM;

[0169] • CSI report configuration for LTM;

[0170] • configurations of early synchronization procedures;

[0171] • configurations for the execution of an LTM cell switch procedure;

[0172] • a configuration which the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to an LTM candidate cell;

[0173] • information to perform security key refresh;

[0174] • an indication to perform a complete configuration;

[0175] • an indication to perform a full configuration, e.g. the RRC field fullConfig; and

[0176] • an indication to perform L2 reset or re-establishment, such as an indication to perform MAC reset, RLC re-establishment, PDCP recovery, PDCP re-establishment for one or multiple bearers.

[0177] In some of the various embodiments described above, the method may further include one or more additional steps, such as where the first network node transmits, to the UE, a message triggering the mobility procedure, such as a handover command or an LTM cell switch command.

[0178] In various embodiments of the techniques described above, the signaling procedure between the first network node and the third network node may use one or more XnAP procedures, e.g., Cell Switch Notification, and / or LTM Information Transparent Transfer, and / or LTM Configuration Update, and / or an extension of an existing XnAP procedure for dual connectivity (e.g., an SN Change Required).

[0179] In some embodiments or instances of the techniques described above, the message sent by the first network node to the third network node may further include an indication, which may be explicit or implicit, for one or more of the following:

[0180] • an indication to the third network node whether it should first decode the message and then send an exact copy of the received message also to the UE;

[0181] • an indication to the third network node whether it should forward the message to the UE without decoding it; and • an indication to the third network node whether it should first decode the message and use or include the content of this decoded message in a second message which is sent to the UE and is generated by the third network node.

[0182] In some embodiments or instances, the indication on whether the third network node should decode the message or forward the message directly to the UE (without decoding it) is not part of the message content but is part of fields that precede the actual message (e.g., a header of control PDU). In some embodiments or instances, the indication on whether the third network node should decode the message or forward the message directly to the UE is determined implicitly by the third network node based on one or more of:

[0183] • the name of the message itself;

[0184] • the encoding (e.g., ASN.1 encoding) of the message;

[0185] • the encoding (e.g., ASN.1 encoding) of the Information Element within the message being transferred as received by the third network node;

[0186] • whether a certain feature is configured or not; and

[0187] • whether a certain interface is configured or not.

[0188] In various embodiments or instances, the mobility-related information consists of or is included as an XnAP message. In some others, the mobility-related information consists of or is included as an RRC message, e.g. an inter-node RRC message.

[0189] Embodiments of the presently disclosed techniques may be understood further as including various methods for a network node playing the role of the third network node as described above, e.g., acting as a Master Node or Master gNB-CU for a UE configured with NR-DC, to handle the network signaling for the transfer of mobility-related information during a mobility procedure for the UE, such as an inter-SN mobility procedure for the UE between a first network node and a second network node. Example embodiments of these methods may thus include the steps of receiving, from the first network node, a message including mobility-related information, and transmitting, to a second network node, a message including the mobility related information. The third network node thus relays the mobility-related information received from the first network node to the second network node.

[0190] In some embodiments, the received message includes one or more of: • an indication of a second network node, such as a node acting as a Secondary Node for the UE;

[0191] • an indication of a target cell; and

[0192] • an indication of a UE context.

[0193] As was discussed in the detailed examples described above, the received mobility-related information may be transparent for the third network node, which is to say that the third network need not (and need not be able to) read, parse, and / or interpret the mobility-related information that it relays to the second network node. In various examples, the transmitted mobility related information includes one or more of:

[0194] • an indication of a second network node, such as a Secondary Node, a Secondary gNB-DU or a Secondary gNB-CU;

[0195] • an indication of a target cell;

[0196] • a mobility related request to the second network node;

[0197] • a response of the previously transmitted mobility related request;

[0198] • a request to prepare a mobility configuration for the UE;

[0199] • a response including a mobility configuration for the UE;

[0200] • an indication of execution of a mobility procedure for the UE;

[0201] • LTM-related information;

[0202] • information related to subsequent mobility; and

[0203] • early sync information, such as random access preamble(s) or Timing Advance (TA) information, beam-related information such as TCI state information for an candidate cell.

[0204] In some embodiments or instances, the first network node is acting as the serving Secondary Node for the UE. In others, the first network node may be acting as a candidate Secondary Node for the UE. The candidate Secondary Node may control an LTM candidate cell for the UE, for example.

[0205] Various embodiments may include information transfers in both directions, such that, for example, the serving Secondary Node and the candidate Secondary Node play both roles (the first network node and the second network node), for different information transfers.

[0206] In some embodiments, the mobility-related information comprises or consists of LTM-related information, which may include at least one of: • LTM candidate cell configuration(s);

[0207] • inter-CU LTM candidate cell configuration(s);

[0208] • inter-MN LTM configuration(s);

[0209] • reference configuration(s);

[0210] • lower layer information;

[0211] • higher layer information;

[0212] • configuration of measurements for LTM;

[0213] • configuration for measurement reports for LTM;

[0214] • CSI resource configuration(s) for LTM;

[0215] • CSI report configuration for LTM;

[0216] • configurations of early synchronization procedures;

[0217] • configurations for the execution of an LTM cell switch procedure;

[0218] • a configuration which the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to an LTM candidate cell;

[0219] • information to perform security key refresh;

[0220] • an indication to perform a complete configuration;

[0221] • an indication to perform a full configuration, e.g. the RRC field fullConfig; and

[0222] • an indication to perform L2 reset or re-establishment, such as an indication to perform MAC reset, RLC re-establishment, PDCP recovery, PDCP re-establishment for one or multiple bearers.

[0223] In various embodiments of the techniques described above, the signaling procedure between the third network node and either of the first or second network nodes may use one or more XnAP procedures, e.g., Cell Switch Notification, and / or LTM Information Transparent Transfer, and / or LTM Configuration Update, and / or an extension of an existing XnAP procedure for dual connectivity (e.g., an SN Change Required).

[0224] In some embodiments or instances of the techniques described above, the message received by the third network node from the first network node may further include an indication, which may be explicit or implicit, for one or more of the following: an indication to the third network node whether it should first decode the message and then send an exact copy of the received message also to the UE; • an indication to the third network node whether it should forward the message to the UE without decoding it; and

[0225] • an indication to the third network node whether it should first decode the message and use or include the content of this decoded message in a second message which is sent to the UE and is generated by the third network node.

[0226] In these embodiments, the method may further comprise forwarding all or parts of the message to the UE, accordingto this indication.

[0227] Embodiments of the presently disclosed techniques may be understood still further as including various methods for a network node playing the role of the second network node as described above, to handle the network signaling for the transfer of mobility-related information during a mobility procedure for the UE, such as an inter-SN mobility procedure for the UE between a first network node and the second network node, via a third network node. Example embodiments of these methods may thus include the steps of receiving, from a third network node, such as a node acting as a Master Node or Master gNB-CU for the UE, a message including mobility-related information like any of the examples of mobility-related information described above.

[0228] In some embodiments or instances, the received message may include one or more of:

[0229] • an indication of a network node, such as the second network node;

[0230] • an indication of a target cell, such as a cell that is controlled by the second network node; and

[0231] • indication of a UE context.

[0232] As was discussed in the several examples detailed above, the received mobility-related information may have been transparent for the third network node, e.g., in a transparent container or transparent message that the third network node has relayed to the second network node, without reading or interpreting the information. In various examples, the received mobility-related information includes one or more of:

[0233] • an indication of a second network node, such as a Secondary Node, a Secondary gNB-DU or a Secondary gNB-CU;

[0234] • an indication of a target cell;

[0235] • a mobility related request to the second network node; • a response of the previously transmitted mobility related request;

[0236] • a request to prepare a mobility configuration for the UE;

[0237] • a response including a mobility configuration for the UE;

[0238] • an indication of execution of a mobility procedure for the UE;

[0239] • LTM-related information;

[0240] • information related to subsequent mobility; and

[0241] • early sync information, such as random access preamble(s) or Timing Advance (TA) information, beam-related information such as TCI state information for an candidate cell.

[0242] In some embodiments or instances, the second network node is acting as the serving Secondary Node for the UE. In others, the second network node may be acting as a candidate Secondary Node for the UE. The candidate Secondary Node may control an LTM candidate cell for the UE, for example. Various embodiments may include information transfers in both directions, such that, for example, the serving Secondary Node and the candidate Secondary Node play both roles (the first network node and the second network node) for different information transfers.

[0243] In some embodiments, the mobility-related information comprises or consists of LTM-related information, which may include at least one of:

[0244] • LTM candidate cell configuration(s);

[0245] • inter-CU LTM candidate cell configuration(s);

[0246] • inter-MN LTM configuration(s);

[0247] • reference configuration(s);

[0248] • lower layer information;

[0249] • higher layer information;

[0250] • configuration of measurements for LTM;

[0251] • configuration for measurement reports for LTM;

[0252] • CSI resource configuration(s) for LTM;

[0253] • CSI report configuration for LTM;

[0254] • configurations of early synchronization procedures;

[0255] • configurations for the execution of an LTM cell switch procedure;

[0256] • a configuration which the UE needs to start to operate accordingly when it performs an LTM cell switch procedure to an LTM candidate cell; information to perform security key refresh;

[0257] • an indication to perform a complete configuration;

[0258] • an indication to perform a full configuration, e.g. the RRC field fullConfig; and

[0259] • an indication to perform L2 reset or re-establishment, such as an indication to perform MAC reset, RLC re-establishment, PDCP recovery, PDCP re-establishment for one or multiple bearers.

[0260] In various embodiments of the techniques described above, the signaling procedure between the second network node and the third network node may use one or more XnAP procedures, e.g., Cell Switch Notification, and / or LTM Information Transparent Transfer, and / or LTM Configuration Update, and / or an extension of an existing XnAP procedure for dual connectivity (e.g., an SN Change Required).

[0261] In some embodiments or instances of the various methods described above, the second network node decodes contents of the received mobility related information. The second network node may further act on at least one part of the contents included within the received mobility-related information.

[0262] In some embodiments or instances, the message received by the second network node from the third network node may include an explicit indication for one or more of the following:

[0263] • an indication to the second network node whether it should first decode the message and then send an exact copy of the received message also to the UE;

[0264] • an indication to the second network node whether it should forward the message to the UE without decoding it; and

[0265] • an indication to the second network node whether it should first decode the message and use or include the content of this decode message in a second message which is sent to the UE and is generated by the second network node.

[0266] In some embodiments or instances, the indication on whether the second network node should decode the message or forward the message directly to the UE (without decoding it) is not part of the message content but is part of fields that precede the actual message (e.g., a header of control PDU). In some embodiments or instances, the indication on whetherthe second network node should decode the message or forward the message directly to the UE is determined implicitly by the second network node based on one or more of:

[0267] • the name of the message itself;

[0268] • the encoding (e.g., ASN.1 encoding) of the message;

[0269] • the encoding (e.g., ASN.1 encoding) of the Information Element within the message being transferred as received by the third network node;

[0270] • whether a certain feature is configured or not; and

[0271] • whether a certain interface is configured or not.

[0272] In various embodiments or instances, the mobility-related information consists of or is included as an XnAP message. In some others, the mobility-related information consists of or is included as an RRC message, e.g. an inter-node RRC message.

[0273] Other embodiments of the presently disclosed techniques may be understood as including various methods for a UE for handling the secondary cell group (SCG), such as an UE undergoing an inter- SN mobility procedure between a first network node and a second network node, where inter-SN communications are transferred via a third network node. Example embodiments of these methods may thus include the steps of receiving, receiving, from the first network node, a message that a mobility procedure is executed, e.g., inter-SN LTM, and transmitting, to the second network node, a message to indicate that the mobility procedure has been completed.

[0274] In some embodiments or instances, the message received from the first network node may be a Medium Access Control Control Element (MAC CE), e.g., an LTM Cell Switch Command. In some of these and in some other embodiments or instances, the message transmitted to the second network node may be an RRC message, e.g., RRCReconfigurationComplete.

[0275] In some embodiments or instances, the UE receives an RRC message from a first network node which includes a second RRC message from a second network node. The second RRC message is included within the first RRC message may be received within a container or an ASN.1 OCTET STRING type, for example.

[0276] Figure 8 is a process flow diagram illustrating an example method, in a first network node, for handling mobility-related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between the first network node and a second network node. The illustrated method may be considered as a generalization of several of the techniques described above, and thus the terminology used below to describe this and the several other methods described below should be understood as at least encompassing similar or clearly related terminology used above, where there are differences, unless the context specifically indicates otherwise.

[0277] As show at block 810, the method comprises the step of determining a need to communicate mobility-related information to the second network node. As shown at block 820, the method further comprises the step of transmitting, to a third network node acting as a master node (MN) for the UE, a message including mobility-related information to be relayed by the third network node to the second network node.

[0278] In various embodiments or instances, the message includes any of: an identifier of the second network node; an identifier of a target cell for the inter-SN mobility procedure; and an indication of a UE context for the UE. The mobility-related information included in the message may comprise any one or more of the following, for example: a mobility-related request to the second network node; a response to a mobility-related request previously received by the first network node; a request to prepare a mobility configuration for the UE; a response including a mobility configuration for the UE; indication of execution of a mobility procedure for the UE; Layer-1 triggered mobility (LTM) -related information; information related to subsequent mobility; and early sync information for a candidate cell.

[0279] In some embodiments or instances, the mobility-related information comprises LTM-related information, the LTM-related information comprising any one or more of: an LTM candidate cell configuration; an inter-CU LTM candidate cell configuration; an inter-MN LTM configuration; a reference configuration; configuration of measurements for LTM; configuration of measurement reports for LTM; a channel-state information (CSI) resource configuration for LTM; a CSI report configuration for LTM; a configuration of an early synchronization procedure; a configuration for the execution of an LTM cell switch procedure; information to perform security key refresh; an indication to perform a complete configuration; an indication to perform a full configuration; and an indication to perform Layer 2 reset or re-establishment. In some embodiments or instances, transmitting the message to the third network node uses an XnAP procedure. In some, the mobility-related information is included in an XnAP message within the message transmitted to the third network node.

[0280] In some embodiments or instances, the mobility-related information is included in an RRC message within the message transmitted to the third network node.

[0281] In some embodiments or instances, the message comprises an indication to the third network node of any of the following: that the third network node is to decode the mobility-related information and send an exact copy of the mobility-related information to the UE; that the third network is to forward the mobility-related information to the UE without decoding the mobility- related information; that the third network node is to decode the mobility-related information and use the content of the mobility-related information to generate a message to be sent to the UE. This indication may implicitly based on any one of more of any of the following, in some embodiments or instances: a name of the message; encoding of the message; and encoding of an information element in the message to be transferred to the second network node. In other embodiments or instances, the indication is an explicit indication included in one or more fields preceding the message content.

[0282] The first network node carrying out the method shown in Figure 8 may be a serving secondary node for the UE and the second network node a candidate secondary node for the UE, in some embodiments or instances. In others, the first network node may be a candidate secondary node for the UE and the second network node a serving secondary node for the UE. In some of either of these embodiments or instances, the candidate secondary node may control a Layer-2 Triggered Mobility (LTM) candidate cell for the UE.

[0283] Figure 9 is a process flow diagram illustrating another example method for handling mobility-related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between a first network node and a second network node, in this case the method being performed in a third network node acting as a master node (MN) for the UE. Again, the illustrated method may be considered as a generalization of several of the techniques described above, and thus the terminology used below to describe this and the several other methods described below should be understood as at least encompassing similar or clearly related terminology used above, where there are differences, unless the context specifically indicates otherwise. As shown at block 910, the method comprises receiving, from the first network node, a message including mobility-related information to be relayed by the third network node to the second network node. As shown at block 920, the method further comprises transmitting the mobility- related information to the second network node.

[0284] As previously discussed, the message may include any of: an identifier of the second network node; an identifier of a target cell for the inter-SN mobility procedure; and an indication of a UE context for the UE. In various embodiments or instances, the mobility-related information included in the message may comprise any one or more of: a mobility-related request to the second network node; a response to a mobility-related request previously received by the first network node; a request to prepare a mobility configuration for the UE; a response including a mobility configuration for the UE; indication of execution of a mobility procedure for the UE; Layer-1 triggered mobility (LTM) -related information; information related to subsequent mobility; and early sync information for a candidate cell.

[0285] In some embodiments or instances, the mobility-related information comprises LTM-related information, the LTM-related information comprising any one or more of: an LTM candidate cell configuration; an inter-CU LTM candidate cell configuration; an inter-MN LTM configuration; a reference configuration; configuration of measurements for LTM; configuration of measurement reports for LTM; a channel-state information (CSI) resource configuration for LTM; a CSI report configuration for LTM; a configuration of an early synchronization procedure; a configuration for the execution of an LTM cell switch procedure; information to perform security key refresh; an indication to perform a complete configuration; an indication to perform a full configuration; and an indication to perform Layer 2 reset or re-establishment.

[0286] In some embodiments or instances, the mobility-related information is included in an XnAP message within the message transmitted to the third network node. In some embodiments or instances, the mobility-related information is included in an RRC message within the message transmitted to the third network node.

[0287] In some embodiments or instances, the third network node forwards at least some of the mobility- related information to the UE, according to an indication in the message that indicates any one of the following: that the third network node is to decode the mobility-related information and send an exact copy of the mobility-related information to the UE; that the third network is to forward the mobility-related information to the UE without decoding the mobility-related information; and that the third network node is to decode the mobility-related information and use the content of the mobility-related information to generate a message to be sent to the UE. This is shown at block 930 in Figure 9. This indication may implicitly based on any one of more of any of the following, in some embodiments or instances: a name of the message; encoding of the message; and encoding of an information element in the message to be transferred to the second network node. In other embodiments or instances, the indication is an explicit indication included in one or more fields preceding the message content.

[0288] In some embodiments or instances of the method shown in Figure 9, the first network node may be a serving secondary node for the UE while the second network node is a candidate secondary node for the UE. In others, the first network node may be a candidate secondary node for the UE while the second network node is a serving secondary node for the UE. In either case, the candidate secondary node may control a Layer-2 Triggered Mobility (LTM) candidate cell for the UE, in some examples.

[0289] Figure 10 is a process flow diagram illustrating another example method for handling mobility- related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between a first network node and a second network node, in this case the method being performed in the second network node. Again, the illustrated method may be considered as a generalization of several of the techniques described above, and thus the terminology used below to describe this and the several other methods described below should be understood as at least encompassing similar or clearly related terminology used above, where there are differences, unless the context specifically indicates otherwise.

[0290] As shown at block 1010, the method comprises the step of receiving, from a third network node acting as a master node (MN) for the UE, a message including mobility-related information relayed by the third network node to the second network node from the first network node.

[0291] As previously discussed, the message may include any of: an identifier of the second network node; an identifier of a target cell for the inter-SN mobility procedure; and an indication of a UE context for the UE. In various embodiments or instances, the mobility-related information included in the message may comprise any one or more of: a mobility-related request to the second network node; a response to a mobility-related request previously received by the first network node; a request to prepare a mobility configuration for the UE; a response including a mobility configuration for the UE; indication of execution of a mobility procedure for the UE; Layer-1 triggered mobility (LTM) -related information; information related to subsequent mobility; and early sync information for a candidate cell.

[0292] In some embodiments or instances, the mobility-related information comprises LTM-related information, the LTM-related information comprising any one or more of: an LTM candidate cell configuration; an inter-CU LTM candidate cell configuration; an inter-MN LTM configuration; a reference configuration; configuration of measurements for LTM; configuration of measurement reports for LTM; a channel-state information (CSI) resource configuration for LTM; a CSI report configuration for LTM; a configuration of an early synchronization procedure; a configuration for the execution of an LTM cell switch procedure; information to perform security key refresh; an indication to perform a complete configuration; an indication to perform a full configuration; and an indication to perform Layer 2 reset or re-establishment.

[0293] In some embodiments or instances, the message received from the third network node is received as part of an XnAP procedure.

[0294] In some embodiments or instances, the method comprises decoding the mobility-related information, as shown at block 1020. The method may still further comprise acting on at least part of the contents of the mobility-related information, as shown at block 1030.

[0295] Figure 11 is a process flow diagram illustrating an example method for handling mobility-related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between a first network node and a second network node, the method being performed in the UE. As shown at block 1110, the method comprises receiving, from the first network node, a message indicating that the mobility procedure is to be executed. As shown at block 1120, the method further comprises transmitting, to the second network node, a message indicating that the mobility procedure has been completed.

[0296] In some embodiments or instances, the message received from the first network node is a MAC CE, e.g., LTM Cell Switch Command. In some embodiments or instances, the message transmitted to the second network node is an RRC message, e.g., RRCReconfigurationComplete. In some embodiments or instances, the message received from the first network node is a first RRC message that includes a second RRC message from the second network node. The second RRC message included within the first RRC message may be received within a container or an ASN.1 OCTET STRING type, for example.

[0297] Figure 12 shows an example of a communication system 1200, in accordance with some embodiments, in which the techniques described above may be implemented.

[0298] In the example, the communication system 1200 includes a telecommunication network 1202 that includes an access network 1204, such as a radio access network (RAN), and a core network 1206, which includes one or more core network nodes 1208. The access network 1204 includes one or more access network nodes, such as network nodes 1210a and 1210b (one or more of which may be generally referred to as network nodes 1210), or any other similar 3rd Generation Partnership Project (3GPP) access nodes or non-3GPP access points. Moreover, as will be appreciated by those of skill in the art, a network node is not necessarily limited to an implementation in which a radio portion and a baseband portion are supplied and integrated by a single vendor. Thus, it will be understood that network nodes include disaggregated implementations or portions thereof. For example, in some embodiments, the telecommunication network 1202 includes one or more Open- RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 1202 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 the telecommunication network 1202, including one or more network nodes 1210 and / or core network nodes 1208.

[0299] 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-realtime) hosting software or software plug-ins, such as a near-realtime control application (e.g., xApp) or a non-realtime control application (e.g., rApp), or any combination thereof (the adjective “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 A1 , F1, W1 , E1 , 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 O-RAN Alliance or comparable technologies. The network nodes 1210 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 1212a, 1212b, 1212c, and 1212d (one or more of which may be generally referred to as UEs 1212) to the core network 1206 over one or more wireless connections.

[0300] 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, the communication system 1200 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. The communication system 1200 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0301] The UEs 1212 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 1210 and other communication devices. Similarly, the network nodes 1210 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 1212 and / or with other network nodes or equipment in the telecommunication network 1202 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 1202.

[0302] In the depicted example, the core network 1206 connects the network nodes 1210 to one or more hosts, such as host 1216. 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. The core network 1206 includes one more core network nodes (e.g., core network node 1208) 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 the core network node 1208. 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).

[0303] The host 1216 may be under the ownership or control of a service provider other than an operator or provider of the access network 1204 and / or the telecommunication network 1202, and may be operated by the service provider or on behalf of the service provider. The host 1216 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.

[0304] As a whole, the communication system 1200 of Figure 12 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 Mobile Telecommunications 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.

[0305] In some examples, the telecommunication network 1202 is a cellular networkthat implements 3GPP standardized features. Accordingly, the telecommunications network 1202 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 1202. For example, the telecommunications network 1202 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.

[0306] In some examples, the UEs 1212 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 1204 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 1204. 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 (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

[0307] In the example, the hub 1214 communicates with the access network 1204 to facilitate indirect communication between one or more UEs (e.g., UE 1212c and / or 1212d) and network nodes (e.g., network node 1210b). In some examples, the hub 1214 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 1214 may be a broadband router enabling access to the core network 1206 for the UEs. As another example, the hub 1214 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, network nodes 1210, or by executable code, script, process, or other instructions in the hub 1214. As another example, the hub 1214 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, the hub 1214 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 1214 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 1214 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 1214 acts as a proxy server or orchestratorfor the UEs, in particular if one or more of the UEs are low energy loT devices.

[0308] The hub 1214 may have a constant / persistent or intermittent connection to the network node 1210b. The hub 1214 may also allow for a different communication scheme and / or schedule between the hub 1214 and UEs (e.g., UE 1212c and / or 1212d), and between the hub 1214 and the core network 1206. In other examples, the hub 1214 is connected to the core network 1206 and / or one or more UEs via a wired connection. Moreover, the hub 1214 may be configured to connect to an M2M service provider over the access network 1204 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 1210 while still connected via the hub 1214 via a wired or wireless connection. In some embodiments, the hub 1214 may be a dedicated hub -that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 121 Ob. In other embodiments, the hub 1214 may be a non-dedicated hub -that is, a device which is capable of operating to route communications between the UEs and network node 1210b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0309] Figure 13 shows a UE 1300 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customer-premise equipment (CPE), vehicle, vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3GPP), including a narrow band internet of things (NB-loT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0310] A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP 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 UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE 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 UE 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). The UE 1300 includes processing circuitry 1302 that is operatively coupled via a bus 1304 to an input / output interface 1306, a power source 1308, a memory 1310, a communication interface 1312, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 13. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0311] The processing circuitry 1302 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 the memory 1310. The processing circuitry 1302 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), together with appropriate software; or any combination of the above. For example, the processing circuitry 1302 may include multiple central processing units (CPUs).

[0312] In the example, the input / output interface 1306 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 1300. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0313] In some embodiments, the power source 1308 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. The power source 1308 may further include power circuitry for delivering power from the power source 1308 itself, and / or an external power source, to the various parts of the UE 1300 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1308. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1308 to make the power suitable for the respective components of the UE 1300 to which power is supplied.

[0314] The memory 1310 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, the memory 1310 includes one or more application programs 1314, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1316. The memory 1310 may store, for use by the UE 1300, any of a variety of various operating systems or combinations of operating systems.

[0315] The memory 1310 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 disc drive, 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 (eUlCC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 1310 may allow the UE 1300 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 the memory 1310, which may be or comprise a device-readable storage medium.

[0316] The processing circuitry 1302 may be configured to communicate with an access network or other network using the communication interface 1312. The communication interface 1312 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1322. The communication interface 1312 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 UE or a network node in an access network). Each transceiver may include a transmitter 1318 and / or a receiver 1320 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1318 and receiver 1320 may be coupled to one or more antennas (e.g., antenna 1322) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0317] In the illustrated embodiment, communication functions of the communication interface 1312 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and / or standards, such as IEEE 802.11 , Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / internet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0318] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1312, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output 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., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0319] As another example, a UE comprises 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 response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0320] A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is 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 head-mounted 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, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and / or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE 1300 shown in Figure 13.

[0321] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-loT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0322] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0323] A UE like the UE 1300 shown in Figure 13 may be configured, e.g., with appropriate program code stored in program memory for execution by one or more processors in the UE, to carry out a method like those described above, e.g., as illustrated in Figure 11 . More generally, a wireless device, which term encompasses the industry term “UE,” may be configured to carry out such a method. Thus, an example wireless device according to various embodiments described herein may comprise radio circuitry configured to communicate with one or more wireless networks and processing circuitry operatively coupled to the radio circuitry, where the processing circuitry (e.g., one or more processors executing stored program instructions) is configured to receive, from a wireless network, a configuration for logging MDT measurements, determine that the received configuration does not identify one or more SNPNs in an area scope for the configuration, and, responsive to said determining, store an SNPN identifier for an SNPN with which the wireless device is currently registered, in a variable associated with logged MDT measurements. In some embodiments or instances, the processing circuitry may be configured to determine that the received configuration does not identify one or more SNPNs in the area scope for the configuration by determining an absence, in the configuration, of any one or more of: a list of SNPNs; a list of PLMNs; and a list of PNI NPN identities.

[0324] In some embodiments or instances, the processing circuitry is further configured to, responsive to said determining, store one or more identifiers for equivalent SNPNs to the SNPN with which the wireless device is currently registered.

[0325] In some embodiments or instances, the processing circuitry is further configured to use the stored SNPN identifier and the configuration for determining collection of logged measurements, subsequently to said storing, while in an RRC idle state or RRC inactive state. The processing circuitry may be further configured to use an identifier for each of one or more equivalent SNPNs to the SNPN identifier, and the configuration, while the wireless device is in said RRC idle state or RRC inactive state, for determining collection of logged measurements. In some embodiments or instances, the processing circuitry may be further configured to, subsequently to said determining collection of logged measurements while in the RRC idle state or inactive, enter an RRC connected state and use the stored SNPN identifier to determine whether to transmit, to the wireless network to which the wireless device is connected, an indication of available logged MDT measurements. In some embodiments or instances, the processing circuitry may be further configured to, while the wireless device is in said RRC connected state, using an identifier for each of one or more equivalent SNPNs to the SNPN identifier, to determine whether to transmit, to the wireless network to which the wireless device is connected, an indication of available logged MDT measurements. In some embodiments or instances, the processing circuitry may be further configured to control the wireless device such that when the wireless determine determines, upon entering the RRC connected state, that the wireless device is connected to an SNPN corresponding to the stored SNPN identifier and transmits the indication of available logged MDT measurements, the processing circuity further controls the wireless device to receive, from the wireless network, a request for logged MDT measurements, and transmit, to the wireless network, logged measurements associated with the stored SNPN identifier. The SNPN corresponding to the stored SNPN identifier may be, in some embodiments or instances, an equivalent SNPN to the SNPN havingthe SNPN identifier.

[0326] Figure 14 shows a network node 1400 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU).

[0327] Base stations 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. A base station may be a relay node or a relay donor node controlling a relay. A network node may also 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).

[0328] Other examples of network nodes 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 / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, SelfOrganizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0329] The network node 1400 includes a processing circuitry 1402, a memory 1404, a communication interface 1406, and a power source 1408. The network node 1400 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. In certain scenarios in which the network node 1400 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, the network node 1400 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1404 for different RATs) and some components may be reused (e.g., a same antenna 1410 may be shared by different RATs). The network node 1400 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1400, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1400.

[0330] The processing circuitry 1402 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 network node 1400 components, such as the memory 1404, to provide network node 1400 functionality.

[0331] In some embodiments, the processing circuitry 1402 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1402 includes one or more of radio frequency (RF) transceiver circuitry 1412 and baseband processing circuitry 1414. In some embodiments, the radio frequency (RF) transceiver circuitry 1412 and the baseband processing circuitry 1414 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 1412 and baseband processing circuitry 1414 may be on the same chip or set of chips, boards, or units.

[0332] The memory 1404 may comprise 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 the processing circuitry 1402. The memory 1404 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 capable of being executed by the processing circuitry 1402 and utilized by the network node 1400. The memory 1404 may be used to store any calculations made by the processing circuitry 1402 and / or any data received via the communication interface 1406. In some embodiments, the processing circuitry 1402 and memory 1404 is integrated.

[0333] The communication interface 1406 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 1406 comprises port(s) / terminal(s) 1416 to send and receive data, for example to and from a network over a wired connection. The communication interface 1406 also includes radio front-end circuitry 1418 that may be coupled to, or in certain embodiments a part of, the antenna 1410. Radio front-end circuitry 1418 comprises filters 1420 and amplifiers 1422. The radio frontend circuitry 1418 may be connected to an antenna 1410 and processing circuitry 1402. The radio front-end circuitry may be configured to condition signals communicated between antenna 1410 and processing circuitry 1402. The radio front-end circuitry 1418 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 1418 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1420 and / or amplifiers 1422. The radio signal may then be transmitted via the antenna 1410. Similarly, when receiving data, the antenna 1410 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1418. The digital data may be passed to the processing circuitry 1402. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0334] In certain alternative embodiments, the network node 1400 does not include separate radio frontend circuitry 1418, instead, the processing circuitry 1402 includes radio front-end circuitry and is connected to the antenna 1410. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1412 is part of the communication interface 1406. In still other embodiments, the communication interface 1406 includes one or more ports or terminals 1416, the radio front-end circuitry 1418, and the RF transceiver circuitry 1412, as part of a radio unit (not shown), and the communication interface 1406 communicates with the baseband processing circuitry 1414, which is part of a digital unit (not shown).

[0335] The antenna 1410 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1410 may be coupled to the radio front-end circuitry 1418 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1410 is separate from the network node 1400 and connectable to the network node 1400 through an interface or port.

[0336] The antenna 1410, communication interface 1406, and / orthe processing circuitry 1402 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna 1410, the communication interface 1406, and / orthe processing circuitry 1402 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment. The power source 1408 provides power to the various components of network node 1400 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1408 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1400 with powerfor performing the functionality described herein. For example, the network node 1400 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1408. As a further example, the power source 1408 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0337] Embodiments of the network node 1400 may include additional components beyond those shown in Figure 14 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, the network node 1400 may include user interface equipment to allow input of information into the network node 1400 and to allow output of information from the network node 1400. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1400.

[0338] Figure 15 is a block diagram illustrating a virtualization environment 1500 in which functions implemented by 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 1500 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 1500 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an 0-2 interface. Virtualization may facilitate distributed implementations of a network node, UE, core network node, or host.

[0339] Applications 1502 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 1500 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0340] Hardware 1504 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1506 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1508a and 1508b (one or more of which may be generally referred to as VMs 1508), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1506 may present a virtual operating platform that appears like networking hardware to the VMs 1508.

[0341] The VMs 1508 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1506. Different embodiments of the instance of a virtual appliance 1502 may be implemented on one or more of VMs 1508, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0342] In the context of NFV, a VM 1508 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1508, and that part of hardware 1504 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1508 on top of the hardware 1504 and corresponds to the application 1502. Hardware 1504 may be implemented in a standalone network node with generic or specific components. Hardware 1504 may implement some functions via virtualization. Alternatively, hardware 1504 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1510, which, among others, oversees lifecycle management of applications 1502. In some embodiments, hardware 1504 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that 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 1512 which may alternatively be used for communication between hardware nodes and radio units.

[0343] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non- computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware. In certain embodiments, some or all ot the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device- readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

[0344] EXAMPLE EMBODIMENTS

[0345] Embodiments of the techniques and apparatuses described herein include, but are not limited to, the following enumerated examples:

[0346] 1 . A method, in a first network node, for handling mobility-related information during an intersecondary node (inter-SN) mobility procedure for a user equipment (UE) between the first network node and a second network node, the method comprising: determining a need to communicate mobility-related information to the second network node; and transmitting, to a third network node acting as a master node (MN) for the UE, a message including mobility-related information to be relayed by the third network node to the second network node.

[0347] 2. The method of example embodiment 1, wherein the message includes any of: an identifier of the second network node; an identifier of a target cell for the inter-SN mobility procedure; and an indication of a UE context for the UE.

[0348] 3. The method of example embodiment 1 or 2, wherein the mobility-related information included in the message comprises any one or more of: a mobility-related request to the second network node; a response to a mobility-related request previously received by the first network node; a request to prepare a mobility configuration for the UE; a response including a mobility configuration for the UE; indication of execution of a mobility procedure for the UE;

[0349] Layer-1 triggered mobility (LTM) -related information; information related to subsequent mobility; and early sync information for a candidate cell.

[0350] 4. The method of example embodiment 3, wherein the mobility-related information comprises LTM- related information, the LTM-related information comprising any one or more of: an LTM candidate cell configuration; an inter-CU LTM candidate cell configuration; an inter-MN LTM configuration; a reference configuration; configuration of measurements for LTM; configuration of measurement reports for LTM; a channel-state information (CSI) resource configuration for LTM; a CSI report configuration for LTM; a configuration of an early synchronization procedure; a configuration for the execution of an LTM cell switch procedure; information to perform security key refresh; an indication to perform a complete configuration; an indication to perform a full configuration; and an indication to perform Layer 2 reset or re-establishment.

[0351] 5. The method of any one of example embodiments 1-4, wherein transmitting the message to the third network node uses an XnAP procedure.

[0352] 6. The method of any one of example embodiments 1-5, wherein the mobility-related information is included in an XnAP message within the message transmitted to the third network node. 7. The method of any one of example embodiments 1-5, wherein the mobility-related information is included in an RRC message within the message transmitted to the third network node.

[0353] 8. The method of any one of example embodiments 1-7, wherein the message comprises an indication to the third network node of any of the following: that the third network node is to decode the mobility-related information and send an exact copy of the mobility-related information to the UE; that the third network is to forward the mobility-related information to the UE without decoding the mobility-related information; that the third network node is to decode the mobility-related information and use the content of the mobility-related information to generate a message to be sent to the UE.

[0354] 9. The method of example embodiment 8, wherein the indication is implicitly based on any one of more of any of: a name of the message; encoding of the message; and encoding of an information element in the message to be transferred to the second network node.

[0355] 10. The method of example 8, wherein the indication is an explicit indication included in one or more fields preceding the message content.

[0356] 11 . The method of any one of example embodiments 1-10, wherein the first network node is a serving secondary node for the UE and the second network node is a candidate secondary node for the UE.

[0357] 12. The method of any one of example embodiments 1-10, wherein the first network node is a candidate secondary node for the UE and the second network node is a serving secondary node for the UE. 13. The method of example embodiment 11 or 12, wherein the candidate secondary node controls a Layer-2 Triggered Mobility (LTM) candidate cell for the UE.

[0358] 14. A method for handling mobility-related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between a first network node and a second network node, the method being performed in a third network node acting as a master node (MN) for the UE, and the method comprising: receiving, from the first network node, a message including mobility-related information to be relayed by the third network node to the second network node; and transmitting the mobility-related information to the second network node.

[0359] 15. The method of example embodiment 14, wherein the message includes any of: an identifier of the second network node; an identifier of a target cell for the inter-SN mobility procedure; and an indication of a UE context for the UE.

[0360] 16. The method of example embodiment 14 or 15, wherein the mobility-related information included in the message comprises any one or more of: a mobility-related request to the second network node; a response to a mobility-related request previously received by the first network node; a request to prepare a mobility configuration for the UE; a response including a mobility configuration for the UE; indication of execution of a mobility procedure for the UE;

[0361] Layer-1 triggered mobility (LTM) -related information; information related to subsequent mobility; and early sync information for a candidate cell.

[0362] 17. The method of example embodiment 16, wherein the mobility-related information comprises LTM-related information, the LTM-related information comprising any one or more of: an LTM candidate cell configuration; an inter-CU LTM candidate cell configuration; an inter-MN LTM configuration; a reference configuration; configuration of measurements for LTM; configuration of measurement reports for LTM; a channel-state information (CSI) resource configuration for LTM; a CSI report configuration for LTM; a configuration of an early synchronization procedure; a configuration for the execution of an LTM cell switch procedure; information to perform security key refresh; an indication to perform a complete configuration; an indication to perform a full configuration; and an indication to perform Layer 2 reset or re-establishment.

[0363] 18. The method of any one of example embodiments 14-17, wherein the mobility-related information is included in an XnAP message within the message transmitted to the third network node.

[0364] 19. The method of any one of example embodiments 14-17, wherein the mobility-related information is included in an RRC message within the message transmitted to the third network node.

[0365] 20. The method of any one of example embodiments 14-19, wherein the third network node forwards at least some of the mobility-related information to the UE, according to an indication in the message that indicates any one of the following: that the third network node is to decode the mobility-related information and send an exact copy of the mobility-related information to the UE; that the third network is to forward the mobility-related information to the UE without decoding the mobility-related information; that the third network node is to decode the mobility-related information and use the content of the mobility-related information to generate a message to be sent to the

[0366] UE. 21 . The method of example embodiment 20, wherein the indication is implicitly based on any one of more of any of: a name of the message; encoding of the message; and encoding of an information element in the message to be transferred to the second network node.

[0367] 22. The method of example 20, wherein the indication is an explicit indication included in one or more fields preceding the message content.

[0368] 23. The method of any one of example embodiments 14-22, wherein the first network node is a serving secondary node for the UE and the second network node is a candidate secondary node for the UE.

[0369] 24. The method of any one of example embodiments 14-22, wherein the first network node is a candidate secondary node for the UE and the second network node is a serving secondary node for the UE.

[0370] 25. The method of example embodiment 23 or 24, wherein the candidate secondary node controls a Layer-2 Triggered Mobility (LTM) candidate cell for the UE.

[0371] 26. A method for handling mobility-related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between a first network node and a second network node, the method being performed in the second network node and comprising: receiving, from a third network node acting as a master node (MN) for the UE, a message including mobility-related information relayed by the third network node to the second network node from the first network node.

[0372] 27. The method of example embodiment 26, wherein the message includes any of: an identifier of the second network node; an identifier of a target cell for the inter-SN mobility procedure; and an indication of a UE context for the UE. 28. The method of example embodiment 26 or 27, wherein the mobility-related information included in the message comprises any one or more of: a mobility-related request to the second network node; a response to a mobility-related request previously received by the first network node; a request to prepare a mobility configuration for the UE; a response including a mobility configuration for the UE; indication of execution of a mobility procedure for the UE;

[0373] Layer-1 triggered mobility (LTM) -related information; information related to subsequent mobility; and early sync information for a candidate cell.

[0374] 29. The method of example embodiment 28, wherein the mobility-related information comprises LTM-related information, the LTM-related information comprising any one or more of: an LTM candidate cell configuration; an inter-CU LTM candidate cell configuration; an inter-MN LTM configuration; a reference configuration; configuration of measurements for LTM; configuration of measurement reports for LTM; a channel-state information (CSI) resource configuration for LTM; a CSI report configuration for LTM; a configuration of an early synchronization procedure; a configuration for the execution of an LTM cell switch procedure; information to perform security key refresh; an indication to perform a complete configuration; an indication to perform a full configuration; and an indication to perform Layer 2 reset or re-establishment.

[0375] 30. The method of any one of example embodiments 26-29, wherein the message received from the third network node is received as part of an XnAP procedure. 31 . The method of any one of example embodiments 26-30, wherein the method comprises decoding the mobility-related information.

[0376] 32. The method of any one of example embodiments 26-31, wherein the second network node acts on at least part of the contents of the mobility-related information.

[0377] 33. A method for handling mobility-related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between a first network node and a second network node, the method being performed in the UE and comprising: receiving, from the first network node, a message indicating that the mobility procedure is to be executed; and transmitting, to the second network node, a message indicating that the mobility procedure has been completed.

[0378] 34. The method of example embodiment 33, wherein the message received from the first network node is a MAC CE, e.g., LTM Cell Switch Command.

[0379] 35. The method of example embodiment 33 or 34, wherein the message transmitted to the second network node is an RRC message, e.g., RRCReconfigurationComplete.

[0380] 36. The method of example embodiment 33, wherein the message received from the first network node is a first RRC message that includes a second RRC message from the second network node.

[0381] 37. The method of example embodiment 36, wherein the second RRC message included within the first RRC message is received within a container or an ASN.1 OCTET STRING type.

[0382] 38. A network node adapted to carry out a method according to any one of example embodiments 1-32.

[0383] 39. A network node comprising communication interface circuitry configured to communicate with one or more other network nodes and processing circuitry operatively coupled to the communication interface circuitry, wherein the processing circuitry is configured to carry out a method accordingto any one of example embodiments 1-32.

[0384] 40. A wireless device (e.g., a UE) adapted to carry out a method according to any one of example embodiments 33-37.

[0385] 41 . A wireless device (e.g., a UE) comprising communication interface circuitry configured to communicate with one or more network nodes and further comprising processing circuitry operatively coupled to the communication interface circuitry, wherein the processing circuitry is configured to carry out a method according to any one of example embodiments 33-37.

[0386] ABBREVIATIONS

[0387] Abbreviations Explanation

[0388] 5GC or 5GCN 5G Core Network

[0389] ACK Acknowledgement

[0390] AMF Access and Mobility management Function

[0391] AP Application Protocol

[0392] ARQ Automatic Repeat Request

[0393] C-RNTI Cell Radio NetworkTemporary Identifier

[0394] CA Carrier Aggregation

[0395] CE Control Element

[0396] CGI Cell Global Identity

[0397] CHO Conditional Handover

[0398] CN Core Network

[0399] CP Control Plane

[0400] CP Cyclic Prefix

[0401] CSI Channel State Information CU Central Unit

[0402] DC Dual Connectivity

[0403] DL Downlink

[0404] DU Distributed Unit

[0405] Interface between Central Unit and Distributed Unit gNB NR base station

[0406] GTP-U GPRS Tunneling Protocol - User Plane

[0407] IE Information Element

[0408] IP Internet Protocol

[0409] LTE Long Term Evolution

[0410] LTM L1 / L2-Triggered Mobility

[0411] MCG Master Cell Group

[0412] MAC Medium Access Control

[0413] MAC CE MAC Control Element

[0414] MN Master Node

[0415] MR-DC Multi-Radio Dual Connectivity

[0416] NAS Non Access Stratum

[0417] NASC NAS Container

[0418] NG-RAN Next Generation Radio Access Network

[0419] NCC Next hop Chaining Counter

[0420] NG Next Generation

[0421] NH Next Hop

[0422] NR New Radio

[0423] NSSAI Network Slice Selection Assistance Information

[0424] PDCP Packet Data Convergence Protocol PCell Primary Cell

[0425] PCI Physical Cell Identity

[0426] PDCCH Physical Downlink Control Channel

[0427] PDN Packet Data Network

[0428] PHR Power headroom report

[0429] PLMN Public Land Mobile Network

[0430] PSCell Primary Secondary Cell (in LTE) or Primary SCG Cell (in NR)

[0431] RACH Random Access Channel

[0432] RAT Radio Access Technology

[0433] RLC Radio Link Control

[0434] RLF Radio Link Failure

[0435] RRC Radio Resource Control

[0436] SCell Secondary Cell

[0437] SCG Secondary Cell Group

[0438] SCS Subcarrier Spacing

[0439] SeNB Secondary eNB

[0440] SgNB Secondary gNB

[0441] SINR Signal to Interference plus Noise Ratio

[0442] SN Secondary Node

[0443] SR Scheduling Request

[0444] SSB Synchronization Signal Block

[0445] SpCell Special Cell, the primary cell of a master or secondary cell group

[0446] TA Timing Advance

[0447] TAT Time Alignment Timer

[0448] TCI Transmission Configuration Indication TDD Time Division Duplex

[0449] TEID Tunnel Endpoint IDentifier

[0450] TNL Transport Network Layer

[0451] T-SN Target Secondary Node

[0452] UCI UplinkControl Information

[0453] UPF User Plane Function

[0454] UE User Equipment

[0455] UL Uplink

[0456] UL-SCH UplinkShared Channel

[0457] UP User Plane

[0458] Xn Interface between base stations

[0459] APPENDIX - STANDARDIZATION PROPOSALS

[0460] Below are examples of how the techniques and concepts described herein might be implemented in 3GPP standards. For example, 3GPPTS 38.423, v 18.2.0 (2024-06), “Xn Application Protocol

[0461] (XnAP),” might be modified to include the following. Note that a proposed figure for the 3GPP specifications is omitted from the following, and is shown as Figure 16 in the attached drawings.

[0462] - begin proposed specification excerpts -

[0463] 8.3.x LTM T ransparent Information T ransfer

[0464] 8.3.X.1 General

[0465] The purpose of the LTM Transparent Information Transfer procedure is to enable the S-NG-RAN node to inform the M-NG-RAN node about the initiation of the cell switch command to the UE. It also enables the M-NG-RAN node to inform the S-NG-RAN node about the initiation of the cell switch command to the UE. This procedure is also used to transfer LTM related information from the S-NG-RAN node to the M-NG-RAN node and also from the M-NG-RAN node to the S-NG-RAN node. The procedure uses UE-associated signalling.

[0466] 8.3.X.2 Successful Operation

[0467] [Figure omitted - See Fig. 16 ]

[0468] Figure 8.3.X.2-1 : LTM Transparent Information Transfer procedure. Successful operation.

[0469] The M-NG-RAN-NODE initiates the procedure by sending the LTM TRANSPARENT INFORMATION TRANSFER message to the S-NG-RAN-NODE orthe S-NG-RAN-NODE initiates the procedure by sending the LTM TRANSPARENT INFORMATION TRANSFER message to the M-NG-RAN-NODE.

[0470] Upon reception of the LTM TRANSPARENT INFORMATION TRANSFER message, the S-NG-RAN- NODE shall, if supported, consider that a cell switch command was sent to the UE where the target cell is indicated by the included Cell ID IE. or upon reception of the LTM TRANSPARENT INFORMATION TRANSFER message, the M-NG-RAN-NODE shall, if supported, consider that a cell switch command was sent to the UE where the target cell is indicated by the included Cell ID IE.

[0471] Upon reception of the LTM TRANSPARENT INFORMATION TRANSFER message, the S-NG-RAN- NODE shall, send it transparently to the M-NG-RAN-NODE or upon reception of the LTM TRANSPARENT INFORMATION TRANSFER message, the M-NG-RAN-NODE shall, send it transparently to the S-NG-RAN-NODE

[0472] 8.3.X.3 Unsuccessful Operation

[0473] Not applicable. 8.3.X.4 Abnormal Conditions Not applicable.

[0474] 9.1.2.x LTM Transparent Information Transfer

[0475] This message is sent by the S-NG-RAN node to the M-NG-RAN node to enable the S-NG-RAN node to inform the M-NG-RAN node about the initiation of the cell switch command to the UE. This message is also sent by the M-NG-RAN node to the S-NG-RAN node to enable the M-NG-RAN node to inform the S-NG-RAN node about the initiation of the cell switch command to the UE.

[0476] Direction: M-NG-RAN node node and

[0477] Direction: S-NG-RAN node node. end proposed specification excerpts

[0478] As another example, shown below, the S-NODE CHANGE REQUIRED and the S-NODE CHANGE CONFIRM XnAP messages are extended to transfer LTM related information in a transparent way (encoded as OCTET STRING) from source SN to MN and from MN to source SN: begin proposed specification excerpts

[0479] 9.1.2.11 S-NODE CHANGE REQUIRED

[0480] This message is sent by the S-NG-RAN node to the M-NG-RAN node to trigger the change of the S- NG-RAN node.

[0481] Direction: S-NG-RAN node node.

[0482] 9.1.2.12 S-NODE CHANGE CONFIRM

[0483] This message is sent by the M-NG-RAN node to inform the S-NG-RAN node that the preparation of the S-NG-RAN node initiated S-NG-RAN node change was successful.

[0484] Direction: M-NG-RAN node node. end proposed specification excerpts

Claims

CLAIMSWhat is claimed is:1 . A method, in a first network node, for handling mobility-related information during an intersecondary node (inter-SN) mobility procedure for a user equipment (UE) between the first network node and a second network node, the method comprising: determining a need to communicate mobility-related information to the second network node; and transmitting, to a third network node acting as a master node (MN) for the UE, a message including mobility-related information to be relayed by the third network node to the second network node.

2. The method of claim 1 , wherein the message includes any of: an identifier of the second network node; an identifier of a target cell for the inter-SN mobility procedure; and an indication of a UE context for the UE.

3. The method of claim 1 or 2, wherein the mobility-related information included in the message comprises any one or more of: a mobility-related request to the second network node; a response to a mobility-related request previously received by the first network node; a request to prepare a mobility configuration for the UE; a response including a mobility configuration for the UE; indication of execution of a mobility procedure for the UE;Layer-1 triggered mobility (LTM) -related information; information related to subsequent mobility; and early sync information for a candidate cell.

4. The method of claim 3, wherein the mobility-related information comprises LTM-related information, the LTM-related information comprising any one or more of: an LTM candidate cell configuration; an inter-CU LTM candidate cell configuration;an inter-MN LTM configuration; a reference configuration; configuration of measurements for LTM; configuration of measurement reports for LTM; a channel-state information (CSI) resource configuration for LTM; a CSI report configuration for LTM; a configuration of an early synchronization procedure; a configuration for the execution of an LTM cell switch procedure; information to perform security key refresh; an indication to perform a complete configuration; an indication to perform a full configuration; and an indication to perform Layer 2 reset or re-establishment.

5. The method of any one of claims 1-4, wherein transmitting the message to the third network node uses an XnAP procedure.

6. The method of any one of claims 1-5, wherein the mobility-related information is included in an XnAP message within the message transmitted to the third network node.

7. The method of any one of claims 1-5, wherein the mobility-related information is included in an RRC message within the message transmitted to the third network node.

8. The method of any one of claims 1-7, wherein the message comprises an indication to the third network node of any of the following: that the third network node is to decode the mobility-related information and send an exact copy of the mobility-related information to the UE; that the third network is to forward the mobility-related information to the UE without decoding the mobility-related information; that the third network node is to decode the mobility-related information and use the content of the mobility-related information to generate a message to be sent to theUE.

9. The method of claim 8, wherein the indication is implicitly based on any one of more of any of: a name of the message; encoding of the message; and encoding of an information element in the message to be transferred to the second network node.

10. The method of example 8, wherein the indication is an explicit indication included in one or more fields preceding the message content.11 . The method of any one of claims 1-10, wherein the first network node is a serving secondary node for the UE and the second network node is a candidate secondary node for the UE.

12. The method of any one of claims 1-10, wherein the first network node is a candidate secondary node for the UE and the second network node is a serving secondary node for the UE.

13. The method of claim 11 or 12, wherein the candidate secondary node controls a Layer-2 Triggered Mobility (LTM) candidate cell for the UE.

14. A method for handling mobility-related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between a first network node and a second network node, the method being performed in a third network node acting as a master node (MN) for the UE, and the method comprising: receiving, from the first network node, a message including mobility-related information to be relayed by the third network node to the second network node; and transmitting the mobility-related information to the second network node.

15. The method of claim 14, wherein the message includes any of: an identifier of the second network node; an identifier of a target cell for the inter-SN mobility procedure; and an indication of a UE context for the UE.

16. The method of claim 14 or 15, wherein the mobility-related information included in the message comprises any one or more of: a mobility-related request to the second network node; a response to a mobility-related request previously received by the first network node; a request to prepare a mobility configuration for the UE; a response including a mobility configuration for the UE; indication of execution of a mobility procedure for the UE;Layer-1 triggered mobility (LTM) -related information; information related to subsequent mobility; and early sync information for a candidate cell.

17. The method of claim 16, wherein the mobility-related information comprises LTM-related information, the LTM-related information comprising any one or more of: an LTM candidate cell configuration; an inter-CU LTM candidate cell configuration; an inter-MN LTM configuration; a reference configuration; configuration of measurements for LTM; configuration of measurement reports for LTM; a channel-state information (CSI) resource configuration for LTM; a CSI report configuration for LTM; a configuration of an early synchronization procedure; a configuration for the execution of an LTM cell switch procedure; information to perform security key refresh; an indication to perform a complete configuration; an indication to perform a full configuration; and an indication to perform Layer 2 reset or re-establishment.

18. The method of any one of claims 14-17, wherein the mobility-related information is included in an XnAP message within the message transmitted to the third network node.

19. The method of any one of claims 14-17, wherein the mobility-related information is included in an RRC message within the message transmitted to the third network node.

20. The method of any one of claims 14-19, wherein the third network node forwards at least some of the mobility-related information to the UE, according to an indication in the message that indicates any one of the following: that the third network node is to decode the mobility-related information and send an exact copy of the mobility-related information to the UE; that the third network is to forward the mobility-related information to the UE without decoding the mobility-related information; that the third network node is to decode the mobility-related information and use the content of the mobility-related information to generate a message to be sent to the UE.21 . The method of claim 20, wherein the indication is implicitly based on any one of more of any of: a name of the message; encoding of the message; and encoding of an information element in the message to be transferred to the second network node.

22. The method of example 20, wherein the indication is an explicit indication included in one or more fields preceding the message content.

23. The method of any one of claims 14-22, wherein the first network node is a serving secondary node for the UE and the second network node is a candidate secondary node for the UE.

24. The method of any one of claims 14-22, wherein the first network node is a candidate secondary node for the UE and the second network node is a serving secondary node for the UE.

25. The method of claim 23 or 24, wherein the candidate secondary node controls a Layer-2 Triggered Mobility (LTM) candidate cell for the UE.

26. A method for handling mobility-related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between a first network node and a second network node, the method being performed in the second network node and comprising: receiving, from a third network node acting as a master node (MN) for the UE, a message including mobility-related information relayed by the third network node to the second network node from the first network node.

27. The method of claim 26, wherein the message includes any of: an identifier of the second network node; an identifier of a target cell for the inter-SN mobility procedure; and an indication of a UE context for the UE.

28. The method of claim 26 or 27, wherein the mobility-related information included in the message comprises any one or more of: a mobility-related request to the second network node; a response to a mobility-related request previously received by the first network node; a request to prepare a mobility configuration for the UE; a response including a mobility configuration for the UE; indication of execution of a mobility procedure for the UE;Layer-1 triggered mobility (LTM) -related information; information related to subsequent mobility; and early sync information for a candidate cell.

29. The method of claim 28, wherein the mobility-related information comprises LTM-related information, the LTM-related information comprising any one or more of: an LTM candidate cell configuration; an inter-CU LTM candidate cell configuration; an inter-MN LTM configuration; a reference configuration; configuration of measurements for LTM; configuration of measurement reports for LTM; a channel-state information (CSI) resource configuration for LTM;a CSI report configuration for LTM; a configuration of an early synchronization procedure; a configuration for the execution of an LTM cell switch procedure; information to perform security key refresh; an indication to perform a complete configuration; an indication to perform a full configuration; and an indication to perform Layer 2 reset or re-establishment.

30. The method of any one of claims 26-29, wherein the message received from the third network node is received as part of an XnAP procedure.31 . The method of any one of claims 26-30, wherein the method comprises decoding the mobility- related information.

32. The method of any one of claims 26-31 , wherein the second network node acts on at least part of the contents of the mobility-related information.

33. A method for handling mobility-related information during an inter-secondary node (inter-SN) mobility procedure for a user equipment (UE) between a first network node and a second network node, the method being performed in the UE and comprising: receiving, from the first network node, a message indicating that the mobility procedure is to be executed; and transmitting, to the second network node, a message indicating that the mobility procedure has been completed.

34. The method of claim 33, wherein the message received from the first network node is a MAC CE, e.g., LTM Cell Switch Command.

35. The method of claim 33 or 34, wherein the message transmitted to the second network node is an RRC message, e.g., RRCReconfigurationComplete.

36. The method of claim 33, wherein the message received from the first network node is a first RRC message that includes a second RRC message from the second network node.

37. The method of claim 36, wherein the second RRC message included within the first RRC message is received within a container or an ASN.1 OCTET STRING type.

38. A network node adapted to carry out a method according to any one of claims 1-32.

39. A network node comprising communication interface circuitry configured to communicate with one or more other network nodes and processing circuitry operatively coupled to the communication interface circuitry, wherein the processing circuitry is configured to carry out a method according to any one of claims 1-32.

40. A wireless device (e.g., a UE) adapted to carry out a method according to any one of claims 33- 37.41 . A wireless device (e.g., a UE) comprising communication interface circuitry configured to communicate with one or more network nodes and further comprising processing circuitry operatively coupled to the communication interface circuitry, wherein the processing circuitry is configured to carry out a method according to any one of claims 33-37.

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