Signaling for semi-persistent or aperiodic channel-state information reference signal measurements

Abstract

Methods for signaling for semi-periodic or aperiodic channel-state information reference signal measurements, are disclosed herein. Corresponding systems and apparatuses are also disclosed. The method performed by a first network node comprises sending, to a second network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells. The method further comprises receiving, from the second network node, an indication of the operational status of the reference signal corresponding to the one or more candidate cells. The method further comprises sending, to a UE, the indication of the operational status of the reference signal, where the UE sends or stops sending individual measurement reports based on the reference signal in accordance with the indication.

Description

SIGNALING FOR SEMI-PERSISTENT OR APERIODIC CHANNEL-STATE INFORMATION REFERENCE SIGNAL MEASUREMENTSFIELD

[0001] The present disclosure relates generally to communication systems, and more specifically to measuring channel state information reference signals in wireless communication networks.BACKGROUNDL1 / L2 Triggered Mobility (LTM) in 3GPP Release 18 (Rel-18)

[0002] Layer 1, LI, / Layer 2, L2, Triggered Mobility (LTM) is a procedure in which a gNB (gNodeB) receives LI measurement report(s) from a User Equipment (UE) and, on their basis, the gNB changes the UE serving cell by a cell switch command signaled via a Medium Access Control - Control Element (MAC CE). The cell switch command indicates an LTM candidate configuration that the gNB previously prepared and provided to the UE through RRC signaling. Then the UE switches to the target configuration according to the cell switch command [1],

[0003] When configured by the network, it is possible to activate Transmission Configuration Indicator (TCI) states of one or multiple cells that are different from the current serving cell. This is sometimes called pre-activation of a candidate TCI state, since this is pre-activating a TCI state of an LTM candidate cell before the UE receives the LTM cell switch command, i.e., before the LTM cell switch procedure. For instance, the TCI states of the LTM candidate cells can be activated in advance before any of the candidate cells become the serving cell. This allows the UE to be downlink (DL) synchronized with those cells (or DL pre-sync), thereby facilitating a faster cell switch to one of those cells when cell switch is triggered. The cell switch command is conveyed in a MAC CE, which contains the necessary information to perform the LTM cell switch. The overall procedure, between a UE 102 and a gNB 104, for LTM is shown in Figure 1.

[0004] The procedure 100 for LTM is as follows:Step 1 SI 10. The UE sends a MeasurementReport message to the gNB. The gNB decides to configure LTM and initiates LTM preparation.Step 2 S120. The gNB transmits a Radio Resource Control reconfiguration (RRCReconfiguration) message to the UE including the LTM candidate configurations.Step 3 S130. The UE stores the LTM candidate configurations and transmits an RRCReconfigurationComplete message to the gNB.Step 4a S140. The UE performs DL synchronization with the candidate cell(s) before receiving the cell switch command. This is triggered upon reception by the UE of a “Candidate Cell TCI States Activation / Deactivation MAC CE” for LTM candidate cell(s) configured in CandidateTCI-State and CandidateTCI-UL-State. Upon reception, in the UE’s MAC entity, the UE’s MAC entity receives a Candidate Cell TCI States Activation / Deactivation MAC CE on a Serving Cell, the UE indicates to lower layers the information regarding the Candidate Cell TCI States Activation / Deactivation MAC CE.Step 4b S145. The UE may also perform UL pre-synchronization with the LTM candidate cell(s) if the UE receives the Physical Downlink Control Channel (PDCCH) order for early timing advance (TA) acquisition for those candidate cells.Step 5 SI 50. The UE performs LI measurements on the configured candidate cell(s) and transmits LI measurement reports to the gNB. LI measurement should be performed as long as RRC reconfiguration (step 2) is applicable.Step 6 SI 60. The gNB decides to execute a cell switch to a target cell and transmits a MAC CE triggering the cell switch by including the candidate configuration index of the target cell. The UE switches to the target cell and applies the configuration indicated by candidate configuration index.Step 7 SI 70. The UE performs the random-access procedure towards the target cell, if the UE does not have valid TA of the target cell. Otherwise, if the UE receives a valid TA value in the LTM cell switch command using the early TA acquisition method in step 4b, the UE is not required to perform random-access.Step 8 SI 80. The UE completes the LTM cell switch procedure by sending a Radio Resource Control reconfiguration complete (RRCReconfigurationComplete) message to the target cell. If the UE has performed a random-access procedure in Step 7 S170, the UE considers that the LTM cell switch execution is successfully completed when the randomaccess procedure is successfully completed. For Random-Access Channel (RACH) -less LTM, the UE considers that the LTM cell switch execution is successfully completed when the UE determines that the network has successfully received its first UL data.Support for CSI-RS measurements for LTM in 3 GPP Release 19 (Rel-19)

[0005] LTM was introduced in Rel-18 and can offer improvements in handover latency and interruption time compared to Layer 3 based mobility. However, LTM as introduced in Rel-18also has a number of limitations compared to Layer 3 mobility. The Rel-19 work item aims to remove a number of these limitations. One of the objectives for the Rel-19 Work Item (WID) “NR mobility enhancements Phase 4” [1] is as below:• Measurements related enhancements for purpose of supporting LTM: [RAN2, RANI]• Measurement related enhancements are applicable to Intra-CU MCG / SCG LTM and Inter-CU MCG / SCG LTM• Specify necessary components to support event triggered LI measurement reporting [RAN2, RANI]• Specify support for CSLRS measurements for LTM procedures and enable CSI-RS based beam management [RANI]• Specify CSI acquisition on candidate cell(s) based on CSLRS before or during LTM cell switch [RANI]

[0006] NOTE: The RANI Work Group (WG) is to decide on whether to support CSI report before or during the LTM cell switch, as part of the CSI acquisition procedure.SUMMARY

[0007] Various computer-implemented systems, methods, and articles of manufacture related to candidate cell reference signal measurements in wireless communication networks are described herein. In one embodiment, a method performed by a first network node for reference signal measurements comprises sending, to a second network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells. The method further comprises receiving, from the second network node, an indication of the operational status of the reference signal corresponding to the one or more candidate cells. The method further comprises sending, to a User Equipment, UE, the indication of the operational status of the reference signal, where the UE sends or stops sending individual measurement reports based on the reference signal in accordance with the indication. The method may further comprise sending, to the UE, a configuration for measuring the reference signal corresponding to the one or more candidate cells. The method may further comprise sending, to the UE, a configuration for reporting measurements based on the reference signal corresponding to the one or more candidate cells. The method may further comprise sending, to the UE, an indication to send or stop sending individual measurement reports based on the reference signal. The method may further comprise sending, to the second network node, a request for a subscription to receive the indication of the operational status of thereference signal corresponding to the one or more candidate cells. The method may further comprise receiving, from the second network node, an indication of whether the request for the subscription has been accepted or rejected. The method may further comprise receiving, from the second network node, an indication of the operational status of the reference signal when the request for the subscription has been accepted.

[0008] In one embodiment, a method performed by a second network node for reference signal measurements comprises receiving, from a first network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells. The method further comprises sending, to a third network node, the request to change an operational status. The method further comprises receiving, from the third network node, an indication of an operational status of the reference signal corresponding to the one or more candidate cells, where the indication comprises a response to the request to change the operational status of the reference signal. The method further comprises sending, to the first network node, the indication of the operational status of the reference signal corresponding to the one or more candidate cells.

[0009] In one embodiment, a method performed by a second network node for reference signal measurements comprises receiving, from a third network node or from a fourth network node, an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi -persistently or aperiodically. The method further comprises sending, to a first network node, the indication of the operational status of the reference signal corresponding to the one or more candidate cells.

[0010] In one embodiment, a method performed by a second network node for reference signal measurements comprises receiving, from a first network node, a request for a subscription to receive an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi -persistently or aperiodically. The method further comprises sending, to a third network node, the request for the subscription to receive the indication of the operational status of the reference signal and a request for the indication of the operational status of the reference signal. The method further comprises receiving, from the third network node, at least one of: the indication of whether the request for the subscription has been accepted or rej ected, or indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference. The method further comprises sending, to the first network node, at least one of the indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference.

[0011] In one embodiment, a method performed by a third network node for reference signal measurements comprises receiving, from a second network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells, where the request corresponds to at least one User Equipment, UE. The method further comprises sending, to a fourth network node, the request to change the operational status. The method further comprises receiving, from the fourth network node, an indication of an operational status of the reference signal corresponding to the one or more candidate cells, where the indication comprises a response to the request to change the operational status of the reference signal. The method further comprises sending, to the second network node, the indication of the operational status of the reference signal corresponding to the one or more candidate cells.

[0012] In one embodiment, a method performed by a third network node for reference signal measurements comprises receiving, from a second network node, a request for a subscription to receive an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi -persistently or aperiodically, and where the request corresponds to at least one User Equipment, UE. The method further comprises sending, to a fourth network node, the request for the subscription to receive the indication of the operational status of the reference signal and a request for the indication of the operational status of the reference signal. The method further comprises receiving, from the fourth network node, at least one of an indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference. The method further comprises sending, to the second network node, at least one of the indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference.

[0013] In one embodiment, a method performed by a fourth network node for reference signal measurements comprises receiving, from a third network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi-persistently or aperiodically, and where the request corresponds to at least one User Equipment, UE. The method further comprises sending, to the third network node, an indication of the operational status of the reference signal corresponding to the one or more candidate cells, where the indication comprises a response to the request to change the operational status of the reference signal.

[0014] In one embodiment, a method performed by a fourth network node for reference signal measurements comprises receiving, from a third network node, a request for a subscription to receive an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi-persistently or aperiodically, andwhere the request corresponds to at least one User Equipment, UE. The method further comprises sending, to the third network node, at least one of an indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference.

[0015] In one embodiment, a method performed by a user equipment, UE, for reference signal measurements comprises receiving, from a first network node, an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi-persistently or aperiodically. The method further comprises sending, to the first network node, individual measurement reports based on the reference signal in accordance with the indication. The method may further comprise receiving, from the first network node, a configuration for measuring the reference signal corresponding to the one or more candidate cells. The method may further comprise receiving, from the first network node, a configuration for reporting measurements based on the reference signal corresponding to the one or more candidate cells. The method may further comprise receiving, from the first network node, an indication to send individual measurement reports based on the reference signal. The method may further comprise receiving, from the first network node, an indication to stop sending individual measurement reports based on the reference signal.

[0016] In one embodiment, a user equipment comprises processing circuitry configured to receive, from a first network node, an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi- persistently or aperiodically; and send, to the first network node, individual measurement reports based on the reference signal in accordance with the indication. The UE further comprises power supply circuitry configured to supply power to the processing circuitry.

[0017] In one embodiment, a first network node comprises processing circuitry configured to send, to a second network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells; receive, from the second network node, an indication of an operational status of the reference signal corresponding to the one or more candidate cells; and send, to a User Equipment, UE, the indication of the operational status of the reference signal, where the UE sends or stops sending individual measurement reports based on the reference signal in accordance with the indication. The first network node further comprises power supply circuitry configured to supply power to the processing circuitry.

[0018] In one embodiment, a second network node comprises processing circuitry configured to receive, from a first network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells; send, to a third network node, the request to changean operational status; receive, from the third network node, an indication of an operational status of the reference signal corresponding to the one or more candidate cells, where the indication comprises a response to the request to change the operational status of the reference signal; and send, to the first network node, the indication of the operational status of the reference signal corresponding to the one or more candidate cells. The second network node further comprises power supply circuitry configured to supply power to the processing circuitry.

[0019] In one embodiment, a third network node comprises processing circuitry configured to receive, from a second network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells, where the request corresponds to at least one User Equipment, UE; send, to a fourth network node, the request to change the operational status; receive, from the fourth network node, an indication of an operational status of the reference signal corresponding to the one or more candidate cells, where the indication comprises a response to the request to change the operational status of the reference signal; and send, to the second network node, the indication of the operational status of the reference signal corresponding to the one or more candidate cells. The third network node further comprises power supply circuitry configured to supply power to the processing circuitry.

[0020] In one embodiment, a fourth network node comprises processing circuitry configured to receive, from a third network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi- persistently or aperiodically, and where the request corresponds to at least one User Equipment, UE; and send, to the third network node, an indication of the operational status of the reference signal corresponding to the one or more candidate cells, where the indication comprises a response to the request to change the operational status of the reference signal. The fourth network node further comprises power supply circuitry configured to supply power to the processing circuitry.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0022] Figure 1 illustrates the overall procedure for LTM.

[0023] Figure 2 illustrates signaling flows for source gNB-DU requesting to start / stop CSI- RS, in accordance with some embodiments of the present disclosure.

[0024] Figure 3 illustrates signaling flows for target gNB-DU informing the source of start / stop CSI-RS, in accordance with some embodiments of the present disclosure.

[0025] Figure 4 illustrates signaling flows for target gNB-DU informing the source of start / stop CSI-RS based on subscription, in accordance with some embodiments of the present disclosure.

[0026] Figure 5 illustrates a flowchart showing a method performed by a first network node for reference signal measurements, in accordance with some embodiments.

[0027] Figure 6 illustrates a flowchart showing a method performed by a second network node for reference signal measurements, in accordance with some embodiments.

[0028] Figure 7 illustrates a flowchart showing a method performed by a second network node for reference signal measurements, in accordance with some embodiments.

[0029] Figure 8 illustrates a flowchart showing a method performed by a second network node for reference signal measurements, in accordance with some embodiments.

[0030] Figure 9 illustrates a flowchart showing a method performed by a third network node for reference signal measurements, in accordance with some embodiments.

[0031] Figure 10 illustrates a flowchart showing a method performed by a third network node for reference signal measurements, in accordance with some embodiments.

[0032] Figure 11 illustrates a flowchart showing a method performed by a fourth network node for reference signal measurements, in accordance with some embodiments.

[0033] Figure 12 illustrates a flowchart showing a method performed by a fourth network node for reference signal measurements, in accordance with some embodiments.

[0034] Figure 13 illustrates a flowchart showing a method performed by a user equipment, UE for reference signal measurements, in accordance with some embodiments.

[0035] Figure 14 shows an example of a communication system in accordance with some embodiments of the present disclosure.

[0036] Figure 15 shows a User Equipment device (UE) in accordance with some embodiments of the present disclosure.

[0037] Figure 16 shows a network node in accordance with some embodiments of the present disclosure.

[0038] Figure 17 is a block diagram illustrating a virtualization environment in which functions implemented by some embodiments may be virtualized in accordance with some embodiments of the present disclosure.DETAILED DESCRIPTION

[0039] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Uponreading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0040] Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

[0041] There currently exist certain challenges. In the case of supporting CSI-RS measurements for LTM in Rel-19, the source network node needs to acquire the CSI from the UE either periodically, semi-statically, or dynamically (using aperiodic reporting). The UE performs measurements on CSI-RS from a candidate cell only if a particular CSI-RS reference signal is transmitted by the candidate cell. CSI-RS reference signals can be transmitted periodically, semi- statically and aperiodically, meaning that CSI-RS signals are not like the periodic SSB reference signals, which must always be broadcast by a network. Due to this, and due to the fact that the candidate cell with activate or deactivate the transmission of the CSI-RS reference signals, it should be possible for the serving cell (or source cell) to understand whether a certain CSI-RS reference signal is activated / deactivated or not. In fact, if a semi-persistent or aperiodic CSI-RS is not activated / broadcast, the serving network node may configure a UE to perform and report measurements based on one or more a CSI-RS reference signals and get nothing in return, as the UE cannot measure reference signals which are not transmitted / broadcast. This is a reason is why a coordination between a source node (serving cell) and a target node (candidate cell(s) is preferred, e.g., such that a source node can request the semi-persistent and aperiodic reports from the UE and get a valid CSI information.

[0042] Certain aspects of the disclosure and their embodiments may provide solutions to these or other challenges. In order to address the above challenges, some embodiments of the current disclosure present solutions to perform a request for a reference signal (e.g., CSI-RS) configuration for the UE, e.g., during an Ll / L2-triggered mobility (LTM) procedure.

[0043] The source network node (comprising both the source gNB-DU and source gNB-CU) coordinates with the candidate network node (including both the candidate gNB-DU and candidate gNB-CU) by sending a request to activate or deactivate the transmission of the CSI-RS resource for measurements on LTM candidate cell(s). In response, the candidate network node indicates its status to the source network node. The source network node then notifies the UE to either initiate or stop measurement reports based on the CSI-RS reference signal. This request may also includea subscription request to specify whether the transmission of CSI-RS in the LTM candidate cell(s) can be informed by the target node.

[0044] The solutions also describe the actions performed by the UE when it receives the command regarding activation / deactivation of CSI-RS reference signals, and reports the measurements to the network.

[0045] Certain embodiments may provide one or more of the following technical advantages. Semi-persistent and aperiodic CSI-RS can reduce the signaling overhead compared to periodic CSI-RS which generally consumes a lot of resources. Additionally, semi -persistent and aperiodic CSI-RS could reduce the number of measurements that a UE has to perform for LTM. But to enable semi-persistent or aperiodic CSI-RS, coordination between the source and candidate nodes is essential to decide when to start or stop CSI-RS transmissions from the candidate cell.

[0046] With a coordination between the source and target node so the source node knows when and which CSI-RS reference signals are broadcast by the target node, the source node is able to configure a UE to measure the CSI-RS reference signal and report measurements on one or more CSI-RS reference signals. The teachings of certain embodiments may improve e.g., the data rate, latency, power consumption, etc. of a mobile communication network.Initial description

[0047] The disclosure herein refers to the term “L1 / L2 based inter-cell mobility” as used in the Work Item Description in 3GPP, though it interchangeably also uses the terms L1 / L2 mobility, Ll-mobility, LI based mobility, Ll / 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 an included serving cell (e.g., signaling to change a PCell, from a source to a target PCell), wherein a lower layer signaling is a message / signaling of a lower layer protocol (e.g. lower than RRC), 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., the change of the 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 Master Cell Group (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.

[0048] 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 herein a candidate cell or a neighbor 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 a 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 cells and target cells in an 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.

[0049] The disclosure herein refers to at least one LTM candidate cell configuration. This is also sometimes referred to as a configuration of an 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. An 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 for 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).

[0050] 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 an 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).

[0051] 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., a 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 the 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 a change of security key(s).

[0052] The disclosure herein 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.

[0053] 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.

[0054] The disclosure herein 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.

[0055] An inter-CU LTM candidate cell configuration may be the same as an LTM candidate cell configuration, but it may also include information in addition to what is included in the LTM candidate cell configuration used for inter-CU cell switch. This additional information may be, for example:• Information to perform a security key refresh, e.g., the RRC IE MasterKeyUpdate or a RRC IE RadioBearerConfig that includes SecurityConfig with Security AlgorithmConfig• Indication to perform PDCP re-establishment.• Indication to perform a full configuration, e.g., the RRC field fullConfig.

[0056] The disclosure herein 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 (CP AC). The solutions described herein sometimes use 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.

[0057] The disclosure herein 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).

[0058] 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:• LTM candidate cell configured on(s),• inter-CU LTM candidate cell configuration(s),• Lower layer information, such as physical layer configuration, MAC layer configuration or RLC layer configuration, Cell Group configuration, serving cell configuration.• Higher layer information, such as RRC protocol parameters, such as timer values, PDCP layer configuration, radio bearer configuration or measurement configuration• Configuration(s) of measurements for LTMConfiguration(s) for measurement reports for LTMCSI resource configuration(s) for LTM• CSI report configuration(s) for LTM• Configurations of early synchronization procedures, such as• Configurations for DL pre-sync for LTM, such as configurations for early TCI state activation• Configurations for UL pre-sync for LTM, such as configurations for reception ofPDCCH ordered triggered preamble transmission and reception of TA.• 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.• 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.• Information to perform security key refresh, e.g., the RRC IE MasterKeyUpdate or a RRC IE RadioBearerConfig that includes SecurityConfig with Security AlgorithmConfig.• An indication to perform a full configuration, e.g., the RRC field fullConfig.• An indication to perform L2 re-establishment, such as an indication to perform PDCP re-establishment for one or multiple bearers.

[0059] The term “subsequent LTM” sometimes also referred to as “subsequent LTM cell switch (procedures)” refers to when 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.

[0060] 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 “Tracking Reference Signal” (“TRS”). This isjust to clarify that the embodiments of the current disclosure do not target specifically a scenario where there is a cell, but rather when a UE uses a set of source radio resources and needs 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. l structures or IES. The disclosure herein uses the term “early DL synchronization” to describe the action performed by the UE of pre-activating a TCI state of at least one LTM candidate cell configuration before performing an LTM cell switch execution. In this case, the TCI state on a given LTM candidate cell is “activated in advance”, or “pre-activated”. Therefore, the terms “early DL synchronization”, or “early TCI state activation”, or “early TCI state pre-activation” can be exchanged in the methods without any loss of meaning. Moreover, the disclosure herein uses the terms “first network node” and “second network node” to refer to a source cell / serving cell / source gNB-DU / S-DU and a candidate cell / candidate gNB- DU / C-DU, respectively.

[0061] The disclosure herein uses terms such as “measurement report based on CSLRS reference signals” or “CSI-RS measurement” and these terms are basically used to identify a measurement framework where the reference signal configured to be measured is one or more CSI-RS reference signals. In particular, the UE gets one or more measurement configurations which indicates to the UE which CSI-RS reference signals the UE should measure for one or more configured candidate cells. In addition, the UE also receives a measurement report which is linked to the one or more received measurement configuration which indicates to the UE which CSI-RS reference signals the UE should measure. The UE, based on this received measured report configuration and, for some cases, based also from an indication received by the network, will send a measurement report to the network which include measurement quantities (e.g., RSRP) for each of the reported CSI-RS reference signals.

[0062] Some embodiments include some of the following features:

[0063] AL Methods for a first network node (such as a serving gNB-DU), which configured the UE with at least one LTM CSI resource configuration where the reference signal is a CSI-RS and configured the UE also with an LTM CSI report configuration to report measurement based on CSI-RS reference signals, the method comprising one or more of the following: Transmitting a message to a second network node which includes an indication to request for activation / tuming on / off transmission of a CSI-RS resource for the CSI-RS measurements for one or more LTM candidate cell (s) . Receiving a message from the second network node which includes an indication about activation / tuming on / off CSI-RS resource transmission for one or more LTM candidate cell(s). Transmitting a lower layer signaling to the UE to indicate the activation (or in alternative the deactivation) of a semi-persistent or aperiodic CSI-RS resource set. Transmitting a lower layersignaling to the UE to indicate to trigger the sending of a measurement report based on CSI-RS reference signal for one or more LTM candidate cell(s), or in the alternative, transmitting a lower layer signaling to the UE to indicate to stop sending measurement reports based on a CSI-RS reference signal for one or more LTM candidate cell(s).

[0064] A2a. The method in Al, wherein the indication included in the message transmitted to the second network node is a request to activate or deactivate one or more CSI-RS reference signals (CSI-RS resource or CSI-RS resource set) of an LTM candidate cell for a given UE. In one example, the indication includes an enumerated value for each of the one or more included CSI- RS reference signals related to one or more LTM candidate cells which indicates the request to start or stop the CSI-RS reference signal. For example, a value equal to “0” or “stop” to indicate the request to stop / deactivate the CSI-RS reference signal, or a value equal to “1” or “start” to request to start / activate the CSI-RS reference signal, where the indication applies to at least one (or any, or all, or each) LTM candidate cell configured by the gNB-DU, in one F1AP message. The F1AP message can be either UE associated, e.g., UE CONTEXT MODIFICATION REQUIRED message, or a non-UE associated message. In one example, the indication includes an enumerated value for each of the CSI-RS resource set or CSI-RS resource index / ID related to one or more LTM candidate cells which indicate the request to start or stop the CSI-RS reference signal. In one example, the indication includes the start time and / or stop time of the CSLreference signal or CSI-Resource set or CSI resource related to one or more LTM candidate cells. In one example, the indication is one value which is common to each of the one or more included CSI- RS reference signals or CSI-RS resource set or CSI-RS resource related to one or more LTM candidate cells which need to be “all” stopped or started or activated or deactivated. In one example, the indication includes a UE identifier and / or an identifier of a previously provided CSI- RS configuration by a fourth network node (e.g., a C-DU of the LTM candidate cell for which the CSI-RSs are to be transmitted).

[0065] A2b. The method in Al, wherein the indication included in the message received from the second network node is an indication on which CSI-RS reference signals are activated or deactivated (or that will be activated, or that will be deactivated) for one or more candidate cells. In one example, the indication includes an enumerated value for each of the one or more included CSI-RS reference signals related to one or more LTM candidate cells which indicate the status of the reference CSI-RS reference signal (e.g., whether the CSI-RS reference signal is activated or started or stopped or deactivated). For example, a value equal to “0” or “stop”, to indicate the CSI- RS reference signal is deactivated or stopped or deactivated, or a value “1” or “start” to indicate the CSI-RS reference signal is started or activated, wherein the indication applies to at least one(or any, or all, or each) LTM candidate cell configured by the gNB-DU, in one F1AP message. The F1AP message can be either UE associated, e.g., UE CONTEXT MODIFICATION REQUIRED message, or a non-UE associated message. In one example, the indication includes an enumerated value for each of the one or more included CSI-RS resource set or CSI-RS resource index related to one or more LTM candidate cell which indicates the status of the reference CSI- RS reference signal (e.g., whether the CSI-RS resource set or CSI-RS resource is activated or started or stopped or deactivated). In one example, the indication is one value which is common to each of the one or more included CSI-RS reference signals related to one or more LTM candidate cell and which indicates that “all” CSI-RS reference signals are stopped or started or activated or deactivated.

[0066] A2c. The method in Al and A2a, wherein the indication in the message transmitted by the first network node is a request to activate, start, stop, or deactivate one or more CSI-RS reference signals or CSI-RS resource set or CSI-RS resource index related to one or more candidate cell. In such a case, the first network node does not indicate any particular CSI-RS reference signal, but leaves the decision of which one to activate to the second network node.

[0067] In one alternative (corresponding to the signaling flow chart in Figure 2 below) of embodiment Al, when the first network node (such as a serving gNB-DU), is configured with at least one LTM candidate configuration that includes CSI resources that are transmitted by the candidate cell, the first network node does not transmit an indication to request for the second network node to start or stop CSI-RS reference signal. The method comprising one or more of Receiving a message from the second network node to indicate whether the CSI-RS transmission is turned on / off for the UE; transmitting a lower layer signaling (e.g., a MAC CE) to the UE to indicate the activation (or in alternative the deactivation) of semi -persistent CSI-RSI resource; transmitting a lower layer signaling to the UE to indicate to trigger the sending of a measurement report based on CSI-RS reference signal for one or more LTM candidate cell(s), or in alternative transmitting a lower layer signaling to the UE to indicate to stop sending measurement report base on CSI-RS reference signal for one or more LTM candidate cell(s).

[0068] In one embodiment (corresponding to the signaling flow chart in Figure 2 below), alternative to Al, when the first network node (such as a serving gNB-DU), is configured with at least one LTM candidate configuration that includes CSI resources that are transmitted by the candidate cell, the first network node transmits a request (e.g., a subscription request) to receive from the second network node indication(s) concerning activation or deactivation of CSI-RS reference signals. The method comprising one or more of Transmitting a message to the second network node comprising a subscription request (or an interest) to receive indication, indicatingwhether transmission of CSI-RS in LTM candidate cell(s) is started, or is stopped, or is ongoing; optionally receiving a response from the second network node to accept or reject the subscription request; receiving a message from the second network node to indicate whether the transmission of CSI-RS is turned on / off or is ongoing; transmitting a lower layer signaling (e.g., a MAC CE) to the UE to indicate the activation (or in alternative the deactivation) of semi -persistent CSI-RS resource; and transmitting a lower layer signaling to the UE to indicate to trigger the sending of a measurement report based on CSI-RS reference signal for one or more LTM candidate cell(s), or in alternative transmitting a lower layer signaling to the UE to indicate to stop sending measurement report base on CSI-RS reference signal for one or more LTM candidate cell(s).

[0069] In one embodiment, the first network node (S-DU) transmits, from the second network node (CU), a request for a CSI-RS configuration for a UE served by the S-DU, wherein the CSI- RS configuration requested is associated to an LTM candidate cell of a fourth network node (e.g., C-DU), wherein the CSI-RS configuration request includes an indication of a preferred timedomain pattern, determined by the first network node (e.g., periodic, semi-persistent, aperiodic). In other words, the S-DU requests the C-DU to transmit CSI-RSs of an LTM candidate cell so that the UE served by the S-DU and configured with LTM may perform measurements on these CSI- RSs and report them.

[0070] In one option, the S-DU receives the CSI-RS configuration of the candidate LTM cell for the UE according to the requested configuration. When that is received, it may include an indication of the time-domain pattern. In one option, when the S-DU requests the time-domain pattern to be of a certain type (e.g., semi-persistent, aperiodic), the C-DU has the option to accept or reject that particular request, but it cannot provide another pattern. In another option, when the S-DU requests the time-domain pattern to be of a certain type (e.g., semi-persistent, aperiodic) the C-DU has the option to accept that particular request, reject that particular request, or provide a configuration with a different pattern, e.g., the S-DU requests the CSI-RSs to be periodic but the C-DU provides a configuration of semi-persistent CSI-RSs. In the case where the C-DU provides CSI-RS configuration(s) for an LTM candidate cell which are semi -persistent or periodic, the methods above are applicable (e.g., to coordinate the activation / deactivation of CSI-RSs).

[0071] In one embodiment, when the first network node is indicated by the C-DU (e.g., via the CU) that CSI-RSs are periodic, the S-DU assumes they are being transmitted, i.e., the S-DU assumes it can configure the UE from the moment it has received the CSI-RS configuration.

[0072] In one embodiment, when the first network node (e.g., S-DU) is indicated by the fourth network node (C-DU, e.g., via the CU) that CSI-RSs are aperiodic, the S-DU assumes they are not being transmitted yet, i.e., the S-DU can configure the UE with CSI-RSs deactivated. Then, uponreceiving an indication of activation from the fourth network node (e.g. C-DU), the first network node determines whether to activate the CSI-RSs for the UE.

[0073] In one embodiment, when the first network node (e.g., S-DU) is indicated by the fourth network node (C-DU, e.g., via the CU) that CSI-RSs are semi-persistent, the S-DU assumes they are not being transmitted yet, i.e., the S-DU can configure the UE with CSI-RSs deactivated. Then, upon receiving an indication of activation from the fourth network node (e.g., C-DU), the first network node determines whether to activate the CSI-RSs for the UE.

[0074] In one embodiment, when the first network node (e.g., S-DU) is indicated by the fourth network node (C-DU, e.g., via the CU) that CSI-RSs are semi-persistent, the S-DU assumes they are being transmitted, i.e., the S-DU can configure the UE with CSI-RSs activated. Then, upon receiving an indication of deactivation from the fourth network node (e.g., C-DU), the first network node determines to deactivate the semi-persistent CSI-RSs for the UE.

[0075] In one embodiment, when the first network node (e.g., S-DU) is indicated by the fourth network node (C-DU, e.g., via the CU) that CSI-RSs are semi-persistent, the S-DU also receives an indication of the current state of the CSI-RSs, e.g., activated / deactivated.

[0076] In one embodiment, the first network node (e.g., S-DU) indicates to the CU the (latest) ‘state’ of a CSI-RS configuration of a second LTM candidate cell, upon triggering an LTM cell switch to a first LTM candidate cell. The CU indicates such ‘state’ of the CSI-RS configuration of the second LTM candidate cell to the C-DU of the first LTM candidate cell, which now becomes the new S-DU. In this option, when an LTM cell switch is triggered, the UE assumes that the latest state of CSI-RS transmissions remains the same as before the LTM cell switch.

[0077] In one embodiment, the first network node (e.g., S-DU) indicates to the CU the (latest) ‘state’ of a CSI-RS configuration of a second LTM candidate cell, upon triggering an LTM cell switch to a first LTM candidate cell. The CU indicates then LTM Cell Switch to the CU, so that the CU indicates to the C-DU of the second LTM candidate cell, that may deactivate the CSI-RS configuration, if activated. As such, the new S-DU (i.e., the S-DU of the first LTM candidate cell may later decide to activate or not activate that CSI-RS configuration of the second LTM candidate cell). In this option, when an LTM cell switch is triggered, the UE assumes that the latest state of CSI-RS transmissions does not remain the same as before the LTM cell switch; in other words, upon LTM cell switch the UE deactivates one or more activated CSI-RSs associated to LTM candidate cells.

[0078] BL Methods for a second network node (such as a serving gNB-CU), which is handling the mobility control and control plane for the first network node, the method comprising one or more of: Receiving a message from the first network node which includes an indicationabout CSI-RS measurements for one or more candidate cell(s); transmitting a message with the above indicator to the third network node. This message can be an XnAP message, for example, HANDOVER REQUEST, or a new message. The method further comprises receiving a message from the third network node with the information on CSI-RS measurements for one or more candidate cell; and transmitting a message to the first network node with the information on CSI- RS measurements for one or more candidate cells.

[0079] B2a. The method in Bl, wherein the indication included in the message transmitted to the third network node is a request to activate or deactivate one or more CSI-RS reference signals. In one example, the indication includes an enumerated value for each of the one or more included CSI-RS reference signals related to one or more candidate cells which indicates the request to start or stop the CSI-RS reference signal. For example, a value equal to “0” or “stop” indicates stop / deactivation of CSI-RS reference signal, or “1” or “stop” indicates start / activation of CSI-RS reference signal, where the indication applies to at least one (or any, or all, or each) LTM candidate cell configured by the gNB-DU, in one XnAP message. The XnAP message can be either UE- associated, or a non-UE associated message. In one example, the indication is one value which is common to each of the one or more included CSI-RS reference signals related to one or more LTM candidate cells which need to be “all” stopped or started or activated or deactivated. In one example, the indication includes the start time and / or stop time of the CSI-reference signal or CSL Resource set or CSI resource related to one or more LTM candidate cells, where the CSI reference signal may be a CSI-RS resource set or CSI-RS resource.

[0080] B2b. The method in Bl, wherein the indication included in the message received from the third network node is an indication on which CSI-RS reference signals are activated or deactivated for one or more candidate cells. In one example, the indication includes an enumerated value for each of the one or more included CSI-RS reference signals related to one or more LTM candidate cells which indicate the status of the reference CSI-RS reference signal (e.g., whether the CSI-RS reference signal is activated or started or stopped or deactivated). For example, a value equal to “0” or “1” or “start” or “stop” for each LTM candidate cell configured by the gNB-DU, in one XnAP message. The XnAP message can be either UE-associated, e, or a non-UE associated message. In one example, the indication is one value which is common to each of the one or more included CSI-RS reference signals related to one or more LTM candidate cell and which indicates that “all” CSI-RS reference signals are stopped or started or activated or deactivated.

[0081] B2c. The method in B 1 and B2b, wherein the message (and its content) received by the third network node is sent to the first network node.

[0082] B2d. The method in Bl and B2a, wherein the indication in the message transmitted to the third network node is a request to activate, start, stop, or deactivate one or more CSI-RS reference signals related to one or more candidate cells. In such a case, the second network node does not indicate any particular CSI-RS reference signal, but leaves the decision of which one to activate to the first network node.

[0083] In one alternative (corresponding to the signaling flow chart in Figure 2 below) of embodiment B 1, the second network node (such as a serving gNB-CU), does not receive a request from the first network node about CSI-RS measurements for one or more candidate cell, and the method comprises one or more of: Receiving a message from a third network node (such as a candidate gNB-CU), or from a fourth network node (such as a candidate gNB-DU) - indirectly via the third network node or directly, the message comprising: an indication of a start of CSI-RS transmission in LTM candidate cell(s), an indication of a stop of CSI-RS transmission in LTM candidate cell(s), or an indication that CSI-RS transmission in LTM candidate cell(s) is ongoing. In one example of implementation, this message can be an existing message, such as HANDOVER REQUEST ACKNOWLEDGE Xn message, or a new message (e.g., an LTM Information Transmission Control). The method further comprises transmitting a message to the first network node, the message comprising: an indication of a start of CSI-RS transmission in LTM candidate cell(s), an indication of a stop of CSI-RS transmission in LTM candidate cell(s), or an indication that CSI-RS transmission in LTM candidate cell(s) is ongoing.

[0084] In one alternative (corresponding to the signaling flow chart in Figure 3 below) of embodiment Bl, the second network node (such as a serving gNB-CU), which is handling the mobility control and control plane for the first network node, does not receive a request from the first network node about CSI-RS measurements for one or more candidate cell, and the method comprises one or more of: Receiving a message from the first network node comprising a request (or an interest) of the first network node to receive indication, indicating whether transmission of CSI-RS in LTM candidate cell(s) is started, or is stopped, or is ongoing; and transmitting a message based on the above request to the third network node. In the alternative, the method may comprise transmitting a message to the third network node, comprising a subscription request (or an interest) to receive indication, indicating whether transmission of CSI-RS in LTM candidate cell(s) is started, or is stopped, or is ongoing. Optionally, the method may comprise the second network node receiving from the third network node a response to accept or reject the subscription request; and receiving a message from the third network node with the information on whether CSI-RS transmission is turned on / off / ongoing in the configured LTM candidate cell(s).

[0085] Cl. Methods for a third network node (such as a candidate gNB-CU), which is handling the mobility control and control plane for the fourth network node, the method comprising one or more of: Receiving a message from the second network node with an indication to request for starting or stopping CSI-RS for the UE. This message can be an XnAP message, for example, HANDOVER REQUEST, or a new message. The method further comprises transmitting a message with the above indicator to the fourth network node. This message can be an F1AP message, either UE associated, for example, UE CONTEXT MODIFICATION REQUEST message, or a non-UE associated message. The method further comprises receiving a message from the fourth network node with the response on whether CSI-RS is turned on / off for the configured candidate cell. This message can be an F1AP message, either UE associated, for example, UE CONTEXT MODIFICATION RESPONSE message, or a non-UE associated message. The method further comprises transmitting the above information to the second network node. This message can be an XnAP message, for example, HANDOVER REQUEST ACKNOWLEDGE, or a new message.

[0086] In one alternative (corresponding to the signaling flow chart in Figure 2 below) of embodiment Cl, the third network node (such as a candidate gNB-CU) does not send a request to the fourth network node originally sent by the first network node, and the method comprises: Receiving a message from a fourth network node (such as a candidate gNB-DU), the message comprising an indication indicating start of CSI-RS transmission in LTM candidate cell(s), or indicating stop of CSI-RS transmission in LTM candidate cell(s).

[0087] In one alternative (corresponding to the signaling flow chart in Figure 3 below) of embodiment Cl the third network node (such as a candidate gNB-CU) does not send a request to the fourth network node originally sent by the first network node, and, the method comprises: Receiving a message from the second network node comprising a request (or an interest) to receive indication, indicating whether transmission of CSI-RS in LTM candidate cell(s) is started, or is stopped, or is ongoing. The method may further comprise transmitting a message based on the above request to the fourth network node. In the alternative, The method may further comprise transmitting a message to the fourth network node, comprising a subscription request (or an interest) to receive indication, indicating whether transmission of CSI-RS in LTM candidate cell(s) is started, or is stopped, or is ongoing. Optionally, The method may further comprise the third network node receiving from the fourth network node a response to accept or reject the subscription request. The method may further comprise receiving a message from the fourth network node with the information on whether CSI-RS is turned on / off / ongoing for the configured LTM candidate cell(s).

[0088] DI. Methods for a fourth network node (such as a candidate gNB-DU), which is configured with at least one LTM candidate cell, the method comprising: Receiving a message from the third network node by indicating a request whether CSI-RS needs to be started or stopped for the UE, for example, an enumerated value, corresponding to “0” or “1” or “start” or “stop” for each LTM candidate cell configured by the gNB-DU, in one F1AP message. The F1AP message can be either UE associated, e g., UE CONTEXT MODIFICATION REQUEST message, or a non-UE associated message. The method may further comprise transmitting a message to the third network node to indicate whether the CSI-RS is turned on or off or will be turned off at a given time for the UE.

[0089] In one alternative (corresponding to the signaling flow chart in Figure 2 below) of embodiment DI, the fourth network node (such as a candidate gNB-DU) does not receive a message from the third network node indicating a request concerning CSI-RS transmission start / stop, and the method comprises: transmitting a message to a third network node (such as a candidate gNB-CU), the message comprising an indication of the start of CSI-RS transmission in LTM candidate cell(s), an indication of the stop of CSI-RS transmission in LTM candidate cell(s), or an indication that CSI-RS transmission in LTM candidate cell(s) is ongoing.

[0090] In one alternative (corresponding to the signaling flow chart in Figure 3 below) of embodiment DI, the fourth network node (such as a candidate gNB-DU) performs one or more steps such as: Receiving a message from the third network node comprising a subscription request to receive from the fourth network node information concerning CSI-RS transmission start / stop; and optionally transmitting a response to accept or reject the subscription request; and / or transmitting a message to a third network node (such as a candidate gNB-CU), a message comprising an indication of the start of CSI-RS transmission in LTM candidate cell(s), an indication of the stop of CSI-RS transmission in LTM candidate cell(s), or an indication that CSI- RS transmission in LTM candidate cell(s) is ongoing.

[0091] EL Methods for a User Equipment (UE), which is configured with at least one LTM candidate configuration which has a measurement configuration which include one or more CSI- RS reference signals, the method comprising: Receiving the activation / deactivation of CSI-RS reference signals from the first network node. The method further comprises receiving a lower layer indication to send a measurement report which includes one or more measurement quantities for one or more CSI-RS reference signals. The method further comprises sending a measurement report which include one or more measurement quantity for one or more CSI-RS reference signals according to the received indication. The method further comprises receiving theactivation / deactivation command of the CSI-RS reference signals from the first NW node to activate the CSI-RS of the candidate cell.

[0092] The activation / deactivation command of the CSI-RS reference signals may be a new MAC CE and MAC CE containing one or more of the following fields.• Candidate cell ID;• Bandwidth Part (BWP) ID;• CSI-RS resource set ID;• CSI-RS resource set ID for interference measurement;• TCI state of the CSI-RS resource within the CSI-RS resource set; or• Start time / stop time of the CSI-RS.

[0093] The MAC CE for activating CSI-RS of the candidate cells may be differentiated by a different Logical Channel ID (LCID) from the MAC CE for serving cell CSI-RS activation.

[0094] In case of the aperiodic CSI reporting, the aperiodic CSI trigger state sub-selection may be indicated by a new MAC CE, and the new MAC CE may comprise one or more of the following:• Candidate cell ID;• BWP ID; or• Trigger state of the CSI-RS.

[0095] Figure 2 illustrates signaling flows for source gNB-DU requesting to start / stop CSI- RS, in accordance with some embodiments of the present disclosure. An interaction between a UE (e.g., UE 200), a Source DU (e.g., Source DU 202), a Source CU (e.g., Source CU 204), a Target CU (e.g., Target CU 206), and a Target DU (e.g., Target DU 208) is shown. In Figure 2, the first network node (source DU) requests to start (or stop) CSI-RS transmission. For example, the request is forwarded to the fourth network node (target DU) via the second network node (source CU) and the third network node (target CU). The fourth network node sends the information to the first network node via the third network node and the second network node. The first network node informs the UE about CSI-RS activation or deactivation and triggers measurement reports based on CSI-RS. At Step S210, the first network node issues a request for the fourth network node to turn on / off CSI-RS. At Steps S220 and S230, the request is forwarded to the fourth network node via the second and third network node. At Steps S240, S250, and S260, the fourth network node responds to the first network node via the third and second network node. At Step S270, the firstnetwork node informs the UE about CSI-RS activation or deactivation and triggers sending measurement reports based on CSI-RS.

[0096] Figure 3 illustrates signaling flows for target gNB-DU informing the source of start / stop CSI-RS, in accordance with some embodiments of the present disclosure. An interaction between a UE (e.g., UE 300), a Source DU (e.g., Source DU 302), a Source CU (e.g., Source CU 304), a Target CU (e.g., Target CU 306), and a Target DU (e.g., Target DU 308) is shown. In Figure 3, the first network node (source DU) receives from the fourth network node (target DU) an indication indicating whether CSI-RS transmission has started or stopped, wherein the indication is provided via the third network node (target CU) and the second network node (source CU). At Step S310, the fourth network node informs the first network node about CSI-RS activation / deactivation. At Steps S320 and S330, the information is forwarded to the first network node via the third and second network node. At Step S340, the first network node informs the UE about CSI-RS activation or deactivation and triggers sending measurement reports based on CSI- RS.

[0097] Figure 4 illustrates signaling flows for target gNB-DU informing the source of start / stop CSI-RS based on subscription, in accordance with some embodiments of the present disclosure. An interaction between a UE (e.g., UE 400), a Source DU (e.g., Source DU 402), a Source CU (e.g., Source CU 404), a Target CU (e.g., Target CU 406), and a Target DU (e.g., Target DU 408) is shown. In Figure 4, the first network node (source DU) sends to the second network node (source CU) a request / subscription request (or notification of interest) to receive (from the fourth network node, i.e., target DU) information on whether CSI-RS transmission has started or stopped, or is ongoing, wherein the information is provided by the fourth network node (target DU) via the third network node (target CU) and the second network node (source CU). At Step S410, the first network node subscribes to receive information from the fourth network node, concerning the CSI-RS activation / deactivation. At Steps S420 and S430, the subscription request is forwarded to the fourth network node via the second and third network node. At Step S440, the fourth network node informs the first network (via the third and second network nodes at Steps S450 and S460) about CSI-RS activation / deactivation. At Step S470, the first network node informs the UE about CSI-RS activation or deactivation and triggers sending measurement reports based on CSI-RS.

[0098] Figure 5 illustrates a flowchart 500 showing a method performed by a first network node, e.g., network node 1410 in Figure 14 below, for reference signal measurements, in accordance with some embodiments. For example, the first network node may comprise a source gNB-DU or a source gNB-CU. In some embodiments, the reference signal measurements mayrelate to a Layer 1, LI, / Layer 2, L2, triggered mobility, LTM, procedure and the reference signal may comprise a Channel State Information Reference Signal, CSI-RS, corresponding to the one or more candidate cells. In some embodiments, the first network node (e.g., a source gNB-DU), may be configured with at least one configuration for LTM candidates that includes CSI resources that are transmitted by the one or more candidate cells.

[0099] At Block 510, comprises sending, to a second network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells (e.g., a reference signal resource for the one or more candidate cells). For example, the second network node may comprise a serving gNB-DU or a serving gNB-CU. In some embodiments, the reference signal may be transmitted semi-persistently or aperiodically. For example, the operational status of the reference signal may include whether the reference signal is activated or deactivated, or whether the reference signal has been started, stopped, or is ongoing, e.g., at least semi-persistent. In some embodiments, the request to change the operational status may comprise an enumerated value indicating to change an operational status of individual reference signals corresponding to the one or more candidate cells (e.g., an enumerated value for the operational status, e.g., activate, start, stop, deactivate all individual reference signals). In some embodiments, the request to change the operational status may comprise an enumerated value to change an operational status of individual CSI-RS resource sets or a CSI-RS resource index or identifier (ID) related to the one or more candidate cells. In some embodiments, the request to change the operational status may comprise a requested start time or stop time for at least one individual reference signal, individual CSI-RS resource set, or a CSI-RS resource index or identifier related to the one or more candidate cells. In some embodiments, the request to change the operational status may comprise an identifier of the UE or of a configuration for reference signals corresponding to the one or more candidate cells. For example, the configuration for reference signals may be a previously provided CSI-RS configuration, e.g., provided by a C-DU of an LTM candidate cell for which the CSI-RSs are to be transmitted.

[0100] At Block 520, the method further comprises receiving, from the second network node, an indication of the operational status of the reference signal corresponding to the one or more candidate cells. As disclosed above, the one or more candidate cells individually may comprise sets of radio resources, beams, Transmission Configuration Indication (TCI) states, or Tracking Reference Signals (TRS). In some embodiments, the indication may comprise a response to the request to change the operational status of the reference signal corresponding to the one or more candidate cells. For example, the indication may comprise an enumerated value indicating the operational status of individual CSI-RS resource sets or a CSI-RS resource index or identifierrelated to the one or more candidate cells. Further, the indication may comprise an indication of individual reference signals corresponding to the one or more candidate cells that are activated or deactivated, or are to be activated or deactivated. For example, the indication may comprise an enumerated value indicating the operational status of individual reference signals corresponding to the one or more candidate cells (e.g., an enumerated value for the operational status that is common to all individual reference signals).

[0101] At Block 530, the method further comprises sending, to a User Equipment, UE, the indication of the operational status of the reference signal, where the UE sends or stops sending individual measurement reports based on the reference signal in accordance with the indication.

[0102] The method may further comprise sending, to the UE, a configuration for measuring the reference signal corresponding to the one or more candidate cells. The method may further comprise sending, to the UE, a configuration for reporting measurements based on the reference signal corresponding to the one or more candidate cells. The method may further comprise sending, to the UE, an indication to send or stop sending individual measurement reports based on the reference signal. The method may further comprise sending, to the second network node, a request for a subscription to receive the indication of the operational status of the reference signal corresponding to the one or more candidate cells. The method may further comprise receiving, from the second network node, an indication of whether the request for the subscription has been accepted or rejected. The method may further comprise receiving, from the second network node, an indication of the operational status of the reference signal when the request for the subscription has been accepted.

[0103] Figure 6 illustrates a flowchart 600 showing a method performed by a second network node, e.g., network node 1410 in Figure 14 below, for reference signal measurements, in accordance with some embodiments. For example, the second network node may comprise a serving gNB-DU or a serving gNB-CU. At Block 610, the method comprises receiving, from a first network node (e.g., a source gNB-DU or a source gNB-CU), a request to change an operational status of a reference signal (e.g., radio resources, beams, TCI states, or TRS) corresponding to one or more candidate cells. At Block 620, the method further comprises sending, to a third network node (e.g., a candidate gNB-CU), the request to change an operational status. In some embodiments, the request sent to the third network node may comprise an Xn Application Protocol (XnAP) message (e.g., a HANDOVER REQUEST, or another new message). At Block 630, the method further comprises receiving, from the third network node, an indication of an operational status of the reference signal corresponding to the one or more candidate cells, where the indication comprises a response to the request to change the operational status of the referencesignal. At Block 640, the method further comprises sending, to the first network node, the indication of the operational status of the reference signal corresponding to the one or more candidate cells.

[0104] Figure 7 illustrates a flowchart 700 showing a method performed by a second network node, e.g., network node 1410 in Figure 14 below, for reference signal measurements, in accordance with some embodiments. For example, the second network node may comprise a serving gNB-DU or a serving gNB-CU. At Block 710, the method comprises receiving, from a third network node (e.g., a candidate gNB-CU) or from a fourth network node (e.g., a candidate gNB-DU), an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi -persistently or aperiodically. For example, the indication may be received from the fourth network node either indirectly via the third network node or directly. The indication of an operational status of the reference signal may one or more of indicate the start of CSI-RS transmission in LTM candidate cell(s), indicate the stop of CSI-RS transmission in LTM candidate cell(s), or indicate that CSI-RS transmission in LTM candidate cell(s) is ongoing. At Block 720, the method further comprises sending, to a first network node, the indication of the operational status of the reference signal corresponding to the one or more candidate cells.

[0105] Figure 8 illustrates a flowchart 800 showing a method performed by a second network node, e.g., network node 1410 in Figure 14 below, for reference signal measurements, in accordance with some embodiments. At Block 810, the method comprises receiving, from a first network node, a request for a subscription to receive an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi-persistently or aperiodically. At Block 820, the method further comprises sending, to a third network node, the request for the subscription to receive the indication of the operational status of the reference signal and a request for the indication of the operational status of the reference signal. For example, the request for the subscription may be a message based on the request from the first network node that is sent to the third network node. Alternatively, the request sent to the third network node may comprise a specific subscription request (or an interest) to receive an indication of whether transmission of CSI-RS in LTM candidate cell(s) has started, is stopped, or is ongoing. At Block 830, the method further comprises receiving, from the third network node, at least one of: the indication of whether the request for the subscription has been accepted or rejected, or indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference. At Block 840, the method further comprises sending, to the first network node, at least one of the indication of whether therequest for the subscription has been accepted or rejected, or the indication of the operational status of the reference.

[0106] Figure 9 illustrates a flowchart 900 showing a method performed by a third network node, e.g., network node 1410 in Figure 14 below, for reference signal measurements, in accordance with some embodiments. For example, the third network node may be a candidate gNB-CU. At Block 910, the method comprises receiving, from a second network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells, where the request corresponds to at least one User Equipment, UE. For example, the request may comprise a message from the second network node with an indication to request starting or stopping CSI-RS for the at least one UE. In some embodiments, this message may be an XnAP message, e.g., HANDOVER REQUEST, or another message. At Block 920, the method further comprises sending, to a fourth network node, the request to change the operational status. For example, the request transmitted to the fourth network node may be an Fl Application Protocol (F1AP) message, either as a UE-associated message, e g., a UE CONTEXT MODIFICATION REQUEST message, or as a non-UE associated message. At Block 930, the method further comprises receiving, from the fourth network node, an indication of an operational status of the reference signal corresponding to the one or more candidate cells, where the indication comprises a response to the request to change the operational status of the reference signal. For example, the message received from the fourth network node may be an F1AP message, either UE-associated, e g., a UE CONTEXT MODIFICATION RESPONSE message, or non-UE associated. At Block 940, the method further comprises sending, to the second network node, the indication of the operational status of the reference signal corresponding to the one or more candidate cells. For example, the indication may comprise an XnAP message, e.g., HANDOVER REQUEST ACKNOWLEDGE, or another new message.

[0107] Figure 10 illustrates a flowchart 1000 showing a method performed by a third network node, e.g., network node 1410 in Figure 14 below, for reference signal measurements, in accordance with some embodiments. For example, the third network node may be a candidate gNB-CU. At Block 1010, the method comprises receiving, from a second network node, a request for a subscription to receive an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi- persistently or aperiodically, and where the request corresponds to at least one User Equipment, UE. For example, the request may comprise a request (or an interest) to receive an indication of whether transmission of CSI-RS in LTM candidate cell(s) has started, stopped, or is ongoing. At Block 1020, the method further comprises sending, to a fourth network node (e.g., a candidategNB-DU), the request for the subscription to receive the indication of the operational status of the reference signal and a request for the indication of the operational status of the reference signal. For example, the subscription request (or interest to receive the indication) may comprise a request for the indication of whether transmission of CSI-RS in LTM candidate cell(s) is started, stopped, or is ongoing. At Block 1030, the method further comprises receiving, from the fourth network node, at least one of an indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference signal (e.g., information on whether CSI-RS is turned on / off / ongoing for the configured LTM candidate cell(s)). At Block 1040, the method further comprises sending, to the second network node, at least one of the indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference signal.

[0108] Figure 11 illustrates a flowchart 1100 showing a method performed by a fourth network node, e.g., network node 1410 in Figure 14 below, for reference signal measurements, in accordance with some embodiments. For example, the fourth network node may be a candidate gNB-CU. At Block 1110, the method comprises receiving, from a third network node, a request to change an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi-persistently or aperiodically, and where the request corresponds to at least one User Equipment, UE. For example, this request may indicate whether a CSI-RS needs to be started or stopped for the at least one UE. In some embodiments, the request may include an enumerated value, corresponding to “0” or “1” or “start” or “stop” for each LTM candidate cell configured by the gNB-DU, e.g., in an F1AP message. At Block 1120, the method further comprises sending, to the third network node, an indication of the operational status of the reference signal corresponding to the one or more candidate cells, where the indication comprises a response to the request to change the operational status of the reference signal. For example, the indication may be an F1AP message, either UE-associated, e.g., a UE CONTEXT MODIFICATION RESPONSE message, or non-UE associated.

[0109] Figure 12 illustrates a flowchart 1200 showing a method performed by a fourth network node, e.g., network node 1410 in Figure 14 below, for reference signal measurements, in accordance with some embodiments. For example, the fourth network node may be a candidate gNB-CU. At Block 1210, the method comprises receiving, from a third network node, a request for a subscription to receive an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi- persistently or aperiodically, and where the request corresponds to at least one User Equipment, UE. For example, the request may comprise a request (or an interest) to receive an indication ofwhether transmission of CSI-RS in LTM candidate cell(s) has started, stopped, or is ongoing. At Block 1220, the method further comprises sending, to the third network node, at least one of an indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference signal. For example, the indication may include a response to accept or reject the subscription request and / or an indication of a start of a CSI-RS transmission in LTM candidate cell(s), a stop of a CSI-RS transmission in LTM candidate cell(s), or that a CSI-RS transmission in LTM candidate cell(s) is ongoing.

[0110] Figure 13 illustrates a flowchart 1300 showing a method performed by a user equipment, UE, e.g., UE 1412 in Figure 14 below, for reference signal measurements, in accordance with some embodiments. At Block 1310, the method comprises receiving, from a first network node, an indication of an operational status of a reference signal corresponding to one or more candidate cells, where the reference signal is transmitted semi-persistently or aperiodically. At Block 1320, the method further comprises sending, to the first network node, individual measurement reports based on the reference signal in accordance with the indication. The method may further comprise receiving, from the first network node, a configuration for measuring the reference signal corresponding to the one or more candidate cells and / or a configuration for reporting measurements based on the reference signal corresponding to the one or more candidate cells. The method may further comprise receiving, from the first network node, an indication to send or stop sending individual measurement reports based on the reference signal.

[0111] Figure 14 shows an example of a communication system 1400 in accordance with some embodiments.

[0112] In the example, the communication system 1400 includes a telecommunication network 1402 that includes an access network 1404, such as a radio access network (RAN), and a core network 1406, which includes one or more core network nodes 1408. The access network 1404 includes one or more access network nodes, such as network nodes 1410a and 1410b (one or more of which may be generally referred to as network nodes 1410), or any other similar 3rdGeneration 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 1402 includes one or more Open -RAN (ORAN) network nodes. An ORAN network node is a node in the telecommunication network 1402 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operatealone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 1402, including one or more network nodes 1410 and / or core network nodes 1408.

[0113] Examples of an ORAN network node include an open radio unit (O-RU), an open distributed unit (O-DU), an open central unit (O-CU), including an O-CU control plane (O-CU- CP) or an O-CU user plane (O-CU-UP), a RAN intelligent controller (near-real time or non-real time) hosting software or software plug-ins, such as a near-real time control application (e.g., xApp) or a non-real time control application (e.g., 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 Al, Fl, Wl, El, E2, X2, Xn interface, an open fronthaul user plane interface, or an open fronthaul management plane interface. Moreover, an ORAN access node may be a logical node in a physical node. Furthermore, an ORAN network node may be implemented in a virtualization environment (described further below) in which one or more network functions are virtualized. For example, the virtualization environment may include an O-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an O-2 interface defined by the 0-RAN Alliance or comparable technologies. The network nodes 1410 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 1412a, 1412b, 1412c, and 1412d (one or more of which may be generally referred to as UEs 1412) to the core network 1406 over one or more wireless connections.

[0114] 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 1400 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 1400 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0115] The UEs 1412 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 1410 and other communication devices. Similarly, the network nodes 1410 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 1412 and / or with other network nodes or equipment in the telecommunication network 1402 toenable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 1402.

[0116] In the depicted example, the core network 1406 connects the network nodes 1410 to one or more host computing systems, such as host 1416. 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 1406 includes one more core network nodes (e.g., core network node 1408) 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 1408. 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).

[0117] The host 1416 may be under the ownership or control of a service provider other than an operator or provider of the access network 1404 and / or the telecommunication network 1402. The host 1416 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.

[0118] As a whole, the communication system 1400 of Figure 14 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.

[0119] In some examples, the telecommunication network 1402 is a cellular network that implements 3GPP standardized features. Accordingly, the telecommunications network 1402 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 1402. For example, the telecommunications network 1402 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.

[0120] In some examples, the UEs 1412 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 1404 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 1404. 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, e.g. 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).

[0121] In the example, the hub 1414 communicates with the access network 1404 to facilitate indirect communication between one or more UEs (e.g., UE 1412c and / or 1412d) and network nodes (e.g., network node 1410b). In some examples, the hub 1414 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 1414 may be a broadband router enabling access to the core network 1406 for the UEs. As another example, the hub 1414 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 1410, or by executable code, script, process, or other instructions in the hub 1414. As another example, the hub 1414 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 1414 may be a content source. For example, for a UE that is a VR device, display, loudspeaker, or other media delivery device, the hub 1414 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 1414 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 1414 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy loT devices.

[0122] The hub 1414 may have a constant / persistent or intermittent connection to the network node 1410b. The hub 1414 may also allow for a different communication scheme and / or schedulebetween the hub 1414 and UEs (e.g., UE 1412c and / or 1412d), and between the hub 1414 and the core network 1406. In other examples, the hub 1414 is connected to the core network 1406 and / or one or more UEs via a wired connection. Moreover, the hub 1414 may be configured to connect to an M2M service provider over the access network 1404 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 1410 while still connected via the hub 1414 via a wired or wireless connection. In some embodiments, the hub 1414 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 1410b. In other embodiments, the hub 1414 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 1410b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0123] Figure 15 shows a UE 1500 in accordance with some embodiments. The UE 1500 presents additional details of some embodiments of the UE 1412 of Figure 1. 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 / playback device, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop-embedded equipment (LEE), laptop -mounted equipment (LME), an Augmented Reality (AR) or Virtual Reality (VR) 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-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0124] 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).

[0125] The UE 1500 includes processing circuitry 1502 that is operatively coupled via a bus 1504 to an input / output interface 1506, a power source 1508, a memory 1510, a communication interface 1512, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 15. 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.

[0126] The processing circuitry 1502 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 1510. The processing circuitry 1502 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 1502 may include multiple central processing units (CPUs).

[0127] In the example, the input / output interface 1506 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 1500. 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.

[0128] In some embodiments, the power source 1508 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 1508 may further include power circuitry for delivering power from the power source 1508 itself, and / or an external power source, to the various parts of the UE 1500 via input circuitry or an interface such as an electricalpower cable. Delivering power may be, for example, for charging of the power source 1508. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1508 to make the power suitable for the respective components of the UE 1500 to which power is supplied.

[0129] The memory 1510 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 1510 includes one or more application programs 1514, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1516. The memory 1510 may store, for use by the UE 1500, any of a variety of various operating systems or combinations of operating systems.

[0130] The memory 1510 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 (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 1510 may allow the UE 1500 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 1510, which may be or comprise a device-readable storage medium.

[0131] The processing circuitry 1502 may be configured to communicate with an access network or other network using the communication interface 1512. The communication interface 1512 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1522. The communication interface 1512 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 1518 and / or a receiver 1520 appropriate to provide network communications (e.g., optical, electrical, frequencyallocations, and so forth). Moreover, the transmitter 1518 and receiver 1520 may be coupled to one or more antennas (e.g., antenna 1522) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0132] In the illustrated embodiment, communication functions of the communication interface 1512 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.

[0133] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1512, 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).

[0134] 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.

[0135] 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 conditioningsystem 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 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 1500 shown in Figure 15.

[0136] 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 3 GPP NB-IoT 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.

[0137] 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.

[0138] Figure 16 shows a network node 1600 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)), 0-RAN nodes or components of an 0-RAN node (e g., 0-RU, 0-DU, O-CU).

[0139] 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, ormacro 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).

[0140] 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, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0141] The network node 1600 includes a processing circuitry 1602, a memory 1604, a communication interface 1606, and a power source 1608. The network node 1600 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 1600 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 1600 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1604 for different RATs) and some components may be reused (e.g., a same antenna 1610 may be shared by different RATs). The network node 1600 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1600, 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 1600.

[0142] The processing circuitry 1602 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 operableto provide, either alone or in conjunction with other network node 1600 components, such as the memory 1604, to provide network node 1600 functionality.

[0143] In some embodiments, the processing circuitry 1602 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1602 includes one or more of radio frequency (RF) transceiver circuitry 1612 and baseband processing circuitry 1614. In some embodiments, the radio frequency (RF) transceiver circuitry 1612 and the baseband processing circuitry 1614 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 1612 and baseband processing circuitry 1614 may be on the same chip or set of chips, boards, or units.

[0144] The memory 1604 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 1602. The memory 1604 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 1602 and utilized by the network node 1600. The memory 1604 may be used to store any calculations made by the processing circuitry 1602 and / or any data received via the communication interface 1606. In some embodiments, the processing circuitry 1602 and memory 1604 is integrated.

[0145] The communication interface 1606 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 1606 comprises port(s) / terminal(s) 1616 to send and receive data, for example to and from a network over a wired connection. The communication interface 1606 also includes radio front-end circuitry 1618 that may be coupled to, or in certain embodiments a part of, the antenna 1610. Radio front-end circuitry 1618 comprises filters 1620 and amplifiers 1622. The radio front-end circuitry 1618 may be connected to an antenna 1610 and processing circuitry 1602. The radio front-end circuitry may be configured to condition signals communicated between antenna 1610 and processing circuitry 1602. The radio front-end circuitry 1618 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio frontend circuitry 1618 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1620 and / or amplifiers 1622. The radiosignal may then be transmitted via the antenna 1610. Similarly, when receiving data, the antenna 1610 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1618. The digital data may be passed to the processing circuitry 1602. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0146] In certain alternative embodiments, the network node 1600 does not include separate radio front-end circuitry 1618, instead, the processing circuitry 1602 includes radio front-end circuitry and is connected to the antenna 1610. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1612 is part of the communication interface 1606. In still other embodiments, the communication interface 1606 includes one or more ports or terminals 1616, the radio front-end circuitry 1618, and the RF transceiver circuitry 1612, as part of a radio unit (not shown), and the communication interface 1606 communicates with the baseband processing circuitry 1614, which is part of a digital unit (not shown).

[0147] The antenna 1610 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1610 may be coupled to the radio front-end circuitry 1618 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1610 is separate from the network node 1600 and connectable to the network node 1600 through an interface or port.

[0148] The antenna 1610, communication interface 1606, and / or the processing circuitry 1602 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 1610, the communication interface 1606, and / or the processing circuitry 1602 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.

[0149] The power source 1608 provides power to the various components of network node 1600 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1608 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1600 with power for performing the functionality described herein. For example, the network node 1600 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 1608. As a further example, the power source 1608 maycomprise 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.

[0150] Embodiments of the network node 1600 may include additional components beyond those shown in Figure 16 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 1600 may include user interface equipment to allow input of information into the network node 1600 and to allow output of information from the network node 1600. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1600. In some embodiments providing a core network node, such as core network node 108 of FIG. 14, some components, such as the radio front-end circuitry 1618 and the RF transceiver circuitry 1612 may be omitted.

[0151] Figure 17 is a block diagram illustrating a virtualization environment 1700 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 1700 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 1700 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and Orchestration Framework via an O-2 interface. Virtualization may facilitate distributed implementations of a network node, UE, core network node, or host.

[0152] Applications 1702 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment Q400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0153] Hardware 1704 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 1706 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1708a and 1708b (one or more of which may be generally referred to as VMs 1708), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1706 may present a virtual operating platform that appears like networking hardware to the VMs 1708.

[0154] The VMs 1708 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1706. Different embodiments of the instance of a virtual appliance 1702 may be implemented on one or more of VMs 1708, 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.

[0155] In the context of NFV, a VM 1708 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 1708, and that part of hardware 1704 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 1708 on top of the hardware 1704 and corresponds to the application 1702.

[0156] Hardware 1704 may be implemented in a standalone network node with generic or specific components. Hardware 1704 may implement some functions via virtualization. Alternatively, hardware 1704 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 1710, which, among others, oversees lifecycle management of applications 1702. In some embodiments, hardware 1704 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, somesignaling can be provided with the use of a control system 1712 which may alternatively be used for communication between hardware nodes and radio units.

[0157] Additional embodiments are described below.EMBODIMENTSGroup A Embodiments1. A method performed by a user equipment, the method comprising: receiving the activation / deactivation of CSI-RS reference signals from the first network node; receiving a lower layer indication which indicate to send a measurement report which include one or more measurement quantity for one or more CSI-RS reference signals; sending a measurement report which include one or more measurement quantity for one or more CSI-RS reference signals according to the received indication; receiving the activation / deactivation command of the CSI-RS reference signals from the first NW node to activate the CSI-RS of the candidate cell.2. The method of embodiment 1 further comprising the step of any of the Group B Embodiments.Group B Embodiments3. A method performed by a network node, the method comprising one or more of: configuring a UE with at least one LTM CSI resource configuration; configuring the UE also with an LTM CSI report configuration to report measurement based on CSI-RS reference signals; transmitting a message to a second network node which include an indication to request for activation / tuming on / off transmission about CSI-RS resource for the CSI-RS measurements for one or more LTM candidate cell(s); receiving a message from the second network node which includes an indication about activation / tuming on / off CSI-RS resource transmission for one or more LTM candidate cell(s); transmitting a lower layer signalling to the UE to indicate the activation (or in alternative the deactivation) of semi -persistent or aperiodic CSI-RS resource set; and transmitting a lower layer signalling to the UE to indicate to trigger the sending of a measurement report based on CSI-RS reference signal for one or more LTM candidate cell(s), or in alternative transmitting a lower layer signaling to the UE to indicate to stop sending measurement report base on CSI-RS reference signal for one or more LTM candidate cell(s).4. A method performed by a network node, the method comprising one or more of: being configured with at least one LTM candidate configuration that includes CSI resources that are transmitted by the candidate cell; not transmitting an indication to request for the second network node to start or stop CSI-RS reference signal; receiving a message from the second network node to indicate whether the CSI-RS transmission is turned on / off for the UE; transmitting a lower layer signaling (e.g., a MAC CE) to the UE to indicate the activation (or in alternative the deactivation) of semi-persistent CSI-RSI resource; transmitting a lower layer signalling to the UE to indicate to trigger the sending of a measurement report based on CSI-RS reference signal for one or more LTM candidate cell(s); and transmitting a lower layer signaling to the UE to indicate to stop sending measurement report base on CSI-RS reference signal for one or more LTM candidate cell(s).5. A method performed by a network node, the method comprising one or more of being configured with at least one LTM candidate configuration that includes CSI resources that are transmitted by the candidate cell; transmits a request (e.g., a subscription request) to receive from the second network node indication(s) concerning activation or deactivation of CSLSR reference signals; transmitting a message to the second network node comprising a subscription request (or an interest) to receive indication, indicating whether transmission of CSI-RS in LTM candidate cell(s) is started, or is stopped, or is ongoing; optionally receiving a response from the second network node to accept or reject the subscription request; receiving a message from the second network node to indicate whether the transmission of CSI-RS is turned on / off or is ongoing; transmitting a lower layer signaling (e.g., a MAC CE) to the UE to indicate the activation (or in alternative the deactivation) of semi-persistent CSI-RS resource; transmitting a lower layer signalling to the UE to indicate to trigger the sending of a measurement report based on CSI-RS reference signal for one or more LTM candidate cell(s); and transmitting a lower layer signaling to the UE to indicate to stop sending measurement report based on CSI-RS reference signal for one or more LTM candidate cell(s).6. A method performed by a second network node (e.g., a serving gNB-CU), the method comprising one or more of: receiving a message from the first network node which includes an indication about CSI-RS measurements for one or more candidate cell(s); transmitting a message with the above indicator to the third network node. This message can be an XnAP message, for example, HANDOVER REQUEST, or a new message; receiving a message from the third network node with the information on CSI-RS measurements for one or more candidate cell; and transmitting a message to the first network node with the information on CSI-RS measurements for one or more candidate cell.7. A method performed by a second network node (e.g., a serving gNB-CU), the method comprising one or more of receiving a message from a third network node (such as a candidate gNB-CU), or from a fourth network node (such as a candidate gNB-DU) - indirectly via the third network node or directly, the message comprising an indication, indicating start of CSI-RS transmission in LTM candidate cell(s), or indicating stop of CSI-RS transmission in LTM candidate cell(s), or indicating that CSI-RS transmission in LTM candidate cell(s) is ongoing; and transmitting a message to the first network node, the message comprising an indicator, indicating start of CSI-RS transmission in LTM candidate cell(s), or indicating stop of CSI-RS transmission in LTM candidate cell(s), or indicating that CSI-RS transmission in LTM candidate cell(s) is ongoing.8. A method performed by a second network node (e.g., a serving gNB-CU), the method comprising one or more of receiving a message from the first network node comprising a request (or an interest) of the first network node to receive indication, indicating whether transmission of CSI-RS in LTM candidate cell(s) is started, or is stopped, or is ongoing; and transmitting a message based on the above request to the third network node. In alternative, transmitting a message to the third network node, comprising a subscription request (or an interest) to receive indication, indicating whether transmission of CSI-RS in LTM candidate cell(s) is started, or is stopped, or is ongoing; and receiving a message from the third network node with the information on whether CSI-RS transmission is turned on / off / ongoing in the configured LTM candidate cell(s).9. A method performed by a third network node (e.g., a candidate gNB-CU), the method comprising one or more of: receiving a message from the second network node with an indication to request for starting or stopping CSI-RS for the UE. This message can be an XnAP message, for example, HANDOVER REQUEST, or a new message; transmitting a message with the above indicator to the fourth network node. This message can be an F1AP message, either UE associated, for example, UE CONTEXT MODIFICATION REQUEST message, or a non-UE associated message; receiving a message from the fourth network node with the response on whether CSI-RS is turned on / off for the configured candidate cell. This message can be an Fl AP message, either UE associated, for example, UE CONTEXT MODIFICATION RESPONSE message, or a non-UE associated message; transmitting the above information to the second network node. This message can be an XnAP message, for example, HANDOVER REQUEST ACKNOWLEDGE, or a new message; receiving a message from a fourth network node (such as a candidate gNB-DU), the message comprising an indication indicating start of CSI-RS transmission in LTM candidate cell(s), or indicating stop of CSI-RS transmission in LTM candidate cell(s); receiving a message from the second network node comprising a request (or an interest) to receive indication, indicating whether transmission of CSI-RS in LTM candidate cell(s) is started, or is stopped, or is ongoing; transmitting a message based on the above request to the fourth network node. In alternative, transmitting a message to the fourth network node, comprising a subscription request (or an interest) to receive indication, indicating whether transmission of CSI-RS in LTM candidate cell(s) is started, or is stopped, or is ongoing; and receiving a message from the fourth network node with the information on whether CSI-RS is turned on / off / ongoing for the configured LTM candidate cell(s).10. A method performed by a fourth network node (e.g., a candidate gNB-DU), the method comprising one or more of receiving a message from the third network node by indicating a request whether CSI-RS needs to be started or stopped for the UE, for example, an enumerated value, corresponding to “0” or “1” or “start” or “stop” for each LTM candidate cell configured by the gNB-DU, in one F1AP message;transmitting a message to the third network node to indicate whether the CSI-RS is turned on or off or will be turned off at a given time for the UE; transmitting a message to a third network node (such as a candidate gNB-CU), the message comprising an indication, indicating the start of CSI-RS transmission in LTM candidate cell(s), or indicating the stop of CSI-RS transmission in LTM candidate cell(s), or indicating that CSI-RS transmission in LTM candidate cell(s) is ongoing; receiving a message from the third network node comprising a subscription request to receive from the fourth network node information concerning CSI-RS transmission start / stop; optionally transmitting a response to accept or reject the subscription request; and transmitting a message to a third network node (such as a candidate gNB-CU), the message comprising an indication, indicating the start of CSI-RS transmission in LTM candidate cell(s), or indicating the stop of CSI-RS transmission in LTM candidate cell(s), or indicating that CSI-RS transmission in LTM candidate cell(s) is ongoing.11. The method of any of the previous embodiments, wherein the reference signal is a CSI-RS.12. The method of any of the previous embodiments, wherein the indication included in the message transmitted to the second network node is a request to activate or deactivate one or more CSI-RS reference signals (CSI-RS resource or CSI-RS resource set) of an LTM candidate cell for a given UE.13. The method of any of the previous embodiments, wherein the indication includes an enumerated value for each of the one or more included CSI-RS reference signals related to one or more LTM candidate cells which indicates the request to start or stop the CSI-RS reference signal.14. The method of any of the previous embodiments, wherein the indication includes an enumerated value for each of the CSI-RS resource set or CSI-RS resource index / ID related to one or more LTM candidate cells which indicate the request to start or stop the CSI-RS reference signal.15. The method of any of the previous embodiments, wherein the indication includes the start time and / or stop time of the CSI-reference signal or CSI-Resource set or CSI resource related to one or more LTM candidate cells.16. The method of any of the previous embodiments, wherein the indication is one value which is common to each of the one or more included CSI-RS reference signals or CSI-RS resource set or CSI-RS resource related to one or more LTM candidate cells which need to be “all” stopped or started or activated or deactivated.17. The method of any of the previous embodiments, wherein the indication includes a UE identifier and / or an identifier of a previously provided CSI-RS configuration by a fourth network node (e.g. C-DU of the LTM candidate cell for which the CSLRSs are to be transmitted).18. The method of any of the previous embodiments, wherein the indication included in the message received from the second network node is an indication on which CSI-RS reference signals are activated or deactivated (or that will be activated, or that will be deactivated) for one or more candidate cells.19. The method of any of the previous embodiments, wherein the indication includes an enumerated value for each of the one or more included CSI-RS reference signals related to one or more LTM candidate cell which indicate the status of the reference CSI-RS reference signal.20. The method of any of the previous embodiments, wherein the indication includes an enumerated value for each of the one or more included CSI-RS resource set or CSI-RS resource index related to one or more LTM candidate cell which indicates the status of the reference CSI- RS reference signal.21. The method of any of the previous embodiments, wherein the indication is one value which is common to each of the one or more included CSI-RS reference signals related to one or more LTM candidate cell and which indicates that “all” CSI-RS reference signals are stopped or started or activated or deactivated.22. The method of any of the previous embodiments, wherein the indication in the message transmitted by the first network node is just a request to activate, start, stop, or deactivated one or more CSI-RS reference signals or CSI-RS resource set or CSI-RS resource index related to one or more candidate cell.23. The method of any of the previous embodiments, wherein the first network node (such as aserving gNB-DU), is configured with at least one LTM candidate configuration that includes CSI resources that are transmitted by the candidate cell.24. The method of any of the previous embodiments, wherein the first network node does not transmit an indication to request for the second network node to start or stop CSI-RS reference signal.Group C Embodiments25. A user equipment, comprising: processing circuitry configured to perform any of the steps of any of the Group A embodiments; and power supply circuitry configured to supply power to the processing circuitry.26. A network node, the network node comprising: processing circuitry configured to perform any of the steps of any of the Group B embodiments; power supply circuitry configured to supply power to the processing circuitry.27. A user equipment (UE), the UE comprising: an antenna configured to send and receive wireless signals; radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry; the processing circuitry being configured to perform any of the steps of any of the Group A embodiments; an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry; an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and a battery connected to the processing circuitry and configured to supply power to the UE.

[0158] Although the computing devices described herein (e.g., UEs, network nodes) 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 neededto 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.

[0159] In certain embodiments, some or all of 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.

[0160] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.ABBREVIATIONSAt least some of the following abbreviations may be used in this disclosure. If there is an inconsistency between abbreviations, preference should be given to how it is used above. If listed multiple times below, the first listing should be preferred over any subsequent listing(s).3 GPP 3rd Generation Partnership Project 5G 5th Generation 6G 6thGeneration ABS Almost Blank Subframe ARQ Automatic Repeat Request AWGN Additive White Gaussian Noise BCCH Broadcast Control Channel BCH Broadcast Channel CA Carrier Aggregation CC Carrier Component CCCH SDU Common Control Channel SDU CDMA Code Division Multiplex Access CGI Cell Global Identity CIR Channel Impulse Response CP Cyclic Prefix CPICH Common Pilot Channel CQI Channel Quality Information C-RNTI Cell RNTI CSI Channel State Information DCCH Dedicated Control Channel DL Downlink DM Demodulation DMRS Demodulation Reference Signal DRX Discontinuous Reception DTX Discontinuous Transmission DTCH Dedicated Traffic Channel DUT Device Under Test E-CID Enhanced Cell-ID (positioning method) Ec / No Received energy per chip divided by the power density in the band eMBMS Evolved Multimedia Broadcast Multicast Services ECGI Evolved CGI eNB E-UTRAN NodeB ePDCCH Enhanced Physical Downlink Control Channel E-SMLC Evolved Serving Mobile Location Center E-UTRAN Evolved Universal Terrestrial Radio Access Network FDD Frequency Division Duplex FFS For Further StudyBase station in NRGNSS Global Navigation Satellite SystemHARQ Hybrid Automatic Repeat RequestHO HandoverHSPA High Speed Packet AccessHRPD High Rate Packet DataLOS Line of SightLPP LTE Positioning Protocol LTE Long-Term Evolution MAC Medium Access Control MAC Message Authentication Code MBSFN Multimedia Broadcast Multicast Service Single Frequency Network MBSFN ABS MBSFN Almost Blank Subframe MDT Minimization of Drive Tests MIB Master Information Block MME Mobility Management Entity MSC Mobile Switching Center NPDCCH Narrowband Physical Downlink Control Channel NR New Radio OCNG OFDMA Channel Noise Generator OFDM Orthogonal Frequency Division Multiplexing OFDMA Orthogonal Frequency Division Multiple Access OSS Operations Support System OTDOA Observed Time Difference of Arrival O&M Operation and Maintenance PBCH Physical Broadcast Channel P-CCPCH Primary Common Control Physical Channel PCell Primary Cell PCFICH Physical Control Format Indicator Channel PDCCH Physical Downlink Control Channel PDCP Packet Data Convergence Protocol PDP Power Delay Profile PDSCH Physical Downlink Shared Channel PGW Packet Gateway PHICH Physical Hybrid-ARQ Indicator Channel PLMN Public Land Mobile Network PMI Precoding Matrix Indicator PRACH Physical Random Access Channel PRS Positioning Reference Signal PSS Primary Synchronization Signal PUCCH Physical Uplink Control Channel PUSCH Physical Uplink Shared Channel RACH Random Access Channel QAM Quadrature Amplitude Modulation RAN Radio Access Network RAT Radio Access Technology RLC Radio Link Control RLM Radio Link Monitoring RNC Radio Network Controller RNTI Radio Network Temporary Identifier RRC Radio Resource Control RRM Radio Resource Management RS Reference Signal RSCP Received Signal Code Power RSRP Reference Symbol Received Power ORReference Signal Received PowerRSRQ Reference Signal Received Quality ORReference Symbol Received QualityRS SI Received Signal Strength Indicator RSTD Reference Signal Time Difference SCH Synchronization Channel SCell Secondary Cell SDAP Service Data Adaptation Protocol SDU Service Data Unit SFN System Frame Number SGW Serving Gateway SI System Information SIB System Information Block SNR Signal to Noise Ratio SON Self-Organizing Network ss Synchronization Signal sss Secondary Synchronization Signal TDD Time Division Duplex TDOA Time Difference of Arrival TOA Time of Arrival TSS Tertiary Synchronization Signal TTI Transmission Time Interval UE User Equipment UL Uplink UMTS Universal Mobile Telecommunications System USIM Universal Subscriber Identity Module UTDOA Uplink Time Difference of Arrival WCDMA Wideband CDMA WLAN Wireless Local Area NetworkREFERENCES1. RP-242356, Revised Work Item: NR mobility enhancements Phase 4, 3GPP TSG RANMeeting #1052. 3GPP TS 38.300, vl8.3.0 (2024-09), NR and NG-RAN Overall Description; Stage 2 3. 3GPP TS 38.401, vl8.3.0 (2024-09), NG-RAN; Architecture description4. 3GPP TS 38.423, vl8.3.0 (2024-09), Xn Application Protocol (XnAP)5. 3GPP TS 38.473, vl8.3.0 (2024-09), Fl Application Protocol (F1AP)6. 3GPP TS 38.321, vl8.3.0 (2024-09), MAC protocol specification

Claims

CLAIMS1. A method (500) performed by a first network node (202) for reference signal measurements, the method comprising: sending (510), to a second network node (204), a request to change an operational status of a reference signal corresponding to one or more candidate cells; receiving (520), from the second network node (204), an indication of the operational status of the reference signal corresponding to the one or more candidate cells; and sending (530), to a User Equipment, UE, (200) the indication of the operational status of the reference signal, wherein the UE (200) sends or stops sending individual measurement reports based on the reference signal in accordance with the indication.

2. The method of claim 1, wherein the reference signal measurements relate to a Layer 1, LI, / Layer 2, L2, triggered mobility, LTM, procedure and the reference signal comprises a Channel State Information Reference Signal, CSI-RS, corresponding to the one or more candidate cells.

3. The method of any of claims 1-2, wherein the request to change the operational status comprises an enumerated value indicating to change an operational status of individual reference signals corresponding to the one or more candidate cells (e.g., an enumerated value for the operational status, e.g., activate, start, stop, deactivate all individual reference signals).

4. The method of any of claims 1-3, wherein the request to change the operational status comprises an enumerated value to change an operational status of individual CSI-RS resource sets or a CSI-RS resource index or identifier related to the one or more candidate cells.

5. The method of any of claims 1-4, wherein the request to change the operational status comprises a requested start time or stop time for at least one individual reference signal, individual CSI-RS resource set, or a CSI-RS resource index or identifier related to the one or more candidate cells.

6. The method of any of claims 1-5, wherein the request to change the operational status comprises at least one of an identifier of the UE or an identifier of a configuration for reference signals corresponding to the one or more candidate cells.

7. The method of any of claims 1-6, wherein the indication comprises a response to the requestto change the operational status of the reference signal corresponding to the one or more candidate cells.

8. The method of any of claims 1-7, wherein the reference signal is transmitted semi- persistently or aperiodically.

9. The method of any of claims 1-8, further comprising: sending, to the UE, a configuration for measuring the reference signal corresponding to the one or more candidate cells.

10. The method of any of claims 1-9, further comprising: sending, to the UE, a configuration for reporting measurements based on the reference signal corresponding to the one or more candidate cells.

11. The method of any of claims 1-10, further comprising: sending, to the UE, an indication to send individual measurement reports based on the reference signal.

12. The method of any of claims 1-11, further comprising: sending, to the UE, an indication to stop sending individual measurement reports based on the reference signal.

13. The method of any of claims 1-12, further comprising: sending, to the second network node (404), a request for a subscription to receive the indication of the operational status of the reference signal corresponding to the one or more candidate cells.

14. The method of claim 13, further comprising: receiving, from the second network node (404), an indication of whether the request for the subscription has been accepted or rejected.

15. The method of claim 14, further comprising: receiving, from the second network node (404), an indication of the operational status of the reference signal when the request for the subscription has been accepted.

16. The method of any of claims 1-15, wherein the indication comprises an enumerated value indicating the operational status of individual reference signals corresponding to the one or more candidate cells (e.g., an enumerated value for the operational status common to all individual reference signals).

17. The method of any of claims 1-16, wherein the indication comprises an enumerated value indicating the operational status of individual CSI-RS resource sets or a CSI-RS resource index or identifier related to the one or more candidate cells.

18. The method of any of claims 1-17, wherein the indication comprises an indication of individual reference signals corresponding to the one or more candidate cells that are activated or deactivated, or are to be activated or deactivated.

19. The method of any of claims 1-18, wherein the first network node (202), is configured with at least one configuration for LTM candidates that includes CSI resources that are transmitted by the one or more candidate cells.

20. The method of any of claims 1-19, wherein the first network node (202) comprises a source gNB-DU or a source gNB-CU.

21. The method of any of claims 1-20, wherein the second network node (204) comprises a serving gNB-DU or a serving gNB-CU.

22. A method (600) performed by a second network node (204) for reference signal measurements, the method comprising: receiving (610), from a first network node (202), a request to change an operational status of a reference signal corresponding to one or more candidate cells; sending (620), to a third network node (206), the request to change an operational status; receiving (630), from the third network node (206), an indication of an operational status of the reference signal corresponding to the one or more candidate cells, wherein the indication comprises a response to the request to change the operational status of the reference signal; and sending (640), to the first network node (202), the indication of the operational status of the reference signal corresponding to the one or more candidate cells.

23. The method of claim 22, wherein the request sent to the third network node (206) comprises an Xn Application Protocol (XnAP) message.

24. A method (700) performed by a second network node (204) for reference signal measurements, the method comprising: receiving (710), from a third network node (206) or from a fourth network node (208), an indication of an operational status of a reference signal corresponding to one or more candidate cells, wherein the reference signal is transmitted semi -persistently or aperiodically; and sending (720), to a first network node (202), the indication of the operational status of the reference signal corresponding to the one or more candidate cells.

25. A method (800) performed by a second network node (404) for reference signal measurements, the method comprising: receiving (810), from a first network node (402), a request for a subscription to receive an indication of an operational status of a reference signal corresponding to one or more candidate cells, wherein the reference signal is transmitted semi -persistently or aperiodically; sending (820), to a third network node (406), the request for the subscription to receive the indication of the operational status of the reference signal and a request for the indication of the operational status of the reference signal; receiving (830), from the third network node (406), at least one of: the indication of whether the request for the subscription has been accepted or rejected, or indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference; and sending (840), to the first network node (402), at least one of: the indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference.

26. A method (900) performed by a third network node (206) for reference signal measurements, the method comprising: receiving (910), from a second network node (204), a request to change an operational status of a reference signal corresponding to one or more candidate cells, wherein the request correspondsto at least one User Equipment, UE; sending (920), to a fourth network node (208), the request to change the operational status; receiving (930), from the fourth network node (208), an indication of an operational status of the reference signal corresponding to the one or more candidate cells, wherein the indication comprises a response to the request to change the operational status of the reference signal; and sending (940), to the second network node (204), the indication of the operational status of the reference signal corresponding to the one or more candidate cells.

27. A method (1000) performed by a third network node (406) for reference signal measurements, the method comprising: receiving (1010), from a second network node (404), a request for a subscription to receive an indication of an operational status of a reference signal corresponding to one or more candidate cells, wherein the reference signal is transmitted semi-persistently or aperiodically, and wherein the request corresponds to at least one User Equipment, UE; sending (1020), to a fourth network node (408), the request for the subscription to receive the indication of the operational status of the reference signal and a request for the indication of the operational status of the reference signal; receiving (1030), from the fourth network node (408), at least one of: an indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference; and sending (1040), to the second network node (404), at least one of: the indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference.

28. A method (1100) performed by a fourth network node (208) for reference signal measurements, the method comprising: receiving (1110), from a third network node (206), a request to change an operational status of a reference signal corresponding to one or more candidate cells, wherein the reference signal is transmitted semi-persistently or aperiodically, and wherein the request corresponds to at least one User Equipment, UE (200); and sending (1120), to the third network node (206), an indication of the operational status of the reference signal corresponding to the one or more candidate cells, wherein the indicationcomprises a response to the request to change the operational status of the reference signal.

27. A method (1200) performed by a fourth network node (408) for reference signal measurements, the method comprising: receiving (1210), from a third network node (406), a request for a subscription to receive an indication of an operational status of a reference signal corresponding to one or more candidate cells, wherein the reference signal is transmitted semi-persistently or aperiodically, and wherein the request corresponds to at least one User Equipment, UE (400); sending (1220), to the third network node (406), at least one of: an indication of whether the request for the subscription has been accepted or rejected, or the indication of the operational status of the reference.

28. A method (1300) performed by a user equipment, UE, (200) for reference signal measurements, the method comprising: receiving (1310), from a first network node (202), an indication of an operational status of a reference signal corresponding to one or more candidate cells, wherein the reference signal is transmitted semi-persistently or aperiodically; and sending (1320), to the first network node (202), individual measurement reports based on the reference signal in accordance with the indication.

29. The method of claim 28, further comprising: receiving, from the first network node (202), a configuration for measuring the reference signal corresponding to the one or more candidate cells.

30. The method of any of claims 28-29, further comprising: receiving, from the first network node (202), a configuration for reporting measurements based on the reference signal corresponding to the one or more candidate cells.

31. The method of any of claims 28-30, further comprising: receiving, from the first network node (202), an indication to send individual measurement reports based on the reference signal.

32. The method of any of claims 28-31, further comprising:receiving, from the first network node (202), an indication to stop sending individual measurement reports based on the reference signal.

33. A user equipment (200), comprising: processing circuitry configured to: receive, from a first network node (202), an indication of an operational status of a reference signal corresponding to one or more candidate cells, wherein the reference signal is transmitted semi-persistently or aperiodically; and send, to the first network node (202), individual measurement reports based on the reference signal in accordance with the indication; and power supply circuitry configured to supply power to the processing circuitry.

34. A first network node (202), comprising: processing circuitry configured to: send, to a second network node (204), a request to change an operational status of a reference signal corresponding to one or more candidate cells; receive, from the second network node (204), an indication of an operational status of the reference signal corresponding to the one or more candidate cells; and send, to a User Equipment, UE (200), the indication of the operational status of the reference signal, wherein the UE sends or stops sending individual measurement reports based on the reference signal in accordance with the indication; and power supply circuitry configured to supply power to the processing circuitry.

35. A second network node (204), comprising: processing circuitry configured to: receive, from a first network node (202), a request to change an operational status of a reference signal corresponding to one or more candidate cells; send, to a third network node (206), the request to change an operational status; receive, from the third network node (206), an indication of an operational status of the reference signal corresponding to the one or more candidate cells, wherein the indication comprises a response to the request to change the operational status of the reference signal; and send, to the first network node (202), the indication of the operational status of the reference signal corresponding to the one or more candidate cells; andpower supply circuitry configured to supply power to the processing circuitry.

36. A third network node (206), comprising: processing circuitry configured to: receive, from a second network node (204), a request to change an operational status of a reference signal corresponding to one or more candidate cells, wherein the request corresponds to at least one User Equipment, UE (200); send, to a fourth network node (208), the request to change the operational status; receive, from the fourth network node (208), an indication of an operational status of the reference signal corresponding to the one or more candidate cells, wherein the indication comprises a response to the request to change the operational status of the reference signal; and send, to the second network node (204), the indication of the operational status of the reference signal corresponding to the one or more candidate cells; and power supply circuitry configured to supply power to the processing circuitry.

37. A fourth network node (208), comprising: processing circuitry configured to: receive, from a third network node (206), a request to change an operational status of a reference signal corresponding to one or more candidate cells, wherein the reference signal is semi-persistent or aperiodic, and wherein the request corresponds to at least one User Equipment, UE; and send, to the third network node (206), an indication of the operational status of the reference signal corresponding to the one or more candidate cells, wherein the indication comprises a response to the request to change the operational status of the reference signal; and power supply circuitry configured to supply power to the processing circuitry.

38. A user equipment, UE (1500), comprising: an antenna configured to send and receive wireless signals; radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry; the processing circuitry being configured to: receive, from a first network node (1600), an indication of an operational status ofa reference signal corresponding to one or more candidate cells, wherein the reference signal is transmitted semi-persistently or aperiodically; and send, to the first network node (1600), individual measurement reports based on the reference signal in accordance with the indication; an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry; an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and a battery connected to the processing circuitry and configured to supply power to the UE.

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