Methods, apparatus and computer-readable media related to mobility in communication networks

Abstract

An example method performed by a user equipment comprises receiving (402) a conditional Layer 1 / Layer 2 Triggered Mobility (LTM) configuration. The LTM configuration comprises an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration. The method further comprises: monitoring (404) the execution condition and, responsive to fulfilment of the execution condition, initiating (406) an LTM mobility procedure to the candidate cell using the LTM candidate cell configuration. The indication of the execution condition comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

Description

METHODS, APPARATUS AND COMPUTER-READABLE MEDIA RELATED TO MOBILITY IN COMMUNICATION NETWORKS TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to communication networks, andparticularly to methods, apparatus and computer-readable media related to mobility in communication networks. BACKGROUND

[0002] Layer 1 (L1) / Layer 2 (L2) Triggered Mobility (LTM) is a procedure in which agNB receives L1 measurement report(s) from a User Equipment (UE), and on the basis of thosereports the gNB changes the UE’s serving cell by a cell switch command signalled via aMedium Access Control (MAC) Control element (CE). The cell switch command indicates an LTM candidate configuration that the gNB previously prepared and provided to the UE throughRadio Resource Control (RRC) signalling. Then the UE switches to the target configurationaccording to the cell switch command. See 3rd Generation Partnership Project (3GPP)Technical Specification (TS) 38.300 v18.0.0.

[0003] LTM supports both intra-gNB Distributed Unit (DU) and intra-gNBCentral / Centralized Unit (CU) inter-gNB-DU mobility (that is, mobility between cells or otherlogical entities served by the same gNB-DU, and mobility between cells or other logical entities served by different gNB-DUs which are connected to the same gNB-CU). LTM supports both intra-frequency and inter-frequency mobility, including mobility to an inter-frequency cell thatis not a current serving cell. LTM is currently supported only for licensed spectrum. The cellswitch command is conveyed in a MAC CE, which contains the necessary information to perform the LTM cell switch.

[0004] Figure 1 shows a signaling flow for LTM according to current Release 18 (Rel-18) standards.

[0005] At step 101, the UE sends a measurement report to the gNB.

[0006] At step 102, the gNB transmits an RRC reconfiguration message to the UEincluding an LTM candidate cell configuration.

[0007] At step 103, the UE transmits an RRC reconfiguration complete message to thegNB.

[0008] At step 104a, the UE performs Downlink (DL) synchronization with the candidatecell(s).

[0009] At step 104b, the UE performs Uplink (UL) synchronization with the candidatecell(s).

[0010] At step 105, the UE transmits an L1 measurement report to the gNB.

[0011] The gNB makes an LTM decision and, at step 106, transmits a cell switchcommand (corresponding to a MAC CE) to the UE.

[0012] The UE detaches from the source cell and applies the target cell configurations. Atstep 107, the UE performs a random access procedure towards the target cell.

[0013] At step 108, the UE completes the LTM cell switch procedure.

[0014] LTM was introduced in Rel-18 and can offer improvements in handover latencyand interruption time compared to Layer 3 (L3) based mobility. However, LTM as introducedin Rel-18 also has a number of limitations compared to Layer 3 mobility. A Rel-19 work itemaims to remove a number of these limitations (see 3GPP RP-234036). Layer 3 mobility hasevolved over several releases. Conditional handover (CHO) and other conditional mobilityprocedures (Conditional Primary Secondary Cell Group (SCG) Cell (PSCell) Addition orChange (CPAC), Subsequent CPAC (SCPAC)) were developed to achieve high robustness byenabling the procedure to be executed without necessitating a signalling exchange with thesource cell beforehand. LTM as introduced in Rel-18 offers short interruption time but not with the same level of robustness as the conditional L3 mobility procedures. In Rel-19, enhancements should be specified so that the system can benefit from both the high robustness and short interruption.

[0015] Regarding conditional LTM, the following objectives have been captured in thework item: ^Specify support of conditional LTM [RAN2, RAN3, RAN1]^ Specify UE evaluated conditions for triggering LTM^ Aim to support conditional LTM including subsequent LTMSUMMARY

[0016] There currently exist certain challenge(s).

[0017] To specify conditional LTM, the UE should be configured with conditional LTMexecution conditions (which may be simply called execution condition(s)) to be evaluated, sothat upon their fulfillment the UE needs to execute an LTM cell switch.

[0018] In CHO, a similar principle is applicable. However, CHO is a higher layerprocedure where the associated execution conditions to be evaluated by the UE refer to a higher layer (layer 3) measurement configuration. The same is applicable for conditional PSCelladdition (CPA) and conditional PSCell change (CPC).

[0019] LTM is a mobility procedure that is triggered on layer 1 / layer 2 level where thedecision to trigger / execute the cell switch is taken by the serving DU (S-DU), e.g. based on L1measurements. The existing framework for configuring execution conditions for CHO (or CPA / CPC), where the execution conditions refer to the L3 measurement configuration, is thus not suitable for conditional LTM.

[0020] Certain aspects of the disclosure and their embodiments may provide solutions tothese or other challenges.

[0021] In a first aspect of the disclosure, a method is performed by a UE. The methodcomprises receiving a conditional LTM configuration, comprising an LTM candidate cellconfiguration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration. The method further comprises: monitoring the executioncondition; and responsive to fulfilment of the execution condition, initiating an LTM mobilityprocedure to the candidate cell using the LTM candidate cell configuration. The indication of the execution condition comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

[0022] In a second aspect of the disclosure, a method is performed by a DU for a networknode. The method comprises receiving, from a CU for the network node, a request messagecomprising information related to an LTM candidate cell for a UE served by the DU, and anindication that conditional LTM is configured. The method further comprises transmitting, to the CU, a response message comprising an indication of an execution condition to be fulfilledfor the UE to initiate an LTM mobility procedure to the LTM candidate cell. The indication ofthe execution condition in the response message comprises an indication of a lower-layermeasurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

[0023] In a third aspect of the disclosure, a method is performed by a CU for a networknode. The method comprises transmitting to a UE, via a DU for the network node, a conditionalLTM configuration, comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration. The indication of the execution condition comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

[0024] In a fourth aspect of the disclosure, a UE comprises processing circuitry configuredto cause the UE to receive a conditional LTM configuration, comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration. The processing circuitry is further configured to cause the UE to: monitor the execution condition; and responsive to fulfilment of the execution condition, initiate an LTM mobility procedure to the candidate cell using the LTM candidate cell configuration. The indication of the execution condition comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

[0025] In a fifth aspect of the disclosure, a UE is adapted to receive a conditional LTMconfiguration, comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration. TheUE is further adapted to: monitor the execution condition; and responsive to fulfilment of theexecution condition, initiate an LTM mobility procedure to the candidate cell using the LTMcandidate cell configuration. The indication of the execution condition comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

[0026] In a sixth aspect of the disclosure, a DU for a network node comprises processingcircuitry configured to cause the DU to receive, from a CU for the network node, a requestmessage comprising information related to an LTM candidate cell for a UE served by the DUand an indication that conditional LTM is configured. The processing circuitry is furtherconfigured to cause the DU to transmit, to the CU, a response message comprising an indicationof an execution condition to be fulfilled for UE to initiate an LTM mobility procedure tothe LTM candidate cell. The indication of the execution condition in the response message comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

[0027] In a seventh aspect of the disclosure, a DU for a network node is adapted to receive,from a CU for the network node, a request message comprising information related to an LTMcandidate cell for a UE served by the DU, and an indication that conditional LTM is configured.The DU is further adapted to transmit, to the CU, a response message comprising an indicationof an execution condition to be fulfilled for the UE to initiate an LTM mobility procedure tothe LTM candidate cell. The indication of the execution condition in the response message comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

[0028] In an eighth aspect of the disclosure, a CU for a network node comprises processingcircuitry configured to cause the CU to transmit to a UE, via a DU for the network node, aconditional LTM configuration, comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration. The indication of the execution condition comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

[0029] In a ninth aspect of the disclosure, a CU for a network node is adapted to transmitto a UE, via a DU for the network node, a conditional LTM configuration, comprising an LTMcandidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration. The indication of the execution condition comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

[0030] In a tenth aspect of the disclosure, computer-readable storage medium stores codewhich, when executed by processing circuitry of a UE, causes the UE to perform a method according to embodiments of the first aspect.

[0031] In an eleventh aspect of the disclosure, computer-readable storage medium storescode which, when executed by processing circuitry of a DU of a network node, causes the DUto perform a method according to of the second aspect.

[0032] In a twelfth aspect of the disclosure, computer-readable storage medium storescode which, when executed by processing circuitry of a CU of a network node, causes the CUto perform a method according to embodiments of the third aspect.

[0033] Certain embodiments may provide one or more of the following technicaladvantage(s). One of the benefits of embodiments of the disclosure is that the same networknode which is responsible for the LTM Cell Switch may also be responsible for defining theexecution conditions for the UE for executing conditional LTM. This is the network nodewhich determines whether to trigger LTM cell Switch in the case of legacy LTM, so that itmakes sense that it is also the S-DU which determines the LTM execution conditions. It is also the S-DU which determines whether a report for legacy LTM is periodic, aperiodic or semi- persistent.

[0034] Another benefit is that by defining the conditional LTM execution condition(s) aspart of the lower layer measurement configuration, the UE performs measurements accordingto its existing configuration(s), and simply associates these measurements as an input to theevaluation of the conditional LTM execution condition(s), which simplifies the signaling structure and reduces the number of bits for configuring conditional LTM.

[0035] Yet another benefit is that the conditional LTM execution condition(s) have lowerlayer measurements as input, which requires the UE to perform lower layer measurements; this simplifies the UE processes to perform lower layer measurements for the evaluation of the conditional LTM execution conditions also based on the lower layer measurement configuration(s), thanks to the association via the lower layer measurement configuration identifier.

[0036] The teachings of certain embodiments may improve the data rate, as well as thelatency and robustness of mobility procedures, by enabling the UE to decide itself to initiate an LTM mobility procedure with very low overheads. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] For a better understanding of the embodiments of the present disclosure, and toshow how it may be put into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0038] Fig. 1 is a signalling flow for LTM;

[0039] Fig. 2 show examples of a reconfiguration message according to embodiments ofthe disclosure;

[0040] Fig. 3 is a signaling flow for conditional LTM according to embodiments of thedisclosure;

[0041] Fig. 4 is a flow chart illustrating a method in accordance with some embodiments;

[0042] Fig. 5 is a flow chart illustrating a method in accordance with some embodiments;

[0043] Fig. 6 is a flow chart illustrating a method in accordance with some embodiments;

[0044] Figs. 7 and 8 show examples of a reconfiguration message according to furtherembodiments of the disclosure;

[0045] Fig. 9 shows an example of a communication system in accordance with someembodiments;

[0046] Fig. 10 shows a UE in accordance with some embodiments;

[0047] Fig. 11 shows a network node in accordance with some embodiments; and

[0048] Fig. 12 is a block diagram illustrating a virtualization environment in whichfunctions implemented by some embodiments may be virtualized. DETAILED DESCRIPTION

[0049] Some of the embodiments contemplated herein will now be described more fullywith 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.

[0050] According to some embodiments of this disclosure, a method at a User Equipmentcapable of conditional LTM, comprises: ^Receiving a conditional LTM configuration including an LTM candidate cellconfiguration, associated to an LTM candidate cell; ^Receiving a conditional LTM execution condition (or simply called an LTMexecution condition) associated to a measurement configuration identifier of a lower layer measurement configuration, wherein the LTM candidate cell configuration is associated to the conditional LTM execution condition by being associated to the measurement configuration identifier of the lower layer measurement configuration; and^ Evaluating the fulfillment of the conditional LTM execution condition inresponse to the reception of the conditional LTM configuration including the LTM candidate cell configuration associated to the conditional LTM execution condition associated to the configuration identifier of the lower layer measurement configuration of the UE’s current configuration.

[0051] In other words, the UE relies on a lower layer measurement configuration,generated by the S-DU the UE is connected to (or being served by), to determine the conditional LTM execution condition(s) associated to a given LTM candidate cell configuration, thanks to the association between the LTM candidate configuration and the measurement configuration identifier. The lower layer measurement configuration may correspond to an LTM ChannelState Information (CSI) measurement configuration part of the UE’s current configuration,such as the servingCellConfig of the serving cell the UE is served by (e.g. Primary Cell (PCell)) in the S-DU when the UE is configured with LTM.

[0052] In one embodiment, the lower layer measurement configuration corresponds to anLTM CSI reporting configuration, wherein the measurement configuration identifier may correspond to a reporting configuration identifier.

[0053] Additionally or alternatively, in response to receiving the lower layer measurementconfiguration for configuring the conditional LTM execution condition associated to a measurement configuration identifier, the UE performs one or more measurements (e.g.Reference Signal (RS) Received Power (RSRP) and / or RS Received Quality (RSRQ)measurements for serving cell and / or LTM candidate cell(s), lower layer measurements, L1-RSRP for Synchronization Signal (SS) Block (SSB) and / or CSI-RS, SS-RSRP, SS-RSRQ, SSSignal-to-Interference-plus-Noise Ratio (SINR) (SS-SINR) e.g. or any other measurements asdefined, e.g., in 3GPP TS 38.215 v 18.1.0) used as input to the evaluation of the fulfillment ofthe conditional LTM execution condition.

[0054] Additionally or alternatively, upon fulfillment of the conditional LTM executioncondition whose measurement configuration identifier is associated to the LTM candidate cell configuration, the UE applies the LTM candidate cell configuration.

[0055] Figure 2 illustrates an example in which the UE receives, in an RRCReconfiguration message 202, a Conditional LTM configuration 204 and a Lower layermeasurement configuration 206. An LTM candidate cell configuration of the Conditional LTMconfiguration 202 is associated with a conditional LTM execution condition of the Lower layer measurement configuration 204 via a measurement configuration identifier.

[0056] In another embodiment, the conditional LTM execution condition is associated tomultiple measurement configuration identifier(s) e.g. two, and in one option the conditional LTM execution condition is considered fulfilled when each of the condition(s) associated toboth identifiers is fulfilled. In another option the conditional LTM execution condition isconsidered fulfilled when at least one of condition(s) associated to both identifiers isfulfilled. Further, in one option, the multiple measurement configuration identifier(s) may be associated to different RS types e.g. first with SSB, second with CSI-RS.

[0057] According to some other embodiments of this disclosure, a method at a networknode operating as an S-DU comprises:^ Receiving a request message from a CU including a resource configuration andan indication that Conditional LTM is being configured or it has been configured; ^In response, transmitting a response message to the CU including a lower layermeasurement configuration including a configuration of a conditional LTM execution condition associated to a measurement configuration identifier.

[0058] In one option, the S-DU also includes in the response an association between themeasurement configuration identifier of the lower layer measurement configuration and an LTM candidate cell configuration included in the received resource configuration.

[0059] In another option, the S-DU receives in the request message from the CU, theassociation between a measurement configuration identifier of the lower layer measurement configuration and an LTM candidate cell configuration. For example, the CU may indicate to the S-DU that for a given LTM candidate ID=7 there should be a conditional LTM execution condition with measurement configuration identifier set to e.g. X. In response, the S-DU generates an updated version of the lower layer measurement configuration of the UE’s current configuration, includes the measurement configuration identifier=X, and configures there the conditional LTM execution condition for the LTM candidate ID=7.

[0060] In one option, the so-called resource configuration includes an indication of anLTM candidate cell for conditional LTM which the UE is going to be configured with, so that the S-DU determines and / or generates the conditional LTM execution conditions associated for that LTM candidate cell. In other words, as the S-DU is the node which would have provide to the UE the LTM Cell Switch Command in response to a received lower layer LTM measurement report, whose configuration would have been defined by the S-DU, it is also theS-DU which determines the conditional LTM execution condition for that LTM candidate cellbeing configured, provides to the CU, to be wrapped in an RRC Reconfiguration in the conditional LTM configuration and forwarded to the UE.

[0061] In one option, the so-called resource configuration includes indications of one ormore beams and / or RS ID(s), e.g. SSB indexes, for an LTM candidate cell configured for conditional LTM.

[0062] In one option, the S-DU determines and generates the conditional LTM executioncondition associated to the measurement configuration identifier (e.g. LTM-CSI- ReportConfigId), and associates to an LTM candidate cell, so that the CU generates the LTM configuration to the UE, which needs to know the association; thanks to the association the UE knows which measurements to perform to be used as input to conditional LTM execution conditions and, when these are fulfilled, which LTM candidate cell configuration to apply. Onebenefit is that this would be the same network node as that which determines whether to triggerLTM cell Switch in case of legacy LTM, so that it makes sense that it is also the S-DU which determines the LTM execution conditions. It is also the S-DU which determines whether a report for legacy LTM is periodic, aperiodic or semi-persistent.

[0063] In one option, the request message may correspond to a UE CONTEXTMODIFICATION REQUEST message, and the response message is the UE CONTEXT MODIFICATION RESPONSE message. The request message may be received by the S-DUafter the CU obtained confirmation from Candidate DU(s) (C-DU(s)) of the acceptance of LTMcandidate cells for conditional LTM, and the lower layer configuration(s) from the C-DU(s) for accepted cell(s), based on which the CU has generated the LTM Candidate configuration (e.g. RRCReconfiguration, including the lower layer configuration(s)) which is to be applied by the UE upon fulfillment of the conditional LTM execution condition.

[0064] In one option, the S-DU receives a request for LTM configuration from the CU anddecides that the configuration should be a conditional LTM configuration. In other words, in this option it is the serving DU that decides that an LTM configuration should be conditional, and in case it decides it is conditional it determines associated execution conditions. The S-DU then indicates to the CU that the LTM configuration is a conditional one and provides information for the associated execution conditions according to the methods described in this disclosure. In one example, the S-DU receives in the request message from the CU, an indication that conditional LTM is supported and / or acceptable for the UE.

[0065] According to further embodiments of this disclosure, a method at a network nodeoperating as an S-CU comprises:^ Determining to initiate configuration of LTM for a UE, for at least one candidatecell. In one alternative, the S-CU decides to configure the UE with conditional LTM, i.e. so that the UE is configured with associated execution conditions for the at least one LTM candidate cell.^ Transmitting a request message to the S-DU for configuring LTM for the UE,including a resource configuration and (optionally) an indication that the request is for Conditional LTM; and^ Receiving a response message from the S-DU including a lower-layermeasurement configuration including a configuration of a conditional LTM execution condition associated to a measurement configuration identifier; ^The S-CU may then generate an RRC configuration for the UE, comprising aconditional LTM configuration, which includes an LTM candidate cell configuration, associated to an LTM candidate cell, and a conditional LTM execution condition associated to a measurement configuration identifier of a lower layer measurement configuration; ^Wherein the LTM candidate cell configuration is associated to the conditionalLTM execution condition by being associated to the measurement configuration identifier of the lower layer measurement configuration. ^Sending the RRC configuration with the conditional LTM configuration to theUE (via the S-DU).

[0066] According to some embodiments, the request message is a UE CONTEXTMODIFICATION REQUEST message and the response message is a UE CONTEXT MODIFICATION RESPONSE message.

[0067] Optionally, the S-CU may request and receive an LTM candidate configurationfrom another node, such as another DU (a C-DU) or another CU. This may occur before the S- CU transmits the request to the S-DU.

[0068] Certain embodiments may provide one or more of the following technicaladvantage(s). One of the benefits of embodiments of the disclosure is that the same networknode which is responsible for the LTM Cell Switch may also be responsible for defining theexecution conditions for the UE for executing conditional LTM. This is the network nodewhich determines whether to trigger LTM cell Switch in the case of legacy LTM, so that itmakes sense that it is also the S-DU which determines the LTM execution conditions. It is also the S-DU which determines whether a report for legacy LTM is periodic, aperiodic or semi- persistent.

[0069] Another benefit is that by defining the conditional LTM execution condition(s) aspart of the lower layer measurement configuration, the UE performs measurements accordingto its existing configuration(s), and simply these measurements as an input to theevaluation of the conditional LTM execution condition(s), which simplifies the signaling structure and reduces the number of bits for configuring conditional LTM.

[0070] Another benefit is that the conditional LTM execution condition(s) have lowerlayer measurements as input, which requires the UE to perform lower layer measurements; thissimplifies the UE processes to perform lower layer measurements for the evaluation of theconditional LTM execution conditions also based on the lower layer measurement configuration(s), thanks to the association via the lower layer measurement configuration identifier.

[0071] The teachings of certain embodiments may improve the data rate, as well as thelatency and robustness of mobility procedures, by enabling the UE to decide itself to initiate an LTM mobility procedure with very low overheads.

[0072] The text mentions “conditional LTM”, which may be seen as a conditionalreconfiguration in which execution conditions are associated to the evaluation of conditionsassociated to lower layer measurements, e.g. L1 RSRP, and / or SS-RSRP, based on SSB(s)and / or CSI-RSs of a serving cell and / or of an LTM candidate cell. In this context, a conditional LTM uses an execution condition (or conditional LTM execution condition) or a combination of multiple executing conditions, that is / are evaluated, and when fulfilled, results in that the UE performs an action, such as executing the conditional reconfiguration (sometimes known as executing the condition) or conditional LTM; for example applying a message, parts of a message or at least one information element, or performing a serving cell switch or change. Known existing examples of conditional reconfiguration are CHO, CPC and CPA. Accordingto the methods in the disclosure upon fulfillment of the execution conditions(s) the UEperforms an LTM Cell Switch.

[0073] The text refers to “an LTM candidate cell for conditional LTM”, which may becalled a conditional LTM candidate cell, or, in the context of the disclosure simply candidatecell; or L1 / L2 inter-cell mobility candidate cell or target candidate cell for L1 / L2 inter-cell mobility to refer to a cell the UE is configured with when configured with conditional L1 / L2inter-cell mobility; which is a cell the UE moves to or switches to in the execution of aconditional L1 / L2 inter-cell mobility procedure upon fulfillment of the associated execution condition. These cells may also be called candidate cells, candidates, mobility candidates, non- serving cells, additional cells, deactivated cells, etc.

[0074] In some methods disclosed herein, the UE receives an “LTM candidate cellconfiguration for conditional LTM”, for an LTM candidate cell. The LTM candidate cell configuration may be received in the form of an RRC Reconfiguration message (e.g. RRCReconfiguration) which the UE stores and applies upon fulfillment of the conditional LTM execution condition associated to that LTM candidate cell. The LTM candidate cell configuration may contain one or more parameters the UE uses to operate in the associated LTM candidate cell when the UE moves to it in an LTM Cell switch. The LTM candidate cellconfiguration may be applied on top of or in addition to the UE’s current configuration and / oron top of or in addition to a reference configuration (also received by the UE e.g. as part of aconditional LTM configuration).

[0075] In some methods disclosed herein, the UE receives a “conditional LTM executioncondition”. That may correspond to the UE receiving an indication of a conditional LTM execution condition and / or one or more parameters for configuring a conditional LTM execution condition e.g. event identifier, offset(s), threshold(s), reference signal type, trigger quantity, time to trigger, etc.

[0076] The “lower-layer measurement configuration” may correspond to a measurementconfiguration provided to the UE by the network instructing the UE to perform measurements on reference signal(s) for which measurements are typically reported on one or more message(s) on a protocol layer lower than the RRC and / or lower than L3 protocol layer in the UE’s protocol stack. These lower layer measurements derived by the UE are according to the lower layer measurement configuration are typically reported as Uplink Control Information (UCI) over a Physical Uplink Control Channel (PUCCH) and / or UCI over Physical Uplink Shared Channel (PUSCH).Signaling flows – inter-gNB (intra-CU)

[0077] Figure 3 is a signalling flow for configuration of conditional LTM executionconditions according to embodiments of the present disclosure, particularly in the context of intra-CU mobility. Further detail regarding the steps of the signalling flow are set out below:

[0078] Step 301: The UE sends a MeasurementReport message (L3 measurement result)to the source gNB-DU containing measurements of neighbouring cells. The source gNB-DUsends an UL RRC MESSAGE TRANSFER message conveying the receivedMeasurementReport message to the gNB-CU.

[0079] Step 302: The gNB-CU determines to initiate conditional LTM configuration.

[0080] Step 303: The gNB-CU sends a UE CONTEXT SETUP REQUEST messageincluding an indication of conditional LTM to the candidate gNB-DU(s) for each candidatecell, containing one target candidate cell ID, the LTM configuration ID of the candidate cell.

[0081] Step 304: If the candidate gNB-DU accepts the request of LTM configuration, itresponds with a UE CONTEXT SETUP RESPONSE message including the generated lower layer RRC configurations for the accepted target candidate cell.

[0082] Step 305: The gNB-CU sends a UE CONTEXT MODIFICATION REQUESTmessage to the source gNB-DU including the LTM configuration IDs for the accepted target candidate cell(s) in other gNB-DU(s) for conditional LTM, also including a resource configuration (e.g. indication of one or LTM Candidate cell(s) for conditional LTM).

[0083] In one embodiment, the UE CONTEXT MODIFICATION REQUEST alsoincludes an association between a measurement configuration identifier of the lower layer measurement configuration (e.g. reporting configuration identifier) and an LTM candidate cellconfiguration (e.g. LTM candidate ID). For example, the gNB-CU indicates to the source gNB-DU that for a given LTM candidate ID=7 there should be a conditional LTM execution condition with measurement configuration identifier is set to e.g. X. In response, the S-DU generates an updated version of the lower layer measurement configuration of the UE’s current configuration, includes the measurement configuration identifier=X, and configures there the conditional LTM execution condition for the LTM candidate ID=7.

[0084] Step 306: The source gNB-DU responds with a UE CONTEXTMODIFICATION RESPONSE message which includes an updated lower layer configuration, e.g., containing the updated CSI report configuration of the source cell, including a configuration of a conditional LTM execution condition associated to a measurement configuration identifier.

[0085] In one option, the source gNB-DU also includes in the response an associationbetween the measurement configuration identifier of the lower layer measurement configuration and an LTM candidate cell configuration included in the received resource configuration.

[0086] Step 307: The gNB-CU may send a UE CONTEXT MODIFICATIONREQUEST message to the candidate gNB-DU(s) containing the information for subsequent LTM or for updating the configurations of candidate cells. The gNB-CU may also provide the lower layer part of the reference configuration to the candidate gNB-DU(s).

[0087] Step 308: The candidate gNB-DU responds with a UE CONTEXTMODIFICATION RESPONSE message including the updated lower layer configuration(e.g., the updated CSI report configuration).

[0088] Step 309: The gNB-CU sends a DL RRC MESSAGE TRANSFER message tothe source gNB-DU, which includes the generated RRCReconfiguration message with the LTMconfiguration.

[0089] Step 310: The source gNB-DU forwards the received RRCReconfigurationmessage to the UE.

[0090] Step 311: The UE responds to the source gNB-DU with anRRCReconfigurationComplete message. The source gNB-DU forwards theRRCReconfigurationComplete message to the gNB-CU via an UL RRC MESSAGETRANSFER message.

[0091] In step 312: the UE may evaluate the conditional LTM execution condition for thefirst cell based on the measurement configuration identifier.

[0092] In step 313, upon fulfillment of the conditional LTM execution condition for thefirst cell, the UE executes an LTM cell switch to the first cell. Steps for performing the LTMcell switch are illustrated as step 314.

[0093] The following statements set out methods and apparatus in a UE, in a serving DUand in a serving CU, for configuring the UE with conditional LTM execution condition(s). Inone embodiment, the methods may be read in the context of the signalling flow shown in Figure3, including interactions between the UE, the S-DU and the S-CU as shown in that Figure.

[0094] Figure 4 depicts a method in accordance with particular embodiments. The methodof Figure 4 may be performed by a UE or wireless device (e.g. the UE 912 or UE 1000 asdescribed later with reference to Figures 9 and 10 respectively). Figures 5 and 6 set outcomplementary methods performed by a serving DU and a serving CU respectively, and may be read in conjunction with the method shown in Figure 4. At least some of the steps described herein may correspond to actions and signalling of the UE in Figure 3.

[0095] The method begins at step 402, in which the UE receives a conditional LTMconfiguration, comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration. In some embodiments, step 402 may correspond to step 310 in Figure 3 above.

[0096] In one embodiment, the indication of the execution condition comprises anindication of a lower-layer measurement (e.g., LTM CSI reporting configuration)associated with the LTM candidate cell configuration. For example, the lower-layer measurement configuration may itself comprise the execution condition, or define the execution condition. The lower-layer measurement configuration may comprise a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages in a protocol layer which is lower than L3. Alternatively or additionally, the lower-layer measurement configuration may comprise a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages over physical uplink control channel and / or uplink control information.

[0097] The indication of the lower-layer measurement configuration received in step 402may comprise an identifier of the lower-layer measurement configuration. The LTM candidatecell configuration and the lower-layer measurement configuration may be in separatecontainers within a reconfiguration message received in step 402 (see Figures 2, 7 and 8, forexample). Such containers may correspond to different fields, different information elements, etc.

[0098] In step 404, the UE monitors the execution condition. In some embodiments, step404 may correspond to step 312 in Figure 3 above.

[0099] The execution condition may utilize one or more of: radio measurements ontransmissions by a source cell or a source radio access network node; and radio measurements on transmissions by a candidate cell or a candidate radio access network node. For example, the UE may perform measurements on one or more reference signals transmitted by its serving cell and / or one or more reference signals transmitted by the candidate cell. Such measurements may be configured or specified in the lower-layer measurement configuration.

[0100] In some embodiments, the execution condition comprises a plurality of executionsub-conditions. Fulfilment of the execution condition may comprise fulfilment of one of theexecution sub-conditions, more than one of the execution sub-conditions or all of the executionsub-conditions.

[0101] In step 406, responsive to fulfilment of the execution condition, the UE initiates anLTM mobility procedure to the candidate cell using the LTM candidate cell configuration. In some embodiments, step 406 may correspond to steps 313 and / or 314 described above with respect to Figure 3. Thus, the UE initiates a cell switch to the candidate cell, and uses the parameters in the LTM candidate cell configuration to connect to and / or communicate with the LTM candidate cell.

[0102] Although the method of Figure 4 has been described in the context of conditionalLTM to a single candidate cell, it will be apparent to those skilled in the art that the procedure may be modified such that the UE is configured with a plurality of LTM configurations associated with respective execution conditions. The UE may therefore monitor multiple execution conditions and initiate an LTM mobility procedure to the candidate cell associated with the fulfilled execution condition.

[0103] Figure 5 depicts a method in accordance with particular embodiments. The methodof Figure 5 may be performed by a network node (e.g. the network node 910 or network node1100 as described later with reference to Figures 9 and 11 respectively), and particularly maybe performed by a DU of a radio access network node. Figures 4 and 6 set out complementarymethods performed by a UE and a serving CU respectively, and may be read in conjunction with the method shown in Figure 5. At least some of the steps described herein may correspond to actions and signalling of the S-DU in Figure 3.

[0104] The method begins at step 502, in which the DU receives, from a centralized unitfor the network node, a request message (e.g., UE context modification request message)comprising information related to an LTM candidate cell for a user equipment served by the distributed unit, and an indication that conditional LTM is configured. Step 502 may correspond to step 305 in Figure 3 above.

[0105] The information related to the LTM candidate cell may comprise a resourceconfiguration for the LTM candidate cell, such as an indication of resources on which measurements of reference signals transmitted on the LTM candidate cell are to be measured by the user equipment. In other embodiments, the resource configuration and / or the information related to the LTM candidate cell may comprise an identifier for the candidate cell.

[0106] In step 504, optionally, the DU determines an execution condition which the UE isto evaluate, and use as a trigger for initiating an LTM mobility procedure to the candidate cell.

[0107] In step 506, the DU transmits, to the centralized unit, a response message (e.g., UEcontext modification response message) comprising an indication of an execution condition to be fulfilled for the user equipment to initiate an LTM mobility procedure to the LTM candidate cell. Step 506 may correspond to step 306 in Figure 3 above.

[0108] In one embodiment, the indication of the execution condition comprises anindication of a lower-layer measurement configuration (e.g., LTM CSI reporting configuration) associated with the LTM candidate cell configuration. For example, the lower-layer measurement configuration may itself the execution condition, or define theexecution condition. The lower-layer measurement configuration may comprise a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages in a protocol layer which is lower than L3. Alternatively or additionally, the lower-layer measurement configuration may comprise a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages over physical uplink control channel and / or uplink control information.

[0109] The indication of the lower-layer measurement configuration received in step 402may comprise an identifier of the lower-layer measurement configuration. The LTM candidatecell configuration and the lower-layer measurement configuration may be in separatecontainers within a reconfiguration message received in step 402 (see Figures 2, 7 and 8, forexample). Such containers may correspond to different fields, different information elements, etc.

[0110] The execution condition may utilize one or more of: radio measurements ontransmissions by a source cell or a source radio access network node; and radio measurements on transmissions by a candidate cell or a candidate radio access network node. For example, the UE may perform measurements on one or more reference signals transmitted by its serving cell and / or one or more reference signals transmitted by the candidate cell. Such measurements may be configured or specified in the lower-layer measurement configuration.

[0111] In some embodiments, the execution condition comprises a plurality of executionsub-conditions. Fulfilment of the execution condition may comprise fulfilment of one of theexecution sub-conditions, more than one of the execution sub-conditions or all of the executionsub-conditions.

[0112] Figure 6 depicts a method in accordance with particular embodiments. The methodof Figure 5 may be performed by a network node (e.g. the network node 910 or network node1100 as described later with reference to Figures 9 and 11 respectively) , and particularly maybe performed by a CU of a radio access network node. Figures 4 and 5 set out complementarymethods performed by a UE and a serving DU respectively, and may be read in conjunction with the method shown in Figure 6. At least some of the steps described herein may correspond to actions and signalling of the S-CU in Figure 3.

[0113] The method begins at step 602, in which the CU optionally (e.g., in embodimentswhere the DU determines the execution condition) transmits, to the DU, a request message(e.g., UE context modification request comprising information related to an LTMcandidate cell for the user equipment, and an indication that conditional LTM is configured. Step 602 may correspond to step 305 in Figure 3 above.

[0114] The information related to the LTM candidate cell may comprise a resourceconfiguration for the LTM candidate cell, such as an indication of resources on which measurements of reference signals transmitted on the LTM candidate cell are to be measured by the user equipment. In other embodiments, the resource configuration and / or the information related to the LTM candidate cell may comprise an identifier for the candidate cell.

[0115] In step 604, the CU receives, from the distributed unit, a response message (e.g.,UE context modification response message) comprising an indication of the execution condition to be fulfilled for the user equipment to initiate an LTM mobility procedure to theLTM candidate cell. Step 604 may correspond to step 306 in Figure 3 above.

[0116] The execution condition may utilize one or more of: radio measurements ontransmissions by a source cell or a source radio access network node; and radio measurements on transmissions by a candidate cell or a candidate radio access network node. For example, the UE may perform measurements on one or more reference signals transmitted by its serving cell and / or one or more reference signals transmitted by the candidate cell. Such measurements may be configured or specified in the lower-layer measurement configuration.

[0117] In some embodiments, the execution condition comprises a plurality of executionsub-conditions. Fulfilment of the execution condition may comprise fulfilment of one of theexecution sub-conditions, more than one of the execution sub-conditions or all of the executionsub-conditions.

[0118] In step 606, the CU transmits to the user equipment, via a distributed unit for thenetwork node, a conditional LTM configuration, comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated withthe LTM candidate cell configuration. Step 606 may correspond to step 309 in Figure 3 above.

[0119] In one embodiment, the indication of the execution condition comprises anindication of a lower-layer measurement configuration (e.g., LTM CSI reporting configuration) associated with the LTM candidate cell configuration. For example, the lower-layer measurement configuration may itself comprise the execution condition, or define the execution condition. The lower-layer measurement configuration may comprise a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages in a protocol layer which is lower than L3. Alternatively or additionally, lower-layer measurement configuration maycomprise a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages over physical uplink control channel and / or uplink control information.

[0120] The indication of the lower-layer measurement configuration received in step 402may comprise an identifier of the lower-layer measurement configuration. The LTM candidatecell configuration and the lower-layer measurement configuration may be in separatecontainers within a reconfiguration message received in step 402 (see Figures 2, 7 and 8, forexample). Such containers may correspond to different fields, different information elements, etc. Further details from the UE perspective

[0121] The disclosure thus provides a method at a User Equipment capable of conditionalLTM, comprising the steps of: ^Receiving a conditional LTM configuration including an LTM candidate cellconfiguration, associated to an LTM candidate cell; ^Receiving a conditional LTM execution condition associated to a measurementconfiguration identifier of a lower layer measurement configuration; ^Wherein the LTM candidate cell configuration is associated to the conditionalLTM execution condition by being associated to the measurement configuration identifier of the lower layer measurement configuration; ^Evaluating the fulfillment of the conditional LTM execution condition inresponse to the reception of the conditional LTM configuration including the LTM candidate cell configuration associated to the conditional LTM execution condition associated to the measurement configuration identifier of the lower layer measurement configuration of the UE’s current configuration.

[0122] This may also be expressed that the LTM execution conditions for the LTMcandidate cell configuration correspond to that the LTM candidate cell configuration is associated to the measurement configuration identifier of the lower layer measurement configuration.

[0123] One example of the association between the LTM candidate cell configurationbeing associated to the conditional LTM execution condition by being associated to the measurement configuration identifier of the lower layer measurement configuration, is theLTM candidate cell configuration being included in the same Information Element (IE) as thefield for the execution condition, which has an which indicates a measurement configurationidentifier (e.g. LTM-CSI-ReportConfigId). The included measurement configuration identifier indicates a configuration in the lower layer measurement configuration in which the execution condition is configured e.g. the event indication, thresholds, offsets, filter parameters, etc.

[0124] According to the method, the UE uses the received lower layer measurementconfiguration, as generated by the S-DU the UE is connected to (or being served by) forexample, to determine the conditional LTM execution condition(s) (e.g. one or more parameters associated to the condition) associated to a given LTM candidate cell configuration, thanks to the association between the LTM candidate configuration and the measurement configuration identifier (which may be an LTM CSI reporting configuration identifier). In other words, the UE looks at the measurement configuration identifier which points to the received lower layer measurement configuration, such as an LTM CSI reporting configuration in which parameters configuring the execution condition are included e.g. thresholds, offsets, an indication of the even defining the execution condition, etc. The lower layer measurement configuration may correspond to an LTM CSI measurement configuration part of the UE’s current configuration, such as the servingCellConfig of the serving cell the UE is served by (e.g. PCell) in the S-DU when the UE is configured with LTM.

[0125] In one option, if the lower layer measurement configuration corresponds to an LTMCSI measurement configuration, this is a dedicated LTM CSI measurement configuration specific for conditional LTM. This means that each LTM CSI measurement configuration configures the UE to measure reference signals which belong to a specific LTM candidate cell configuration. Alternatively, if the lower layer measurement configuration corresponds to an LTM CSI measurement configuration, the LTM CSI measurement configuration includes a measurement configuration identifier and a conditional LTM candidate cell configuration identifier so UE can understand which of the LTM candidate cells which are part of the LTM CSI measurement configuration is the conditional LTM candidate cell configuration.

[0126] According to the method, in response to receiving the conditional LTMconfiguration including an LTM candidate cell configuration associated to the conditional LTM execution condition by being associated to the measurement configuration identifier of the lower layer measurement configuration, the UE evaluates the fulfillment of the conditional LTM execution condition. In other words, the UE determines what condition to evaluate for a given LTM candidate cell by determining the measurement configuration identifier associated to the LTM candidate cell, and checking the lower layer measurement configuration associated to that measurement configuration identifier.

[0127] According to the method, in response to receiving the lower layer measurementconfiguration for configuring the conditional LTM execution condition associated to a measurement configuration identifier, the UE performs one or more lower layer measurements (e.g. L1 RSRP, RSRP and / or RSRQ measurements for serving cell and / or LTM candidate cell(s)) used as input to the evaluation of the fulfillment of the conditional LTM execution condition. ^In one option, the UE performs lower layer measurements associated to thelower layer measurement configuration in which the conditional LTM execution condition is included, when the measurement configuration identifier is referred as a conditional LTM execution condition i.e. when that is included in a conditional LTM configuration for a given LTM candidate cell. ^In one option, the UE does not perform lower layer measurements associated tothe lower layer measurement configuration in which the conditional LTM execution condition is included, when the measurement configuration identifier is NOT referred as a conditional LTM execution condition i.e. when that is NOT included in a conditional LTM configuration for a given LTM candidate cell. ^In one option, the UE perform lower layer measurements associated to the lowerlayer measurement configuration for evaluating the conditional LTM execution condition, when at least one of the LTM candidate cell configuration which are part of the lower layer measurement configuration is tagged as “conditional”. ^This means that the lower layer measurement configuration shouldcontain a reporting configuration which points to a resource configuration which includes at least one LTM candidate cell which is aconditional LTM candidate cell.

[0128] According to the method, the UE applies the LTM candidate cell configurationupon fulfillment of the conditional LTM execution condition whose measurement configuration identifier is associated to the LTM candidate cell configuration.

[0129] According to the method, the lower layer measurement configuration maycorrespond to an LTM CSI reporting configuration, wherein the measurement configuration identifier may correspond to a reporting configuration identifier. One example of a LTM CSIreporting configuration is the LTM-CSI-ReportConfig IE (or an instance of the IE) whichincludes the configuration of the conditional LTM execution condition.^ In one option, the conditional LTM execution condition is configured as a reporttype (reportType) within the LTM-CSI-ReportConfig (even if this is not leading to report); ^In one option, the conditional LTM execution condition is configured as atrigger type within the LTM-CSI-ReportConfig; ^In one option, the conditional LTM execution condition is configured as areportType indicating an event triggered report (e.g. reportType set to ‘event- triggered’ in LTM-CSI-ReportConfig), which is the same trigger type for configuring an event triggered report by the UE. However, the UE determines that this is for conditional LTM and not for event triggered report when the reporting configuration identifier is referred in the conditional LTM configuration and associated to an LTM candidate cell configuration. Otherwise, the UE determines that this is for event triggered report when the reporting configuration identifier is NOT referred in the conditional LTM configuration. ^In one option, the conditional LTM execution condition is configured as a reporttype (e.g. reportType) or trigger type within the LTM CSI reporting configuration, and the UE determine that this reportType is a conditional LTM execution condition for a particular LTM candidate cell if the LTM CSI reporting configuration points to an LTM CSI resource configuration which include at least one conditional LTM configuration to measure.

[0130] In one alternative, the measurement configuration identifier may correspond to anidentifier to a new reporting configuration, e.g. a new LTM event based reportingconfiguration. In one option the new LTM event based reporting configuration is a new part ofthe lower layer measurement configuration, e.g. part of the LTM CSI measurement configuration. In one option, the LTM event based reporting configuration includes one or more configurations associated to events for the lower layer measurements and the measurement configuration identifier is an identifier to a configuration with conditional events.That is, when the configured event(s) is / are fulfilled, the corresponding LTM executioncondition is then considered as fulfilled.

[0131] According to the method, the conditional LTM configuration may correspond toan Information Element which the UE receives in in RRC Reconfiguration message e.g. Cond- LTM-Config-r19. That IE may include an list and / or Release list structure to addand / or modify and / or release configuration(s) associated to conditional LTM. Each element of the AddMod list may include one or more parameters and / or configuration(s) per conditional LTM candidate cell being configured (e.g. in the IE Conditional-LTM-Candidate-r19), including an LTM Candidate ID (e.g. LTM-CandidateId-r18), the LTM candidate cell configuration which is to be applied by the UE during conditional LTM execution (e.g. an RRC Reconfiguration message which is stored upon reception), and the measurement configuration identifier of the lower layer measurement configuration configuring the conditional LTM execution condition. In other words, the conditional LTM execution condition is configured in the lower layer measurement configuration (e.g. offsets, threshold, event identifier, timer to trigger, filtering configuration(s), trigger quantity, reference signal type, etc.) which has a lower layer measurement configuration identifier; and, the UE determines that a given conditional LTM execution condition is associated to a given LTM candidate cell configuration when it receives the LTM candidate cell configuration associated to the measurement configuration identifier of the lower layer measurement configuration configuring the conditional LTM execution condition. For example, the LTM candidate cell configuration and the measurement configuration identifier being included in the same IE per conditional LTM candidate cell (e.g. included in the IE Conditional-LTM-Candidate-r19), means that for that conditional LTM candidate cell the UE needs to use as the conditional LTM execution condition the one pointed the included measurement configuration identifier.

[0132] An example is shown below:Conditional-LTM-Candidate-r19 ::= SEQUENCE { ltm-CandidateId-r18 LTM-CandidateId-r18, [...] ltm-CandidateConfig-r18 OCTET STRING (CONTAININGRRCReconfiguration) OPTIONAL, -- Need M[…] csi-MeasConfig-Id-r19 INTEGER (0..max-Number)

[0133] In one option, the conditional LTM configuration may correspond to anInformation Element or a field which the UE receives in in RRC Reconfiguration message within an existing LTM-related field e.g., LTM-Config-r18. In this case, the existing field can be extended (or enhanced) so to indicate to the UE that a particular LTM-Candidate-r18 IE is referring to a conditional LTM candidate configuration. Further information such as conditional LTM execution conditions and measurement configuration identifier can also be included within the LTM-Candidate-r18 IE.

[0134] In one option, the conditional including an LTM candidate cellconfiguration, associated to an LTM candidate cell and the conditional LTM executioncondition associated to a measurement configuration identifier of a lower layer measurement configuration, are received in the same message e.g. an RRCReconfiguration message. Alternatively, the conditional LTM configuration including an LTM candidate cell configuration, associated to an LTM candidate cell is received in a first message (e.g. first RRCReconfiguration), and the conditional LTM execution condition associated to a measurement configuration identifier of a lower layer measurement configuration is received in a second message (e.g. second RRCReconfiguration).

[0135] In one option, the lower layer measurement configuration corresponds to a CSILTM reporting configuration e.g. configured in an IE LTM-CSI-ReportConfig (NOTE: in this case, this would not be configuring a report, but a trigger condition for conditional LTM, which could be defined as a kind of report type, not leading to a report.). The measurement configuration identifier may correspond to a reporting configuration identifier (e.g. ltm-CSI- ReportConfigId). The LTM CSI reporting configuration may also include an identifier associated to a resource configuration (e.g. LTM-CSI-ResourceConfigId); each resource may correspond to a RS indicated by an RS index (ID) e.g. SSB ID and an LTM Candidate ID.

[0136] An example is shown below:[…]r18 }

[0137] In one option, since the UE knows the actual LTM candidate cell associated to themeasurement configuration identifier anyway, the resource configuration may be ignored.

[0138] In another option, the resource configuration includes RS ID(s) for that LTMcandidate cell and, these RS ID(s) e.g. SSB ID(s), of the LTM candidate cell are considered bythe UE as “applicable” SSB(s): in other words, these are the SSBs allowed to be used by theUE as input to the entering condition(s) of the Conditional LTM execution condition(s).

[0139] For example, when the Conditional LTM execution condition is defined as“strongest SSB of an LTM candidate is offset better than the strongest SSB of the PCell”, the UE evaluates the strongest SSB of an LTM candidate cell only among the SSB(s) in the associated resource configuration.

[0140] Figures 7 and 8 show an illustration of examples of the configuration the UE mayreceive in an RRC Reconfiguration message, an LTM candidate cell configurationwith a measurement configuration is, Figure 7 illustrates a reconfigurationmessage 702 (including a conditional LTM configuration 704 and a lower layer measurementconfiguration 706) according to embodiments of the disclosure whilst Figure 8 illustrates areconfiguration message 802 (including a conditional LTM configuration 804 and a lower layer measurement configuration 806) according to further embodiments of the disclosure.

[0141] Notice that, in Figures 7 and 8, there is one measurement configuration identifier= x associated to an LTM candidate cell configuration, and that points to a lower layer measurement configuration with the same identifier, wherein it is in that lower layer measurement configuration with matching identifier that the UE finds the configuration for the LTM execution condition associated for that LTM candidate cell.

[0142] In the exemplary illustration shown in Figure 8, another level of detail is provided.The LTM candidate cell configuration is associated to a field in which the execution condition is configured and that field has an IE defined as a measurement configuration identifier (e.g. LTM-CSI-ReportConfigId). That points to the measurement configuration identifier in thelower layer measurement configuration in which the UE finds the configuration for the LTMexecution conditions, such as event identifier, threshold(s), offsets, time filtering parameters, etc.

[0143] In one option, the conditional LTM execution condition may correspond to thefollowing “LTM candidate cell becomes amount of offset better than PCell (or PSCell, whenthis is for the Secondary Cell Group)”. The UE considers the conditional LTM condition asfulfilled when the condition(s) applicable for this event is fulfilled for the applicable cell (i.e. LTM candidate cell associated to the condition) for all measurements taken during the corresponding time to trigger defined for this event (in case a time to trigger is defined). The so-called entry condition(s) for such an event, associated to the conditional LTM execution condition may be defined so that the UE shall consider the condition for this event to be satisfied when the condition below, as specified below, is fulfilled: Mn – Hys > Mp + Off

[0144] The variables in the formula are defined as follows:

[0145] Mn is the lower layer measurement result (e.g. L1 RSRP) of the LTM candidatecell, not taking into account any offsets.

[0146] Mp is the lower layer measurement result (e.g. L1 RSRP) of the serving cell(Special Cell (SpCell)=), not taking into account any offsets.

[0147] Hys is the hysteresis parameter for this event (i.e. hysteresis as defined withinreportConfigNR for this event).

[0148] Off is the offset parameter for this event (i.e. Offset as defined within LTM-CSI-ReportConfigNR for this event).

[0149] Mn, Mp are expressed in dBm in case of RSRP, or in dB.

[0150] Hys, Off are expressed in dB.

[0151] In one option, the conditional LTM execution condition may correspond to thefollowing “an SSB of the LTM candidate cell becomes amount of offset better than the serving SSB”. Or, alternatively, the conditional LTM execution condition may correspond to the following “best SSB of the LTM candidate cell becomes amount of offset better than the serving SSB”. ^The best SSB of the LTM candidate cell may corresponds to the SSB withhighest trigger quantity e.g. when the trigger quantity is set to RSRP, the best SSB of the LTM candidate cell is the SSB with highest L1 RSRP or RSRP. ^The serving SSB may correspond to the SSB of the serving cell (e.g. PCell,SpCell) with highest trigger quantity e.g. when the trigger quantity is set to RSRP, the best SSB of the PCell is the SSB with highest L1 RSRP or RSRP of the PCell. Alternatively, the serving SSB may correspond to the SSB whose SSB index is configured as Quasi-Co-Location (QCL) source of the activated Transmission Configuration Indication (TCI) state of the serving cell (e.g. of the PCell).

[0152] The UE considers the conditional LTM condition as fulfilled when the condition(s)applicable for this event is fulfilled for the applicable cell (i.e. LTM candidate cell associated to the condition) for all measurements taken during the corresponding time to trigger defined for this event (in case a time to trigger is defined). The so-called entry condition(s) for such an event, associated to the conditional LTM execution condition may be defined so that the UE shall consider the condition for this event to be satisfied when the condition below, as specified below, is fulfilled: Mn – Hys > Mp + Off

[0153] The variables in the formula are defined as follows:

[0154] Mn is the lower layer measurement result (e.g. L1 RSRP) of the best SSB of theLTM candidate cell, not taking into account any offsets.

[0155] Mp is the lower layer measurement result (e.g. L1 RSRP) of the best SSB of theserving cell (SpCell=), not taking into account any offsets.

[0156] Hys is the hysteresis parameter for this event (i.e. hysteresis as defined withinreportConfigNR for this event).

[0157] Off is the offset parameter for this event (i.e. Offset as defined within LTM-CSI-ReportConfigNR for this event).

[0158] Mn, Mp are expressed in dBm in case of RSRP, or in dB.

[0159] Hys, Off are expressed in dB.

[0160] In one option, the conditional LTM execution condition may correspond to thefollowing “best beam of the LTM candidate cell becomes amount of offset better than the current beam”. ^The best beam of the LTM candidate cell may corresponds to the beam (spatialdirection) with highest trigger quantity e.g. when the trigger quantity is set to RSRP, the best beam of the LTM candidate cell is the beam with highest L1 RSRP or RSRP. ^The serving beam, or current beam, may correspond to the beam of the servingcell (e.g. beam of the PCell, beam of the SpCell) with highest trigger quantity e.g. when the trigger quantity is set to RSRP, the best beam of the PCell is the beam with highest L1 RSRP or RSRP of the PCell. Alternatively, the serving beam may correspond to the beam whose beam index is configured as QCL source of the activated TCI state of the serving cell (e.g. of the PCell).

[0161] The lower layer measurement configuration associated to the conditional LTMexecution condition may include one or more of the following parameters: ^Conditional event identifier: the identifier identifies the exact event the UE shallmonitor / evaluate; ^Offset: indicates to the UE the offset value in dB to be used for comparing theLTM candidate cell with the serving cell. That is associated to a trigger quantity, such as L1 RSRP, L1 RSRQ, L1 SINR, which is also part of the configuration. ^Trigger quantity: indicates to the UE the trigger quantity the UE needs tomeasure for the serving cell (e.g. PCell / PSCell) and the LTM candidate cell (for evaluating the trigger condition); ^Time to Trigger: indication of amount of time for how long lower layermeasurements needs to fulfill the conditional LTM execution condition for the UE to consider the condition as fulfilled. ^Hysteresis: indication of an amount of hysteresis to be consider in the condition;^ Reference Signal type: indication of the RS type for which measurements are tobe performed such as SSB or CSI-RS. In one option, the configuration of the RS type may indicate to the UE to consider only the resources in the resource configuration for that Rs type. ^Report needed: A flag which indicates to the UE whether it needs to send areport to the network or not. This is for the case where the same lower layer measurement configuration is used for both conditional LTM and normal LTM.

[0162] In one option, the lower layer measurement configuration associated to theconditional LTM execution condition is associated to a resource configuration. For example, the lower layer measurement configuration may correspond to a reporting configuration which includes a pointer to a resource configuration.

[0163] In one example, the resource configuration which is indicated in the lower layermeasurement configuration (e.g. a resource configuration ID within an LTM CSI ReportConfig) may be associated to one or more LTM candidate cell(s) and / or one or more RS identifier(s) e.g. a list of LTM candidate ID(s) and a list of SSB indexes. For example, let usassume an instance of the IE LTM-CSI-ResourceConfig-r18 (having an associated identifiere.g. ltm-CSI-ResourceConfigId-r18) and being grouped as a resource set (e.g. in the IE LTM-CSI-SSB-ResourceSet-r18), wherein the resource set may be structure as a first list and asecond list, wherein the first list comprises one or more SSB indexes and the second list comprises one or more LTM candidate cell identifiers (IDs), wherein the position in the list is associated to an LTM CSI resource in that LTM CSI resource configuration e.g. the instance of the IE LTM-CSI-ResourceConfig includes the following lists ltm-CSI-SSB-ResourceList- r18 and ltm-CandidateIdList-r18:ltm-CSI-SSB-ResourceList-r18 ltm-CandidateIdList-r18[SSB1] [LTM Candidate cell ID 1][SSB2] [LTM Candidate cell ID 1][SSB3] [LTM Candidate cell ID 1][SSB4] [LTM Candidate cell ID 1][SSB5] [LTM Candidate cell ID 1][SSB1] [LTM Candidate cell ID 2][SSB2] [LTM Candidate cell ID 2][SSB3] [LTM Candidate cell ID 2][SSB4] [LTM Candidate cell 2][SSB5] [LTM Candidate cell ID 2][SSB1] [LTM Candidate cell ID 3][SSB2] [LTM Candidate cell ID 3][SSB3] [LTM Candidate cell ID 3][SSB4] [LTM Candidate cell ID 3][SSB5] [LTM Candidate cell ID 3][SSB1] [LTM Candidate cell ID 4][SSB2] [LTM Candidate cell ID 4][SSB3] [LTM Candidate cell ID 4][SSB4] [LTM Candidate cell ID 4][SSB5] [LTM Candidate cell ID 4][SSB1] [LTM Candidate cell ID 5][SSB2] [LTM Candidate cell ID 5][SSB3] [LTM Candidate cell ID 5][SSB4] [LTM Candidate cell ID 5][SSB5] [LTM Candidate cell ID 5]

[0164] In that option, the UE considers only the indicated RS ID(s) as applicable. Forexample, when the conditional LTM execution condition uses as input the best SSB, this would be the best SSB among the SSBs indicated in the resource configuration for the LTM Candidate Cell associated to the measurement configuration identifier as indication of execution condition.

[0165] In one option, assuming the resource configuration above in which an element isan RS ID of an LTM Candidate cell, the conditional LTM execution condition may correspondto the following “An RS ID becomes amount of offset better than the current beam”. In thiscase, the RS ID is any pair (RS ID, LTM Candidate cell ID) in the resource configuration.

[0166] In another option, the resource configuration may simply be one or moreindications of LTM candidate cells or information identifying the LTM candidate cells for which the S-DU should generate and provide a conditional LTM execution condition.

[0167] In another option, the resource configuration is not indicated in the lower layermeasurement configuration configuring the conditional LTM execution condition, or the UE ignores it. That is possible since the UE knows the LTM candidate cell to be evaluated since the measurement configuration identifier is associated to the LTM candidate cell, and that is the applicable cell for that event i.e. the cell evaluated.

[0168] In one option, the UE lower layer measurement configuration corresponds to anLTM-CSI-ReportConfig where the conditional LTM execution condition is part of a configuration which is specifically for a conditional LTM candidate cell where the lower layer measurement configuration is used for both conditional LTM or not. In such a case, the conditional LTM execution condition(s) are on the same level as the reporting type of the LTM CSI reporting configuration and may include one or more of the following: ^A list of event(s) that needs to be evaluated for a particular conditional LTMcandidate cell (which is the configuration which include the LTM-CSI- ReportConfigId) ^A list of SSB to measure, which can be the same as or different than the oneincluded in LTM-CSI-ResourceConfigId. In such a case, the UE may ignore the content related to LTM-CSI-ResourceConfigId LTM-CSI- r18 ::=conditionalConfiguration-r19 ConditionalConfiguration-r19 OPTIONAL, ]] } }to anLTM-CSI-ReportConfig where the conditional LTM execution condition is part of a configuration which is specifically for a conditional LTM candidate cell where the lower layer measurement configuration is used for both conditional LTM or not. In such a case, the conditional LTM execution condition are within the reporting type of the LTM CSI reporting configuration and which is used for the LTM cell switch procedure (no conditional) and may include one or more of the following: ^A list of event that needs to be evaluated for a particular conditional LTMcandidate cell (which is the configuration which include the LTM-CSI- ReportConfigId) ^A list of SSB to measure, which can be the same as or different than the oneincluded in LTM-CSI-ResourceConfigId. If this information is included, thenthe UE may ignore the content related to LTM-CSI-ResourceConfigId.reportSlotOffsetList-r18 SEQUENCE (SIZE (1.. maxNrofUL-Allocations-r16)) OF INTEGER (0..128),reportSlotOffsetListDCI-0-2-r18 SEQUENCE (SIZE (1.. maxNrofUL-Allocations-r16)) OF INTEGER (0..128), reportSlotOffsetListDCI-0-1-r18 SEQUENCE (SIZE (1.. r19 }Event-r19 EventConfig-r19, ssbToMeasure-r19 SSB-ToMeasure } Further details from the S-DU perspective

[0170] As noted previously (see Figures 3 and 5, for example), the disclosure also providesa method at a network node operating as an S-DU comprising:^ Receiving a request message from a CU including a resource configuration andan indication that Conditional LTM is being configured or it has been configured; ^In response, transmitting a response message to the CU including: a lower layermeasurement configuration including a configuration of a conditional LTM execution condition associated to a measurement configuration identifier.

[0171] In one option, the S-DU also includes in the response an association between themeasurement configuration identifier of the lower layer measurement configuration and an LTM candidate cell configuration included in the received resource configuration.

[0172] In another option, the S-DU receives in the request message from the CU, theassociation between a measurement configuration identifier of the lower layer measurement configuration and an LTM candidate cell configuration. For example, the CU indicates to the S-DU that for a given LTM candidate ID=7 there should be a conditional LTM execution condition with measurement configuration identifier is set to e.g. X. In response, the S-DU generates an updated version of the lower layer measurement configuration of the UE’s current configuration, includes the measurement configuration identifier=X, and configures there the conditional LTM execution condition for the LTM candidate ID=7.

[0173] In one option, the S-DU determines and generates the conditional LTM executioncondition associated to a measurement configuration identity (e.g. LTM-CSI-ReportConfigId), and associates to an LTM candidate cell, so the CU generates the LTM configuration to the UE, which needs to know the association; thanks to the association the UE knows whichmeasurements to perform to be used as input to conditional LTM execution conditions and, when these are fulfilled, which LTM candidate cell configuration to apply. One benefit is thatthis would be the network node determining to trigger LTM cell Switch in case of legacy LTM,so that it makes sense that it is also the S-DU which determines the LTM execution conditions. It is also the S-DU which determines whether a report for legacy LTM is periodic, aperiodic or semi-persistent.

[0174] In one option, the request message may correspond to a UE CONTEXTMODIFICATION REQUEST message, and the response message is the UE CONTEXT MODIFICATION RESPONSE message.

[0175] In one option, the S-DU may associate the same conditional LTM executioncondition to multiple LTM candidate cell(s).

[0176] Figure 9 shows an example of a communication system 900 in accordance withsome embodiments.

[0177] In the example, the communication system 900 includes a telecommunicationnetwork 902 that includes an access network 904, such as a radio access network (RAN), and a core network 906, which includes one or more core network nodes 908. The access network 904 includes one or more access network nodes, such as network nodes 910a and 910b (one or more of which may be generally referred to as network nodes 910), or any other similar 3rdGeneration Partnership Project (3GPP) access nodes or non-3GPP access points. Moreover, aswill 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 bya single vendor. Thus, it will be understood that network nodes include disaggregatedimplementations or portions thereof. For example, in some embodiments, thetelecommunication network 902 includes one or more Open-RAN (ORAN) network nodes. AnORAN network node is a node in the telecommunication network 902 that supports an ORAN specification (e.g., a specification published by the O-RAN Alliance, or any similar organization) and may operate alone or together with other nodes to implement one or more functionalities of any node in the telecommunication network 902, including one or more network nodes 910 and / or core network nodes 908.

[0178] Examples of an ORAN network node include an open radio unit (O-RU), an opendistributed 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 plug-ins, such as a near-real time controlapplication (e.g., xApp) or a non-real time control application (e.g., rApp), or any combinationthereof (the adjective “open” designating support of an ORAN specification). The networknode may support a specification by, for example, supporting an interface defined by the ORAN specification, such as an A1, F1, W1, E1, E2, X2, Xn interface, an open fronthaul userplane interface, or an open fronthaul management plane interface. Moreover, an ORAN accessnode may be a logical node in a physical node. Furthermore, an ORAN network node may beimplemented in a virtualization environment (described further below) in which one or morenetwork functions are virtualized. For example, the virtualization environment may include anO-Cloud computing platform orchestrated by a Service Management and Orchestration Framework via an O-2 interface defined by the O-RAN Alliance or comparable technologies. The network nodes 910 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 912a, 912b, 912c, and 912d (one or more of which may be generally referred to as UEs 912) to the core network 906 over one or more wireless connections.

[0179] Example wireless communications over a wireless connection include transmittingand / 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 900 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 900 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system.

[0180] The UEs 912 may be any of a wide variety of communication devices, includingwireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 910 and other communication devices. Similarly, the network nodes 910 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 912 and / or with other network nodes or equipment in the telecommunication network 902 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 902.

[0181] In the depicted example, the core network 906 connects the network nodes 910 toone or more host computing systems, such as host 916. 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 906 includes one more core network nodes(e.g., core network node 908) 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 generallyapplicable to the corresponding components of the core network node 908. Example corenetwork 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).

[0182] The host 916 may be under the ownership or control of a service provider otherthan an operator or provider of the access network 904 and / or the telecommunication network 902. The host 916 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.

[0183] As a whole, the communication system 900 of Figure 9 enables connectivitybetween 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 / orother 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.

[0184] In some examples, the telecommunication network 902 is a cellular network thatimplements 3GPP standardized features. Accordingly, the telecommunications network 902 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication 902. For example, the telecommunicationsnetwork 902 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 IoT services to yet further UEs.

[0185] In some examples, the UEs 912 are configured to transmit and / or receiveinformation without direct human interaction. For instance, a UE may be designed to transmit information to the access network 904 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 904. Additionally,a UE may be configured for operating in single- or multi-RAT or multi-standard mode. Forexample, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio – Dual Connectivity (EN-DC).

[0186] In the example, the hub 914 communicates with the access network 904 to facilitateindirect communication between one or more UEs (e.g., UE 912c and / or 912d) and network nodes (e.g., network node 910b). In some examples, the hub 914 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 914 may be a broadband router enabling access to the core network 906 for the UEs. As another example, the hub 914 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 910, or by executable code, script, process, or other instructions in the hub 914. As another example, the hub 914 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 914 may be a content source. For example,for a UE that is a VR device, display, loudspeaker, or other media delivery device, the hub 914may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 914 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 914 acts as a proxy server or orchestrator for the UEs, in particular if one or more of the UEs are low energy IoT devices.

[0187] The hub 914 may have a constant / persistent or intermittent connection to thenetwork node 910b. The hub 914 may also allow for a different communication scheme and / or schedule between the hub 914 and UEs (e.g., UE 912c and / or 912d), and between the hub 914 and the core network 906. In other examples, the hub 914 is connected to the core network 906 and / or one or more UEs via a wired Moreover, the hub 914 may be configured toconnect to an M2M service provider over the access network 904 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 910 while still connected via the hub 914 via a wired or wireless connection. In someembodiments, the hub 914 may be a dedicated hub – that is, a hub whose primary function isto route communications to / from the UEs from / to the network node 910b. In otherembodiments, the hub 914 may be a non-dedicated hub – that is, a device which is capable ofoperating to route communications between the UEs and network node 910b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0188] Figure 10 shows a UE 1000 in accordance with some embodiments. The UE 1000presents additional details of some embodiments of the UE 912 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 ordevice, music storage / playback device, wearable terminal device, wireless endpoint, mobilestation, 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.

[0189] A UE may support device-to-device (D2D) communication, for example byimplementing 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).

[0190] The UE 1000 includes processing circuitry 1002 that is operatively coupled via abus 1004 to an input / output interface 1006, a power source 1008, a memory 1010, a communication interface 1012, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in Figure 10. 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.

[0191] The processing circuitry 1002 is configured to process instructions and data andmay be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 1010. The processing circuitry 1002 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 1002 may include multiple central processing units (CPUs). The processing circuitry 1002 may be configured to cause the UE 1002 to perform the methods as described with reference to Figure 4, and / or the signalling or actions of the UE shown in Figure 3.

[0192] In the example, the input / output interface 1006 may be configured to provide aninterface 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 1000. 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.

[0193] In some embodiments, the power source 1008 is structured as a battery or batterypack. 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 1008 may further include power circuitry for delivering power from the power source 1008 itself, and / or an external power source, to the various parts of the UE 1000 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1008. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1008 to make the power suitable for the respective components of the UE 1000 to which power is supplied.

[0194] The memory 1010 may be or be configured to include memory such as randomaccess 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 1010 includes one or more application programs 1014, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1016. The memory 1010 may store, for use by the UE 1000, any of a variety of various operating systems or combinations of operating systems.

[0195] The memory 1010 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 1010 may allow the UE 1000 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 1010, which may be or comprise a device-readable storage medium.

[0196] The processing circuitry 1002 may be configured to communicate with an accessnetwork or other network using the communication interface 1012. The communication interface 1012 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1022. The communication interface 1012 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 1018 and / or a receiver 1020 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1018 and receiver 1020 may be coupled to one or more antennas (e.g., antenna 1022) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0197] In the illustrated embodiment, communication functions of the communicationinterface 1012 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.

[0198] Regardless of the type of sensor, a UE may provide an output of data captured byits sensors, through its communication interface 1012, 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).

[0199] As another example, a UE comprises an actuator, a motor, or a switch, related to acommunication interface configured to wireless input from a network node via awireless 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.

[0200] A UE, when in the form of an Internet of Things (IoT) device, may be a device foruse 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 IoT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a wearable for tactileaugmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, asensor 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 IoT device comprises circuitry and / or software in dependence of the intended application of the IoT device in addition to other components as described in relation to the UE 1000 shown in Figure 10.

[0201] As yet another specific example, in an IoT scenario, a UE may represent a machineor other device that performs monitoring and / or measurements, and transmits the results ofsuch monitoring and / or measurements to another UE and / or a network node. The UE may inthis case be an M2M device, which may in a 3GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-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.

[0202] In practice, any number of UEs may be used together with respect to a single usecase. 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 an actuator) to increase or decrease thedrone’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.

[0203] Figure 11 shows a network node 1100 in accordance with some embodiments. Asused herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)), O-RAN nodes or components of an O-RAN node (e.g., O-RU, O-DU, O-CU).

[0204] Base stations may be categorized based on the amount of coverage they provide(or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units, distributed units (e.g., in an O-RAN access node) and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0205] 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).

[0206] The network node 1100 includes a processing circuitry 1102, a memory 1104, acommunication interface 1106, and a power source 1108. The network node 1100 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 1100 comprises multiple separate components (e.g., BTS and components), one or more of the separatecomponents 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 1100 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1104 for different RATs) and some components may be reused (e.g., a same antenna 1110 may be shared by different RATs). The network node 1100 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1100, 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 1100.

[0207] The processing circuitry 1102 may comprise a combination of one or more of amicroprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 1100 components, such as the memory 1104, to provide network node 1100 functionality. For example, the processing circuitry 1102 may be configured to cause the network node to perform the methodsas described with reference to Figure 5 and / or the signalling or actions of the S-DU (whenconfigured as a DU) or Figure 6 and / or the signalling or actions of the S-CU (when configuredas a CU).

[0208] In some embodiments, the processing circuitry 1102 includes a system on a chip(SOC). In some embodiments, the processing circuitry 1102 includes one or more of radio frequency (RF) transceiver circuitry 1112 and baseband processing circuitry 1114. In some embodiments, the radio frequency (RF) transceiver circuitry 1112 and the baseband processing circuitry 1114 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 1112 and baseband processing circuitry 1114 may be on the same chip or set of chips, boards, or units.

[0209] The memory 1104 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 (for example, a hard disk), removable storagemedia (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 1102. The memory 1104 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 1102 and utilized by the network node 1100. The memory 1104 may be used to store any calculations made by the processing circuitry 1102 and / or any data received via the communication interface 1106. In some embodiments, the processing circuitry 1102 and memory 1104 is integrated.

[0210] The communication interface 1106 is used in wired or wireless communication ofsignaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 1106 comprises port(s) / terminal(s) 1116 to send and receive data, for example to and from a network over a wired connection. The communication interface 1106 also includes radio front-end circuitry 1118 that may be coupled to, or in certain embodiments a part of, the antenna 1110. Radio front-end circuitry 1118 comprises filters 1120 and amplifiers 1122. The radio front-end circuitry 1118 may be connected to an antenna 1110 and processing circuitry 1102. The radio front-end circuitry may be configured to condition signals communicated between antenna 1110 and processing circuitry 1102. The radio front-end circuitry 1118 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 1118 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1120 and / or amplifiers 1122. The radio signal may then be transmitted via the antenna 1110. Similarly, when receiving data, the antenna 1110 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1118. The digital data may be passed to the processing circuitry 1102. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0211] In certain alternative embodiments, the network node 1100 does not includeseparate radio front-end circuitry 1118, instead, the processing circuitry 1102 includes radio front-end circuitry and is connected to the antenna 1110. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1112 is part of the communication interface 1106. In still other embodiments, the communication interface 1106 includes one or more ports or terminals 1116, the radio front-end circuitry and the RF transceiver circuitry 1112, aspart of a radio unit (not shown), and the communication interface 1106 communicates with the baseband processing circuitry 1114, which is part of a digital unit (not shown).

[0212] The antenna 1110 may include one or more antennas, or antenna arrays, configuredto send and / or receive wireless signals. The antenna 1110 may be coupled to the radio front- end circuitry 1118 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1110 is separate from the network node 1100 and connectable to the network node 1100 through an interface or port.

[0213] The antenna 1110, communication interface 1106, and / or the processing circuitry1102 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 1110, the communication interface 1106, and / or the processing circuitry 1102 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.

[0214] The power source 1108 provides power to the various components of network node1100 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1108 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1100 with power for performing the functionality described herein. For example, the network node 1100 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 1108. As a further example, the power source 1108 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0215] Embodiments of the network node 1100 may include additional componentsbeyond those shown in Figure 11 for providing certain aspects of the network node’sfunctionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 1100 may include user interface equipment to allow input of information into the network node 1100 and to allow output of information from the network node 1100. This may allow a user to perform diagnostic, maintenance, repair, and administrative functions for the networknode 1100. In some embodiments providing a core network node, such as core network node 108 of FIG. 9, some components, such as the radio front-end circuitry 1118 and the RF transceiver circuitry 1112 may be omitted.

[0216] Figure 12 is a block diagram illustrating a virtualization environment 1200 inwhich 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 1200 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., acore network node or host), then the node may be entirely virtualized. In some embodiments,the virtualization environment 1200 includes components defined by the O-RAN Alliance, such as an O-Cloud environment orchestrated by a Service Management and OrchestrationFramework via an O-2 interface. Virtualization may facilitate distributed implementations of anetwork node, UE, core network node, or host.

[0217] Applications 1202 (which may alternatively be called software instances, virtualappliances, 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.

[0218] Hardware 1204 includes processing circuitry, memory that stores software and / orinstructions 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 1206 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1208a and 1208b (one or more of which may be generally referred to as VMs 1208), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1206 may present a virtual operating platform that appears like networking hardware to the VMs 1208.

[0219] The VMs 1208 comprise virtual processing, virtual memory, virtual networking orinterface and virtual storage, and may be run by a corresponding virtualization layer 1206. Different embodiments of the instance of a virtual appliance 1202 may be implemented on one or more of VMs 1208, 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.

[0220] In the context of NFV, a VM 1208 may be a software implementation of a physicalmachine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1208, and that part of hardware 1204 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 1208 on top of the hardware 1204 and corresponds to the application 1202.

[0221] Hardware 1204 may be implemented in a standalone network node with generic orspecific components. Hardware 1204 may implement some functions via virtualization. Alternatively, hardware 1204 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 1210, which, among others, oversees lifecycle management of applications 1202. In some embodiments, hardware 1204 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1212 which may alternatively be used for communication between hardware nodes and radio units.

[0222] Although the computing devices described herein (e.g., UEs, network nodes) mayinclude the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations herein may be performed by processingcircuitry, 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.

[0223] In certain embodiments, some or all of the functionality described herein may beprovided 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 theprocessing circuitry alone or to other components of the computing device, but are enjoyed bythe computing device as a whole, and / or by end users and a wireless network generally.

[0224] The following groups of numbered statements set out some embodiments of thedisclosure: Group A Embodiments 1. A method performed by a user equipment, the method comprising:receiving a conditional LTM configuration, comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration; monitoring the execution condition; andresponsive to fulfilment of the condition, initiating an LTM mobilityprocedure to the candidate cell using the LTM candidate cell configuration.2. The method of embodiment 1, wherein the indication of the execution conditioncomprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration.3. The method of embodiment 2, wherein the lower-layer measurement configurationcomprises the execution condition.4. The method of embodiment 2 or 3, wherein the lower-layer measurement configurationcorresponds to a LTM CSI reporting configuration.5. The method of embodiment 2 or 3, wherein the lower-layer measurement configurationcomprises a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages in a protocol layer which is lower than L3.6. The method of embodiment 2 or 3, wherein the lower-layer measurement configurationcomprises a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages over physical uplink control channel and / or uplink control information.7. The method of any one of embodiments 2 to 6, wherein the indication of the lower-layermeasurement configuration comprises an identifier of the lower-layer measurement configuration.8. The method of any one of embodiments 2 to 7, wherein the LTM candidate cellconfiguration and the lower-layer measurement configuration are in separate containers within a reconfiguration message.9. The method of any one of the preceding embodiments, wherein the execution conditionutilizes one or more of: radio measurements on transmissions by a source cell or a source radio access network node; and radio on transmissions by a candidate cell or a candidate radio access network node.10. The method of any one of the preceding embodiments, wherein the execution conditioncomprises a plurality of execution sub-conditions, and wherein fulfilment of the execution condition comprises fulfilment of one or more or all of the execution sub-conditions. Group B Embodiments11. A method performed by a distributed unit for a network node, the method comprising:receiving, from a centralized unit for the network node, a request message comprising information related to an LTM candidate cell for a user equipment served by the distributed unit, and an indication that conditional LTM is configured; and transmitting, to the centralized unit, a response message comprising an indication of an execution condition to be fulfilled for the user equipment to initiate an LTM mobility procedure to the LTM candidate cell.12. The method of embodiment 11, wherein the information related to the LTM candidatecell comprises a resource configuration for the LTM candidate cell.13. The method of embodiment 12, wherein the resource configuration comprises anindication of resources on which measurements of reference signals transmitted on the LTM candidate cell are to be measured by the user equipment.14. The method of any one of embodiments 11 to 13, further comprising determining theexecution condition.15. The method of any one of embodiments 11 to 14, wherein the indication of the executioncondition in the response message comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration.16. The method of embodiment 15, wherein the lower-layer measurement configurationcomprises the execution condition.17. The method of embodiment 15 or 16, wherein the response message comprises the lower-layer measurement configuration.18. The method of any one of embodiments 15 to 17, wherein the lower-layer measurementconfiguration corresponds to a LTM CSI reporting configuration.19. The method of any one of embodiments 15 to 17, wherein the lower-layer measurementconfiguration comprises a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages in a protocol layer which is lower than L3.20. The method of any one of embodiments 15 to 17, wherein the lower-layer measurementconfiguration comprises a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages over physical uplink control channel and / or uplink control information.21. The method of any one of embodiments 15 to 20, wherein the indication of the lower-layer measurement configuration comprises an identifier of the lower-layer measurement configuration.22. The method of any one of embodiments 15 to 21, wherein the LTM candidate cellconfiguration and the lower-layer measurement configuration are in separate containers withinthe response message.23. The method of any one of embodiments 11 to 22, wherein the execution condition utilizesone or more of: radio measurements on transmissions by a source cell or a source radio access network node; and radio measurements on transmissions by a candidate cell or a candidate radio access network node.24. The method of any one of embodiments 11 to 23, wherein the execution conditioncomprises a plurality of execution sub-conditions, and wherein fulfilment of the execution condition comprises fulfilment of one or more or all of the execution sub-conditions.25. The method of any one of embodiments 11 to 24, wherein the request message comprisesa UE context modification request message, wherein the response message comprises a UE context modification response message.26. A method performed by a centralized unit for a network node, the method comprising:transmitting to a user equipment, via a distributed unit for the network node, a conditional LTM configuration, comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration.27. The method of embodiment 26, wherein the indication of the execution conditioncomprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration.28. The method of embodiment 27, wherein the lower-layer measurement configurationcomprises the execution condition.29. The method of embodiment 27 or 28, wherein the lower-layer measurementconfiguration corresponds to a LTM CSI reporting configuration.30. The method of embodiment 27 or 28, wherein the lower-layer measurementconfiguration comprises a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages in a protocol layer which is lower than L3.31. The method of embodiment 27 or 28, wherein the lower-layer measurementconfiguration comprises a measurement configuration for performing measurements on one or more reference signals, wherein the measurements are reported in one or more messages over physical uplink control channel and / or uplink control information.32. The method of any one of embodiments 27 to 31, wherein the indication of the lower-layer measurement configuration comprises an identifier of the lower-layer measurement configuration.33. The method of any one of embodiments 27 to 32, wherein the LTM candidate cellconfiguration and the lower-layer measurement configuration are in separate containers withina reconfiguration message.34. The method of any one of embodiments 26 to 33, wherein the execution condition isdetermined by the distributed unit.35. The method of embodiment 34, further comprising;transmitting, to the distributed unit, a request message comprising information relatedto an LTM candidate cell for the user equipment, and an indication that conditional LTM isconfigured; and receiving, from the distributed unit, a response message comprising an indication of the execution condition to be fulfilled for the user equipment to initiate an LTM mobility procedure to the LTM candidate cell.36. The method of embodiment 35, wherein the information related to the LTM candidatecell comprises a resource configuration for the LTM candidate cell.37. The method of embodiment 36, wherein the resource configuration comprises anindication of resources on which measurements of reference signals transmitted on the LTM candidate cell are to be measured by the user equipment.38. The method of any one of embodiments 35 to 37, wherein the request message comprisesa UE context modification request message, and / or wherein the response message comprises a UE context modification response message.39. The method of any one of embodiments 26 to 38, wherein the execution condition utilizesone or more of: radio measurements on transmissions by a source cell or a source radio access network node; and radio measurements on transmissions by a candidate cell or a candidate radio access network node.40. The method of any one of embodiments 26 to 39, wherein the execution conditioncomprises a plurality of execution sub-conditions, and wherein fulfilment of the execution condition comprises fulfilment of one or more or all of the execution sub-conditions.Group C Embodiments41. A user equipment, comprising:processing circuitry configured to cause the user equipment to perform any of the stepsof any of the Group A embodiments; and power supply circuitry configured to supply power to the processing circuitry.42. A network node, the network node comprising:processing circuitry configured to cause the network node to perform any of the steps of any of the Group B embodiments; power supply circuitry configured to supply power to the processing circuitry.43. 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 cause the user equipment 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.

Claims

CLAIMS1. A method performed by a user equipment (1000), the method comprising:receiving (402) a conditional Layer 1 / Layer 2 Triggered Mobility, LTM, configuration,comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration; monitoring (404) the execution condition; andresponsive to fulfilment of the execution condition, initiating (406) an LTM mobility procedure to the candidate cell using the LTM candidate cell configuration, wherein the indication of the execution condition comprises an indication of a lower- layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

2. The method of claim 1, wherein the lower-layer measurement configurationcorresponds to a LTM Channel State Information, CSI, reporting configuration.

3. The method of any one of claims 1 to 2, wherein the indication of the lower-layermeasurement configuration comprises an identifier of the lower-layer measurement configuration.

4. The method of any one of the preceding claims, wherein the execution conditionutilizes one or more of: radio measurements on transmissions by a source cell or a source radio access network node; and radio measurements on transmissions by a candidate cell or a candidate radio access network node.

5. The method of any one of the preceding embodiments, wherein the execution conditioncomprises a plurality of execution sub-conditions, and wherein fulfilment of the execution condition comprises fulfilment of one or more or all of the execution sub-conditions.

6. A method performed by a distributed unit (1100) for a network node, the methodcomprising: receiving (502), from a centralized unit (1100) for the network node, a request messagecomprising information related to a Layer 2 Triggered Mobility, LTM, candidate cellfor a user equipment (1000) served by the distributed unit, and an indication that conditional LTM is configured; and transmitting (506), to the centralized unit, a response message comprising an indicationof an execution condition to be fulfilled for the user equipment to initiate an LTM mobility procedure to the LTM candidate cell, wherein the indication of the execution condition in the response message comprises an indication of a lower-layer measurement configuration associated with the LTM candidatecell configuration and the lower-layer measurement configuration corresponds to a reportingconfiguration.

7. The method of claim 6, wherein the lower-layer measurement configurationcorresponds to a LTM Channel State Information, CSI, reporting configuration.

8. The method of any one of claims 6 or 7, wherein the indication of the lower-layermeasurement configuration comprises an identifier of the lower-layer measurement configuration.

9. The method of any one of claims 6 to 8, wherein the information related to the LTMcandidate cell comprises a resource configuration for the LTM candidate cell.

10. The method of claim 9, wherein the resource configuration comprises an indication ofresources on which measurements of reference signals transmitted on the LTM candidate cell are to be measured by the user equipment.

11. The method of any one of claims 6-10, wherein the response message comprises thelower-layer measurement configuration.

12. A method performed by a centralized unit (1100) for a network node, the methodcomprising: transmitting (606) to a user equipment (1000), via a distributed unit (1100) for thenetwork node, a conditional Layer 1 / Layer 2 Triggered Mobility, LTM, configuration,comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM cell configuration,wherein the indication of the execution condition comprises an indication of a lower- layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

13. The method of claim 12, wherein the lower-layer measurement configurationcorresponds to a LTM Channel State Information, CSI, reporting configuration.

14. The method of any one of claims 12 or 13, wherein the indication of the lower-layermeasurement configuration comprises an identifier of the lower-layer measurement configuration.

15. The method of any one of claims 12-14, further comprising;transmitting (602), to the distributed unit, a request message comprising informationrelated to an LTM candidate cell for the user equipment, and an indication that conditional LTM is configured; and receiving (604), from the distributed unit which determines the execution condition, aresponse message comprising an indication of the execution condition to be fulfilled for the user equipment to initiate an LTM mobility procedure to the LTM candidate cell.

16. A user equipment (1000) comprising processing circuitry (1002) configured to causethe user equipment to: receive (402) a conditional Layer 1 / Layer 2 Triggered Mobility, LTM, configuration,comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration; monitor (404) the execution condition; andresponsive to fulfilment of the execution condition, initiate (406) an LTM mobilityprocedure to the candidate cell using the LTM candidate cell configuration, wherein the indication of the execution condition comprises an indication of a lower- layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

17. The user equipment of claim 16, wherein the lower-layer measurement configurationcorresponds to a LTM Channel State CSI, reporting configuration.

18. The user equipment of claim 16 or 17, wherein the indication of the lower-layer measurement configuration comprises an identifier of the lower-layer measurement configuration.

19. The user equipment of any of claims 16-18, wherein the execution condition utilizes one or more of: radio measurements on transmissions by a source cell or a source radio access network node; and radio measurements on transmissions by a candidate cell or a candidate radio access network node.

20. The user equipment of any of claims 16-19, wherein the execution condition comprises a plurality of execution sub-conditions, and wherein fulfilment of the execution condition comprises fulfilment of one or more or all of the execution sub-conditions.

21. A user equipment (1000) adapted to:receive (402) a conditional Layer 1 / Layer 2 Triggered Mobility, LTM, configuration,comprising an LTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration; monitor (404) the execution condition; andresponsive to fulfilment of the execution condition, initiate (406) an LTM mobilityprocedure to the candidate cell using the LTM candidate cell configuration, wherein the indication of the execution condition comprises an indication of a lower- layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

22. The user equipment of claim 21, further adapted to perform the method of any of claims 2-5.

23. A distributed unit (1100) for a network node, the distributed unit comprising processingcircuitry (1102) configured to cause the distributed unit to:receive (502), from a centralized unit (1100) for the network node, a request messagecomprising information related to a Layer 1 / Layer 2 Triggered Mobility, LTM, candidate cellfor a user equipment (1000) served by the distributed unit, and an indication that conditional LTM is configured; and transmit (506), to the centralized unit, a response message comprising an indication ofan execution condition to be fulfilled for the user equipment to initiate an LTM mobility procedure to the LTM candidate cell, wherein the indication of the execution condition in the response message comprises an indication of a lower-layer measurement configuration associated with the LTM candidatecell configuration and the lower-layer measurement configuration corresponds to a reportingconfiguration.

24. The distributed unit of claim 23, wherein the lower-layer measurement configurationcorresponds to a LTM Channel State Information, CSI, reporting configuration.

25. The distributed unit of claim 23 or 24, wherein the indication of the lower-layermeasurement configuration comprises an identifier of the lower-layer measurement configuration.

26. The distributed unit of any of claims 23-25, wherein the information related to the LTMcandidate cell comprises a resource configuration for the LTM candidate cell.

27. The distributed unit of claim 26, wherein the resource configuration comprises anindication of resources on which measurements of reference signals transmitted on the LTM candidate cell are to be measured by the user equipment.

28. The distributed unit of any of claims 23-27, wherein the response message comprisesthe lower-layer measurement configuration.

29. A distributed unit (1100) for a network node, the distributed unit adapted to:receive (502), from a centralized unit (1100) for the network node, a request messagecomprising information related to a Layer 1 / Layer 2 Triggered Mobility, LTM, candidate cellfor a user equipment (1000) served by the distributed unit, and an indication that conditional LTM is configured; andtransmit (506), to the centralized unit, a response message comprising an indication ofan execution condition to be fulfilled for the user equipment to initiate an LTM mobility procedure to the LTM candidate cell, wherein the indication of the execution condition in the response message comprises an indication of a lower-layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

30. The distributed unit of claim 29, further adapted to perform the method of any of claims 7-11.

31. A centralized unit (1100) for a network node, the centralized unit comprising processingcircuitry (1102) configured to cause the centralized unit to:transmit (606) to a user equipment (1000), via a distributed unit (1100) for the networknode, a conditional Layer 1 / Layer 2 Triggered Mobility, LTM, configuration, comprising anLTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration, wherein the indication of the execution condition comprises an indication of a lower- layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

32. The centralized unit of claim 31, wherein the lower-layer measurement configurationcorresponds to a LTM Channel State Information, CSI, reporting configuration.

33. The centralized unit of claim 31 or 32, wherein the indication of the lower-layermeasurement configuration comprises an identifier of the lower-layer measurement configuration.

34. The centralized unit of any of claim 31-33, wherein the processing circuitry is furtherconfigured to cause the centralized unit to: transmit (602), to the distributed unit, a request message comprising information relatedto an LTM candidate cell for the user equipment, and an indication that conditional LTM is configured; andreceive (604), from the distributed unit which determines the execution condition, a response message comprising an indication of the execution condition to be fulfilled for the user equipment to initiate an LTM mobility procedure to the LTM candidate cell.

35. A centralized unit (1100) for a network node, the centralized unit adapted to: transmit (606) to a user equipment (1000), via a distributed unit (1100) for the networknode, a conditional Layer 1 / Layer 2 Triggered Mobility, LTM, configuration, comprising anLTM candidate cell configuration for a candidate cell and an indication of an execution condition associated with the LTM candidate cell configuration, wherein the indication of the execution condition comprises an indication of a lower- layer measurement configuration associated with the LTM candidate cell configuration and the lower-layer measurement configuration corresponds to a reporting configuration.

36. The centralized unit of claim 35, further adapted to perform the method of any of claims13-15.

37. A computer-readable storage medium storing code which, when executed by processing circuitry (1002) of a user equipment (1000), causes the user equipment to perform a method according to any one of claims 1 to 5.

38. A computer-readable storage medium storing code which, when executed by processing circuitry (1102) of a distributed unit (1100) of a network node, causes the distributed unit to perform a method according to any one of claims 6 to 11.

39. A computer-readable storage medium storing code which, when executed by processing circuitry (1102) of a centralized unit (1100) of a network node, causes the centralized unit to perform a method according to any one of claims 12 to 15.

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