Measurement enhancement for ltm

Abstract

A UE receives configuration to perform L1 measurements for RSs in a RS set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer. The UE performs measurements of cell quality using the RSs or RS(s) for a cell for the given layer. The UE determines that the measurements of the cell quality or the RS(s) for the cell for the given layer are above threshold(s) according to the event trigger. The UE determines a PCI for the cell. The UE performs, based on the measurements of the cell quality or RS(s) for the given layer being above the threshold(s), the L1 measurements for event-triggered measurement reporting associated with the PCI. A network node provisions the threshold value(s) and RS set for L1 measurements and sends configuration of the same to the UE.

Description

Measurement Enhancement for LTMTECHNICAL FIELD

[0001] Examples of embodiments herein relate generally to mobility for user equipment (UEs) in cellular systems and, more specifically, relate to L1 / L2 Triggered Mobility (LTM) in cellular systems.BACKGROUND

[0002] L1 / L2 Triggered Mobility (or lower layer triggered mobility) (LTM) is a feature in 5G (fifth generation) New Radio (NR) that enables more efficient handovers between cells. In the context of 5GNR, LI (layer 1) refers to the Physical Layer (PHY), which includes the physical channels used for transmission and reception of data. L2 (layer 2), on the other hand, refers to the Medium Access Control (MAC) layer, which manages the allocation of resources and controls the flow of data.

[0003] Triggered mobility is a technique that allows the 5G NR network to predictively prepare for a handover between cells. This is performed by detecting changes in the user equipment's (UE) signal strength and quality from the serving cell and other cells, which can indicate an upcoming need to switch from the serving cell to another.

[0004] The LTM process involves the following steps. The UE measures the signal strength and quality in LI of the current serving cell (e.g., received signal strength indicator (RSSI), reference signal received power (RSRP), and reference signal received quality (RSRQ)). The UE's MAC layer (L2) evaluates the measurement results and determines if a handover is likely to be needed. If the L2 evaluation indicates that a handover might be necessary, the UE sends an “L1 / L2 Trigger” message to the network (via the serving cell).

[0005] Upon receiving the trigger, the network prepares for the upcoming handover by activating the target cell (the cell the UE is likely to move to) and allocating resources, and updating the UE's context information in the target cell. When the UE actually moves to the target cell, the handover process commences, and the network completes the transition by releasing the serving cell and assigning the UE to the new as the serving cell.

[0006] LTM provides several benefits: (1) reduced latency, where, by predicting the need for a handover, the network can prepare in advance, minimizing the time spent on the actual handover process; (2) improved performance, where triggered mobility helps to reduce packet loss and ensure seamless connectivity during handovers; and enhanced user experience as, with more efficient handovers, users can enjoy better coverage and fewer interruptions.

[0007] In summary, LTM is a 5G NR feature that enables proactive preparation for handovers between cells, leading to faster and more reliable handover processes. While LTM is useful, it can be improved.BRIEF SUMMARY

[0008] This section is intended to include examples and is not intended to be limiting.

[0009] In an exemplary embodiment, a method is disclosed that includes receiving, by a user equipment, configuration for the user equipment to perform layer 1 (LI) measurements for reference signals in a reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer; performing, by the user equipment, measurements of cell quality using the reference signals or one or more of the reference signals for a cell for the given layer; determining, by the user equipment, that the measurements of the cell quality or the one or more reference signals for the cell for the given layer are above one or more thresholds according to the event trigger; determining, by the user equipment, a physical cell identifier associated with the cell; and performing, by the user equipment and based on the measurements of the cell quality or one or more reference signals for the given layer being above the one or more thresholds, the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0010] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer- readable medium bearing the instructions embodied therein for use with the apparatus.Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[0011] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus at least to perform: receiving, by a user equipment, configuration for the user equipment to perform layer 1 (LI) measurements for reference signals in a reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer; performing, by the user equipment, measurements of cell quality using the reference signals or one or more of the reference signals for a cell for the given layer; determining, by the user equipment, that the measurements of the cell quality or the one or more reference signals for the cell for the given layer are above one or more thresholds according to the event trigger; determining, by the user equipment, a physical cell identifier associated with the cell; and performing, by the user equipment and based on the measurements of the cell quality or one or more reference signals for the given layer being above the one or more thresholds, the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0012] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receiving, by a user equipment, configuration for the user equipment to perform layer 1 (LI) measurements for reference signals in a reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer; performing, by the user equipment, measurements of cell quality using the reference signals or one or more of the reference signals for a cell for the given layer; determining, by the user equipment, that the measurements of the cell quality or the one or more reference signals for the cell for the given layer are above one or more thresholds according to the event trigger; determining, by the user equipment, a physical cell identifier associated with the cell; and performing, by the user equipment and based on the measurements of the cell quality or one or more reference signals for the given layer being above the one or more thresholds, the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0013] In another exemplary embodiment, an apparatus comprises means for: receiving, by a user equipment, configuration for the user equipment to perform layer 1 (LI) measurements for reference signals in a reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer; performing, by the user equipment, measurements of cell quality using the reference signals or one or more of the reference signals for a cell for the given layer; determining, by the user equipment, that the measurements of the cell quality or the one or more reference signals for the cell for the given layer are above one or more thresholds according to the event trigger; determining, by the user equipment, a physical cell identifier associated with the cell; and performing, by the user equipment and based on the measurements of the cell quality or one or more reference signals for the given layer being above the one or more thresholds, the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0014] In an exemplary embodiment, a method is disclosed that includes performing, at a network node, provision of threshold values for evaluation whether a user equipment starts LI measurements for lower layer triggered mobility; performing, at the network node, provision of a reference signal set for LI measurements that the user equipment is configured to measure based on measurements for a given layer; and sending, by the network node to the user equipment, configuration for the user equipment to perform layer 1 measurements for reference signals in the reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer, wherein the event trigger comprises the threshold values.

[0015] An additional exemplary embodiment includes a computer program, comprising instructions for performing the method of the previous paragraph, when the computer program is run on an apparatus. The computer program according to this paragraph, wherein the computer program is a computer program product comprising a computer- readable medium bearing the instructions embodied therein for use with the apparatus. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the apparatus.

[0016] An exemplary apparatus includes one or more processors and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus at least to perform: performing, at a network node, provision of threshold values for evaluation whether a user equipment starts LI measurements for lower layer triggered mobility; performing, at the network node, provision of a reference signal set for LI measurements that the user equipment is configured to measure based on measurements for a given layer; and sending, by the network node to the user equipment, configuration for the user equipment to perform layer 1 measurements for reference signals in the reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer, wherein the event trigger comprises the threshold values.

[0017] An exemplary computer program product includes a computer-readable storage medium bearing instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: performing, at a network node, provision of threshold values for evaluation whether a user equipment starts LI measurements for lower layer triggered mobility; performing, at the network node, provision of a reference signal set for LI measurements that the user equipment is configured to measure based on measurements for a given layer; and sending, by the network node to the user equipment, configuration for the user equipment to perform layer 1 measurements for reference signals in the reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer, wherein the event trigger comprises the threshold values.

[0018] In another exemplary embodiment, an apparatus comprises means for: performing, at a network node, provision of threshold values for evaluation whether a user equipment starts LI measurements for lower layer triggered mobility; performing, at the network node, provision of a reference signal set for LI measurements that the user equipment is configured to measure based on measurements for a given layer; and sending, by the network node to the user equipment, configuration for the user equipment to perform layer 1 measurements for reference signals in the reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger forthe measurements for the given layer, wherein the event trigger comprises the threshold values.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings use reference numerals, where the same reference numerals may be used to refer to like parts throughout, but parts having the same reference numeral can differ in operation and components. In the attached drawings:

[0020] FIG. 1 is a signaling diagram of a signaling procedure for LTM;

[0021] FIG. 2 is a block diagram of a measurement model;

[0022] FIG. 3A is a flow diagram of a method performed by a UE for measurement enhancement for LTM;

[0023] FIG. 3B is a flow diagram of a method performed by a network node for measurement enhancement for LTM;

[0024] FIG. 4 is a signaling diagram of an example an example of one proposed method using L3 measurements on an associated set to select RSs for event evaluation for LI event-triggered measurement reporting;

[0025] FIG. 5 is a signaling diagram of an example of one proposed method using L3 events to select RSs for event evaluation for LI event-triggered measurement reporting; and

[0026] FIG. 6 is a block diagram of one possible and non-limiting exemplary system in which the exemplary embodiments may be practiced.DETAILED DESCRIPTION OF THE DRAWINGS

[0027] Abbreviations that may be found in the specification and / or the drawing figures are defined below, at the end of the detailed description section.

[0028] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described in this Detailed Description are exemplary embodiments provided to enable persons skilled in the art to make or use the examples.

[0029] When more than one drawing reference numeral, word, or acronym is used within this description withand in general as used within this description, the “ / ” may be interpreted as “or”, “and”, or “both”. As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or,” mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

[0030] As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0031] It is noted that capital and lowercase words or phrases are considered to be the same herein. For instance, the words Slice and slice are the same, as are the phrases Network Repository Function and network repository function.

[0032] Any flow diagram (FIGS. 3 A and 3B) or signaling diagram (FIGS. 1, 2, 4 and 5) herein is considered to be a logic flow diagram, and illustrates the operation of an exemplary method, results of execution of computer program instructions embodied on a computer readable memory, and / or functions performed by logic implemented in circuitry. For methods, flow diagrams, and signaling diagrams, the orders of method steps, blocks in the flow, or signaling are not critical and instead are examples.

[0033] Technical context is now provided for technical areas related to the understanding of the examples. One technical area of interest concerns Ll / L2-Triggered Mobility (LTM). LTM may be sometimes be referred to as lower layer triggered mobility. In addition to the overview provided previously, an LTM procedure is described in 3 GPP TS 38.300 as follows. See, e.g., clause 9.2.3.5 of 3GPP TS 38.300 VI 8.2.0 (2024-06).

[0034] It is helpful to view FIG. 1 also, which is a signaling diagram of a signaling procedure for LTM between a UE (user equipment 10) and a gNB 70. The signaling in FIG. 1 is divided into the following sections: LTM preparation 110; early synch (synchronization) 120; LTM cell switch execution 130; and LTM cell switch completion 140.

[0035] For the LTM preparation 110, gNB 70 receives LI measurement report(s) (see signaling 1) from a UE 10. The gNB 70 performs LTM candidate preparation after the measurement reports, and sends (signaling 2) an RRC (radio resource control) reconfiguration message in signaling 3 with the parameters of LTM candidate cell configuration. The UE 10 responds with RRC reconfiguration complete in signaling 3. For the early sync 120, the UE and gNB perform DL (downlink) synchronization with candidate cells in signaling 4a and UL (uplink) synchronization with candidate cells in signaling 4B. For the LTM cell switch execution 130, the UE sends an LI measurement report in signaling 5, the gNB makes an LTM decision, and then responds (signaling 6) with a cell switch command (with MAC CE as a parameter). The UE detaches from the source and applies target configurations, and the UE and gNB perform a RACH (random access channel) procedure in signaling 7. In the LTM cell switch completion 140, there is signaling 8 for LTM cell switch completion.

[0036] In further detail, LTM is a procedure in which a gNB 70 receives LI measurement report(s) (see signaling 1) from a UE 10, and on their basis, the gNB changes the UE’s serving cell by a cell switch command signaled via a MAC CE (Medium Access Control Control element). The cell switch command indicates an LTM candidate configuration that the gNB previously prepared and provided to the UE through RRC (radio resource control) signaling. Then the UE switches to the target configuration according to the cell switch command. The LTM procedure can be used to reduce the mobility latency.

[0037] When configured by the network (e.g., gNB 70), it is possible to activate TCI (Transmission configuration indicator) states of one or multiple cells that are different from the current serving cell. For instance, the TCI states of the LTM candidate cells can be activated in advance before any of those cells become the serving cell. This allows the UE to be DL synchronized with those cells, thereby facilitating a faster cell switch to one of those cells when cell switch is triggered.

[0038] When configured by the network, it is possible to initiate UL (timing advance) TA acquisition (called early TA) procedure of one or multiple cells that are different from the current serving cells. If the cell has the same NTA as the current serving cells or NTA=0, early TA acquisition procedure is not required. The network may request the UE to perform early TA acquisition of a candidate cell before a cell switch. The early TA acquisitionprocedure is triggered by PDCCH (physical downlink control channel) order as specified in clause 9.2.6 or realized through UE -based TA measurement as configured by RRC. In the former case, the gNB to which the candidate cell belongs calculates the TA value and sends it to the gNB to which the serving cell belongs. The serving cell sends the TA value in the LTM cell switch command MAC CE when triggering LTM cell switch. In the latter case, the UE performs TA measurement for the candidate cells after being configured by RRC but the exact time the UE performs TA measurement is up to UE implementation. The UE applies the TA value measured by itself and performs RACH-less LTM upon receiving the cell switch command. The network may also send a TA value in the LTM cell switch command MAC CE without early TA acquisition.

[0039] Depending on the availability of a valid TA value, the UE performs either a RACH-less LTM or RACH-based LTM cell switch. If the TA value is provided in the cell switch command, the UE applies the TA value as instructed by the network. In the case where UE-based TA measurement is configured, but no TA value is provided in the cell switch command, the UE applies the TA value by itself if available. Meanwhile, the UE performs RACH-less LTM cell switch upon receiving the cell switch command. If no valid TA value is available, the UE performs RACH-based LTM cell switch.

[0040] Regardless of whether the UE is configured for UE-based TA measurement for a certain candidate cell, it will still follow the PDCCH order, which includes requesting a random access procedure towards the candidate cells. This also applies to the candidate cells for which the UE is capable of deriving TA values by itself. Additionally, regardless of whether the UE has already performed a random access procedure towards the candidate cells, it will still follow the UE-based measurement configuration if configured by the network.

[0041] For RACH-less LTM, the UE accesses the target cell using either a configured grant or a dynamic grant. The configured grant is provided in the LTM candidate configuration, and the UE selects the configured grant occasion associated with the beam indicated in the cell switch command. Upon initiation of LTM cell switch to the target cell, the UE starts to monitor PDCCH on the target cell for dynamic scheduling. Before RACH-less LTM procedure completion, the UE shall not trigger random access procedure if it does not have a valid PUCCH resource for triggered SRs (scheduling requests).

[0042] The following principles apply to LTM:

[0043] 1) Security key is maintained upon an LTM cell switch;

[0044] 2) Subsequent LTM is supported.

[0045] LTM supports both intra-gNB-DU (where DU is distributed unit) and intra- gNB-CU (where CU is central unit) inter-gNB-DU mobility. For instance, intra-gNB-DU is within the same gNB, and intra-gNB-CU inter-gNB-DU mobility may occur within one CU but between DUs connected to the CU. LTM supports both intra-frequency and interfrequency mobility, including mobility to inter-frequency cell that is not a current serving cell. LTM is supported only for licensed spectrum. The following scenarios are supported:

[0046] 1) PCell (primary cell) change in non-CA (non-carrier aggregation) scenario and non-DC (non-dual connectivity)scenario;

[0047] 2) PCell and SCell(s) (secondary cell(s)) change in CA scenario;

[0048] 3) Dual connectivity scenario, PCell and MCG (Master cell group) SCell(s) change and intra-SN (intra-secondary node) PSCell and SCG SCell(s) change without MN (master node) involvement. LTM for simultaneous PCell and PSCell (primary secondary cell) change is not supported.

[0049] While the UE has stored LTM candidate configurations the UE can also execute any L3 handover command sent by the network.

[0050] R19 mobility enhancements are captured in RP-234036 (RP -234036, Intel,“New WID: NR mobility enhancements Phase 4”, 3GPP TSG RAN Meeting #102, Edinburgh, Scotland, December 11-15, 2023).

[0051] 1) Measurements related enhancements for purpose of supporting LTM:[RAN2, RANI],

[0052] a) Measurement related enhancements are applicable to Intra-CU MCG / SCG LTM and Inter-CU MCG / SCG LTM.

[0053] b) Specify necessary components to support event-triggered LI measurement reporting [RAN2, RANI].

[0054] RANI and RAN2 to progress independently on the event-triggered measurements objectives of their respective MIMO (multiple input multiple output) andMobility enhancement WIs (work items). Review progress at RAN#105 to see if any modification of objectives is required to avoid / manage any overlap in the work

[0055] c) Specify support for CSI-RS (channel state information - reference signal) measurements for LTM procedures and enable CSI-RS based beam management, and / or other necessary physical layer operations on candidate cells before LTM [RANI]

[0056] The following was agreed for LTM in RAN2#127:

[0057] Agreements on measurements:

[0058] 1. LI LTM measurement event configuration is associated with LI measurement resource configuration provided in LTM configuration via RRC signaling.

[0059] See also the following.

[0060] 1. Event-triggered LI measurement should be designed for the followingLTM purposes:

[0061] a. Select the candidate beam / cell to trigger early synchronization.

[0062] b. Select the target beam / cell and trigger LTM cell switch procedure.

[0063] 2. For event-triggered LI measurement, use of beam level measurement result for event evaluation is baseline. FFS (for future study) for the cell level measurement.

[0064] 3. Support the following LTM events based on beam specific quality of serving cell and candidate cells as the LI LTM measurement events.

[0065] a. Event LTM2: Beam of serving cell becomes worse than absolute threshold;

[0066] b. Event LTM3: Beam of candidate cell becomes amount of offset better than beam of serving cell;

[0067] c. Event LTM4: Beam of candidate cell becomes better than absolute threshold;

[0068] d. Event LTM5: Beam of serving cell becomes worse than absolute thresholdl AND Beam of candidate cell becomes better than another absolute threshold2.

[0069] FFS on what beam(s) of the serving cell and neighboring cell is used for event evaluation. FFS on the need of Event LTM1.

[0070] 4. Support the beam config of both SSB and CSI-RS in LI measurement resource configuration in LTM configuration. Working assumption: Same RS type should be used for both serving and neighboring cell for event LTM3 and event LTM5.

[0071] 5. RAN2 assumes filtering of the LI measure results is needed. It’s up toRANI whether the specified LI filtering is needed or ok to leave it to UE implementation.

[0072] 6. For LTM event evaluation, (time to trigger) TTT, hysteresis for entering / leaving, and / or beam specific (FFS for cell specific) offset can be applied. FFS on the need of measurement reporting once leaving condition is met.

[0073] Measurements of beams and reporting of the same are now described. Referring to FIG. 2, this figure is a block diagram of a measurement model, shown as high- level measurement model 200. The measurements described below are also described in part in clause 9.2.4 of 3GPP TS 38.300 V18.2.0 (2024-06), NR; NR and NG-RAN Overall Description; Stage 2 (Release 18).

[0074] In FIG. 2, there is UE implementation specific layerl filtering 220, beam consolidation / selection 230, layer 3 filtering 240 for cell quality, evaluation of reporting criteria 250, L3 beam filtering 260, and beam selection 270 for reporting. Each of these blocks concerns different beams, e.g., as input or output. Operation of this is discussed now.

[0075] In an RRC CONNECTED state, the UE 10 measures multiple beams (at least one) of a cell and the measurements results (power values) are averaged to derive the cell quality. In doing so, the UE is configured to consider a subset of the detected beams. Filtering takes place at two different levels: at the physical layer to derive beam quality; and then at RRC level to derive cell quality from multiple beams. Cell quality from beam measurements is derived in the same way for the serving cell(s) and for the non-serving cell(s). Measurement reports may contain the measurement results of the A best beams if the UE is configured to do so by the gNB.

[0076] The corresponding high-level measurement model 200 is described below:

[0077] NOTE 1 : K beams correspond to the measurements on SSB or CSLRS resources configured for L3 mobility by the gNB 70 and detected by the UE 10 at LI.

[0078] A: these are for gNB beams 1 to K and are measurements (beam specific samples) internal to the physical layer.

[0079] Layer 1 filtering (see reference 220): internal layer 1 filtering of the inputs measured at point A. Exact filtering is implementation dependent. How the measurements are actually executed in the physical layer by an implementation (inputs A and Layer 1 filtering) is not constrained by a standard.

[0080] A1: measurements (i.e., beam specific measurements) reported by layer 1 to layer 3 after layer 1 filtering.

[0081] Beam Consolidation / Selection 230: beam specific measurements are consolidated to derive cell quality. The behavior of the Beam consolidation / selection is standardized and the configuration of this module is provided by RRC signaling (where the RRC signaling configures parameters in reference 231). Reporting period at B equals one measurement period at A1.

[0082] B: a measurement (i.e., cell quality) derived from beam-specific measurements reported to layer 3 after beam consolidation / selection.

[0083] Layer 3 filtering 240 for cell quality: filtering performed on the measurements provided at point B. The behavior of the Layer 3 filters is standardized and the configuration of the layer 3 filters is provided by RRC signaling (as illustrated by the RRC configures parameters in reference 241). Eiltering reporting period at C equals one measurement period at B.

[0084] C: a measurement after processing in the layer 3 filtering 240. The reporting rate is identical to the reporting rate at point B. This measurement is used as input for one or more evaluation of reporting criteria.

[0085] Evaluation of reporting criteria 250: checks whether actual measurement reporting is necessary at point D. The evaluation can be based on more than one flow of measurements at reference point C, e.g., to compare between different measurements. This is illustrated by input C and C1. The UE evaluates the reporting criteria at least every time a new measurement result is reported at point C, C1. The reporting criteria are standardized and the configuration is provided by RRC signaling (e.g., UE measurements, and as illustrated by RRC configures parameters in reference 251).

[0086] D: measurement report information (message) sent on the radio interface.

[0087] L3 Beam filtering 260: filtering performed on the measurements (i.e. beam specific measurements) provided at point A1, wherein there are K beams. The behavior of the beam filters is standardized and the configuration of the beam filters is provided by RRC signaling (see RRC configures parameters in reference 261). Filtering reporting period at E equals one measurement period at A1.

[0088] E: a measurement (i.e., beam-specific measurement) after processing in the L3 beam filtering 260. The reporting rate is identical to the reporting rate at point A1. This measurement is used as input for selecting the X beam measurements to be reported.

[0089] Beam Selection 270 for beam reporting: selects the X beam measurements from the measurements provided at point E. The behavior of the beam selection is standardized and the configuration of this module is provided by RRC signaling (see RRC configures parameters in reference 271).

[0090] F: beam measurement information included in measurement report (sent) on the radio interface.

[0091] Layer 1 filtering introduces a certain level of measurement averaging. How and when the UE exactly performs the required measurements is implementation specific to the point that the output at B fulfils the performance requirements set in 3GPP TS 38.133 (see 3GPP TS 38.133 V18.6.0 (2024-06), Requirements for support of radio resource management). Layer 3 filtering for cell quality and related parameters used are specified in 3GPP TS 38.331 and do not introduce any delay in the sample availability between B and C. Measurement at point C, C1is the input used in the event evaluation. L3 Beam filtering and related parameters used are specified in 3 GPP TS 38.331 and do not introduce any delay in the sample availability between E and F.

[0092] Now that a technical overview has been provided, problems in the technical areas are described. The RAN2 has agreed beam level event evaluation for LTM event-based reporting:

[0093] Support the following LTM events based on beam specific quality of serving cell and candidate cells as the LI LTM measurement events.

[0094] 1) Event LTM2 (or LTM-2): Beam of serving cell becomes worse than absolute threshold;

[0095] 2) Event LTM3 (or LTM-3): Beam of candidate cell becomes amount of offset better than beam of serving cell;

[0096] 3) Event LTM4 (or LTM-4): Beam of candidate cell becomes better than absolute threshold;

[0097] 4) Event LTM5 (or LTM-5): Beam of serving cell becomes worse than absolute threshold 1 AND Beam of candidate cell becomes better than another absolute threshold2.

[0098] Since the UE may be configured with up to 64 measurement RS for the event evaluation (i.e., one or more RS for one or more cells), this may exceed the UE capability for how many RS the UE is able to perform event evaluation / measurements. Furthermore, the UE power consumption may be increased if the UE is required to perform LI measurements constantly (i.e., the LI measurements are meant to trigger cell switch) and it may not be beneficial to perform them unless there is a cell switch. This may specially be an issue when an event (e.g., associated with a measurement RS) using LI measurement is evaluated for a configured time duration (e.g., time to trigger) or for a configured number of times. For example, for a MIMO UE initiated beam management (UEIBM), it has been agreed that an event can be evaluated using a counter.

[0099] Further agreements are as follows. Agreement in RANI #117:

[0100] 1) Regarding the triggering event determination for Event 2:

[0101] a) If within a time window (which is configurable), the number of Event-2 instance(s) for at least one same new beam is greater than or equal to a configurable number M, UE initiated beam report occurs.

[0102] i) Note: Event-2 instance for a new beam is determined if the Ll-RSRP (LI - Reference Signal Received Power) of the new beam becomes a threshold value better than the current beam

[0103] 2) Above feature is subject to UE capability.

[0104] a) Basic feature: Once the Ll-RSRP of the new beam becomes a threshold value better than the current beam, UE initiated beam report occurs.

[0105] FFS: Whether the above is captured in RANI or RAN2 specification.

[0106] The examples herein address these and other problems. An overview is described now, then more details are provided below.

[0107] FIG. 3A is a flow diagram of a method performed by a UE for measurement enhancement for LTM. In block 301, the UE 10 receives configuration for the user equipment to perform layer 1 measurements for reference signals in a reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers (e.g., L3 measurements) and on an event trigger for the measurements for the given layer. In some examples, the given layer may be the L3, i.e., the determining to perform the LTM measurements may be based on L3 measurements. In some examples, the given layer may be the LI, i.e., the determining to perform the LTM measurements may be based on LI measurements. In block 302, the UE 10 performs measurements of cell quality using the reference signals or one or more of the reference signals for a cell for the given layer. In block 304, the UE determines that the measurements of the cell quality or the one or more reference signals for the cell for the given layer are above one or more thresholds according to the event trigger. The UE 10 in block 306 determines a physical cell identifier associated with the cell. The UE in block 308 performs, based on the measurements of the cell quality or one or more reference signals for the given layer being above the one or more thresholds, the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0108] It is noted that, in one example, the UE receives the configuration from a serving cell, e.g., while the UE is connected to the serving cell. The measurements of cell quality or one or more reference signals may be for candidate cells, e.g., possible candidate cells for handover of the serving cell, for the given layer. Further overview for the UE is provided below.

[0109] A network node such as a gNB 70 or other node (e.g., a CU in the gNB) configures the UE and interacts with the UE. Refer to FIG. 3B, which is a flow diagram of a method performed by a network node for measurement enhancement for LTM. In block 392, the network node performs provision of threshold values for evaluation whether a user equipment starts LI measurements for lower layer triggered mobility. The network node in block 394 performs provision of a reference signal set for LI measurements that the UE isconfigured to measure based on measurements for a given layer. In block 396, the network node sends, to the user equipment, configuration for the user equipment to perform layer 1 measurements for reference signals in the reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer, wherein the event trigger comprises the threshold values. FIGS. 4 and 5 contain addition examples of operations performed by a network node (implementing a serving cell).

[0110] With respect to a UE, one example proposes a method to determine measurement resources / RS for LTM LI measurements based on one or more conditions, wherein the conditions may be one or more of the following.

[0111] 1) In one example embodiment, the UE may be configured to perform RS level (e.g., beam level) LI measurement for event evaluation (event-triggered reporting evaluation) based on L3 measurements.

[0112] a. If the UE determines that L3 cell quality measurement for a first cell is above a threshold value (a detection threshold or NW configured threshold), it may determine to perform LI measurement on the LI measurement resources associated with the first cell:

[0113] i. The measurement RS of the cell in the resource set for event-triggered measurement reporting.

[0114] b. If the UE determines that L3 measurement on at least one RS of a first cell is above a threshold value (a detection threshold or NW, network, configured threshold), it may determine to perform LI measurement on the LI measurement resources associated with the first cell:

[0115] i. The measurement RS of the cell in the resource set for event-triggered measurement reporting.

[0116] ii. The specific measurement RS corresponding to the L3 measurement RS in the resource set in the resource set for event-triggered measurement reporting.

[0117] c. The UE may determine to perform the measurement on LI measurement resources of up to N cells with highest L3 cell quality:

[0118] i. The measurement RS of the cell in the resource set for event-triggered measurement reporting.

[0119] In one example, the intra frequency identification requirements are defined in 3 GPP TS 38.133 as follows.

[0120] The UE shall be able to identify a new detectable intra-frequency cell within Tidentify intra without index if the UE is not indicated to report SSB-based RRM (measurement result with the associated SSB index (reportQuantityRsIndexes or maxNrofRSIndexesToReport is not configured), or the UE is indicated that the neighbor cell is synchronous with the serving cell (deriveSSB-IndexFromCell is enabled). Otherwise, the UE shall be able to identify a new detectable intra frequency cell within Tidentify intra with index. The UE shall be able to identify a new detectable intra frequency SS (Synchronization Signal) block of an already detected cell within T identify intra without index.

[0121] Tidentify intra without index = (TPSS / SSS_sync_intra + T SSB_measurement_period_intra) ms; and

[0122] Tidentify intra with index = (TPSS / SSS_sync_intra + T SSB_measurement_period_intra + TSSB time index intra) ms,

[0123] Where:

[0124] TPSS / SSS_sync_intra: it is the time period used in PSS / SSS (Primary Synchronization Signal / Secondary Synchronization Signal) detection;

[0125] TSSB time index intra: it is the time period used to acquire the index of the SSB being measured; and

[0126] T SSB_measurement_period_intra: equal to a measurement period of SSB based measurement.

[0127] 2) In one example embodiment, the UE is configured to perform measurements without SSB index acquisition (or index reading) and the LI measurement event is configured to be triggered based on L3 measurement.

[0128] a. Prior to LI event evaluation / LI measurements, the UE is allowed to perform SSB index reading prior to LI event evaluation. In other words, SSB index reading delay associated with the corresponding measurement (e.g., FR1 intra / inter or FR2 intra / inter index reading).

[0129] 3) In one example embodiment, the UE may be configured to perform LI measurement for event-triggered measurement reporting based on the LI measurements.

[0130] a. The UE may be configured to determine the RS set quality for a certain cell based on the LI measurement resources in a set for the event-triggered measurement reporting. The UE may determine the RS set quality by averaging up to N highest quality RS (that are above a threshold) to determine RS set quality (i.e., the LI cell quality). The UE may determine to perform measurements for the event-triggered measurement reporting on the RS of the RS set based on the RS set quality.

[0131] b. the UE may be configured to determine the at least one RS quality for a certain cell based on the LI measurement resources in a set for the event-triggered measurement reporting. If the UE determines that at least one RS quality is above a threshold in a set of RS for event-triggered measurement reporting, the UE may determine to perform measurements for the event-triggered measurement reporting on the RS set based on the RS quality.

[0132] The UE procedure includes the following.

[0133] In one example, the L3 measurement RS may be associated with LI measurement RS set via explicit configuration or via PCI association:

[0134] 1) The UE may receive configuration of LI measurement RS for LTM measurements (event-triggered).

[0135] 2) The UE measures L3 quality of one or more RS or cells and determines that it is above a threshold value.

[0136] a) The UE may be configured to determine the following: an event based on the threshold value, a condition based on the threshold value, or a reporting based on the threshold value.

[0137] 3) The UE determines the PCI associated with the RS / cell of the L3 measurement.

[0138] a) The UE determines the PCI and SSB index association with the SSB of the L3 measurement.

[0139] 4) The UE determines to measure the LI measurement RS in the set of measurement RS for LTM measurement for event-triggered measurement reporting associated with the PCI.

[0140] Now that an overview has been provided, further details are provided.

[0141] In one example embodiment, an association of one or more L3 / L1 measurement RS and LI RS may be configured in RS level:

[0142] 1) a certain L3 measurement RS or RSs are mapped to a set of LI measurement RSs. If the L3 RS is measured (and / or reported) above a threshold, the UE may determine to measure the set of LI RSs associated with the L3 measurement.

[0143] a) alternatively, a certain LI measurement RS or RSs are mapped to a set of LI measurement RSs. If the LI RS is above a threshold, the UE may determine to measure the associated set of LI RS

[0144] In one example, the LI event associated with a candidate measurement is only enabled if a condition exists in the same measurement resource configured for L3 event and when the L3 event condition is triggered (e.g., UE enters the L3 event).

[0145] 1) In one case, upon entering the L3 event condition, if the UE has been configured with the LI measurement event, the UE will subsequently trigger LI measurement, but not trigger L3 measurement report.

[0146] a) This is performed if measurement reporting is not configured for the L3 event but is configured for the LI measurement resource.

[0147] 2) In another case, upon entering the L3 event condition, if the UE has been configured with the LI measurement event, the UE will subsequently trigger LI measurement, with L3 measurement report prior to the start of the LI measurements.

[0148] a) This is done if the UE is configured measurement reporting for both events.

[0149] b) The L3 triggered report may indicate the starting of LI measurements for one of the candidate IDs in the report.

[0150] In one example, the LI event associated with candidate measurements is stopped once the UE leaves the L3 event condition. This may be configurable by the network.

[0151] 1) For example, the UE enters the L3 condition and initiates LI measurements on the same measurement resource as L3 measurements have been measured.

[0152] 2) During this time, the L3 measurement condition becomes such that the exit condition is met at the L3 measurement reference point. The UE may stop performing LI measurements for the candidate resource or UE is not required to perform measurements for the candidate resource upon exiting the L3 measurement condition.

[0153] In one example embodiment, the phrase “the UE determines to perform the measurements” may refer to the UE selecting a set of measurement resources for LI measurements.

[0154] 1) In one example, the selecting set of measurement resources may refer to limiting measurements to a set of measurement RSs.

[0155] 2) In one example, the selecting set of measurement resources may refer to the UE not requiring measurements of other resources than the set of measurement RSs.

[0156] 3) In one example, the selecting set of measurement resources may refer to the UE requiring measurement of resources that are the determined set of measurement RSs.

[0157] In one example embodiment, the LI measurement resources may be configured in a set of cell specific measurement resources. In one example embodiment, the LI measurement resources may be configured in a set of resources and comprise measurement resources for one or more cells.

[0158] In one example embodiment, the threshold referred to herein may be one of the following:

[0159] 1) The threshold may be a detection threshold for a reference signal / cell;

[0160] 2) The threshold may be configured by RRC and be specific for LTM event-triggered measurement reporting;

[0161] 3) The threshold may be a relative threshold / offset value, i.e., such that

[0162] 4) quantity may be an RSRP or RSRQ (Reference Signal ReceivedQuality ) / SINR (signal-to-interference-plus-noise ratio) threshold.

[0163] In one example embodiment, the L3 event herein may refer to, e.g., A3 / A4 events or similar, where these events include the following:

[0164] 1) Event A3: Neighbor becomes offset better than the serving cell (PCell orSCell);

[0165] 2) Event A4: Neighbor becomes better than the threshold; and / or

[0166] 3) Event A5: Serving cell becomes worse than thresholdl and neighbor becomes better than threshold 2.

[0167] In one example embodiment, the measurement resource herein may refer to one of: SSB; or CSI-RS. In one example embodiment, the UE is required to measure Ll- RSRP for event evaluation for reference signals associated with a PCI for which the L3 RS / cell quality is above a threshold value.

[0168] In one example embodiment, the UE is not required to measure Ll-RSRP for event evaluation for reference signals associated with a PCI (Physical cell ID, where ID is identification) for which the L3 RS / cell quality is below a threshold value.

[0169] In one example embodiment, the UE may indicate its capability in terms of number LI measurements for event evaluation (to be done simultaneously or in parallel). This may be indicated per candidate cell or across multiple / all candidate cells. This may be indicated per BWP (bandwidth part).

[0170] In one example embodiment, the enablement of UE behavior of selecting a sub-set of RSs may be configured (e.g., when NW configures a RS set for measurements containing a number of RSs larger than the UE capability). In one example embodiment, in any of the examples herein, the condition to perform LI measurements (for event-triggered measurement reporting) may be based on L1 / L3 measurements, where the L3 measurement may refer that whether the L1 / L3 has to be a reported measurement or a measurement (i.e., not reported but determined by the UE).

[0171] FIG. 4 is a signaling diagram of an example an example of one proposed method using L3 measurements on an associated set to select RSs for event evaluation for LI event-triggered measurement reporting. In further detail, FIG. 4 shows an LTM configuration and measurement section 305 that starts after the UE 10 has been configured with L3 measurements in signaling 320, in communication with the serving cell 310 (having PCI1), a first candidate cell 315-1 (having PCI2), and a second candidate cell 315-2. It is noted that the cells 310, 315 would be formed by corresponding gNBs 70. Only two candidate cells 315 areillustrated, but this is an example, and more (or fewer) candidate cells may be used. The UE 10 sends an L3 measurement report in signaling 325. The serving cell 310 sends LTM configuration signaling 330, which includes LTM CSI measurement set 1: {SSB 1 to SSB 8 - PCI2, SSB 1 to SSB 8 - PCI3}. That is, both PCI2 and PCI3 will have measurements for SSB 1 to SSB 8, where 1 to 8 are the indexes of the corresponding SSB. These are reference signal LI measurement resources associated with a cell for event-triggered measurement reporting. The SSB 1 to SSB 8 is a resource set, which is used for both PCI2 and PCI3 in this example. In some examples, the configuration signaling may comprise configuration signaling 331 (i.e., the Event Report Configuration) that is associated with the signaling 330. In alternative example, the configuration information in reference 331 may be provisioned in a separate configuration message.

[0172] The event report config (configuration) 331 includes the following: {Event info (information) - Event LTM-3, LI Measurement Set Info - LTM CSI Meas (measurement) Set 1, Information of RS Selection for event evaluation: information of associated L3 Measurement RS s for each cell, cell level threshold)}. The UE 10 sends an L3 measurement report in signaling 340 to the serving cell 310.

[0173] In block 345, based on L3 measurements on the associated RSs, the UE determines that PCI2 is the cell with cell level L3 meas > cell level threshold. In block 350, For Event Report Config 1, the UE 10 selects only PCI 2 for event evaluation. In block 355, the UE 10 performs LTM-3 event evaluation for S SB 1 to SSB 8 of PCI2, and does not trigger LTM-3 event evaluation for S SB 1 to SSB 8 of PCI3. In an example in the block 355 the event evaluation may comprise of performing measurements (LI measurements) on the RS of PCI for which the evaluation is determined (e.g. based on the L3 measurements). In block 360, the UE determines LTM-3 is met only for SSB1 and SSB 2 of PCI2. The UE in signaling 365 sends an LI event-triggered measurement report containing measurements at least for SSB1 and SSB2 of PCI2.

[0174] In block 370, the UE 10, based on L3 measurements on the associated RSs, determines that PCI3 is the cell with cell level L3 meas > cell level threshold. The UE for Event Report Config 1, selects only PCI3 for event evaluation for block 375. For block 380, the UE performs LTM-3 event evaluation for S SB 1 to SSB 8 of PCI3, and does not triggerLTM-3 event evaluation for SSB1 to SSB 8 of PCI2. In block 381, the UE determines LTM-3 is met only for SSB1 and SSB 2 of PCI3. The UE in signaling 383 sends an LI event-triggered measurement report containing measurements at least for SSB1 and SSB2 of PCI3. This ends the LTM configuration, measurements and reporting section 305.

[0175] In signaling 385, the serving cell 310 sends signaling 385 having a message of LTM cell switch with parameters of PCI3, and beam associated with SSB1. In signaling 390, the UE performs a cell switch to PCI3 (the candidate cell 315-2).

[0176] For the example of FIG. 4, for an LI event-triggered measurement reporting, an LI measurement set (see Event Report Config 1 331) is provided along with the information of an associated set of RSs (which are configured for L3 measurements) and a threshold (cell level threshold) to select RSs from the LI measurement set for event evaluation. Based on the L3 measurements on the associated set (if they are above the given threshold or not), the UE selects the RSs (see the LTM SCI measurement set 1 in signaling 330 and blocks 350 and 355) for event evaluation for LI event-triggered measurement reporting. For this example, this is the associated set of RSs for the PCI2 that gets selected. The network (e.g., the gNB that forms the serving cell) does not decide that a cell change is to be performed until after receiving the LI event-triggered measurement report in signaling 383.

[0177] FIG. 5 is a signaling diagram of an example of one proposed method using L3 events to select RSs for event evaluation for LI event-triggered measurement reporting. In FIG. 5, the signaling 320 is the same as in FIG. 4. The LTM configuration and measurements section 305 has different operations, however.

[0178] The LTM configuration 330 is the same as in FIG. 4, but the Event Report Config 1 431 has different information as compared to Event Report Config 1 331. The Event Report Config 1 431 contains Information of RS Selection for event evaluation: L3 event.

[0179] In block 435, the UE determines there is an L3 event on SSB1 and SSB 2 of PCI2 is met. The UE sends an L3 report (if configured to do so) in signaling 440.

[0180] In block 445, the UE 10, for Event Report Config 1, selects SSB 1 and SSB 2 for PCI2 for event evaluation. In block 450, the UE 10 performs LTM-3 event evaluation for SSB1 and SSB 2 of PCI2. The event evaluation may comprise of performing measurements (LI measurements on RS associated with the PCI2). The UE determines the LTM-3 is met forSSB 1 of PCI2 in block 455. The UE signals, in signaling 460, an LI event-triggered measurement report containing measurements at least for SSB 1 PCI2.

[0181] In block 465, the UE performs LTM-3 event evaluation for SSB1 and SSB 2 of PCI2, and the UE determines that an LTM-3 is met to SSB 1 of PCI2 in block 470. The UE 10 sends an LI event-triggered measurement report containing measurements at least for SSB1 PCI2 in signaling 475.

[0182] In block 480, the UE determines an L3 event on SSB1 and SSB 2 of PCI2 is not met. The UE sends an L3 report (if configured) in signaling 485. In block 490, the UE 10 stops LTM-3 event evaluation on SSB 1 and SSB2 of PCI2.

[0183] FIG. 5 illustrates another example where, for an LI event-triggered measurement reporting, an LI measurement set is provided along with the information of using an L3 event to select RSs from the LI measurement set for event evaluation. Upon entering the L3 event condition, the UE subsequently triggers event evaluation on the corresponding RSs from the LI measurement set. The network (e.g., the gNB that forms the serving cell) does not decide that a cell change is to be performed. Because L3 condition does not apply (the L3 event is not met in block 480), the UE determines to stop the LI measurements (i.e., stop the event-triggered measurement reporting evaluation for the cell). In other words, for this and other events, the UE may determine the measurements of the cell quality or reference signals for the cell for a given layer (e.g., L3) are no longer above one or more thresholds according to the event trigger, and this is used to stop event evaluation. This stoppage occurs in block 490.

[0184] Turning to FIG. 6, this figure shows a block diagram of one possible and non-limiting example of a cellular network 1 that is connected to a user equipment (UE) 10. A number of network elements are shown in the cellular network of FIG. 6: base stations (BSs) 70, 70-1, and 70-2; and a core network 90.

[0185] In FIG. 6, a user equipment (UE) 10 is in wireless communication via radio link 11 with the base station 70 of the cellular network 1, and is at least measuring signals from BS 70-1 via radio link 11-1 and from BS 70-2 via radio link 11-2. A UE 10 is a wireless communication device, such as a mobile device, that is configured to access a cellular network. The UE 10 is illustrated with one or more antennas 28. The ellipses 2 indicate therecould be multiple UEs 10 in wireless communication via radio links with the base station 70. The UE 10 includes one or more processors 13, one or more memories 15, and other circuitry 16. The other circuitry 16 includes one or more receivers (Rx(s)) 17 and one or more transmitters (Tx(s)) 18. A program 12 is used to cause the UE 10 to perform the operations described herein. For a UE 10, the other circuitry 16 could include circuitry such as for user interface elements (not shown) like a display. The program 12 may be implemented via instructions stored in memory / memories 15 and executed by processor(s) 13, or by circuitry such being implemented as part of the processor(s) or other circuitry elements, or both.

[0186] The base station 70, as a network element of the cellular network 1, provides the UE 10 access to cellular network 1 and to the data network 91 via the core network 90 (e.g., via a user plane function (UPF) of the core network 90). As such, the base station 70 may be considered to be an access node, which provides access by UE(s) 10 to the cellular network 1. In this example, the other base stations 70-1 and 70-2 are assumed to be similar to base station 70 and the circuitry in base station 70 is assumed to be relevant to these base stations. The base station 70 forms the serving cell 310, the base station 70-1 forms the candidate call 70-1, and the base station 70-2 forms the candidate cell 70-2. It is noted that each base station 70 will likely form multiple cells per base station, as described below, but those cells are not shown.

[0187] The base station 70 is illustrated as having one or more antennas 58. In general, the base station 70 may be referred to as RAN node 70, although many will make reference to this as a gNB (gNode B, a base station for NR, new radio) instead. There are, however, many other examples of RAN nodes including an eNB (evolved Node B) or TRP (Transmission-Reception Point). The base station 70 includes one or more processors 73, one or more memories 75, and other circuitry 76. The other circuitry 76 includes one or more receivers (Rx(s)) 77 and one or more transmitters (Tx(s)) 78. A program 72 is used to cause the base station 70 to perform the operations described herein. The program 72 may be implemented via instructions stored in memory / memories 75 and executed by processor(s) 73, or by circuitry such being implemented as part of the processor(s) or other circuitry elements, or both.

[0188] It is noted that the base station 70 may instead be implemented via other wireless technologies, such as Wi-Fi (a wireless networking protocol that devices use to communicate without direct cable connections). In the case of Wi-Fi, the link 11 could be characterized as a wireless link.

[0189] Two or more base stations 70 communicate using, e.g., link(s) 79. The link(s) 79 may be wired or wireless or both and may implement, e.g., an Xn interface for 5G (fifth generation), an X2 interface for LTE (Long Term Evolution), or other suitable interface for other standards.

[0190] The cellular network 1 may include a core network 90, as a second network element or elements, that may include core network functionality, and which provide connectivity via a link or links 81 with a data network 91, such as a telephone network and / or a data communications network (e.g., the Internet). The core network 90 includes one or more processors 93, one or more memories 95, and other circuitry 96. The other circuitry 96 includes one or more receivers (Rx(s)) 97 and one or more transmitters (Tx(s)) 98. A program 92 is used to cause the core network 90 to perform the operations described herein. The program 92 may be implemented via instructions stored in memory / memories 95 and executed by processor(s) 93, or by circuitry such being implemented as part of the processor(s) or other circuitry elements, or both.

[0191] The core network 90 could be a 5GC (5G core network). The core network 90 can implement or comprise multiple network functions (NF(s)) 99, and the program 92 may comprise one or more of the NFs 99. A 5G core network may use circuitry such as memory and processors, which may implement a virtualization layer. It could be a single standalone computing system, a distributed computing system, or a cloud computing system. The NFs 99, as network elements, of the core network could be containers or virtual machines running on the circuitry of the computing system(s) making up the core network 90.

[0192] Core network functionality for 5G may include access and mobility management functionality that is provided by a network function 99 such as an access and mobility management function (AMF), session management functionality that is provided by a network function such as a session management function (SMF). Core network functionality for access and mobility management in an LTE (Long Term Evolution) network may beprovided by an MME (Mobility Management Entity) and / or SGW (Serving Gateway) functionality, which routes data to the data network. Many others are possible, as illustrated by the examples in FIG. 6: AMF; SMF; MME; SGW; GMLC (Gateway Mobile Location Center); LMF (Location Management Function); UDM (Unified Data Management) / UDR (Unified Data Repository); NRF (Network Repository Function); and / or E-SMLC (Evolved Serving Mobile Location Center). These are merely exemplary core network functionality that may be provided by the core network 90, and note that both 5G and LTE core network functionality might be provided by the core network 90. The base station 70 is coupled via a backhaul link 31 to the core network 90. The base station 70 and the core network 90 may include an NG (Next Generation) interface for 5G, or an SI interface for LTE, or other suitable interface for other radio access technologies for communicating via the backhaul link 31.

[0193] In the data network 91, there is a computer-readable medium 94. The computer-readable medium 94 contains instructions that, when downloaded and installed into the memories 15, 75, or 95 of the corresponding UE 10, base station 70, and / or core network element(s) 90, and executed by processor(s) 13, 73, or 93, cause the respective device to perform corresponding actions described herein. The computer-readable medium 94 may be implemented in other forms, such as via a compact disc or memory stick.

[0194] The programs 12, 72, and 92 contain instructions (as part of a corresponding program 12, 72, and 92) stored by corresponding one or more memories 15, 75, or 95. These instructions, when executed by the corresponding one or more processors 13, 73, or 93, cause the corresponding apparatus 10, 70, or 90, to perform the operations described herein. The computer readable memories 15, 75, or 95 are circuitry and may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, firmware, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The processors 13, 73, and 93, are circuitry and may be of any type suitable to the local technical environment. For example, these processors may include one or more of general-purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), processors based on a multi-core processor architecture, and mayalso include specialized circuits such as field-programmable gate arrays (FPGAs), application specific circuits (ASICs), signal processing devices and other devices, or combinations of these devices, as non-limiting examples. The processors 13, 73, and 93 are circuitry that can be programmed to perform functions via software, firmware or the like (including microcode), but are not solely software.

[0195] The receivers 17, 77, and 97, and the transmitters 18, 78, and 98 may implement wired or wireless interfaces. The receivers and transmitters may be grouped together as transceivers.

[0196] The cellular network 1 may implement network virtualization, which is the process of combining circuitry and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities (such as network functions 99) that result from the network virtualization are still implemented, at some level, using circuitry such as processors 73 and / or 93 and memories 75 and / or 95, and also such virtualized entities create technical effects.

[0197] t is noted that a common way to view “cells” in a cellular system is as a 360-degree oval. However, antennas typically do not radiate over 360 degrees, and therefore a common technique is to have the 360 degrees subdivided into multiple sections. That is, there can be multiple cells per base station. For instance, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360-degree area so that the single base station’s coverage area covers an approximate oval. Furthermore, each cell can correspond to a single carrier and a base station may use multiple carriers. So, if there are three 120-degree cells per carrier and two carriers, then the base station has a total of six cells. While the description herein may indicate that “cells” perform functions, it should be apparent that the base station that forms the cell will perform the functions.

[0198] {Can remove if UE has no inventive feature. } In general, the various embodiments of the user equipment 10 can include, but are not limited to, cellular telephones(such as smart phones, mobile phones, cellular phones, voice over Internet Protocol (IP) (VoIP) phones, and / or wireless local loop phones), tablets, portable computers, vehicles or vehicle-mounted devices for, e.g., wireless V2X (vehicle-to -everything) communication, image capture devices such as digital cameras, gaming devices, music storage and playback appliances, Internet appliances (including Internet of Things, loT, devices), loT devices with sensors and / or actuators for, e.g., automation applications, as well as portable units or terminals that incorporate combinations of such functions, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), Universal Serial Bus (USB) dongles, smart devices, wireless customer-premises equipment (CPE), an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. That is, the UE 10 could be any end device that may be capable of wireless communication. By way of example rather than limitation, the UE may also be referred to as a communication device, terminal device (MT), a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT).

[0199] Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect and / or advantage of one or more of the example embodiments disclosed herein is that the UE power consumption is reduced since it is allowed to limit measurement on specific set of RS.

[0200] The following are additional examples.

[0201] Example 1. A method, comprising: receiving, by a user equipment, configuration for the user equipment to perform layer 1 (LI) measurements for reference signals in a reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer; performing, by the user equipment, measurements of cell quality using the reference signals or one or more of the reference signals for a cell for the given layer; determining, by the user equipment, that the measurements of the cell quality or the one or more reference signals for the cell for the given layer are above one or more thresholds according to the eventtrigger; determining, by the user equipment, a physical cell identifier associated with the cell; and performing, by the user equipment and based on the measurements of the cell quality or one or more reference signals for the given layer being above the one or more thresholds, the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0202] Example 2. The method according to example 1 , wherein the given layer is layer 3, and wherein the configuration indicates to perform layer 1 measurements for the reference signals in the reference signal set for event-triggered measurement reporting evaluation based on measurements for layer 3.

[0203] Example 3. The method according to example 2, wherein: determining that the measurements of the cell quality for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining that cell quality measurement for layer 3 for the cell is above a threshold value; and performing the layer 1 measurements comprises performing layer 1 measurements on reference signal LI measurement resources associated with the cell for event-triggered measurement reporting.

[0204] Example 4. The method according to example 3, wherein the reference signal LI measurement resources comprise reference signals for measurement of the cell using the resource set for the event-triggered measurement reporting.

[0205] Example 5. The method according to example 2, wherein: determining that the measurements of the one or more reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining that at least one of the one or more reference signals for measurement on layer 3 for the cell is above a threshold value; and performing the layer 1 measurements comprises performing layer 1 measurements on reference signal LI measurement resources associated with the cell for event-triggered measurement reporting.

[0206] Example 6. The method according to example 5, wherein the reference signal LI measurement resources comprise reference signals for measurement of the cell using the resource set for the measurements for event-triggered measurement reporting.

[0207] Example 7. The method according to example 5, wherein the one or more reference signals for measurement on layer 3 are specific reference signals for determining event-triggered LI measurements for event-triggered measurement reporting.

[0208] Example 8. The method according to example 2, wherein performing the layer 1 measurements comprises performing the layer 1 measurements on reference signal LI measurement resources of up to N cells with highest layer 3 cell quality or reference signal quality.

[0209] Example 9. The method according to example 8, wherein the reference signal LI measurement resources comprise reference signals for measurement of the cell using the resource set for the event-triggered measurement reporting.

[0210] Example 10. The method according to example 1, wherein the given layer is layer 3 and the configuration for the layer 1 measurements for the reference signals comprise synchronization signal / physical broadcast channel block (SSB) indexes, and wherein the configuration comprises configuration causing the user equipment to perform the layer 1 measurements without SSB index acquisition and the performing the layer 1 measurements, as an LI measurement event, is configured to be triggered based on layer 3 measurement as the event trigger.

[0211] Example 11. The method according to example 10, wherein prior to performing the layer 1 measurements and any corresponding reporting, the method further comprises performing, by the user equipment, SSB index acquisition prior to event evaluation using layer 1 but after the event trigger is triggered based on layer 3 measurement.

[0212] Example 12. The method according to example 1, wherein the given layer is layer 1, wherein the configuration causes the user equipment to be configured to perform LI measurement for event-triggered measurement reporting based on LI measurements.

[0213] Example 13. The method according to example 12, wherein the configuration configures the user equipment to determine reference signal set quality for a certain cell based on reference signal LI measurement resources in a set for the event- triggered measurement reporting.

[0214] Example 14. The method according to example 13, wherein: the method further comprises determining, by the user equipment, reference signal set quality byaveraging up to N highest quality reference signals that are above a threshold to determine the reference signal set quality; and determining that the measurements of the cell quality or reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining using the reference signal set quality to perform measurements for the event-triggered measurement reporting.

[0215] Example 15. The method according to example 13, wherein: the configuration causes the user equipment to be configured to determine at least one reference signal set quality for a certain cell based on LI measurement resources in the reference signal set for the event-triggered measurement reporting; the method further comprises determining, by the user equipment, that at least one reference signal quality for the certain cell is above a threshold in the reference signal set for event-triggered measurement reporting; and determining that the measurements of the cell quality or reference signals for the certain cell for the given layer are above the one or more thresholds according to the event trigger comprises determining, by the user equipment, to perform measurements for the event- triggered measurement reporting on the reference signal set based on the reference signal quality.

[0216] Example 16. The method according to example 1, wherein the given layer is layer 3 and wherein: the performing the layer 1 measurements is performed in response to the measurements of the cell quality or reference signals for the cell for layer 3 being above one or more thresholds according to the event trigger; and the method further comprises: determining the measurements of the cell quality or reference signals for the cell for layer 3 are no longer above one or more thresholds according to the event trigger, and stopping performing the layer 1 measurements because the measurements of the cell quality or reference signals for the cell for layer 3 are no longer above the one or more thresholds according to the event trigger.

[0217] Example 17. The method according to example 1, wherein: the configuration comprises event triggers for the given layer for multiple cells; the determining that the measurements of the cell quality or reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger determines that measurements of the cell quality or reference signals for a first of the multiple cells for the given layer areabove the one or more thresholds according to the event trigger; and the performing the layer 1 measurements is performed for the cell but is not performed for any other cell of the multiple cells.

[0218] Example 18. The method according to any of examples 1 to 17, further comprising reporting the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0219] Example 19. A method, comprising: performing, at a network node, provision of threshold values for evaluation whether a user equipment starts LI measurements for lower layer triggered mobility; performing, at the network node, provision of a reference signal set for LI measurements that the user equipment is configured to measure based on measurements for a given layer; and sending, by the network node to the user equipment, configuration for the user equipment to perform layer 1 measurements for reference signals in the reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer, wherein the event trigger comprises the threshold values.

[0220] Example 20. The method according to example 19, wherein the given layer is layer 3.

[0221] Example 21. The method according to example 19, wherein the given layer is layer 1.

[0222] Example 22. The method according to any of examples 19 to 21, further comprising: receiving, by the network node, one or more measurement reports from the user equipment based on the reference signal set and the event trigger.

[0223] Example 23. An apparatus, comprising means for: receiving, by a user equipment, configuration for the user equipment to perform layer 1 (LI) measurements for reference signals in a reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer; performing, by the user equipment, measurements of cell quality using the reference signals or one or more of the reference signals for a cell for the given layer; determining, by the user equipment, that the measurements of the cell quality or the one or more reference signals for the cell for the given layer are above one or more thresholdsaccording to the event trigger; determining, by the user equipment, a physical cell identifier associated with the cell; and performing, by the user equipment and based on the measurements of the cell quality or one or more reference signals for the given layer being above the one or more thresholds, the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0224] Example 24. The apparatus according to example 23, wherein the given layer is layer 3, and wherein the configuration indicates to perform layer 1 measurements for the reference signals in the reference signal set for event-triggered measurement reporting evaluation based on measurements for layer 3.

[0225] Example 25. The apparatus according to example 24, wherein: determining that the measurements of the cell quality for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining that cell quality measurement for layer 3 for the cell is above a threshold value; and performing the layer 1 measurements comprises performing layer 1 measurements on reference signal LI measurement resources associated with the cell for event-triggered measurement reporting.

[0226] Example 26. The apparatus according to example 25, wherein the reference signal LI measurement resources comprise reference signals for measurement of the cell using the resource set for the event-triggered measurement reporting.

[0227] Example 27. The apparatus according to example 24, wherein: determining that the measurements of the one or more reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining that at least one of the one or more reference signals for measurement on layer 3 for the cell is above a threshold value; and performing the layer 1 measurements comprises performing layer 1 measurements on reference signal LI measurement resources associated with the cell for event-triggered measurement reporting.

[0228] Example 28. The apparatus according to example 27, wherein the reference signal LI measurement resources comprise reference signals for measurement of the cell using the resource set for the measurements for event-triggered measurement reporting.

[0229] Example 29. The apparatus according to example 27, wherein the one or more reference signals for measurement on layer 3 are specific reference signals for determining event-triggered LI measurements for event-triggered measurement reporting.

[0230] Example 30. The apparatus according to example 24, wherein performing the layer 1 measurements comprises performing the layer 1 measurements on reference signal LI measurement resources of up to N cells with highest layer 3 cell quality or reference signal quality.

[0231] Example 31. The apparatus according to example 30, wherein the reference signal LI measurement resources comprise reference signals for measurement of the cell using the resource set for the event-triggered measurement reporting.

[0232] Example 32. The apparatus according to example 23, wherein the given layer is layer 3 and the configuration for the layer 1 measurements for the reference signals comprise synchronization signal / physical broadcast channel block (SSB) indexes, and wherein the configuration comprises configuration causing the user equipment to perform the layer 1 measurements without SSB index acquisition and the performing the layer 1 measurements, as an LI measurement event, is configured to be triggered based on layer 3 measurement as the event trigger.

[0233] Example 33. The apparatus according to example 32, wherein prior to performing the layer 1 measurements and any corresponding reporting, the means are further configured for performing, by the user equipment, SSB index acquisition prior to event evaluation using layer 1 but after the event trigger is triggered based on layer 3 measurement.

[0234] Example 34. The apparatus according to example 23, wherein the given layer is layer 1, wherein the configuration causes the user equipment to be configured to perform LI measurement for event-triggered measurement reporting based on LI measurements.

[0235] Example 35. The apparatus according to example 34, wherein the configuration configures the user equipment to determine reference signal set quality for a certain cell based on reference signal LI measurement resources in a set for the event- triggered measurement reporting.

[0236] Example 36. The apparatus according to example 35, wherein: the means are further configured for determining, by the user equipment, reference signal set quality by averaging up to N highest quality reference signals that are above a threshold to determine the reference signal set quality; and determining that the measurements of the cell quality or reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining using the reference signal set quality to perform measurements for the event-triggered measurement reporting.

[0237] Example 37. The apparatus according to example 35, wherein: the configuration causes the user equipment to be configured to determine at least one reference signal set quality for a certain cell based on LI measurement resources in the reference signal set for the event-triggered measurement reporting; the means are further configured for determining, by the user equipment, that at least one reference signal quality for the certain cell is above a threshold in the reference signal set for event-triggered measurement reporting; and determining that the measurements of the cell quality or reference signals for the certain cell for the given layer are above the one or more thresholds according to the event trigger comprises determining, by the user equipment, to perform measurements for the event- triggered measurement reporting on the reference signal set based on the reference signal quality.

[0238] Example 38. The apparatus according to example 23, wherein the given layer is layer 3 and wherein: the performing the layer 1 measurements is performed in response to the measurements of the cell quality or reference signals for the cell for layer 3 being above one or more thresholds according to the event trigger; and the means are further configured for : determining the measurements of the cell quality or reference signals for the cell for layer 3 are no longer above one or more thresholds according to the event trigger, and stopping performing the layer 1 measurements because the measurements of the cell quality or reference signals for the cell for layer 3 are no longer above the one or more thresholds according to the event trigger.

[0239] Example 39. The apparatus according to example 23, wherein: the configuration comprises event triggers for the given layer for multiple cells; the determining that the measurements of the cell quality or reference signals for the cell for the given layer areabove the one or more thresholds according to the event trigger determines that measurements of the cell quality or reference signals for a first of the multiple cells for the given layer are above the one or more thresholds according to the event trigger; and the performing the layer 1 measurements is performed for the cell but is not performed for any other cell of the multiple cells.

[0240] Example 40. The apparatus according to any of examples 23 to 39, wherein the means are further configured for reporting the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0241] Example 41. An apparatus, comprising means for: performing, at a network node, provision of threshold values for evaluation whether a user equipment starts LI measurements for lower layer triggered mobility; performing, at the network node, provision of a reference signal set for LI measurements that the user equipment is configured to measure based on measurements for a given layer; and sending, by the network node to the user equipment, configuration for the user equipment to perform layer 1 measurements for reference signals in the reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer, wherein the event trigger comprises the threshold values.

[0242] Example 42. The apparatus according to example 41, wherein the given layer is layer 3.

[0243] Example 43. The apparatus according to example 41, wherein the given layer is layer 1.

[0244] Example 44. The apparatus according to any of examples 41 to 43, wherein the means are further configured for: receiving, by the network node, one or more measurement reports from the user equipment based on the reference signal set and the event trigger.

[0245] Example 45. An apparatus, comprising: one or more processors; and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus at least to perform: receiving, by a user equipment, configuration for the user equipment to perform layer 1 (LI) measurements for reference signals in a reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layersand on an event trigger for the measurements for the given layer; performing, by the user equipment, measurements of cell quality using the reference signals or one or more of the reference signals for a cell for the given layer; determining, by the user equipment, that the measurements of the cell quality or the one or more reference signals for the cell for the given layer are above one or more thresholds according to the event trigger; determining, by the user equipment, a physical cell identifier associated with the cell; and performing, by the user equipment and based on the measurements of the cell quality or one or more reference signals for the given layer being above the one or more thresholds, the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0246] Example 46. The apparatus according to example 45, wherein the given layer is layer 3, and wherein the configuration indicates to perform layer 1 measurements for the reference signals in the reference signal set for event-triggered measurement reporting evaluation based on measurements for layer 3.

[0247] Example 47. The apparatus according to example 46, wherein: determining that the measurements of the cell quality for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining that cell quality measurement for layer 3 for the cell is above a threshold value; and performing the layer 1 measurements comprises performing layer 1 measurements on reference signal LI measurement resources associated with the cell for event-triggered measurement reporting.

[0248] Example 48. The apparatus according to example 47, wherein the reference signal LI measurement resources comprise reference signals for measurement of the cell using the resource set for the event-triggered measurement reporting.

[0249] Example 49. The apparatus according to example 46, wherein: determining that the measurements of the one or more reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining that at least one of the one or more reference signals for measurement on layer 3 for the cell is above a threshold value; and performing the layer 1 measurements comprises performing layer 1 measurements on reference signal LI measurement resources associated with the cell for event-triggered measurement reporting.

[0250] Example 50. The apparatus according to example 49, wherein the reference signal LI measurement resources comprise reference signals for measurement of the cell using the resource set for the measurements for event-triggered measurement reporting.

[0251] Example 51. The apparatus according to example 49, wherein the one or more reference signals for measurement on layer 3 are specific reference signals for determining event-triggered LI measurements for event-triggered measurement reporting.

[0252] Example 52. The apparatus according to example 46, wherein performing the layer 1 measurements comprises performing the layer 1 measurements on reference signal LI measurement resources of up to N cells with highest layer 3 cell quality or reference signal quality.

[0253] Example 53. The apparatus according to example 52, wherein the reference signal LI measurement resources comprise reference signals for measurement of the cell using the resource set for the event-triggered measurement reporting.

[0254] Example 54. The apparatus according to example 45, wherein the given layer is layer 3 and the configuration for the layer 1 measurements for the reference signals comprise synchronization signal / physical broadcast channel block (SSB) indexes, and wherein the configuration comprises configuration causing the user equipment to perform the layer 1 measurements without SSB index acquisition and the performing the layer 1 measurements, as an LI measurement event, is configured to be triggered based on layer 3 measurement as the event trigger.

[0255] Example 55. The apparatus according to example 54, wherein prior to performing the layer 1 measurements and any corresponding reporting, the one or more memories further store instructions that, when executed by the one or more processors, cause the apparatus at least to perform performing, by the user equipment, SSB index acquisition prior to event evaluation using layer 1 but after the event trigger is triggered based on layer 3 measurement.

[0256] Example 56. The apparatus according to example 45, wherein the given layer is layer 1, wherein the configuration causes the user equipment to be configured to perform LI measurement for event-triggered measurement reporting based on LI measurements.

[0257] Example 57. The apparatus according to example 56, wherein the configuration configures the user equipment to determine reference signal set quality for a certain cell based on reference signal LI measurement resources in a set for the event- triggered measurement reporting.

[0258] Example 58. The apparatus according to example 57, wherein: the one or more memories further store instructions that, when executed by the one or more processors, cause the apparatus at least to perform determining, by the user equipment, reference signal set quality by averaging up to N highest quality reference signals that are above a threshold to determine the reference signal set quality; and determining that the measurements of the cell quality or reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining using the reference signal set quality to perform measurements for the event-triggered measurement reporting.

[0259] Example 59. The apparatus according to example 57, wherein: the configuration causes the user equipment to be configured to determine at least one reference signal set quality for a certain cell based on LI measurement resources in the reference signal set for the event-triggered measurement reporting; the one or more memories further store instructions that, when executed by the one or more processors, cause the apparatus at least to perform determining, by the user equipment, that at least one reference signal quality for the certain cell is above a threshold in the reference signal set for event-triggered measurement reporting; and determining that the measurements of the cell quality or reference signals for the certain cell for the given layer are above the one or more thresholds according to the event trigger comprises determining, by the user equipment, to perform measurements for the event- triggered measurement reporting on the reference signal set based on the reference signal quality.

[0260] Example 60. The apparatus according to example 45, wherein the given layer is layer 3 and wherein: the performing the layer 1 measurements is performed in response to the measurements of the cell quality or reference signals for the cell for layer 3 being above one or more thresholds according to the event trigger; and the one or more memories further store instructions that, when executed by the one or more processors, cause the apparatus at least to perform: determining the measurements of the cell quality or referencesignals for the cell for layer 3 are no longer above one or more thresholds according to the event trigger, and stopping performing the layer 1 measurements because the measurements of the cell quality or reference signals for the cell for layer 3 are no longer above the one or more thresholds according to the event trigger.

[0261] Example 61. The apparatus according to example 45, wherein: the configuration comprises event triggers for the given layer for multiple cells; the determining that the measurements of the cell quality or reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger determines that measurements of the cell quality or reference signals for a first of the multiple cells for the given layer are above the one or more thresholds according to the event trigger; and the performing the layer 1 measurements is performed for the cell but is not performed for any other cell of the multiple cells.

[0262] Example 62. The apparatus according to any of examples 45 to 61, wherein the one or more memories further store instructions that, when executed by the one or more processors, cause the apparatus at least to perform reporting the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

[0263] Example 63. An apparatus, comprising: one or more processors; and one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus at least to perform: performing, at a network node, provision of threshold values for evaluation whether a user equipment starts LI measurements for lower layer triggered mobility; performing, at the network node, provision of a reference signal set for LI measurements that the user equipment is configured to measure based on measurements for a given layer; and sending, by the network node to the user equipment, configuration for the user equipment to perform layer 1 measurements for reference signals in the reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer, wherein the event trigger comprises the threshold values.

[0264] Example 64. The apparatus according to example 63, wherein the given layer is layer 3.

[0265] Example 65. The apparatus according to example 63, wherein the given layer is layer 1.

[0266] Example 66. The apparatus according to any of examples 63 to 65, wherein the one or more memories further store instructions that, when executed by the one or more processors, cause the apparatus at least to perform: receiving, by the network node, one or more measurement reports from the user equipment based on the reference signal set and the event trigger.

[0267] Example 67. A computer program, comprising instructions which, when the program is executed by an apparatus, cause the apparatus to carry out the methods of any of examples 1 to 22.

[0268] Example 68. The computer program according to example 67, wherein the computer program is a computer program product comprising a computer-readable medium bearing the instructions embodied therein for use with the apparatus.

[0269] Example 69. The computer program according to example 67, wherein the computer program is directly loadable into an internal memory of the apparatus.

[0270] As used in this application, the term “circuitry” may refer to one or more or all of the following:

[0271] (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and

[0272] (b) combinations of hardware circuits and software, such as (as applicable):(i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) (including digital signal processor(s)) with software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

[0273] (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0274] This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multipleprocessors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0275] Embodiments herein may be implemented in software (executed by one or more processors), hardware (e.g., an application specific integrated circuit), or a combination of software and hardware. In an example embodiment, the software (e.g., application logic, an instruction set) is maintained on any one of various conventional computer-readable media. In the context of this document, a “computer-readable medium” may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer, with one example of a computer described and depicted, e.g., in FIG. 6. A computer-readable medium may comprise a computer-readable storage medium (e.g., memories 15, 75, and 95 or other device) that may be any media or means that can contain, store, and / or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable storage medium does not comprise propagating signals, and therefore may be considered to be non-transitory. The term “non- transitory”, as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM, random access memory, versus ROM, read-only memory).

[0276] If desired, the different functions discussed herein may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined.

[0277] Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and / or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

[0278] It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there areseveral variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

[0279] The following abbreviations that may be found in the specification and / or the drawing figures are defined as follows:

[0280] 5G fifth generation

[0281] AMF access and mobility management function

[0282] BWP bandwidth part

[0283] CA Carrier aggregation

[0284] CE Control element

[0285] CSI-RS channel state information - reference signal

[0286] CU central unit

[0287] DC Dual connectivity

[0288] DL downlink (from gNB to UE)

[0289] DU distributed unit

[0290] E-SMLC evolved serving mobile location center

[0291] eNB (or eNodeB) evolved Node B (e.g., an LTE base station)

[0292] FFS for future study

[0293] FR1 frequency range 1

[0294] FR2 frequency range 2

[0295] GMLC Gateway Mobile Location Center

[0296] gNB (or gNodeB) base station for 5G / NR

[0297] ID identification

[0298] I / F interface

[0299] LI layer 1

[0300] L2 layer 2

[0301] L3 layer 3

[0302] LMF Location Management Function

[0303] LIE long term evolution

[0304] LTM L1 / L2 Triggered Mobility

[0305] MAC Medium Access Control

[0306] MCG Master cell group

[0307] MI MO multiple input multiple output

[0308] MME mobility management entity

[0309] MN master node

[0310] NF network function

[0311] ng or NG next generation

[0312] NR new radio

[0313] NRF Network Repository Function

[0314] N / W or NW network

[0315] PCell primary cell

[0316] PCI Physical cell ID

[0317] PDCCH physical downlink control channel

[0318] PHY physical layer

[0319] PSCell primary secondary cell

[0320] PSS Primary Synchronization Signal

[0321] RACH random access channel

[0322] RAN radio access network

[0323] RSRP Reference Signal Received Power

[0324] RSRQ Reference Signal Received Quality

[0325] RRC radio resource control

[0326] RRM radio resource management

[0327] Rx receiver

[0328] SCell secondary cell

[0329] SGW serving gateway

[0330] SINR signal-to-interference-plus-noise ratio

[0331] SMF session management function

[0332] SN secondary node

[0333] SR scheduling request

[0334] SS Synchronization Signal

[0335] SSB SS / PBCH block (Synchronization Signal / Physical broadcast channel block)

[0336] SSS Secondary Synchronization Signal

[0337] TA timing advance

[0338] TCI Transmission configuration indicator

[0339] TRP transmission-reception point

[0340] TTT time to trigger

[0341] Tx transmitter

[0342] UDM unified data management

[0343] UDR unified data repository

[0344] UE user equipment (e.g., a wireless, typically mobile device)

[0345] UEIBM UE initiated beam management

[0346] UL uplink (from UE to gNB)

[0347] UPF user plane function

[0348] WI work item

Claims

What is claimed is:

1. An apparatus, comprising means for: receiving, by a user equipment, configuration for the user equipment to perform layer 1 (LI) measurements for reference signals in a reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer; performing, by the user equipment, measurements of cell quality using the reference signals or one or more of the reference signals for a cell for the given layer; determining, by the user equipment, that the measurements of the cell quality or the one or more reference signals for the cell for the given layer are above one or more thresholds according to the event trigger; determining, by the user equipment, a physical cell identifier associated with the cell; and performing, by the user equipment and based on the measurements of the cell quality or one or more reference signals for the given layer being above the one or more thresholds, the layer 1 measurements for event-triggered measurement reporting associated with the physical cell identifier.

2. The apparatus according to claim 1, wherein the given layer is layer 3, and wherein the configuration indicates to perform layer 1 measurements for the reference signals in the reference signal set for event-triggered measurement reporting evaluation based on measurements for layer 3.

3. The apparatus according to claim 2, wherein: determining that the measurements of the cell quality for the cell for the given layer are above the one or more thresholds according to the event trigger comprises48determining that cell quality measurement for layer 3 for the cell is above a threshold value; and performing the layer 1 measurements comprises performing layer 1 measurements on reference signal LI measurement resources associated with the cell for event- triggered measurement reporting.

4. The apparatus according to claim 3, wherein the reference signal LI measurement resources comprise reference signals for measurement of the cell using the resource set for the event-triggered measurement reporting.

5. The apparatus according to claim 2, wherein: determining that the measurements of the one or more reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining that at least one of the one or more reference signals for measurement on layer 3 for the cell is above a threshold value; and performing the layer 1 measurements comprises performing layer 1 measurements on reference signal LI measurement resources associated with the cell for event- triggered measurement reporting.

6. The apparatus according to claim 2, wherein performing the layer 1 measurements comprises performing the layer 1 measurements on reference signal LI measurement resources of up to N cells with highest layer 3 cell quality or reference signal quality.

7. The apparatus according to claim 1, wherein the given layer is layer 3 and the configuration for the layer 1 measurements for the reference signals comprise synchronization signal / physical broadcast channel block (SSB) indexes, and wherein the configuration comprises configuration causing the user equipment to perform the layer 1 measurements without SSB index acquisition and the performing the layer 1measurements, as an LI measurement event, is configured to be triggered based on layer 3 measurement as the event trigger.

8. The apparatus according to claim 7, wherein prior to performing the layer 1 measurements and any corresponding reporting, the means are further configured for performing, by the user equipment, SSB index acquisition prior to event evaluation using layer 1 but after the event trigger is triggered based on layer 3 measurement.

9. The apparatus according to claim 1, wherein the given layer is layer 1, wherein the configuration causes the user equipment to be configured to perform LI measurement for event-triggered measurement reporting based on LI measurements.

10. The apparatus according to claim 9, wherein the configuration configures the user equipment to determine reference signal set quality for a certain cell based on reference signal LI measurement resources in a set for the event-triggered measurement reporting.

11. The apparatus according to claim 10, wherein: the means are further configured for determining, by the user equipment, reference signal set quality by averaging up to N highest quality reference signals that are above a threshold to determine the reference signal set quality; and determining that the measurements of the cell quality or reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger comprises determining using the reference signal set quality to perform measurements for the event-triggered measurement reporting.

12. The apparatus according to claim 10, wherein: the configuration causes the user equipment to be configured to determine at least one reference signal set quality for a certain cell based on LI measurementresources in the reference signal set for the event-triggered measurement reporting; the means are further configured for determining, by the user equipment, that at least one reference signal quality for the certain cell is above a threshold in the reference signal set for event-triggered measurement reporting; and determining that the measurements of the cell quality or reference signals for the certain cell for the given layer are above the one or more thresholds according to the event trigger comprises determining, by the user equipment, to perform measurements for the event-triggered measurement reporting on the reference signal set based on the reference signal quality.

13. The apparatus according to claim 1, wherein the given layer is layer 3 and wherein: the performing the layer 1 measurements is performed in response to the measurements of the cell quality or reference signals for the cell for layer 3 being above one or more thresholds according to the event trigger; and the means are further configured for : determining the measurements of the cell quality or reference signals for the cell for layer 3 are no longer above one or more thresholds according to the event trigger, and stopping performing the layer 1 measurements because the measurements of the cell quality or reference signals for the cell for layer 3 are no longer above the one or more thresholds according to the event trigger.

14. The apparatus according to claim 1, wherein: the configuration comprises event triggers for the given layer for multiple cells; the determining that the measurements of the cell quality or reference signals for the cell for the given layer are above the one or more thresholds according to the event trigger determines that measurements of the cell quality or reference signals for a first of the multiple cells for the given layer are above the one or more thresholds according to the event trigger; andthe performing the layer 1 measurements is performed for the cell but is not performed for any other cell of the multiple cells.

15. An apparatus, comprising means for: performing, at a network node, provision of threshold values for evaluation whether a user equipment starts LI measurements for lower layer triggered mobility; performing, at the network node, provision of a reference signal set for LI measurements that the user equipment is configured to measure based on measurements for a given layer; and sending, by the network node to the user equipment, configuration for the user equipment to perform layer 1 measurements for reference signals in the reference signal set for lower layer triggered mobility based on measurements for a given one of multiple layers and on an event trigger for the measurements for the given layer, wherein the event trigger comprises the threshold values.

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