Measurement configuration for L1L2 triggered mobility

Abstract

Described herein is a user equipment (UE) configured to support a connection toward a radio access network including, for example, a DU and a CU. The UE transmits a measurement report to the CU, the measurement report including information indicating at least one target cell among at least one neighboring target cell, and receives from the CU a configuration message including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including a resource-related configuration for at least one of a serving cell to which the UE is connected and one target cell for which the UE will perform a cell change as a candidate cell, as well as a cell-specific LTM report-related configuration. The UE performs measurements based at least in part on the received LTM measurement-related configuration and reports the measurement-related information. The report is preferably transmitted to the DU. The UE may receive an updated LTM measurement-related configuration from the DU.

Description

[Technical Field]

[0001] The present disclosure relates to mobility aspects in radio access networks, in particular (Layer 1 / Layer 2) L1L2 Triggered Mobility (LTM), and in particular measurement configurations. [Background technology]

[0002] Any discussion of background art throughout this specification should in no way be taken as an admission that such art is widely known or forms part of the common general knowledge in the art.

[0003] Broadly speaking, for L1L2 triggered mobility management (LTM), the UE reports L1 beam measurements to a serving DU (i.e., source DU), and the serving source DU can determine when to trigger a handover to one or more candidate target cells indicated by the L1 measurement report provided by the UE based on previous L3 measurements provided by the UE indicating that one or more candidate target cells have been determined to be suitable cells to which the UE can be handed over.

[0004] In relation to Layer 1 (L1) Measurement and Reporting for Rel-18 L1 / 2 Triggered Mobility (LTM), For example, the RRC IE for CSI measurement and reporting [3GPP TS 38.331] includes the following:

[0005] CSI-MeasConfig The IE CSI-MeasConfig is used to configure the CSI-RS (Reference Signals) belonging to the serving cell in which the CSI-MeasConfig is contained, the channel state information reports to be transmitted on the PUCCH on the serving cell in which the CSI-MeasConfig is contained, and the channel state information reports on the PUSCH triggered by the DCI received on the serving cell in which the CSI-MeasConfig is contained.

[0006] CSI-ReportConfig The IE CSI-ReportConfig is used to configure periodic or semi-persistent reports to be transmitted on the PUCCH on the cell in which the CSI-ReportConfig is contained, or to configure semi-persistent or aperiodic reports to be transmitted on the PUSCH triggered by DCI received on the cell in which the CSI-ReportConfig is contained (in this case the cell from which the report is transmitted is determined by the received DCI). It provides information on the reference signal (CSI-RS) to be measured for the configured reports.

[0007] CSI-ResourceConfig The IE CSI-ResourceConfig defines a group of one or more NZP-CSI-RS-Resource sets, CSI-IM-Resource sets and / or CSI-SSB-Resource sets.

[0008] CSI-SSB-Resource Set The IE CSI-SSB-ResourceSet is used to configure one SS / PBCH block resource set that references the SS / PBCH as indicated in ServingCellConfigCommon and ServingCellConfig. According to Release 17 Inter-cell Beam Management (ICBM) enhancements, it may include SSBs from other cells (albeit within the DU) by providing the associated PCI information in the form of ServingAdditionalPCIIndex-r17. The mapping between PCI and ServingAdditionalPCIIndex-r17 can be found in SSB-MTC-AdditionalPCI-r17.

[0009] SSB-MTC-AdditionalPCI-r17 SSB-MTC-AdditionalPCI-r17 is used for measurement timing configuration, i.e., configuring the timing occasions at which the UE measures the SSB of configured cells. Summary of the Invention

[0010] For example, in the 3GPP Rel-17 ICBM-based framework, the maximum number of reference signals (RSs) a UE can configure to measure for a single reporting configuration is up to 64, including RSs from both the serving cell and up to seven neighboring cells. Because ICBM is restricted to intra-DU scenarios, UE mobility is limited to a specific coverage area, where both L1 measurements and reporting configuration updates are less frequently required. However, for LTM, UE mobility is considered both within and between DUs, thereby extending the mobility region beyond intra-DU mobility. Given that, additional mechanisms may be required to configure / update the UE with a specific set of reported SSBs, such as deleting / adding RS indices. Continuously updating the CSI resource set by using RRC reconfiguration is costly in terms of signaling overhead and delay. Alternatively, to cover a large set of RSs for LTM, multiple CSI reporting configurations, each configuring up to 64 RSs, may significantly incur measurement overhead at the UE. Additionally, the Rel-17 ICBM-based CSI measurement framework only works for intra-frequency scenarios.

[0011] Additionally, in the Rel-17 ICBM-based CSI measurement framework, since the entire L1 measurement and reporting configuration is given in the serving cell configuration, a cell change requires a complete reconfiguration of L1 measurements and reports for the new serving cell, which may incur significant UE processing costs in case of fast cell change, i.e., every time a cell change is made, and the UE may need to retrieve and process a large set of configurations associated with the new serving cell.

[0012] In solutions where the Rel-17 ICBM-based framework is not used, i.e., the CSI-RS of neighboring cells is not configured in the serving cell configuration, each cell instead has its own CSI-RS configured only in its serving cell configuration. In such a scenario, the serving cell reporting configuration cannot indicate CSI-RS that are not included in the serving cell configuration, and therefore measurements of neighboring candidate target cells cannot be enabled without enhancements.

[0013] Another potential option would be to replicate a Layer 3 (L3)-like measurement framework, where the UE is not provided with the specific RSs and cells to be measured, which would require significantly modifying the L1 measurement and reporting framework, which differs significantly from the Rel-15 / 16 / 17 beam management and CSI framework. Also, in such a configuration, since L1 measurements are bottom-layer messages (intended to be small in size) and are reported more frequently than L3 measurements (which would result in significant signaling overhead in the air interface if the message size were increased), the reporting overhead could be significant as the UE would need to include additional information (e.g., cell identifiers) that is not desirable for L1 measurements.

[0014] Preferably, an L1 measurement and reporting configuration should be designed that can advantageously meet at least one of the following LTM requirements: intra-frequency and inter-frequency measurements with intra-DU and inter-DU measurements from up to 8 cells, fast dynamic switching with minimal configuration changes, and not incurring any significant additional reporting overhead.

[0015] According to one aspect of the present disclosure, there is provided a user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the UE comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: transmitting a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of a radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving, from a first network node, a configuration message including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including a resource-related configuration for at least one of a serving cell to which the UE is connected and a target cell to which the UE will perform a cell change as a candidate cell, and a cell-specific LTM report-related configuration; performing measurements based at least in part on the received LTM measurement-related configuration and reporting measurement-related information.

[0016] In some examples, the user equipment (UE) may be further configured to support that the resource-related configuration includes a common or reference LTM-Meas Config associated with at least a serving cell and one target cell.

[0017] In some examples, a user equipment (UE) may be further configured to support that the resource-related configuration includes at least an LTM-CSI resource set associated with a serving cell and one target cell.

[0018] In some examples, the user equipment (UE) may be further configured to support (cell-specific) LTM reporting related configurations including at least one of an LTM-Reporting Config, a measurement gap, an activated LTM Config index and a bitmap of RS for at least one of the serving cell and one target cell.

[0019] The LTM-Reporting Config, for example, relates to the uplink resource configuration of a cell. Generally, the CSI-Report Config includes some other parameters, such as an indicator of the CSI-Resource Config.

[0020] In some examples, a user equipment (UE) The LTM measurement-related configuration may be further configured to support receiving a configuration message from a second network node, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of a radio access network, the configuration message including information indicating an updated LTM measurement-related configuration.

[0021] In some examples, a user equipment (UE) determining resources for performing measurements based on the received updated configuration; performing a measurement; and reporting the measurement-related information towards the second network node.

[0022] In some examples, the user equipment (UE) may be further configured to support that the LTM report related configuration includes an activation LTM Config index and / or a default bitmap of RS of at least one of a serving cell and one target cell, and the UE: The network node is further configured to receive a configuration message from a second network node, the configuration message including an activated LTM Config index for at least one of the serving cell and one target cell and an updated bitmap of the RS, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network.

[0023] In some examples, a user equipment (UE) may be configured to: reporting the measurement-related information towards a second network node, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of a radio access network; receiving a cell switch command from a second network node to perform a cell change to a target cell; performing a handover to a target cell; determining cell-specific measurement parameters of the target cell based on the cell-specific LTM report-related configuration; performing measurements based on the received common LTM-Meas Config and determined cell-specific, in particular LTM-Reporting Config parameters, for example of the target cell; The wireless access network may be further configured to support reporting the measurement related information towards a third network node supporting the target cell, the third network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network.

[0024] In some examples, the user equipment (UE) may be further configured to support that the LTM measurement-related configuration includes filter criteria for LTM meas of at least one of the serving cell and the target cell.

[0025] In some examples, the user equipment (UE) may be further configured to support that the LTM measurement-related configuration includes a default subset of LTM cells for beam measurements of at least one of the serving cell and the target cell.

[0026] In some examples, a user equipment (UE) It may further be configured to support determining resources, particularly LTM-CSI related resources, for performing measurements based on the received filter criteria.

[0027] In some examples, a user equipment (UE) receiving a configuration message from a second network node, the configuration message including information indicating an updated LTM measurement-related configuration including updated filter criteria, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of a radio access network; determining resources, in particular LTM-CSI related resources, for performing measurements based on the received updated filter criteria; performing a measurement; and reporting the measurement-related information towards the second network node.

[0028] In some examples, a user equipment (UE) reporting the measurement-related information towards a second network node, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of a radio access network; receiving a cell switch command from a second network node to perform a cell change to a target cell; performing a handover to a target cell; determining cell-specific measurement parameters of the target cell based on a cell-specific LTM report-related configuration including filter criteria for the target cell; performing measurements based on the determined cell-specific parameters; The method may further be configured to support reporting the measurement-related information towards a third network node supporting the target cell, the third network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network.

[0029] According to another aspect of the present disclosure, there is provided a user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the UE comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: transmitting a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of a radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving a configuration message from a first network node, the configuration message including information indicating an LTM measurement-related configuration; and receiving a configuration message from a second network node, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of a radio access network, the configuration message including information indicating an updated LTM measurement-related configuration.

[0030] In some examples, the user equipment (UE) may be further configured to support the LTM measurement-related configuration including filter criteria for at least one of the serving cell and the target cell, and the updated LTM measurement-related configuration including updated filter criteria for at least one of the serving cell and the target cell.

[0031] In some examples, the user equipment (UE) may be further configured to support the LTM measurement-related configuration including a cell-specific default bitmap of activated LTM Config indices for at least one of the serving cell and the target cell, and the updated LTM measurement-related configuration including an updated cell-specific bitmap of activated LTM Config indices for at least one of the serving cell and the target cell.

[0032] According to another aspect of the present disclosure, there is provided a user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the UE comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: transmitting a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of a radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving, from a first network node, a configuration message including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including parameters for cell-specific measurements related to a serving cell to which the UE is connected and information for deriving cell-specific parameters related to one target cell; determining parameters for cell-specific measurements associated with a serving cell; performing measurements based on the determined parameters; reporting the measurement-related information towards a second network node supporting a serving cell, the second network node supporting at least one of a distributed unit (DU) function and / or a radio access network Layer 2 protocol; receiving, from a second network node, a cell switch command for performing a handover to a target cell supported by a third network node, the third network node supporting at least one of a distributed unit (DU) function and / or a radio access network Layer 2 protocol; performing a handover to a target cell; determining parameters for cell-specific measurements associated with the target cell; performing measurements based on the determined parameters; and reporting the measurement related information towards a third network node.

[0033] According to another aspect of the present disclosure, there is provided a method for a user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the method comprising: transmitting a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of a radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving, from a first network node, a configuration message including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including a resource-related configuration for at least one of a serving cell to which the UE is connected and a target cell to which the UE will perform a cell change as a candidate cell, and a cell-specific LTM report-related configuration; performing measurements based at least in part on the received LTM measurement-related configuration and reporting measurement-related information.

[0034] According to another aspect of the present disclosure, there is provided a method for a user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the method comprising: transmitting a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of a radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving a configuration message from a first network node, the configuration message including information indicating an LTM measurement-related configuration; receiving a configuration message from a second network node, the configuration message including information indicating an updated LTM measurement-related configuration, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of a radio access network;

[0035] According to another aspect of the present disclosure, there is provided a method for a user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the method comprising: transmitting a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of a radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving, from a first network node, a configuration message including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including parameters for cell-specific measurements related to a serving cell to which the UE is connected and information for deriving cell-specific parameters related to one target cell; determining parameters for cell-specific measurements associated with a serving cell; performing measurements based on the determined parameters; reporting the measurement-related information towards a second network node supporting a serving cell, the second network node supporting at least one of a distributed unit (DU) function and / or a radio access network Layer 2 protocol; receiving, from a second network node, a cell switch command for performing a handover to a target cell supported by a third network node, the third network node supporting at least one of a distributed unit (DU) function and / or a radio access network Layer 2 protocol; performing a handover to a target cell; determining parameters for cell-specific measurements associated with the target cell; performing measurements based on the determined parameters; and reporting the measurement-related information towards a third network node.

[0036] According to another aspect of the present disclosure, there is provided a computer program comprising instructions for causing an apparatus to perform any one of the above methods.

[0037] According to another aspect of the present disclosure, there is provided a memory storing computer readable instructions for causing an apparatus to perform any one of the above methods.

[0038] According to another aspect of the present disclosure, there is provided an apparatus comprising means for performing any one of the above methods.

[0039] According to another aspect of the present disclosure, there is provided a first network node configured to support at least one of a central unit control plane (CU-CP) function and / or a radio access network Layer 3 protocol for controlling user equipment (UE) configured to support a connection towards a radio access network including at least the first network node, wherein the first network node: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first network node to: receiving, from the UE, a measurement report including information indicating at least one target cell among the at least one neighbor target cell; and transmitting to the UE a configuration message including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including a resource-related configuration for at least one of a serving cell to which the UE is connected and one target cell to which the UE will perform a cell change as a candidate cell, and a cell-specific LTM report-related configuration.

[0040] According to another aspect of the present disclosure, there is provided a first network node configured to support at least one of a central unit control plane (CU-CP) function and / or a radio access network Layer 3 protocol for controlling user equipment (UE) configured to support a connection towards a radio access network including at least the first network node, wherein the first network node: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: receiving, from the UE, a measurement report including information indicating at least one target cell among the at least one neighbor target cell; sending a configuration message to the UE, the configuration message including information indicating an LTM measurement-related configuration; and transmitting at least a portion of the LTM measurement-related configuration towards a second network node, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network, to enable the second network to generate and transmit a configuration message including information indicating the updated LTM measurement-related configuration to the UE. Part of the LTM measurement related configuration that the CU may send to the second network node is a default bitmap of activated LTM Config, etc. In this way, the UE may already start measurements based on the default bitmap and activated cells, which may be updated by the second network node to adapt the measurements to provide increasingly better suited measurements, e.g., to enable better visibility for e.g., fast and sustainable cell changes.

[0041] According to another aspect of the present disclosure, there is provided a network node for a radio access network and for connecting a user equipment (UE) towards the radio access network, the network node comprising: a first network node and a second network node; at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: receiving, at a first network node, from the UE, a measurement report including information indicating at least one target cell among the at least one neighbor target cell, the first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of a radio access network; sending a configuration message to the UE including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including parameters for cell-specific measurements related to a serving cell to which the UE is connected and information for deriving cell-specific parameters related to one target cell; receiving, at a second network node, from the UE, a report including measurement-related information directed to a second network node supporting a serving cell, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of a radio access network; and transmitting, to the UE, a cell switch command for performing a handover to a target cell supported by a third network node, the third network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network.

[0042] According to another aspect of the present disclosure, there is provided a second network node, the second network node configured to support at least one of a distributed unit (DU) function and / or a Layer 2 protocol of a radio access network, and configured to connect to a first network node, the first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of the radio access network for controlling a user equipment (UE) configured to support a connection towards a radio access network including at least the first network node and the second network node, and the second network node: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: receiving from the first network node at least a portion of an LTM measurement-related configuration to be provided to the UE, to enable the second network node to generate and send to the UE a configuration message including information indicating the updated LTM measurement-related configuration; and receiving, from the UE, a measurement report based at least in part on the LTM measurement-related configuration.

[0043] The first network node may be implemented as, for example, a network node supporting distributed unit (DU) functionality and / or Layer 2 protocol processing of a radio access network (RAN), a source DU, a serving DU, a serving gNB, a 5G gNB, an NR gNB, and / or a base station, providing broad applicability to various RAN implementations.

[0044] The second network node may be implemented as, for example, a network node supporting distributed unit (DU) functionality and / or Layer 2 protocol processing of a radio access network (RAN), a target DU, a target gNB, a 5G gNB, an NR gNB, and / or a base station, again providing broad applicability to various RAN implementations. The first network node and the second network node may be the same but different nodes.

[0045] The third network node may be implemented, for example, as a network node supporting a central unit (CU) function and / or Layer 3 protocol processing of a radio access network (RAN), a CU, a source CU, a serving CU, a source gNB, a 5G gNB, an NR gNB, and / or a base station. The third network node may control the first network node and / or the second network node. The first network node and the second network node may be controlled by the same node or may be controlled by different nodes. The user equipment may be implemented as, for example, a device or apparatus supporting Radio Access Network (RAN) Layer 2 and Layer 3 protocol processing, a smartphone, and / or a mobile terminal.

[0046] The measurement reports may be implemented as or based on, for example, Layer 1 (L1) measurement reports, Layer 3 (L3) measurement reports.

[0047] Configuration information related to performing measurements on a target cell as a candidate cell for cell change, where the target cell is supported by a second network node (target DU), may be received via an RRC reconfiguration message and / or a Layer 3 (L3) message. The message may be received from a network node that supports L3, e.g., a central unit (CU) function, which may depend on the implementation. The message may also be received from the first network node if it supports L3. The message is used, for example, to configure the UE with L1 measurements that can be used for lower layer mobility (LLM) or LTM-triggered cell change.

[0048] The order of the indicated processing steps is not necessarily sequential. Measurement reports may be sent, for example, periodically or aperiodically (eg, event-based).

[0049] According to some exemplary embodiments, a computer program product is also provided that includes instructions for causing an apparatus to perform the methods as disclosed in the present disclosure.

[0050] According to some exemplary embodiments, a memory storing computer readable instructions for causing the apparatus to perform the methods as disclosed in this disclosure is also provided.

[0051] Additionally, according to some other exemplary embodiments, a computer program product for, for example, a wireless communication device having at least one processor is provided, the computer program product including software code portions for performing each of the steps disclosed in the present disclosure when the product is run on the device. The computer program product may include a computer-readable medium on which the software code portions are stored. Furthermore, the computer program product may be directly loadable into the internal memory of a computer and / or transmittable over a network by using at least one of an upload procedure, a download procedure, and a push procedure.

[0052] Although some exemplary embodiments are described herein with particular reference to the above applications, it will be appreciated that the present disclosure is not limited to such fields of use but is applicable in a broader context.

[0053] In particular, it is understood that the methods according to the present disclosure relate to methods of operating the apparatus according to the above exemplary embodiments and variations thereof, and that each statement made with respect to the apparatus applies equally to the corresponding method, and vice versa, so that similar statements may be omitted for brevity. In addition, the above aspects may be combined in many ways, even if not explicitly disclosed. Those skilled in the art will understand that these combinations of aspects and features / steps are possible unless they create a contradiction that is expressly excluded.

[0054] Implementations of the disclosed apparatus may include, but are not limited to, using one or more processors, one or more application specific integrated circuits (ASICs), and / or one or more field programmable gate arrays (FPGAs). Implementations of the apparatus may also include using other conventional and / or customized hardware, such as software programmable processors, such as graphics processing unit (GPU) processors.

[0055] Based on the above, a first solution, e.g., an L1 measurement and reporting configuration for LTM is proposed that can preferably and advantageously satisfy at least one of the main LTM requirements, namely, intra-frequency and inter-frequency measurements with intra-DU and inter-DU measurements from up to N cells (N=1, 2, 3, 4, 5, ..., e.g., N=8), fast dynamic switching with minimal configuration changes, and not incurring any significant additional reporting overhead. One potential approach could be:

[0056] During the preparation phase, the UE is provided with a common set of CSI resources aggregated across the set of candidate cells, which may be LTM-specific (e.g., an LTM-CSI-Resource-Set), and this set is maintained as part of a common RRC configuration that is preserved across LTM cell switches (among multiple LTM neighbor cells). This set may contain detailed parameters for each RS regarding its timing, frequency, and power configuration. Resources from different cells may be distinguished by an identifier (PCI or a shorter local index to save a few bits, e.g., LTM-Config-Index, which can also be reused later in the cell switch command to provide the target cell identifier).

[0057] For each cell (serving cell and candidate cell), the cell-specific configuration (e.g., differential configuration compared to the common RRC configuration) may include a reporting configuration regarding uplink resources to be used for reporting, a measurement gap configuration to enable inter-frequency measurements, and an initial or default set of activated RSs from the common LTM-CSI-Resource-Set to consider for measurements (e.g., a bitmap of LTM-Config-Indices).

[0058] The initial set of activated RSs may be changed dynamically later based on UE mobility (e.g., via MAC-CE from the serving cell), but no changes to the LTM-CSI-Resource-Set and reporting configuration are required.

[0059] With the above approach, even when a cell switch occurs, the UE can continue to use the same common set of RSs (LTM-CSI-Resource-Set), but switches from the LTM-CSI-Resource-Set to the cell-specific configuration of the new serving cell for reporting and measurement gap configurations and measurement RSs based on the default activation set of RSs. This approach minimizes the RRC configuration processing required on the UE side when a cell switch occurs, and at the same time allows dynamic activation / deactivation of an appropriate set of measurement RSs from candidate cells for LTM L1 measurements. If necessary, the CU may always change the common set of RSs (LTM-CSI-Resource-Set) via RRC reconfiguration, for example, when a new cell needs to be added or removed, although this is expected to occur infrequently.

[0060] It is proposed that for the LTM L1 measurement configuration, a common set of RSs across neighboring cells specific to LTM measurements is provided in the following cases: - detailed parameters for each RS are given regarding its timing, frequency and power configuration, and / or - resources from different cells may be distinguished by an identifier (e.g. LTM-Config-Index, which may also be later reused in the cell switch command to provide the target cell identifier), and / or This configuration may be preserved across LTM cell switches, but may be updated by the CU as needed (eg, cell / RS addition / removal).

[0061] Furthermore, for LTM L1 measurement configuration, along with a common set of measurement RS, cell-specific RRC configurations are provided, including, for example: - a reporting configuration providing the uplink resource configuration for reporting measurements, and / or - measurement gap configuration for inter-frequency measurements, and / or - A set of activated RSs / cells from the common LTM-CSI-Resource-Set to consider for measurements (e.g., a bitmap of LTM-Config-Indices).

[0062] The set of activated RSs from the common LTM-CSI-Resource-Set (e.g., bitmap of LTM-Config-Indices) may be dynamically changed later (e.g., via MAC-CE from the serving cell).

[0063] Other and further exemplary embodiments of the present disclosure will become apparent during the course of the following discussion and by reference to the accompanying drawings.

[0064] Example embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0065] [Figure 1] FIG. 1 is a block diagram of one possible non-limiting system in which the illustrative embodiments may be practiced. [Figure 2]Schematic diagram showing an example of LTM case in rel-18 with inter-CU, intra-CU and inter-DU cell switching. [Figure 3] FIG. 1 is a schematic diagram illustrating an example of common and cell-specific L1 measurement and reporting configurations for L1 / 2 triggered mobility (LTM). [Figure 4] FIG. 1 is a schematic diagram illustrating an example of a first embodiment. [Figure 5] FIG. 10 is a schematic diagram illustrating an example of a second embodiment. [Figure 6] FIG. 1 is a schematic diagram illustrating an example apparatus configured to implement at least one example described herein. [Figure 7] FIG. 1 is a schematic diagram illustrating an example method for implementing at least one example described herein. [Figure 8] FIG. 1 is a schematic diagram illustrating an example method for implementing at least one example described herein. DETAILED DESCRIPTION OF THE INVENTION

[0066] In the following, several different exemplary embodiments will be described using a communication network architecture based on 3GPP standards for communication networks such as 5G / NR as an example of a communication network to which the example embodiments may be applied, but the embodiments are not limited to such an architecture. It will be apparent to those skilled in the art that the embodiments may also be applied to other types of communication networks in which mobile communication principles are integrated with D2D (Device to Device) or V2X (Vehicle to Everywhere) configurations, such as systems using SL (Side Link), e.g., Wi-Fi, Worldwide Interoperable Microwave Access (WiMAX), Bluetooth®, Personal Communications Services (PCS), ZigBee®, Wideband Code Division Multiple Access (WCDMA), Ultra-Wideband (UWB) technologies, Mobile Ad Hoc Networks (MANETs), wired access, etc. Furthermore, without loss of generality, the description of some example embodiments relates to a mobile communication network, but the principles of the present disclosure can be extended and applied to any other type of communication network, such as a wired communication network.

[0067] The above examples and embodiments should be understood as illustrative examples only. Although the specification may refer to "an," "one," or "some" examples or embodiments in some places, this does not necessarily mean that each such reference relates to the same example or embodiment or that the feature applies only to a single example or embodiment. Single features of different embodiments may be combined to provide other embodiments. Furthermore, the words "comprising" and "including" should be understood as not limiting the described embodiments to consisting only of the recited features; such examples and embodiments may also include features, structures, units, modules, etc. that are not specifically recited.

[0068] A basic system architecture of a (tele)communication network, including a mobile communication system, to which some example embodiments are applicable, may include the architecture of one or more communication networks, including a wireless access network subsystem and a core network. Such architecture may include one or more communication network control elements or functions, access network elements, radio access network elements, access service network gateways or base transceiver stations, such as a base station (BS), an access point (AP), a NodeB (NB), an eNB or a gNB, a distributed unit (DU) or a centralized / central unit (CU), which control respective coverage areas or cells, thereby enabling one or more communication stations, such as a communication element or function, such as a user device or terminal device, such as a user equipment (UE), or another device having similar functionality, such as a modem chipset, chip, module, etc., which may be part of a station, element, function or application capable of communicating, such as a UE, element or function usable in a machine-to-machine communication architecture, or which may be attached as a separate element to such an element, function or application capable of communicating, to communicate over one or more channels via one or more communication beams for transmitting several types of data in multiple access domains. Additionally, core network elements or network functions may be included, such as gateway network elements / functions, mobility management entities, mobile switching centers, servers, databases, etc.

[0069] The following description may provide further details of alternatives, modifications and variations, where the gNB, for example, provides NR user plane and control plane protocol termination towards the UE and includes a node connected to the 5GC via an NG interface, for example in accordance with 3GPP TS 38.300 V16.6.0 (June 2021) Section 3.2, which is incorporated by reference.

[0070] The gNB Central Unit (gNB-CU) comprises a logical node that hosts, for example, the gNB's RRC, SDAP and PDCP protocols or the en-gNB's RRC and PDCP protocols that control the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface that is connected to the gNB-DU.

[0071] The gNB distributed unit (gNB-DU) comprises a logical node that hosts, for example, the RLC, MAC, and PHY layers of a gNB or en-gNB, and its operation is partly controlled by the gNB-CU. One gNB-DU supports one or more cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the F1 interface connected to the gNB-CU.

[0072] The gNB-CU-Control Plane (gNB-CU-CP) includes a logical node that hosts, for example, the control plane portion of the RRC and PDCP protocols of the en-gNB or gNB-CU of the gNB. The gNB-CU-CP terminates the E1 interface connected to the gNB-DU-UP and the F1-C interface connected to the gNB-DU.

[0073] The gNB-CU-User Plane (gNB-CU-UP) includes, for example, a logical node that hosts the user plane portion of the PDCP protocol of the gNB-CU of an en-gNB, as well as the user plane portions of the PDCP protocol and SDAP protocol of the gNB-CU of a gNB. The gNB-CU-UP terminates the E1 interface connected to the gNB-CU-UP and the F1-U interface connected to the gNB-DU, for example, in accordance with Section 3.1 of 3GPP TS 38.401 V16.6.0 (July 2021), which is incorporated by reference.

[0074] For example, several different divisions of functionality between the central unit and the distributed units are possible, referred to as options: Option 1 (1A-like division): o The functional division in this option is similar to the 1A architecture in DC: RRC is in the central unit; PDCP, RLC, MAC, physical layer and RF are in distributed units. Option 2 (3C-like division): o The functional division in this option is similar to the 3C architecture in DC: RRC and PDCP are in the central unit; RLC, MAC, physical layer and RF are in the distributed units. Option 3 (Intra-RLC Splitting): o Low RLC (partial functions of RLC), MAC, physical layer and RF are in the distributed units. PDCP and high RLC (other partial functions of RLC) are in the central unit. Option 4 (RLC-MAC Split): o MAC, physical layer and RF are in the distributed units. PDCP and RLC are in the central unit. Or otherwise, for example, divided in accordance with 3GPP TR 38.801 V14.0.0 (March 2017) Section 11, which is incorporated by reference.

[0075] A gNB supports multiple different protocol layers, such as Layer 1 (L1), or the physical layer.

[0076] Layer 2 (L2) of NR is divided into the following sublayers: Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptation Protocol (SDAP), where, for example, o The physical layer provides transport channels to the MAC sublayer. o The MAC sublayer provides logical channels to the RLC sublayer. o The RLC sublayer provides the RLC channel to the PDCP sublayer. o The PDCP sublayer provides the radio bearer to the SDAP sublayer. ○ The SDAP sublayer provides QoS flows to the 5GC. o Comp. refers to header compression and Segm. refers to segmentation. Control channels include (BCCH, PCCH).

[0077] Layer 3 (L3) includes, for example, Radio Resource Control (RRC) according to 3GPP TS 38.300 V16.6.0 (June 2021) Section 6, which is incorporated by reference.

[0078] For example, a RAN (Radio Access Network) node or network node or portion thereof, such as a gNB, base station, gNB CU or gNB DU, may be implemented using an apparatus having at least one processor and / or at least one memory (with computer readable instructions (computer program)) configured to support and / or provide and / or process, for example, CU and / or DU related functions and / or features, and / or at least one protocol (sub)layer of the RAN (Radio Access Network), for example, Layer 2 and / or Layer 3.

[0079] The gNB CU and gNB DU portions may be, for example, co-located or physically separated. The gNB DU may further be divided, for example, into two portions, e.g., one portion including processing equipment and one portion including antennas. The central unit (CU) may also be referred to as a BBU / REC / RCC / C-RAN / V-RAN, O-RAN, or portions thereof. The distributed unit (DU) may also be referred to as an RRH / RRU / RE / RU, or portions thereof. Hereinafter, in various exemplary embodiments of the present disclosure, the CU-CP (or more generally, the CU) may also be referred to as a (first) network node supporting central unit control plane functions or at least one of Layer 3 protocols of the radio access network, and similarly, the DU may also be referred to as a (second) network node supporting distributed unit functions or at least one of Layer 2 protocols of the radio access network.

[0080] The gNB-DU supports one or more cells and may therefore, for example, serve as a serving cell for a user equipment (UE).

[0081] User equipment (UE) may include wireless or mobile devices, devices having a radio interface for interacting with a RAN (Radio Access Network), smartphones, in-vehicle devices, IoT devices, M2M devices, etc. Such UEs or devices may include at least one processor and at least one memory containing computer program code configured by the at least one processor to cause the device to perform at least certain operations, such as, for example, an RRC connection to the RAN. The UE is configured, for example, to generate messages (e.g., including a cell ID) to be transmitted over the air toward the RAN (e.g., to reach and communicate with a serving cell). The UE can generate, send, and receive RRC messages containing one or more RRC PDUs (Packet Data Units).

[0082] The UE may have different states (e.g., according to 3GPP TS 38.331 V16.5.0 (June 2021) Sections 42.1 and 4.4, which are incorporated by reference).

[0083] A UE may be in either an RRC_CONNECTED state or an RRC_INACTIVE state, for example, when an RRC connection is established.

[0084] In the RRC_CONNECTED state, the UE: o AS context may be stored. o Can transfer unicast data to and from the UE. o A control channel associated with a shared data channel may be monitored to determine whether data is scheduled for that data channel. o May provide channel quality and feedback information. o Neighbor cell measurements and measurement reporting may be performed.

[0085] The RRC protocol includes, for example, the following main functions: ○ RRC connection control Measurement configuration and reporting Establishing / modifying / releasing measurement configurations (e.g. intra-frequency, inter-frequency and inter-RAT measurements) ○ Measuring gap setup and release ○ Measurement report

[0086] The 3GPP RAN group is discussing L1L2-triggered mobility (LTM), which specifies mechanisms and procedures for L1 / L2-based inter-cell mobility to reduce mobility latency: configuration and maintenance of multiple candidate cells to enable rapid application of configuration to candidate cells [RAN2, RAN3], dynamic switching mechanisms between multiple candidate serving cells (including SpCell and SCell) for potential applicable scenarios based on L1 / L2 signaling [RAN2, RAN1], L1 enhancements to inter-cell beam management, including L1 measurement and reporting and beam indication [RAN1, RAN2] (Note 1: Early RAN2 involvement is required, including the possibility of further clarification of the interaction between this item and the previous item), timing advance management [RAN1, RAN2], and, if necessary, CU-DU interface signaling to support L1 / L2 mobility [RAN3]. Note 2: FR2-specific enhancements are not excluded if necessary. NOTE 3: L1 / L2 based inter-cell mobility procedures are applicable to the following scenarios: standalone, CA and NR-DC cases with serving cell change within one CG, as well as intra-DU and intra-CU inter-DU cases (applicable to standalone and CA, no new RAN interface introduction is assumed), both intra-frequency and inter-frequency, both FR1 and FR2. The source and target cells may be synchronized or asynchronous.

[0087] The main objective of this work is to reduce the handover latency in the scenarios mentioned above.

[0088] Generally, for L1L2 triggered mobility (LTM), it is assumed that the UE reports L1 beam measurements to the serving DU, so that the serving DU can determine when to trigger a handover. The purpose is to simplify many of the network and UE mobility procedures, as well as reduce the disruption time / delay caused by mobility. Furthermore, network data transfer, scheduling is also expected to benefit from LTM. In LTM, the UE may maintain configurations of multiple cells in order to apply rapid adaptation of each configuration.

[0089] LTM may or may not involve a serving cell change and may use either RACH or RACH-less.

[0090] In LTM, the serving DU triggers the execution of the prepared target cell configuration based on lower layer signaling, which can be either a MAC Control Element (MAC CE) or Downlink Control Information (DCI). When a cell change is triggered, the serving DU notifies the CU so that the CU can stop sending any RRC reconfiguration over the serving cell radio link and, if necessary, start data transfer to the target cell.

[0091] LTM is assumed to use L1 measurements. These measurements have the advantage of allowing the network to avoid delays introduced by L3 filtering and Time to Trigger (TTT) for handover decisions, resulting in a faster response time to radio link degradation on the serving link. This should result in a reduced number of radio link failures compared to baseline handovers.

[0092] Referring to FIG. 1, this figure shows a block diagram of one possible, non-limiting example of an illustration of a wireless network 100 in which embodiments may be practiced. Shown are user equipment (UE) 110, a radio access network (RAN) node 170, and a network element 190. In the embodiment of FIG. 1, the user equipment (UE) 110 is in wireless communication with the RAN node 170. The UE is a device having a radio interface for accessing the wireless network 100. The UE 110 includes, for example, one or more processors 120, one or more memories 125 (storing computer program code), and one or more transceivers 130, interconnected through one or more buses 127 or other wired connections. At least one of the one or more transceivers 130 includes a receiver (Rx) 132 and a transmitter (Tx) 133. The one or more buses 127 may be an address bus, a data bus, or a control bus, and may include any interconnection mechanism, such as a series of wires on a motherboard or integrated circuit, optical fiber or other optical communication equipment, etc. At least one of the one or more transceivers 130 is connected to at least one or more antennas 128. At least one of the one or more memories 125 includes computer program code 123. The UE 110 includes circuitry 140-1 and / or code 140-2, which may be implemented in several ways. The circuitry 140-1 may be implemented in hardware, such as as part of one or more processors 120. The circuitry 140-1 may also be implemented as an integrated circuit or through other hardware, such as a programmable gate array. As another example, the code 140-2 may be implemented as computer program code 123 and executable by the one or more processors 120. For example, the one or more memories 125 and the computer program code 123 may be configured by the one or more processors 120 to cause the user equipment 110 to perform one or more of the operations as described herein.UE 110 communicates with RAN node 170 via wireless or radio link 111. Circuitry 140-1 and / or code 140-2 may provide L2 and / or L3 functionality, for example, L2 and / or L3 control plane signal processing.

[0093] In this embodiment, the RAN node 170 is a base station that provides access to the UE 110. The RAN node 170 may be, for example, a base station for 5G, also known as New Radio (NR). In 5G, the RAN node 170 may be an NG-RAN node, such as a gNB or an ng-eNB. The gNB is a node that provides NR user plane and control plane protocol terminations for UEs and is connected to the 5GC (e.g., network element 190) via an NG interface (e.g., connection 131). The ng-eNB is a node that provides E-UTRA user plane and control plane protocol terminations for UEs and is connected to the 5GC via an NG interface (e.g., connection 131). The NG-RAN node may include multiple gNBs. The gNB may include a central unit (CU) (gNB-CU) 196 and one or more distributed units (DUs) (gNB-DUs), of which DU 195 is shown. It should be noted that the DU 195 may include a radio unit (RU) or may be coupled to the RU to control the RU. The gNB-CU 196 is a logical node that may host the radio resource control (RRC), SDAP, and PDCP protocols of a gNB, or the RRC and PDCP protocols of an en-gNB, which controls the operation of one or more gNB-DUs. The gNB-CU 196 terminates the F1 interface that is connected to the gNB-DU 195. The F1 interface is shown as reference numeral 198, which also denotes a link between a remote element of the RAN node 170 and a central element of the RAN node 170, such as between the gNB-CU 196 and the gNB-DU 195. The gNB-DU 195 is a logical node that may host the RLC, MAC, and PHY layers of a gNB or en-gNB, and its operation is controlled in part by the gNB-CU 196. One gNB-DU 195 supports one or more cells. One cell may be supported by one gNB-DU 195, or one cell may be supported / shared by multiple DUs under RAN sharing.The gNB-DU 195 terminates an F1 interface 198 that is connected to the gNB-CU 196. The gNB-DU 195 may include at least one processor, at least one memory having computer program code stored therein, and a transceiver 160, e.g., as part of a radio unit (RU), although it should be noted that some examples of this may have the transceiver 160, e.g., as part of a separate RU under the control of and connected to the gNB-DU 195. The one or more transceivers 160 are connected to one or more antennas 158. The gNB-DU 195 may further include circuitry and / or code that may provide L2 functionality, e.g., L2 control plane signal processing. The RAN node 170 may also be an eNB (Evolved NodeB) base station for LTE (Long Term Evolution), or any other suitable base station or node.

[0094] The gNB-CU 196 (and / or RAN node 170) may include one or more processors 152, one or more memories 155, one or more network interfaces (N / WI / F) 161, interconnected through one or more buses 157 or other wired connections. At least one of the one or more memories 155 includes computer program code 153, e.g., computer-readable instructions. The DU 195 may also include its own memory and processor, and / or other hardware.

[0095] The RAN node 170 (and / or the CU 196 and / or the DU 195) includes circuitry 150-1 and / or code 150-2, which may be implemented in several ways. The circuitry 150-1 may be implemented in hardware, such as as part of one or more processors 152. The circuitry 150-1 may also be implemented as an integrated circuit or through other hardware, such as a programmable gate array. As another example, the code 150-2 may be implemented as computer program code 153 and executable by one or more processors 152. For example, the one or more memories 155 and the computer program code 153 may be configured by the one or more processors 152 to cause the gNB-CU 196 (and / or the RAN node 170 and / or the DU 195) to perform one or more of the operations as described herein. The circuitry 150-1 and / or code 150-2 may provide L3 functionality, e.g., L3 control plane signal processing.

[0096] One or more network interfaces 161 communicate over a network, such as via links 176 and 131. Two or more gNBs 170 may communicate, for example, using link 176. Link 176 may be wired or wireless or both, and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.

[0097] The one or more buses 157 may be an address bus, a data bus, or a control bus, and may include any interconnection mechanism, such as a series of wires on a motherboard or integrated circuit, optical fiber or other optical communication equipment, a wireless channel, etc. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 in an LTE or distributed unit (DU) 195 in a 5G gNB implementation, with other elements of the RAN node 170 possibly in a different physical location than the RRH / DU 195, and the one or more buses 157 may be implemented in part, for example, as optical fiber cable or other suitable network connection for connecting other elements of the RAN node 170 (e.g., a central unit (CU), gNB-CU 196) to the RRH / DU 195. Reference numeral 198 also indicates such suitable network links.

[0098] It should be noted that while the description herein indicates that a "cell" performs a function, it is clear that the equipment forming the cell may perform the function. A cell constitutes part of a base station; that is, there may be multiple cells per base station. For example, there may be three cells of a single carrier frequency and associated bandwidth, each covering one-third of a 360-degree area, such that the coverage area of ​​a single base station covers an appropriate ellipse or circle. Furthermore, each cell may correspond to a single carrier, and a base station may use multiple carriers. Thus, if there are three 120-degree cells per carrier and two carriers, the base station has a total of six cells.

[0099] The wireless network 100 may include core network functions and one or more network elements 190 that provide connectivity to additional networks, such as telephone networks and / or data communication networks (e.g., the Internet), via one or more links 181. Such core network functions for 5G may include a Location Management Function (LMF), an Access and Mobility Management Function (AMF), a User Plane Function (UPF), and / or a Session Management Function (SMF). Such core network functions for LTE may include an MME (Mobility Management Entity) / SGW (Serving Gateway) function. Such core network functions may include a Self-Organizing / Optimizing Network (SON) function. These are just a few example functions that may be supported by the network element 190; it should be noted that both 5G and LTE functions may be supported. The RAN node 170 is coupled to the network element 190 via a link 131. The link 131 may be implemented as an NG interface for 5G, an S1 interface for LTE, or another appropriate interface for other standards. Network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N / WI / F) 180 interconnected through one or more buses 185. The one or more memories 171 include computer program code 173.

[0100] Wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functions into a single software-based management entity, a virtual network. Network virtualization involves platform virtualization, which is often combined with resource virtualization. Network virtualization is categorized as either external, which combines many networks or portions of networks into virtual units, or internal, which provides network-like functionality to software containers on a single system. It should be noted that the virtualized entities resulting from network virtualization are still implemented at some level using hardware, such as processor 152 or 175 and memory 155 and 171, and such virtualized entities also produce technical effects.

[0101] The computer-readable memories 125, 155, and 171 may be of any type suitable for the local technology environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, non-transitory memory, transient memory, fixed memory, and removable memory. The computer-readable memories 125, 155, and 171 may be means for performing storage functions. The processors 120, 152, and 175 may be of any type suitable for the local technology environment and may include, by way of non-limiting example, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. The processors 120, 152, and 175 may be means for performing functions such as control of the UE 110, the RAN node 170, the network element 190, and other functions as described herein.

[0102] In general, various embodiments of user equipment 110 may include, but are not limited to, mobile phones such as smartphones, tablets, personal digital assistants (PDAs) with wireless communication capabilities, portable computers with wireless communication capabilities, image capture devices such as digital cameras with wireless communication capabilities, gaming devices with wireless communication capabilities, music storage and playback devices with wireless communication capabilities, internet appliances that enable wireless internet access and browsing, tablets with wireless communication capabilities, head-mounted displays such as those implementing virtual / augmented / mixed reality, and portable units or terminals incorporating a combination of such capabilities.

[0103] Thus, UE 110, RAN node 170, and / or network element 190 (and associated memory, computer program code, and modules) may be configured to implement (e.g., in part) embodiments described herein, including enabling the use of per-target-cell CU-UP for CPA / CPC initiation. Thus, computer program code 123, circuit 140-1, code 140-2, and other elements / features shown in FIG. 1 of UE 110 may be configured to implement user equipment-related aspects of embodiments described herein. Similarly, computer program code 153, circuit 150-1, code 150-2, and other elements / features shown in FIG. 1 of RAN node 170, including CU 196 and DU 195, may be configured to implement RAN / gNB / TRP-related aspects of embodiments described herein. Computer program code 173 of network element 190 and other elements / features shown in FIG. 1 may be configured to implement network element-related aspects of embodiments described herein.

[0104] Having thus introduced a suitable, but non-limiting, technical context for the practice of the exemplary embodiments, the exemplary embodiments will now be described more particularly.

[0105] To illustrate different LTM scenarios, Figure 2 shows the difference between inter-CU (L3 handover) and intra-CU, inter-DU cell switching. The work in Release 18 initially focuses on intra-DU and inter-DU cases; the scope can be further expanded in future releases.

[0106] For example, according to NR38.133, V17.6.0 "Technical Specification Group Radio Access Network; NR; Requirements for Support of Radio Resource Management" section 9.13.2, the known cell conditions in 3GPP are defined as follows: A cell with a different physical cell identity (PCI) from the serving cell is considered known if the following conditions in this requirement are met: - the SSB of a cell with a different PCI from the serving cell has the same SCS and center frequency as the SSB of the PCell; - the difference in timing of arrival at the UE between the SSB of the serving cell and the SSB of a cell with a different PCI is less than the CP length of the corresponding SCS; - the UE has sent a valid L3 measurement report within the last 5 seconds, and - SSBs from cells with different PCIs remain detectable according to the cell identification requirements specified in clause 9.2. - Otherwise, the cell is unknown.

[0107] The above conditions are defined from the UE perspective and with reference to a synchronization signal / PBCH block (SSB).

[0108] The first condition states that "the SSB of a cell with a different PCI from the serving cell has the same SCS and center frequency as the SSB of the PCell." This is the definition that RAN4 agreed upon in the last meeting regarding intra-frequency measurements. From the tdoc review from the current meeting, there is a trend that inter-frequency measurements are considered in LTM. As a result, the above known condition needs to be revised for the LTM case.

[0109] The second condition states that "the difference in timing of arrival at the UE between the SSB of the serving cell and the SSB of a cell with a different PCI is less than the CP length of the corresponding SCS." This is the definition of synchronous or asynchronous transmission. It is also debated whether this concept should be adopted in the case of LTM.

[0110] The last two criteria are straightforward because the measurement reports or values ​​are clear, rather than the definitions involved, and therefore these two criteria will be discussed in this disclosure.

[0111] SSB detectability as defined in clauses 9.2 / 9.3 of NR 38.133 means that "even if an explicit neighbor list with physical layer cell IDs is not provided, the UE should be able to identify new intra-frequency / inter-frequency cells and perform SS-RSRP, SS-RSRQ and SS-SINR measurements of identified intra- / inter-frequency cells if the carrier frequency information is provided by the PCell or PSCell."

[0112] An intra-frequency / inter-frequency cell shall be considered detectable if, for each associated SSB: - SS-RSRP related collateral conditions given in clauses 10.1.4 and 10.1.5 of NR 38.133 for the corresponding bands FR1 and FR2, respectively; - SS-RSRQ related collateral conditions given in clauses 10.1.9 and 10.1.10 of NR 38.133 for the corresponding bands FR1 and FR2, respectively; - the SS-SINR related collateral conditions given in clauses 10.1.14 and 10.1.15 of NR 38.133 for the corresponding bands FR1 and FR2, respectively; - SSB_RP and SSB Es^ / Iot according to Annex B.2.3 of NR38.133 in the corresponding band.

[0113] As explained above, the candidate cell RRC configuration is prepared by the CU based on L3 measurements, the UE makes L1 measurements on the candidate cell, and the DU triggers the serving cell change based on those L1 measurements.

[0114] According to some example embodiments, corresponding methods suitable to be performed by devices (network elements / components) such as those mentioned above, such as a UE, a CU, a DU, etc., are also provided.

[0115] L1 / L2 Triggered Mobility (LTM) LTM, also called L1 / 2 inter-cell mobility, is one of the mobility enhancement goals in Rel. 18. According to the paradigm description, the decision regarding cell change is made at the MAC layer in the distributed unit (DU) based on L1 measurements.

[0116] Figure 3 shows an example of one exemplary common and cell-specific L1 measurement and reporting configuration for L1 / 2 triggered mobility (LTM), which can be used, for example, for Solution 1 below.

[0117] A reference or common LTM L1 Meas configuration is generated for cell 1 supported by DU1 and cell 2 supported by DU2. Cell 1 is, for example, the serving cell to which the UE is connected, and cell 2 is, for example, the target cell to which the UE may perform handover. The reference configuration includes multiple parameters related to, for example, physical cell IDs, CSI resources, and for example, timing, frequency, per-cell power configuration, etc.

[0118] A first cell-specific differential LTM L1 Meas and report configuration is generated for cell 1 supported by DU1. The report configuration includes, for example, multiple parameters related to the report, measurement gap, activation set of LTM Config index and its associated RS.

[0119] A second cell-specific differential LTM L1 Meas and report configuration is generated for cell 2 supported by DU2. The report configuration includes, for example, multiple parameters related to the report, measurement gap, activation set of LTM Config index and its associated RS.

[0120] The LTM-Reporting Config, for example, relates to the uplink resource configuration of a cell. Generally, the CSI-Report Config includes some other parameters, such as an indicator of the CSI-Resource Config.

[0121] In particular, for example, a new L1 measurement resource configuration for LTM beam-based switching is proposed, which can also be used for beam switching between a subset of LTM cells (e.g., candidate target cells) without configuration changes similar to ICBM. In particular, two exemplary solutions for building the L1 measurement resource configuration for LTM measurements are proposed. These solutions are described below.

[0122] First, Solution 1 is described in detail, followed by an exemplary implementation as shown in Figure 4: Network configuration of selected CSI-Resources (e.g., SSB or / and CSI-RS) of LTM candidate cells as a new LTM-CSI-Resource-Set for LTM Layer 1 (L1) or beam measurements, which is maintained as a common configuration that is preserved across LTM cell switching.

[0123] Preparation stage As part of the LTM preparation, the CU requests candidate target cells and serving cells to provide a selected subset of CSI resources (e.g., SSB or / and CSI-RS) for LTM L1 / beam measurements. In response, the cells provide the following LTM measurement and reporting related parameters: LTM-CSI-Resource Set (i.e., the set of SSB / CSI-RS selected for LTM).

[0124] Detailed configuration of each RS (SSB / CSI-RS), e.g., timing configuration (timing opportunity), frequency configuration (ARFCN, frequency band, subcarrier / PRB location, etc.), power-related parameters (average power, power offset, etc.).

[0125] In one example, the Rel-17 SSB-MTC-AdditionalPCI information element type configuration may be used for SSB configuration of each cell, with additional configuration parameters to provide frequency configuration information.

[0126] An LTM-Reporting-configuration that includes allocated uplink resources for reporting on LTM (e.g., periodic), which can be used to report LTM L1 measurements, which may differ from the normal CSI-Report configuration.

[0127] A measurement gap configuration for UE to perform inter-frequency measurements for LTM.

[0128] The CU establishes a reference / common configuration for LTM-related measurements by combining the LTM-CSI-Resource sets received from all target cells into a single LTM-CSI-Resource-set towards the UE.

[0129] The resources of different target cells are distinguished by the LTM-Config-Index. One LTM-Config-Index may be provided for each cell, and the CSI-Resource set of a cell may be directly referenced by its LTM-Config-Index. In another example, the LTM-Config-Index of a cell may be provided with each SSB / CSI-RS. The mapping of the LTM-Config-Index of a cell to its Physical Cell ID (PCI) and Naida may also be provided in a common LTM measurement configuration.

[0130] The common configuration may also include detailed configuration parameters for each RS, for example, regarding its timing, frequency, and power configuration.

[0131] In addition to the common LTM measurement configuration, the CU forms the following configurations for each cell (serving cell and candidate target cells) as part of the cell-specific / differential configuration (e.g., differential LTM measurement and reporting configuration compared to the common LTM measurement configuration): A set of LTM-Config indices in the RRC message (e.g., an initial or default bitmap of LTM-Config indices) to activate measurements for only a subset of LTM cells (CSI-Resources) from the common LTM-CSI-Resource set.

[0132] In one embodiment, the initial or default bitmap may be determined based on L3 measurements.

[0133] In another embodiment, the initial or default bitmap may include resources from the current serving cell or the current and previous serving cells, and there may be no activated RS measurements.

[0134] In one solution, for each LTM-Config-Index (LTM cell) that is selected for beam measurement, the UE may also be provided with an initial or default list containing a subset of RSs associated with that LTM cell that will be used for beam measurement. In one embodiment, a bitmap of selected RSs may also be included in the RRC message for each activated LTM-Config-Index.

[0135] In another embodiment, if no information is provided about the RSs of an LTM cell, all RSs may be considered active for that cell.

[0136] Reporting configuration (e.g., uplink resources that will be used for reporting).

[0137] Measurement gap configuration (for inter-frequency measurements).

[0138] The CU provides the UE with both common and cell-specific / differential configurations for LTM measurements and reporting.

[0139] Details of the common configuration are also shared with all LTM cells to enable the cells to interpret the UE LTM reports. As explained below, the UE reports may indicate only resource identifiers and corresponding measurements, and the actual PCI and SSB / CSI-RS indices corresponding to the reported resource IDs may be derived based on details in the common configuration.

[0140] Each cell's specific configuration (mainly the activated LTM cell and the initial / default set of RSs (e.g., bitmap) selected by that cell's CU) is also shared with the cell itself.

[0141] The UE receives the LTM configuration, the common LTM-CSI-Resource-configuration, and the cell-specific configuration including the LTM-L1-Report-Configuration, the (default / initial) bitmap of activated LTM-Config-Indices / RS, and the measurement gap configuration for inter-frequency measurements. The UE starts LTM beam measurements based on the measurement configuration and the bitmap indicating the subset of resources that need to be measured and reported. For measurements, the UE derives the PCI, timing, frequency, and power-related configuration of the reference signals to be measured from the received common configuration.

[0142] The UE may use the measurement gap when inter-frequency measurements need to be performed for each configured activation set.

[0143] Measurement stage The UE reports L1-RSRP measurements based on measurements on selected resources indicated by RRC. The UE transmits the report using the uplink resources configured in the LTM-L1-Report configuration. The UE may be configured to report only the M best measurements (M=1, 2, 3, ..., e.g., M=4) in a single instance of a report. For each L1-RSRP measurement, a resource index may be included. The resource index may be defined only for activated CSI-resources, e.g., in ascending order of the CSI-RS index of each activated LTM cell starting from the lowest LTM-Config-Index. For example, if the activation resources are [{SSB 5,LTM-Config-Index 0},{SSB 9,LTM-Config-Index 0},{SSB 1,LTM-Config-Index 1},{SSB 2,LTM-Config-Index 2},{SSB 5,LTM-Config-Index 2},{SSB 10,LTM-Config-Index 3}], the following resource indexes may be used in the report:

[0144] Resource Index in Resource Report {SSB 5,LTM-Config-Index 0} 0 {SSB 9,LTM-Config-Index 0} 1 {SSB 1,LTM-Config-Index 1} 2 {SSB 2,LTM-Config-Index 2} 3 {SSB 5,LTM-Config-Index 2} 4 {SSB 10,LTM-Config-Index 3} 5

[0145] The DU may determine the LTM-cell switching together with the beam index, where the DU should ensure that the most recently measured beam within a certain time is used to avoid the UE re-requesting the beam during switching.

[0146] In one embodiment, an LTM command for cell switching may include a resource index from an activation set of resources in a common configuration, which implicitly indicates the LTM cell (as a target cell indication) and associated RS (as a QCL reference indication) to be used for cell switching.

[0147] In another example, a set of resources associated with a cell in a common configuration may be assigned a local index within that cell (starting from zero to N-1, where N is the total number of RSs for that cell in the common configuration). An LTM command for cell switching may include an LTM-config-index and a local RS index, which implicitly indicates the LTM cell and associated RSs used for cell switching.

[0148] Based on the L1 or L3 measurements, the DU may decide to modify the list of LTM cells for beam measurement. In this case, the DU sends a command (MAC command, e.g., MAC-CE or DCI) containing a bitmap of LTM-Indices. In one embodiment, the DU / CU may also provide a bitmap of the subset of CSI-RS to be used for beam measurement for each activated LTM cell.

[0149] In another embodiment, the serving CU may also update the list of LTM cells for beam measurement and send it to the UE (via the serving DU) and the serving DU.

[0150] Execution Phase When a cell switch occurs, the common configuration for LTM measurements may not change. After a cell switch, the UE starts using the measurement gap configuration for reporting the new serving cell, LTM L1 measurement reports. The UE performs measurements on activated RSs (e.g., given in the initial / default bitmap of activated LTM cells or / and RSs for measurements by the CU) for the new serving cell, which may be later updated by the serving DU / CU. The default / initial activation set of LTM cells may include at least one of the current serving cell, or the current serving cell and previous serving cell, or no activation configuration, or the configuration indicated in the cell switch command.

[0151] In another example, the UE may be configured / indicated to use the most recent bitmap of activated LTM-cells and / or RSs provided to the UE (by the previous serving cell) before the cell switch. In such a scenario, the serving cell before the cell switch may share the most recent bitmap of activated LTM-cells and / or RSs with the target cell before / during the cell switch.

[0152] Alternative to Solution 1: Instead of providing a bitmap of activated CSI-RS resources for LTM cells from a common LTM-CSI-Resource-Set, multiple reporting configurations may be configured for each cell, each associated with a different set of RSs from the common LTM-CSI-Resource-Set (a set may encompass resources from one or more LTM cells). The reporting configurations may be part of a cell-specific / differential configuration. In this option, UE measurements may be controlled based on a bitmap of CSI-Report-Config-Indices from the DU. The UE measures and reports the configurations that are activated via the DU.

[0153] FIG. 4 shows a schematic example of the first embodiment.

[0154] The UE is connected to a cell C1 supported by a distributed unit source DU and transmits Layer 3 measurement reports to a central unit CU connected to and controlling the distributed unit source DU. The central unit CU prepares an LTM configuration for a detected target cell C2 supported by a distributed unit candidate target DU. Therefore, the CU transmits a UE context modification request to the source DU to request related data, such as an LTM-CSI resource set, an LTM reporting configuration, a Meas Gap configuration, etc. From the source DU, the CU may receive at least one of an LTM CSI resource-related configuration, an LTM reporting configuration, and a Meas Gap configuration, which enable the CU to form an LTM-Meas Config and a cell-specific configuration. The CU further transmits a UE context setup request to the candidate target DU to request related data, such as an LTM-CSI resource set, an LTM reporting configuration, a Meas Gap configuration, etc. Upon receiving the requested data, the CU generates a corresponding LTM measurement-related configuration, including, for example, a common or reference configuration and a cell-specific configuration. The CU forwards the LTM measurement configuration or a part of it or a part of the generated data to the UE, the source DU, and the candidate target DU. Thus, the UE is enabled to determine relevant measurement parameters, perform LTM-related measurements, and report them to the source DU. The source DU is enabled to update at least some parameters and transmit the updated parameters to the UE. The UE is then enabled to perform adapted measurements using the updated parameters. When the source DU sends a cell change / cell switch command to the UE to perform a handover to the target cell C2, the UE switches the measurement gap and reports the config to C2. In this way, the UE is enabled to transmit the results of the adapted measurements immediately after a cell switch to the target cell C2 (new serving cell), for example, without requiring pre-configuration by the target cell C2.However, the target cell C2 may update at least one parameter after the cell switch, for example, the LTM Config index and the RS bitmap, to allow even better measurements.

[0155] First, Solution 2 is described in detail, and then an exemplary implementation as shown in Figure 5 is described: UE-based solution for constructing CSI-RS-Resource for LTM beam measurement with NW assistance for partial decoding of target configuration.

[0156] Preparation stage: In response to preparing the LTM, the candidate-target DU does not provide a separate CSI-RS resource to the CU. Instead, the DU provides "filtering" criteria (e.g., default filtering criteria) to obtain a specific configuration for LTM from the candidate-target DU's LTM-RRC-Configuration. For example, the "filter" may be a CSI-RS-Resource config with SSB as a reference signal and / or a frequency configuration (e.g., ARFCN, frequency band, and / or BWP-ID), and / or a timing configuration set to a specific value (e.g., period, and / or slot / subframe / frame number, etc.). Another example of a filter criterion may be a CSI-RS resource with a specific SSB as a quasi-co-located (QCL) source.

[0157] The CU sends only the LTM RRC configurations of the LTM candidate cells to the UE to initiate LTM measurements. For all LTM configurations, additional filtering criteria or pointers are provided for partial decoding of the configuration to obtain the beam measurement portion.

[0158] The CU may also provide a subset of LTM cells for beam measurement in this message, similar to Solution 1.

[0159] A default subset of LTM cells for beam measurements may be provided for each candidate cell within their cell-specific configuration, which the UE may use initially upon cell switching to that cell.

[0160] In one embodiment, the default subset may include resources from the current serving cell, or the current and previous serving cells, or there may be no activated cell.

[0161] The CU shares with each LTM cell the CSI-Resource Config and filtering criteria (e.g., default filtering criteria) of that candidate cell and a default selected subset of candidate cells for beam measurements.

[0162] Upon receiving the LTM RRC configuration along with the "filter" configuration and the subset of LTM cells for beam measurements, the UE partially decodes the LTM configuration for the given subset of LTM-cells, constructs an LTM-CSI-Resource set and starts measurements based on it.

[0163] Measurement stage: The UE steps during the measurement phase remain the same as in Solution 1. The subset of LTM-cells for beam measurements and / or the filter for one or more selected LTM-cells (e.g., type of resource and BWP-ID of measurement resource) can be controlled via MAC or Layer 1 (DCI) commands from the DU. The UE can apply this new criterion to filter out reference signals and form a new LTM measurement set.

[0164] In another embodiment, the CU may also update the subset of LTM cells for beam measurement and / or the filter (e.g., resource type and BWP-ID of measurement resource) for one or more selected LTM cells and send it to the UE (via the serving DU) and the serving DU.

[0165] Execution stage: Upon cell switch, the UE may determine the LTM-CSI-Resource set of the new serving cell by using given default filtering criteria associated with each LTM cell and considering a default subset of LTM cells for a given beam measurement for the new serving cell.

[0166] Overview of the main methods Solution 1: A new LTM-CSI-Resource set configuration is configured in the UE based on the NW-selected subset of CSI-Resources applicable for LTM switching.

[0167] The subset of CSI resources that are measured and reported can be controlled via RRC and MAC by the LTM-cell-index bitmap.

[0168] Solution 2: A method for the UE to construct an LTM-CSI-Resource-configuration from the RRC-Configuration of LTM candidate cells based on "filter" criteria provisioned by the network.

[0169] A MAC-based command to modify the resource type and BWP information in the LTM-CSI-Resource-configuration used by the UE to reconfigure the LTM-CSI resource set based on these new "filter" criteria.

[0170] FIG. 5 shows a schematic example of the second embodiment.

[0171] The UE is connected to a cell C1 supported by a distributed unit source DU and transmits Layer 3 measurement reports to a central unit CU connected to and controlling the distributed unit source DU. The central unit CU prepares an LTM configuration for a detected target cell C2 supported by a distributed unit candidate target DU. Therefore, the CU transmits a UE context setup or modification request to the source DU to request relevant data, such as an LTM-CSI resource set, an LTM reporting configuration, a Meas Gap configuration, etc., and filtering criteria for determining the relevant data. The CU further transmits a UE context setup request to the candidate target DU to request relevant data, such as an LTM-CSI resource set, an LTM reporting configuration, a Meas Gap configuration, etc., and filtering criteria for determining the relevant data. Upon receiving the requested data, the CU generates a corresponding LTM measurement-related configuration, including, for example, filtering criteria for the cell, to enable the UE to determine the relevant data therefrom. The filtering criteria may be related to the LTM meas and / or default filtering criteria for each cell for a default subset of LTM cells for C1 and C2 beam measurements. The CU forwards the LTM measurement configuration or a portion thereof or a portion of the generated data to the UE, the source DU, and the candidate target DU. Thus, the UE is enabled to determine relevant measurement parameters, perform LTM-related measurements, and report them to the source DU. The source DU is enabled to update at least some parameters and send the updated parameters to the UE. The UE is then enabled to perform adapted measurements using the updated parameters. When the source DU sends a cell change / cell switch command to the UE to perform a handover to the target cell C2, the UE switches the meas gap and reports the config to C2.In this way, the UE is enabled to transmit the results of the adapted measurements immediately after a cell switch to the target cell C2 (new serving cell) without requiring any pre-configuration by the target cell C2, for example. However, the target cell C2 may update at least one parameter after the cell switch, for example, the LTM Config index and the RS bitmap, to enable even better measurements.

[0172] For example, for both the example embodiments of Figures 4 and 5: for simplicity of illustration, only one target cell (C2) is shown in this figure. However, the proposed solution is applicable to multiple target cells, which may be under either the same DU or different DUs. In that case, steps 5, 6 and 10 of Figure 4 and steps 5, 6 and 9 of Figure 5 shall be repeated for those target cells.

[0173] One or more of the following additional advantages may be achieved depending on the circumstances and implementation variations: - Minimal RRC configuration changes to L1 measurement and reporting configuration for LTM on dynamic switching. Dynamic activation / deactivation of an appropriate set of candidate target cells and associated RSs for LTML1 measurements. Both network-based and UE-based solutions are provided. It is possible to enable inter-frequency L1 measurement of LTM.

[0174] An illustrative list of abbreviations: ARFCN Absolute Radio Frequency Channel Number BWP Bandwidth Portion CSI Channel State Information CSI-RS Channel State Information Reference Signal CU Central Unit DCI Downlink Control Information DU Distributed Unit ICBM inter-cell beam measurement L1 Layer 1 L2 Layer 2 LTM L1 / 2 triggered mobility MAC Media Access Control NW Network RRC Radio Resource Control RS reference signal RSRP reference signal received power PUCCH Physical Uplink Control Channel PUSCH Physical Uplink Shared Channel SSB Sync Block UE User Equipment

[0175] FIG. 6 schematically illustrates an exemplary apparatus configured to implement at least one example described herein.

[0176] 6 is an exemplary apparatus 1000, which may be implemented in hardware, configured to perform embodiments described herein. The apparatus 1000 includes at least one processor 1002 (e.g., an FPGA and / or CPU) and at least one memory 1004 containing computer program code 1005, the at least one memory 1004 and the computer program code 1005 configured to cause the at least one processor 1002 to cause the apparatus 1000 to implement circuits, processes, components, modules, or functions (collectively, control 1006) for performing embodiments described herein, including enabling CPA / CPC initiation to use a CU-UP per target cell.

[0177] The device 1000 optionally includes a display and / or I / O interface 1008 that may be used to display aspects or status of the methods described herein (e.g., while one of the methods is being performed or at a later time) or to receive input from a user, such as using a keypad, touch screen, touch area, microphone, biometric circuitry, etc. The device 1000 includes one or more network (N / W) interfaces (I / F) 1010. The N / W / I / F 1010 may be wired and / or wireless and may communicate over the Internet / other networks using any communication technique. The N / W / I / F 1010 may include one or more transmitters and one or more receivers. The N / W / I / F 1010 may include standard, well-known components such as amplifiers, filters, frequency converters, (de)modulators, and encoder / decoder circuits and one or more antennas.

[0178] The apparatus 1000 for performing the functions of control 1006 may be a UE (110), a RAN node 170, a network element 190, or any of the other items depicted in the preceding figures, such as the UE 110, the MN 170, the SN1-CU-CP 196-1, the SN1-CU-UP1 196-2, the SN1-CU-UP2 196-3, the S-GW 190-1, the MME 190-2, the UPF 190-3, the CU-CP1 796, the CU-CP1 896, and the apparatus 900. The apparatus 1000 may be part of a self-organizing / optimizing network (SON) node, such as one in a cloud. The device 1000 may also be distributed throughout the network 100, including within and among the device 1000 and any network elements, including those depicted in the preceding figures (such as a network control element (NCE) 190 and / or a RAN node 170 and / or a UE 110).

[0179] An interface 1012 enables data communication between various items of device 1000, as shown in Figure 6. For example, interface 1012 may be one or more buses, such as an address bus, a data bus, or a control bus, and may include any interconnection mechanism, such as a series of wires on a motherboard or integrated circuit, optical fiber or other optical communication equipment, etc. Computer program code 1005, including control 1006, may include object-oriented software configured to pass data / messages between objects within computer program code 1005. Device 1000 need not have each of the features mentioned or may include other features.

[0180] FIG. 7 illustrates a schematic diagram of an example method for implementing at least one example described herein.

[0181] FIG. 7 is an exemplary method 1100 for configuring: A user equipment (UE) configured to support a connection towards a radio access network including at least a first network node. To implement the method, the UE may comprise: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least some of the following method steps: At 1110, the method includes transmitting a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of a radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell. In step 1120, the method includes receiving, from a first network node, a configuration message including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including a resource-related configuration for at least one of a serving cell to which the UE is connected and a target cell to which the UE will perform a cell change as a candidate cell, and a cell-specific LTM report-related configuration. In step 1130, the method includes performing measurements based at least in part on the received LTM measurement-related configuration and reporting measurement-related information.

[0182] To implement the method, the UE may comprise specific means for performing specific functions / tasks, e.g., to perform one or more of the steps listed above, the UE may include establishing means, receiving means, determining means, obtaining means, and / or monitoring means. The specific means may be implemented using hardware and / or software, e.g., specific circuits and / or specific computer program code.

[0183] FIG. 8 illustrates a schematic diagram of an example method for implementing at least one example described herein.

[0184] 8 is an example method 1200 for configuring a first network node, the first network node being configured to support at least one of a Central Unit Control Plane (CU-CP) function and / or a Layer 3 protocol of a radio access network for controlling user equipment (UE) configured to support a connection towards a radio access network including at least the first network node. To implement the method, the first network node (source DU) may comprise: at least one processor; and at least one memory storing instructions that, when executed by at least one processor, cause a first network node (a source DU) to perform at least some of the following method steps:

[0185] In step 1210, the method includes: A measurement report is received from the UE, the measurement report including information indicating at least one target cell of the at least one neighbor target cell. In step 1220, the method includes transmitting a configuration message to the UE including information indicating an LTM measurement-related configuration. In step 1230, the method includes transmitting at least a portion of the LTM measurement-related configuration to a second network node, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of a radio access network, to enable the second network node to generate and transmit a configuration message including information indicating the updated LTM measurement-related configuration to the UE.

[0186] To implement the method, the first network node may comprise specific means for performing specific functions / tasks, e.g., to perform one or more of the steps listed above, the first network node may include establishing means, receiving means, determining means, obtaining means, and / or monitoring means. The specific means may be implemented using hardware and / or software, e.g., specific circuits and / or specific computer program code.

[0187] Nevertheless, it should be noted that features of the above-described apparatus (devices) may not be explicitly described for the sake of brevity, but correspond to features of the respective methods. The disclosure herein is considered to extend to such method features as well. In particular, the disclosure is understood to relate to methods of operating the above-described devices and / or the provision and / or arrangement of the respective elements of these devices.

[0188] Additionally, according to some further exemplary embodiments, there is also provided a respective device (e.g., implementing a UE, CU, DU, etc. as described above) comprising at least one processing circuit and at least one memory for storing instructions executed by the processing circuit, the at least one memory and instructions configured to cause the respective device to perform at least a respective step as described above, by the at least one processing circuit.

[0189] Furthermore, according to some other exemplary embodiments, there is provided a respective apparatus (e.g., implementing a UE, CU, DU, etc. as described above) comprising respective means configured to perform at least the respective steps as described above.

[0190] It should be noted that the example embodiments of the present disclosure are applicable to a variety of different network configurations. In other words, the examples shown in the above figures, which are used as the basis for the above examples, are merely illustrative and do not limit the present disclosure in any way. That is, additional and further existing and proposed new features available within the corresponding operating environment may be used with the example embodiments of the present disclosure based on the defined principles.

[0191] It should also be noted that the disclosed exemplary embodiments can be implemented in many ways using hardware and / or software configurations. For example, the disclosed embodiments may be implemented using dedicated hardware and / or hardware in association with software executable thereon. The components and / or elements in the figures are merely examples and do not limit the scope of use or functionality of any hardware, software in combination with hardware, firmware, embedded logic components, or combinations of two or more such components, implementing particular embodiments of the present disclosure.

[0192] It should further be noted that the present specification and drawings merely illustrate the principles of the present disclosure. Those skilled in the art will be able to implement various configurations that embody the principles of the present disclosure and are within its spirit and scope, even if not explicitly described or shown herein. Moreover, all examples and embodiments outlined in this disclosure are expressly intended to be solely for illustrative purposes to aid the reader in understanding the principles of the proposed method, in principle. Furthermore, all statements herein providing principles, aspects, and embodiments of the present disclosure, as well as specific examples thereof, are intended to encompass equivalents thereof.

Claims

1. A user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the user equipment (UE) comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: sending a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of said radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving, from the first network node, a configuration message including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including a resource-related configuration for at least one of a serving cell to which the UE is connected and a target cell to which the UE will perform a cell change as a candidate cell, and a cell-specific LTM report-related configuration; performing measurements based at least in part on the received LTM measurement-related configuration and reporting measurement-related information; and A user equipment (UE) that causes the

2. The user equipment (UE) of claim 1, wherein the resource-related configurations include a common or reference LTM-Meas Config associated with at least the serving cell and one target cell.

3. The user equipment (UE) of claim 1, wherein the resource-related configuration includes LTM-CSI resource sets associated with at least the serving cell and one target cell.

4. 2. The user equipment (UE) of claim 1, wherein the LTM reporting related configuration includes at least one of an LTM-Reporting Config, a measurement gap, an activated LTM Config index of at least one of the serving cell and one target cell, and / or a bitmap of RSs.

5. The UE 2. The user equipment (UE) of claim 1, further configured to receive a configuration message from a second network node, the configuration message including information indicating an updated LTM measurement-related configuration, the second network node supporting at least one of a distributed unit (DU) functionality and / or a Layer 2 protocol of the radio access network.

6. The UE determining resources for performing measurements based on the received updated configuration; and performing a measurement; reporting measurement-related information towards the second network node; and 6. The user equipment (UE) of claim 5, further configured to:

7. The LTM report related configuration includes an activated LTM Config index and a default bitmap of RS of at least one of the serving cell and one target cell, and the UE:

2. The user equipment (UE) of claim 1, further configured to receive a configuration message from a second network node, the second network node supporting at least one of a distributed unit (DU) function and a Layer 2 protocol of the radio access network, the configuration message including an activated LTM Config index and / or an updated bitmap of RSs of at least one of the serving cell and one target cell.

8. The UE reporting measurement-related information towards a second network node, the second network node supporting at least one of a distributed unit (DU) functionality and / or a Layer 2 protocol of the radio access network; receiving a cell switch command from the second network node to perform a cell change to a target cell; performing a handover to the target cell; determining cell-specific measurement parameters of the target cell based on the cell-specific LTM report-related configuration; performing measurements based on the received common LTM-Meas Config and the determined cell-specific LTM-Reporting Config parameters of the target cell; reporting measurement-related information towards a third network node supporting the target cell, the third network node supporting at least one of a distributed unit (DU) function and / or a layer 2 protocol of the radio access network; 10. The user equipment (UE) of claim 1 or 7, further configured to:

9. The user equipment (UE) of claim 1 , wherein the LTM measurement-related configuration includes filter criteria for LTM meas of at least one of a serving cell and a target cell.

10. 2. The user equipment (UE) of claim 1, wherein the LTM measurement-related configuration includes a default subset of LTM cells for beam measurements of at least one of a serving cell and a target cell.

11. The UE The user equipment (UE) of claim 9, further configured to determine resources, in particular LTM-CSI related resources, for performing measurements based on the received filter criteria.

12. The UE receiving, from a second network node, a configuration message including information indicating an updated LTM measurement-related configuration including updated filter criteria, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network; determining resources, in particular LTM-CSI related resources, for performing measurements based on the received updated filter criteria; performing a measurement; reporting measurement-related information towards the second network node; and 12. The user equipment (UE) of claim 11, further configured to:

13. The UE reporting measurement-related information towards a second network node, the second network node supporting at least one of a distributed unit (DU) functionality and / or a Layer 2 protocol of the radio access network; receiving a cell switch command from the second network node to perform a cell change to a target cell; performing a handover to the target cell; determining cell-specific measurement parameters of the target cell based on the cell-specific LTM report-related configuration including filter criteria for the target cell; performing measurements based on the determined cell-specific parameters; reporting measurement-related information towards a third network node supporting the target cell, the third network node supporting at least one of a distributed unit (DU) function and / or a layer 2 protocol of the radio access network; 10. The user equipment (UE) of claim 1 or 9, further configured to:

14. A user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the user equipment (UE) comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: sending a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of said radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving a configuration message from the first network node, the configuration message including information indicating an LTM measurement related configuration; receiving a configuration message from a second network node, the configuration message including information indicating an updated LTM measurement-related configuration, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network; A user equipment (UE) that causes the

15. 15. The user equipment (UE) of claim 14, wherein the LTM measurement-related configuration includes filter criteria for at least one of a serving cell and a target cell, and the updated LTM measurement-related configuration includes updated filter criteria for at least one of a serving cell and a target cell.

16. 15. The user equipment (UE) of claim 14, wherein the LTM measurement-related configuration includes a cell-specific default bitmap of activated LTM Config indexes of at least one of a serving cell and a target cell, and the updated LTM measurement-related configuration includes an updated cell-specific bitmap of activated LTM Config indexes of at least one of a serving cell and a target cell.

17. A user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the user equipment (UE) comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: sending a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of said radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving, from the first network node, a configuration message including information indicating a LTM measurement related configuration, the LTM measurement related configuration including parameters for cell-specific measurements related to a serving cell to which the UE is connected and information for deriving cell-specific parameters related to one target cell; determining parameters for cell-specific measurements associated with the serving cell; performing measurements based on the determined parameters; reporting measurement-related information towards a second network node supporting the serving cell, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network; receiving, from the second network node, a cell switch command for performing a handover to a target cell supported by a third network node, the third network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network; performing a handover to the target cell; determining parameters for cell-specific measurements associated with the target cell; performing measurements based on the determined parameters; reporting the measurement related information towards a third network node; A user equipment (UE) that causes the

18. 1. A method for a user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the method comprising: sending a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of said radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving, from the first network node, a configuration message including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including a resource-related configuration for at least one of a serving cell to which the UE is connected and a target cell to which the UE will perform a cell change as a candidate cell, and a cell-specific LTM report-related configuration; performing measurements based at least in part on the received LTM measurement-related configuration and reporting measurement-related information; and A method comprising:

19. 1. A method for a user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the method comprising: sending a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of said radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving a configuration message from the first network node, the configuration message including information indicating an LTM measurement related configuration; receiving a configuration message from a second network node, the configuration message including information indicating an updated LTM measurement-related configuration, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network; A method comprising:

20. 1. A method for a user equipment (UE) configured to support a connection towards a radio access network including at least a first network node, the method comprising: sending a measurement report to a first network node supporting at least one of a central unit control plane (CU-CP) function and / or a Layer 3 protocol of said radio access network, the measurement report including information indicating at least one target cell of the at least one neighbor target cell; receiving, from the first network node, a configuration message including information indicating a LTM measurement related configuration, the LTM measurement related configuration including parameters for cell-specific measurements related to a serving cell to which the UE is connected and information for deriving cell-specific parameters related to one target cell; determining parameters for cell-specific measurements associated with the serving cell; performing measurements based on the determined parameters; reporting measurement-related information towards a second network node supporting the serving cell, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network; receiving, from the second network node, a cell switch command for performing a handover to a target cell supported by a third network node, the third network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network; performing a handover to the target cell; determining parameters for cell-specific measurements associated with the target cell; performing measurements based on the determined parameters; reporting the measurement related information towards a third network node; A method comprising:

21. A computer program comprising instructions for causing an apparatus to carry out the method according to any one of claims 18 to 20.

22. A memory storing computer readable instructions for causing an apparatus to perform the method of any one of claims 18 to 20.

23. Apparatus comprising means for carrying out the steps of the method according to any one of claims 18 to 20.

24. a first network node configured to support at least one of a Central Unit Control Plane (CU-CP) function and / or a Layer 3 protocol of a radio access network for controlling a user equipment (UE) configured to support a connection towards a radio access network including at least the first network node, the first network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first network node to: receiving, from the UE, a measurement report including information indicating at least one target cell among at least one neighbor target cell; sending a configuration message to the UE, the configuration message including information indicating an LTM measurement-related configuration, the LTM measurement-related configuration including a resource-related configuration for at least one of a serving cell to which the UE is connected and a target cell to which the UE will perform a cell change as a candidate cell, and a cell-specific LTM report-related configuration; A first network node causing

25. a first network node configured to support at least one of a Central Unit Control Plane (CU-CP) function and / or a Layer 3 protocol of a radio access network for controlling a user equipment (UE) configured to support a connection towards a radio access network including at least the first network node, the first network node comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: receiving, from the UE, a measurement report including information indicating at least one target cell among at least one neighbor target cell; sending a configuration message to the UE, the configuration message including information indicating an LTM measurement related configuration; transmitting at least a portion of the LTM measurement-related configuration towards the second network node to enable the second network node to generate and transmit a configuration message including information indicating an updated LTM measurement-related configuration to the UE, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network; A first network node causing

26. A network node for a radio access network and for connecting a user equipment (UE) towards said radio access network, said network node comprising: a first network node and a second network node; at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: receiving, at the first network node, from the UE, a measurement report including information indicating at least one target cell among at least one neighbor target cell, the first network node supporting at least one of a Central Unit Control Plane (CU-CP) function and / or a Layer 3 protocol of the radio access network; transmitting a configuration message to the UE, the configuration message including information indicating a LTM measurement related configuration, the LTM measurement related configuration including parameters for cell-specific measurements related to a serving cell to which the UE is connected and information for deriving cell-specific parameters related to one target cell; receiving, at the second network node, from the UE, a report including measurement-related information directed to a second network node supporting the serving cell, the second network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network; sending, to the UE, a cell switch command for performing a handover to a target cell supported by a third network node, the third network node supporting at least one of a distributed unit (DU) function and / or a Layer 2 protocol of the radio access network; A network node that performs the above.

27. a second network node configured to support at least one of a distributed unit (DU) function and / or a layer 2 protocol of a radio access network and configured to connect to a first network node, the first network node supporting at least one of a central unit control plane (CU-CP) function and / or a layer 3 protocol of the radio access network for controlling a user equipment (UE) configured to support a connection towards the radio access network comprising at least the first network node and the second network node; at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform at least: receiving from the first network node at least a portion of an LTM measurement related configuration to be provided to the UE, to enable the second network node to generate and send to the UE a configuration message including information indicating an updated LTM measurement related configuration; receiving a measurement report from the UE based at least in part on the LTM measurement-related configuration; a second network node that causes the

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