Configuration of L1 beam measurement for lower layer mobility

Abstract

SUMMARY [0003] Described herein is a first network node supporting at least one of a Central Unit Control Plane (CU-CP) function or a Layer 3 protocol of a radio access network, 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 at least: determine to prepare a target cell of a third network node for Lower Layer Mobility (LLM) with a source cell of a second network node, wherein each of the second network node and the third network node supports at least one of a Distributed Unit (DU) function or a Layer 2 protocol of the radio access network; obtain an association between a cell identifier of the target cell and a first identifier; and transmit a configuration message to a user equipment (UE) served by the source cell, the configuration message including information indicating the association between the cell identifier of the target cell and the first identifier.

Description

Technical Field

[0001] This disclosure relates to lower layer (L1 / 2) mobility, particularly to enhancing the configuration of L1 beam measurements for lower layer mobility.

Background Art

[0002] Any discussion of background art throughout this specification is not to be construed as an admission that such art is widely known or forms part of common general knowledge in the art.

[0003] Broadly speaking, L1 / 2 inter-cell mobility is one of the pressing goals for mobility enhancement in the next Third Generation Partnership Project (3GPP) release (e.g., Release 18). In contrast to normal / conventional L3 mobility procedures typically determined by the Radio Resource Control (RRC) layer for handovers between two cells, L1 / 2 inter-cell mobility is generally carried out by the Medium Access Control (MAC) layer that terminates in the Distributed Unit (DU) of a typical 5G / NR (New Radio) gNB.

[0004] For beam measurements (including procedures for switching between beams of the same cell), a Channel State Information (CSI) measurement configuration (sometimes simply referred to as "CSI-MeasConfig") is provided from the DU to the CU in a higher layer (e.g., RRC) configuration information element (IE) such as a ServingCellConfig IE shared as an RRC container as part of an F1 (the interface between the CU and the DU) message such as a UE context setup response message. In the prior art, a UE can report only L1 beam measurement values of Synchronization Signal Block (SSB) indexes configured in the CSI-SSB-ResourceSet configuration by the network. Currently, the list of SSB indexes is typically limited to 64 to conform to UE capabilities, i.e., a UE can measure a maximum of 64 indexes simultaneously.

[0005] However, due to UE mobility, some SSB indices that were not part of the configured CSI-SSB-ResourceSet may become more relevant, and therefore the list of configured SSB indices may no longer be appropriate / effective for lower layer inter-cell mobility. On the other hand, as can be understood by those skilled in the art, the continued configuration of the CSI-SSB-ResourceSet results in high signaling overhead across wireless and network interfaces, including: • Overhead across the radio: Updating the CSI-SSB-ResourceSet generally requires, for example, sending an RRC reconfiguration message from the network to the UE, and the corresponding RRC reconfiguration completion message from the UE to the network. • Overhead across network interfaces: To update the CSI-SSB-ResourceSet, the CU generally needs to coordinate the new configuration with the serving / source and target DUs across the F1 interface.

[0006] In addition to signaling overhead, if the CSI-SSB-ResourceSet update is not performed in a timely manner while the UE still has a good serving radio link, it may also be exposed to the risk of mobility disruptions (e.g., due to cell change failures).

[0007] Furthermore, it may be useful to note that, compared to some techniques (such as inter-cell beam measurement (ICBM)) where the UE typically consists of only one non-serving cell (or, in other words, one target cell), in L1 / 2 inter-cell mobility, the UE can consist of multiple cells (e.g., up to eight or even more prepared target cells), which presents even more significant problems.

[0008] Therefore, it is necessary to propose novel measurement-related mechanisms / techniques for use in L1 / 2 (lower layer) inter-cell mobility management, particularly to address some or all of the challenges exemplified above in an efficient, flexible, and reliable manner. [Overview of the project]

[0009] According to one aspect of the present disclosure, a first network node that supports at least one of the following: a central unit control plane (CU-CP) function or a Layer 3 (L3) protocol for a radio access network, At least one processor, The system comprises at least one memory storing instructions, and when an instruction is executed by at least one processor, it sends at least one to a first network node. The decision is to prepare a target cell of a third network node for lower layer mobility (LLM) with the source cell of a second network node, and each of the second and third network nodes will support at least one of the Distributed Unit (DU) function or a Layer 2 (L2) protocol of a radio access network. To obtain an association between the cell identifier of the target cell and the first identifier, Send a configuration message to the user equipment (UE) serviced by the source cell, which includes information indicating the association between the target cell's cell identifier and a first identifier. A first network node is provided to perform this task.

[0010] In some examples, the first network node is: The system is further tasked with sending a message to a third network node containing information indicating the association between the target cell's cell identifier and the first identifier.

[0011] In some examples, the first network node is: The system is further required to receive information from a third network node indicating the number of synchronous signal block (SSB) indices configured in the target cell.

[0012] In some examples, the first network node is: The system is further required to send information indicating the number of SSB indices configured in the target cell to at least one of the second network node, the third network node, or the UE.

[0013] In some examples, the first identifier is a cell index used to distinguish beam measurements from multiple different cells.

[0014] In some examples, obtaining an association between the cell identifier of the target cell and the first identifier is possible. Send a request message containing information indicating the cell identifier of the target cell to the second network node, The second network node receives a response message containing information indicating the association between the cell identifier and cell index of the target cell. Includes.

[0015] In some examples, obtaining an association between the cell identifier of the target cell and the first identifier is possible. The first network node includes determining the association between the cell identifier and cell index of the target cell, The first network node is, The system is further prompted to send a request message to a second network node containing information indicating the association between the cell identifier and cell index of the target cell.

[0016] In some examples, the first identifier is a configuration identifier used to identify the configuration of the prepared target cell used by the UE to perform the handover from the source cell.

[0017] In some examples, obtaining an association between a cell identifier of a target cell and a first identifier comprises determining, by a first network node, an association between a cell identifier of the target cell and a configuration identifier, wherein the first network node is further caused to send, to a second network node, a request message comprising information indicating an association between a physical cell identifier (PCI) of the target cell and the configuration identifier.

[0018] In some examples, the configuration message further comprises information indicating measurement related configuration.

[0019] In some examples, the measurement related configuration comprises information for configuring a user equipment (UE) to report the N strongest beam measurements of a prepared target cell without referring to a single side band (SSB) index or a channel state information reference signal (CSI-RS) index included in the configuration message.

[0020] In some examples, the measurement related configuration comprises information for configuring the UE to make its own decision regarding an SSB index that the UE measures and reports.

[0021] In some examples, the cell identifier is a physical cell identifier (PCI).

[0022] In some examples, the first identifier has a shorter bit length than that of the cell identifier.

[0023] According to another aspect of the present disclosure, a second network node supporting at least one of a distributed unit (DU) function or a layer 2 (L2) protocol of a radio access network, comprising at least one processor, comprising at least one memory storing instructions which, when executed by at least one processor, cause a second network node to obtain, at least, an association between a cell identifier of a target cell of a third network node that supports at least one of a DU function or a layer 2 protocol of a radio access network, and a first identifier, wherein the target cell is prepared for lower layer mobility (LLM) with a source cell of the second network node by a first network that supports at least one of a central unit control plane (CU-CP) function or a layer 3 (L3) protocol of a radio access network, receive, from a user equipment (UE) served by the source cell, a message comprising information indicating a measurement report related to at least one beam of the target cell and the first identifier is provided by the second network node.

[0024] In some examples, the second network node is further caused to receive, from the first network node, information indicating the number of synchronization signal blocks (SSBs) indexes configured in the prepared target cell.

[0025] In some examples, the first identifier is a cell index for distinguishing beam measurement values of a plurality of different cells.

[0026] In some examples, obtaining the association between the cell identifier of the target cell and the first identifier comprises receiving, from the first network node, a request message comprising information indicating the cell identifier of the target cell, and determining, by the second network node, an association between the target cell identifier and the cell index, and the second network node The system is further prompted to send a response message to the first network node containing information indicating the association between the target PCI and the cell index.

[0027] In some examples, obtaining an association between the cell identifier of the target cell and the first identifier is possible. This includes receiving a message from a first network node containing information indicating the association between the cell identifier and cell index of a target cell.

[0028] In some examples, the first identifier is a configuration identifier used to identify the configuration of a target cell that is sent by the first network node to configure the UE for handover to the target cell. Obtaining an association between the cell identifier of the target cell and the first identifier is: This includes receiving a message from a first network node containing information indicating the association between the cell identifier and configuration identifier of a target cell.

[0029] In some examples, the second network node is To generate a measurement-related configuration containing information for configuring the UE to report the N strongest beam measurements of a prepared target cell without referring to the SSB index or the Channel State Information Reference Signal (CSI-RS) index included in the measurement-related configuration, Send a message containing information indicating the measurement-related configuration to the first network node. They are then made to do even more.

[0030] In some examples, the second network node is To generate measurement-related configurations that include information for configuring the UE to make its own decisions regarding the SSB index that the UE measures and reports, Send a message containing information indicating the measurement-related configuration to the first network node. They are then made to do even more.

[0031] In some cases, the message received from the UE further includes information indicating the index of the SSB detected by the UE for measurement of at least one beam of the target cell.

[0032] In some examples, a second network node is further tasked with sending a message containing information indicating the instruction for the UE to switch from the source cell to the target cell.

[0033] In some cases, the cell identifier is the physical cell identifier (PCI).

[0034] In some examples, the first identifier has a shorter bit length than that of the cell identifier.

[0035] According to yet another aspect of this disclosure, a user device (UE) is served by a source cell of a second network node that supports at least one of a distributed unit (DU) function or a Layer 2 (L2) protocol of a wireless access network, At least one processor, The system comprises at least one memory that stores instructions, and when an instruction is executed by at least one processor, the UE receives at least one Obtaining an association between a cell identifier of a target cell of a third network node that supports at least one of the DU function or a Layer 2 protocol of a wireless access network, and a first identifier, A message containing information indicating a measurement report related to at least one beam of the target cell and a first identifier is sent to a second network node. User equipment (UE) is provided to enable this process.

[0036] In some examples, the first identifier is a cell index for distinguishing beam measurements from multiple different cells, and obtaining an association between the cell identifier of the target cell and the first identifier is possible. The process includes receiving a configuration message from a first network node that supports at least one of the following: a central unit control plane (CU-CP) function or a Layer 3 protocol of a radio access network, which contains information indicating the association between the cell identifier and cell index of a target cell.

[0037] In some examples, the incoming configuration message is an RRC reconfiguration message that further includes the CSI measurement-related configuration suitable for supporting L1 / 2 mobility functionality and the number of SSB indices configured in the target cell, while the outgoing message is an L1 measurement report that includes information on the cell index, SSB index, and L1-RSRP.

[0038] In some examples, the first identifier is a configuration identifier associated with the configuration of the target cell for handover by the UE, and obtaining an association between the target cell's cell identifier and the first identifier is possible. The process includes receiving a configuration message from a first network node that supports at least one of the following: a central unit control plane (CU-CP) function or a Layer 3 protocol of a radio access network, the first network node containing information indicating an association between the cell identifier and cell index of a target cell.

[0039] In some examples, the incoming configuration message is an RRC reconfiguration message that further includes the CSI measurement-related configuration suitable for supporting L1 / 2 mobility functionality, and the number of SSB indices configured in the target cell, while the outgoing message is an L1 measurement report that includes the configuration identifier, SSB indices, and information about the L1-RSRP.

[0040] In some examples, the configuration message further includes information indicating a measurement-related configuration that includes information for configuring the UE to report the N strongest beam measurements of the target cell, without referring to a synchronization signal block (SSB) index or a channel status information reference signal (CSI-RS) index included in the configuration message.

[0041] In some examples, the configuration message further includes information indicating measurement-related configurations, which include information for configuring the UE to determine for itself the synchronization signal block (SSB) index that the UE measures and reports.

[0042] In some examples, sending a message involves sending a message containing information that indicates a measurement report related to the strongest beam measurement of the target cell.

[0043] In some examples, the configuration message further includes information indicating the number of SSB indices configured in the target cell.

[0044] In some examples, the message sent to the second network node further includes information indicating the index of the SSB detected by the UE for measurement.

[0045] In some cases, UE is The UE is then prompted to receive a message from a second network node containing information indicating the instruction to switch from the source cell to the target cell.

[0046] In some cases, the cell identifier is the physical cell identifier (PCI).

[0047] In some examples, the first identifier has a shorter bit length than that of the cell identifier.

[0048] In yet another aspect of this disclosure, a method for a first network node that supports at least one of a central unit control plane (CU-CP) function or a Layer 3 (L3) protocol for a radio access network, The decision is to prepare a target cell of a third network node for lower layer mobility (LLM) with the source cell of a second network node, and each of the second and third network nodes will support at least one of the Distributed Unit (DU) function or a Layer 2 protocol of a radio access network. To obtain an association between the cell identifier of the target cell and the first identifier, Send a configuration message to the user equipment (UE) served by the source cell, which includes information indicating the association between the target cell's cell identifier and the first identification information. A method is provided that includes this.

[0049] A method for a second network node that supports at least one of a distributed unit (DU) function or a Layer 2 (L2) protocol of a radio access network, according to yet another aspect of the present disclosure, The means of obtaining an association between a cell identifier of a target cell of a third network node supporting at least one of DU functions or Layer 2 (L2) protocols of a radio access network, and a first identifier, wherein the target cell is prepared for lower layer mobility (LLM) with a source cell of a second network node by a first network supporting at least one of central unit control plane (CU-CP) functions or Layer 3 (L3) protocols of a radio access network, Receiving a message from a user equipment (UE) serviced by the source cell, which includes a measurement report related to at least one beam of the target cell and information indicating a first identifier. A method is provided that includes this.

[0050] A method for user equipment (UE) served by a source cell of a second network node supporting at least one of a distributed unit (DU) function or a Layer 2 (L2) protocol of a radio access network, Obtaining an association between a cell identifier of a target cell of a third network node that supports at least one of the DU function or a Layer 2 (L2) protocol of a wireless access network, and a first identifier, A message containing information indicating a measurement report related to at least one beam of the target cell and a first identifier is sent to a second network node. A method is provided that includes this.

[0051] According to some exemplary embodiments, the apparatus is also provided with a computer program that includes instructions for causing the apparatus to carry out methods such as those disclosed herein.

[0052] According to some exemplary embodiments, the device is also provided with memory for storing computer-readable instructions for performing methods such as those disclosed herein.

[0053] Furthermore, according to some exemplary embodiments, a first network node is provided that supports at least one of a central unit control plane (CU-CP) function or a Layer 3 (L3) protocol for a radio access network, each having appropriate means configured to carry out each of the steps as disclosed herein.

[0054] Similarly, according to some exemplary embodiments, second and third network nodes are also provided that support at least one of a distributed unit (DU) function or a Layer 2 (L2) protocol for a wireless access network, each having appropriate means configured to carry out each of the steps as disclosed herein.

[0055] In addition, according to several other exemplary embodiments, for example, a computer program product for a wireless communication device having at least one processor is provided, which, when the product is operated on the device, includes a portion of software code for performing each of the steps disclosed herein. The computer program product may include a computer-readable medium in which the software code portion is 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.

[0056] While several exemplary embodiments are described herein with particular reference to the above-described applications, it should be understood that this disclosure is not limited to such domains of use and is applicable to a broader context.

[0057] In particular, it is understood that the methods described herein relate to methods for operating the exemplary embodiments and various modifications thereof, and that each statement made relating to the apparatus also applies to the corresponding methods, and vice versa, and that similar prior descriptions may be omitted for brevity. In addition, the above embodiments may be combined in many ways, even if not expressly disclosed. Those skilled in the art will understand that these combinations of embodiments and features / steps are possible, as long as they do not create a contradiction that is expressly excluded.

[0058] Embodiments of the disclosed apparatus may include, but are not limited to, the use of one or more processors, one or more application-specific integrated circuits (ASICs), and / or one or more field-programmable gate arrays (FPGAs). Embodiments of the apparatus may also include the use of other conventional and / or customized hardware, such as software-programmable processors, such as graphics processing unit (GPU) processors.

[0059] Other and further exemplary embodiments of this disclosure will become apparent by reference to the accompanying drawings in the course of the following discussion.

[0060] For illustrative purposes only, exemplary embodiments of the present disclosure will be described here with reference to the attached drawings. [Brief explanation of the drawing]

[0061] [Figure 1] This is a schematic diagram illustrating an example of a signaling / messaging flowchart according to an exemplary embodiment of the present disclosure. [Figure 2] This is a schematic diagram showing an example of a channel status information (CSI) measurement configuration according to an exemplary embodiment of the present disclosure. [Figure 3] This is a schematic diagram showing an example of a CSI measurement-related configuration according to an exemplary embodiment of the present disclosure. [Figure 4] This is a schematic diagram illustrating another example of a signaling / messaging flowchart according to the exemplary embodiments of the present disclosure. [Figure 5] This is a schematic diagram illustrating another example of a signaling / messaging flowchart according to another exemplary embodiment of the present disclosure. [Figure 6] This is a schematic diagram illustrating a further example of a signaling / messaging flowchart according to yet another exemplary embodiment of the present disclosure. [Modes for carrying out the invention]

[0062] In the following, several different exemplary embodiments will be described using a communication network architecture based on the 3GPP standard for communication networks such as 5G / NR as an example of a communication network to which the embodiments may be applied, but the embodiments are not limited to such architectures. It will be apparent to those skilled in the art that the embodiments may also be applied to other types of communication networks where mobile communication principles are integrated with D2D (device-to-device) or V2X (vehicle-to-everything) configurations, such as SL (sidelink), e.g., Wi-Fi, Global Interoperability Microwave Access (WiMAX), Bluetooth®, Personal Communication Services (PCS), ZigBee®, Wideband Code Division Multiple Access (WCDMA), Ultra-Wideband (UWB) technology systems, Mobile Ad Hoc Networks (MANET), and wired access. Furthermore, without loss of generality, although some examples of embodiments are described in relation to mobile communication networks, the principles of this disclosure can be extended and applied to any other type of communication network, such as wired communication networks.

[0063] The following examples and embodiments should be understood as illustrative examples only. While this 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 its features apply only to a single example or embodiment. A single feature from multiple different embodiments may be combined to provide other embodiments. Furthermore, the words “comprising” and “including” should be understood not to limit the embodiments described to consisting only of the features mentioned, and such examples and embodiments may also include features, structures, units, modules, etc., that are not specifically mentioned.

[0064] A basic system architecture of a (remote) communication network, including a mobile communication system to which several examples of embodiments can be applied, may include the architecture of one or more communication networks, including a wireless access network subsystem and a core network. Such an architecture may include one or more communication network control elements or functions, access network elements, radio access network elements, access service network gateways or transceiver base stations, such as base stations (BS), access points (AP), NodeBs (NB), eNBs or gNBs, distributed units (DUs) or centralized / central units (CUs), which control their respective coverage areas or cells, thereby enabling one or more communication stations, such as user equipment (UEs), user devices or terminal devices, or other devices with similar functions, such as modem chipsets, chips, modules, etc., which can be part of a station, element, function or application capable of communicating, or can be attached as a separate element to such a communication-capable element, function or application, such as a UE, element or function usable in a machine-to-machine communication architecture, to communicate via one or more channels via one or more communication beams for transmitting several types of data in multiple access domains. Furthermore, core network elements or network functions may be included, such as gateway network elements / functions, mobility management entities, mobile switching centers, servers, and databases.

[0065] The following description may provide various details of alternative, modified, and variant forms, including, for example, gNB providing NR user plane and control plane protocol termination toward UE, and including nodes connected to 5GC via the NG interface in accordance with Section 3.2 of 3GPP TS 38.300 V16.6.0 (June 2021), incorporated by reference.

[0066] The gNB Central Unit (gNB-CU) includes, for example, a logical node that hosts the RRC, SDAP, and PDCP protocols of the gNB, or the RRC and PDCP protocols of the en-gNB that control the operation of one or more gNB-DUs. The gNB-CU terminates the F1 interface connected to the gNB-DUs.

[0067] A gNB distributed unit (gNB-DU) includes a logical node that hosts, for example, the RLC, MAC, and PHY layers of a gNB or en-gNB, and its operation is partially controlled by a gNB-CU. One gNB-DU supports one or more cells. One cell is supported by only one gNB-DU. A gNB-DU terminates the F1 interface connected to the gNB-CU.

[0068] The gNB-CU control plane (gNB-CU-CP) includes a logical node that hosts the control plane portion of the PDCP protocol for the RRC and the gNB-CU of the en-gNB or gNB, for example. The gNB-CU-CP terminates the E1 interface connected to the gNB-CU-UP and the F1-C interface connected to the gNB-DU.

[0069] The gNB-CU-UserPlane (gNB-CU-UP) includes, for example, a logical node that hosts the user plane portion of the PDCP protocol for the gNB-CU of en-gNB, as well as the user plane portions of the PDCP protocol and SDAP protocol for the gNB-CU of gNB. The gNB-CU-UP terminates the E1 interface connected to the gNB-CU-CP 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.

[0070] For example, several different functional divisions between the central unit and the distributed unit are possible, which are referred to as options, as follows: Option 1 (1A-type division): ○ The functional partitioning in this option is similar to the 1A architecture in a data center. The RRC is located in the central unit. The PDCP, RLC, MAC, physical layer, and RF are located in the distributed units. Option 2 (3C-style division): ○ The functional partitioning in this option is similar to the 3C architecture in a data center. RRC and PDCP are located in the central unit. RLC, MAC, physical layer, and RF are located in the distributed units. Option 3 (RLC internal splitting): Low RLC (partial RLC functionality), MAC, physical layer, and RF are located within the distributed unit. PDCP and high RLC (other partial RLC functionality) are located within the central unit. Option 4 (RLC-MAC splitting): ○ MAC, physical layer, and RF are located within the distributed unit. PDCP and RLC are located within the central unit. Otherwise, follow section 11 of 3GPP TR 38.801 V14.0.0 (March 2017), which is incorporated by reference, for example.

[0071] gNB supports multiple different protocol layers, such as Layer 1 (L1) - the physical layer.

[0072] NR Layer 2 (L2) is divided into the following sublayers: Media Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP), and Service Data Adaptive Protocol (SDAP), where, for example, ○ The physical layer provides a transport channel to the MAC sublayer. ○ The MAC sublayer provides a logical channel to the RLC sublayer. ○ The RLC sublayer provides an RLC channel to the PDCP sublayer. ○ The PDCP sublayer provides wireless bearers to the SDAP sublayer. ○ The SDAP sublayer provides QoS flow to 5GC. ○ Comp. refers to header compression, and Segm. refers to segmentation. ○ The control channels include (BCCH, PCCH).

[0073] Layer 3 (L3) includes, for example, Radio Resource Control (RRC) as defined in Section 6 of 3GPP TS 38.300 V16.6.0 (June 2021), which is incorporated by reference.

[0074] For example, a RAN (Radio Access Network) node or network node or part thereof, such as a gNB, base station, gNB CU or gNB DU, may be implemented using a device having, for example, CU and / or DU-related functions and / or features, and / or at least one processor and / or at least one memory (having computer-readable instructions (computer programs)) configured to support and / or provide and / or process at least one protocol (sub) layer of the RAN (Radio Access Network), for example, Layer 2 and / or Layer 3.

[0075] The gNB CU and gNB DU portions may, for example, be located in the same place or may be physically separated. The gNB DU may be further divided into, for example, two parts, e.g., one part containing processing equipment and one part containing an antenna. The central unit (CU) may also be referred to as BBU / REC / RCC / C-RAN / V-RAN, O-RAN, or a portion thereof. The distributed unit (DU) may also be referred to as RRH / RRU / RE / RU, or a portion thereof. Hereafter in various exemplary embodiments of this disclosure, the CU-CP (or more generally, CU) may be referred to as a (first) network node supporting at least one of the central unit control plane functions or Layer 3 protocols of the radio access network, and similarly, the DU may be referred to as a (second) network node supporting the distributed unit functions or Layer 2 protocols of the radio access network.

[0076] The gNB-DU supports one or more cells and can therefore, for example, serve as a serving cell for a user device (UE).

[0077] 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 UE or device may comprise at least one processor and at least one memory containing computer program code, the at least one memory and computer program code configured by at least one processor to cause the device to perform at least certain operations, such as making an RRC connection to a RAN. The UE is configured, for example, to generate messages (e.g., including a cell ID) that will be transmitted wirelessly to the RAN (e.g., to reach and communicate with a serving cell). The UE can generate, transmit, and receive RRC messages containing one or more RRC PDUs (Packet Data Units).

[0078] UE may have different states (for example, according to sections 42.1 and 4.4 of 3GPP TS 38.331 V16.5.0 (June 2021), incorporated by reference).

[0079] For example, when an RRC connection is established, the UE is in either the RRC_CONNECTED (RRC connected) state or the RRC_INACTIVE (RRC inactive) state.

[0080] In the RRC_CONNECTED state, the UE is: ○ Stores the AS context. ○ Transfer unicast data to and from the UE. ○ Monitor the control channel associated with the shared data channel to determine whether data is scheduled for that data channel. ○ Provide channel quality and feedback information. ○ Conduct measurements of adjacent cells and submit measurement reports.

[0081] The RRC protocol includes, for example, the following key features: ○ RRC connection control ○ Measurement configuration and reporting ○ Establishment / modification / release of measurement configuration (e.g., intra-frequency, inter-frequency, and inter-RAT measurements) ○ Setting up and releasing the measurement gap ○ Measurement Report

[0082] The general functions and interconnections of the elements and functions described, which also depend on the actual network type, are known to those skilled in the art and are described in the corresponding specifications; as a result, detailed descriptions may be omitted herein for the sake of brevity. However, several additional network elements and signaling links may be used for communication between elements, functions, or applications, such as communication endpoints, servers, gateways, communication network control elements such as wireless network controllers, and other elements of the same or other communication networks, in addition to those described in detail below.

[0083] A communication network architecture, such as those considered in the examples of embodiments, may also be able to communicate with other networks, such as public switched telephone networks or the Internet. It should be noted that the communication network may also support the use of cloud services for virtual network elements or their functions, and the virtual network portion of a telecommunications network may also be provided by non-cloud resources, such as an internal network. Network elements such as access systems and core networks, and / or their functions, may be implemented by any node, host, server, access node, or entity suitable for such use. Generally, network functions can be implemented as network elements on dedicated hardware, software instances running on dedicated hardware, or virtualized functions instantiated on a suitable platform, such as a cloud infrastructure.

[0084] Furthermore, network elements such as communication elements like UEs and terminal devices, control elements or functions such as access network elements like base stations / BSs, gNBs, and wireless network controllers, core network control elements or functions such as gateway elements, or other network elements or functions, and any other elements, functions or applications described herein may be implemented by software, for example, by computer program products and / or hardware. The devices, nodes, functions or network elements used in conjunction to perform each of their operations may include several means, modules, units, components, etc. (not shown) required for control, processing and / or communication / signaling functions. Such means, modules, units, and components may include, for example, one or more processors or processor units including one or more processing parts for executing instructions and / or programs and / or processing data; storage or memory units or means for storing instructions, programs and / or data to serve as a workspace for the processor or processing part (e.g., ROM, RAM, EEPROM, etc.); input or interface means for inputting data and instructions by software (e.g., floppy disk, CD-ROM, EEPROM, etc.); user interfaces for providing monitoring and operating capabilities to the user (e.g., screen, keyboard, etc.); other interfaces or means for establishing links and / or connections under the control of the processor unit or part (e.g., wired and wireless interface means, wireless interface means including antenna units, etc., means for forming wireless communication parts, etc.), and each means forming an interface such as a wireless communication part may also be located at a remote site (e.g., a wireless head or radio station, etc.).In this specification, it should be noted that a processing unit should not be considered solely as a physical part of one or more processors, but also as a logical division of a referenced processing task performed by one or more processors. It should be understood that, in some examples, the so-called “liquid” or flexible network concept may be used, where the operation and functionality of network elements, network functions, or other entities of a network can be flexibly implemented in different entities or functions, such as within nodes, hosts, or servers. In other words, the “division of labor” between the involved network elements, functions, or entities may vary from case to case.

[0085] As illustrated above, techniques related to L1 / 2 inter-cell mobility (sometimes also referred to as lower-layer mobility (LLM)) are, for example, one of the pressing mobility enhancement goals considered in Release 18 of the Third Generation Partnership Project (3GPP). In contrast to (conventional) L3 mobility procedures, where the handover procedure between two cells is typically determined by the RRC layer, L1 / 2 inter-cell mobility is generally implemented by the MAC layer, which typically terminates at the DU of a 5G / NR gNB.

[0086] Figure 1 schematically illustrates one exemplary embodiment of a signaling diagram for L1 / 2 inter-cell mobility from a serving / source cell in DU1 (sometimes referred to as the source / serving DU) to a target cell in DU2 (sometimes referred to as the target DU), which can also be considered as an inter-DU intra-CU scenario. The same diagram can also apply to an inter-DU intra-CU cell change / switch case where DU1 is the same as DU2 (with possible adaptations as needed). In such a case, DU1 (or DU2) itself can be referred to as both the source / serving cell and the target cell.

[0087] In particular, the main steps of such an L1 / 2 inter-cell mobility procedure can be summarized as follows:

[0088] In step S101, the UE may send a measurement report that includes, for example, cell quality measurements of the serving / source cell and also of neighboring cells. In some possible cases, the UE may be configured to send the measurement report early if the serving cell still has a good connection to the serving cell. This measurement report is received by DU1 (source / serving DU) and then further propagated to the CU (as illustrated in step S102).

[0089] Using the reported cell quality measurements, the CU can identify a potential set of candidate target cells (from all adjacent cells controlled by the same or different DUs) to which the UE could hand over. In this example, as shown in Figure 1, the CU identifies candidate target cells served by DU1 (the serving DU / cell control) and by another DU2 controlled by the same CU.

[0090] In step S103, the CU may request the preparation of the candidate target cell controlled by the DU1 by sending, for example, a UE context setup request message (or any other appropriate message).

[0091] In step S104, DU1 may provide the configuration of the UE in a corresponding UE context setup response message (or any other appropriate message) that contains a message container from the DU to the CU.

[0092] Similarly, steps S105 and S106 may also be performed by DU2 to prepare a target cell controlled by DU2.

[0093] Once the UE configuration of the candidate target cell is received (as illustrated in steps S104 and S106), the CU may in step S107 generate an RRC reconfiguration message (etc.) which will be sent to the UE in step S108. Among other possible / appropriate information, the RRC reconfiguration message may include: For example, L1 / 2 handover / mobility measurement reporting configurations such as a configuration for reporting L1 beam measurements of the serving cell and target cell in step S110, and For example, when the UE receives a MAC CE command to change / switch a serving cell (i.e., to perform a handover), as shown in step S111, it must configure a prepared candidate cell.

[0094] After confirming the RRC reconstruction to the network in step S109 (for example, by sending a corresponding RRC reconstruction completion message), the UE can then begin reporting L1 beam measurements of the serving cell and candidate target cell (for example, periodically) as shown in step S110.

[0095] If it is determined that there is a target candidate cell with better radio link / beam measurements than that of the serving cell (for example, based on the determination that the L1-RSRP (reference signal received power) of the target beam measurement is greater than the L1-RSRP of the serving beam measurement plus an offset over a certain amount of time, such as time-to-trigger (TTT), or based on any other appropriate criterion), the serving cell may send a MAC control element (MAC CE) or an appropriate L1 message in step S111 to trigger a cell change / switch to the target candidate cell. In some possible cases, the MAC CE may include, for example, transmit setting instruction (TCI) state change information indicating the beam of the target candidate cell.

[0096] As a result of such MAC CE or appropriate L1 message, a (lower-layer) handover from the serving cell to the target cell is performed by the UE in step S112.

[0097] For beam measurements (including the procedure for switching between beams in the same cell), a Channel State Information (CSI) measurement configuration (sometimes simply referred to as "CSI-MeasConfig") is provided from the DU to the CU as part of an F1 message (generally the interface between the CU and DU), such as a UE context setup response message, in a higher-layer (e.g., RRC) configuration information element (IE) such as a ServingCellConfig IE shared as an RRC container (as shown, for example, with reference to steps S104 and S106 in Figure 1).

[0098] Generally speaking, CSI-MeasConfig can be understood as encompassing CSI measurement-related configurations, which may include the following, among other possibilities: For example, a CSI reporting-related configuration that includes exemplary information on how a UE should report L1 beam measurements, and • CSI resource-related configurations that include exemplary information that the UE needs to report beam measurements with respect to its reference signal (RS), such as a synchronization signal block (SSB) or CSI-RS.

[0099] In the example shown in Figure 2, it can be seen that the exemplary CSI-MeasConfig includes two CSI reporting configurations associated with different RSs: SSB (left) and CSI-RS (right).

[0100] In 3GPP Release 17, the CSI measurement-related configuration was extended to potentially better support inter-cell beam management (ICBM), which allows a UE to be served by a ("borrowed") beam from another cell, by enabling the reporting of L1 beam measurements from a non-serving cell. As a result of such an extension, the CSI-SSB-ResourceSet may also be extended to include, in some cases, physical cell identifiers (PCIs) associated with each configured SSB index, in addition to the configuration of SSB indices that a UE should measure and use to report L1 beam measurements. A concrete example of such a possible (extended) configuration is shown in Figure 3 (upper diagram).

[0101] As those skilled in the art will understand and accept, L1 beam measurements are typically provided to the network (e.g., DU, or CU via DU) in a CSI-Report (CSI report) (or any other suitable format / message) which is part of the uplink control information (UCI) sent by the UE, typically via either the Physical Uplink Common Control Channel (PUCCH) or the Physical Uplink Shared Channel (PUSCH). A schematic example of such a possible UCI is shown in the lower left diagram of Figure 3.

[0102] In a broad sense, as schematically shown in the lower right diagram of Figure 3, in some possible (non-limiting) examples, a CSI report may include the following elements (as schematically shown in the lower right diagram of Figure 3): • Channel State Information Reference Signal Resource Indicator (CRI) or SS / PBCH Block Resource Indicator (SSB-RI). Generally, the length of the SSB-RI can depend on the number of SSB indices configured in the CSI-SSB-ResourceSet (as schematically shown in the upper diagram of Figure 3). As a simple example, if a total of 64 SSB indices are defined, the length of the SSB-RI will be 6 bits. • RSRP for each CRI or SSB-RI. In some possible (non-limiting) embodiments, the length of the RSRP for the first reported CRI or SSB-RI may be 7 bits, while the lengths of the remaining, for example, three different indices (if reported), are 4 bits.

[0103] In conventional technology, a UE can only report L1 beam measurements of synchronization signal block (SSB) indices configured by the network in a CSI-SSB-ResourceSet configuration. Currently, the list of SSB indices is typically limited to 64 to fit the UE's capabilities. In other words, a UE can theoretically measure up to 64 indices simultaneously. Furthermore, the maximum number N of L1 beam measurements to be reported is configured by the network. In the example in Figure 3, N is equal to 4, which is far less than the number of SSB indices configured in the CSI-SSB-ResourceSet.

[0104] However, due to UE mobility, for example, if there is higher received power at this point, some SSB indices that were not part of the configured CSI-SSB-ResourceSet may become more relevant, and therefore the list of configured SSB indices may no longer be relevant / effective for lower-layer inter-cell mobility. For example, the network can configure the UE to report L3 measurement reports sent to the CU. It may be useful to note that the L3 measurement configuration is generally controlled by the RRC and at least partially by the MAC, and is entirely separate from the CSI measurement configuration. The L3 measurement report may include cell quality measurements (derived by the UE based on beam measurements) and L3 beam measurements (L3 filtered L1 beam measurements). Using this measurement report, the network can determine whether there are more relevant SSB indices and whether the CSI-SSB-ResourceSet needs to be updated. As a result, if the UE is not instructed to measure a particular set of SSB indices, the network may provide the UE with an alternative L3 measurement configuration. However, as can be understood by those skilled in the art, the continuous configuration of the CSI-SSB-ResourceSet results in high signaling overhead across wireless and network interfaces, including the following: • Overhead across the radio: Updating the CSI-SSB-ResourceSet generally requires, for example, sending an RRC reconfiguration message from the network to the UE, and the corresponding RRC reconfiguration completion message from the UE to the network. • Overhead across network interfaces: To update the CSI-SSB-ResourceSet, the CU generally needs to coordinate the new configuration with the serving / source and target DUs across the F1 interface.

[0105] In addition to signaling overhead, if the CSI-SSB-ResourceIndex update is not performed in a timely manner while the UE still has a good serving radio link, it may be exposed to the risk of mobility disruptions (e.g., due to cell change failures).

[0106] Furthermore, it may be useful to note that, compared to some techniques (such as inter-cell beam management (ICBM)) where the UE typically consists of only one non-serving cell (or, in other words, one target cell), in L1 / 2 inter-cell mobility, the UE can consist of multiple cells (e.g., up to eight or even more prepared target cells), which presents even more significant problems. That is, depending on the various embodiments, the CU may be configured to fetch configurations of up to eight (possible) target cells from various DUs and send those configurations to the UE (for L1 measurement and subsequent switching / mobility).

[0107] Therefore, generally speaking, this disclosure may be seen as seeking to propose techniques / mechanisms for configuring network nodes (and UEs) to support L1 / 2 mobility (or referred to as lower-layer mobility (LLM)) in order to address at least some or all of the challenges exemplified above.

[0108] In broad embodiments, according to some exemplary embodiments, the disclosure generally proposes that a UE can be configured to report the N strongest L1 beam measurements (e.g., one, two, four, or any other suitable number) of a set of prepared target cells without referring to an explicit list of SSB (or CSI-RS) indices (SSB-RI or CRI) for measurement. In some possible embodiments, depending on various circumstances and / or requirements, the decision and judgment regarding the relevant SSB (or CSI-RS) to measure from among those detected may be left to the UE embodiment. More specifically, according to some possible (but not limiting) embodiments, the UE may make entirely its own judgment regarding the SSB index to measure and report.

[0109] A list of target cells to be measured by UEs (for example, up to 8) can be fixed and can correspond to cells prepared for L1 / 2 central mobility. This cell list can be updated by CUs, for example, based on L3 measurement reports, to prepare new target cells and replace or delete target cells.

[0110] According to several other possible (but non-limiting) embodiments, the number Q of SSB indices to be measured and used for L1 beam measurement reporting can still be less than 64 (or any other suitable maximum number of SSB indices configured by the upper layers), where Q + M = 64, and M generally refers to the number of SSB indices configured for measurement by the network in the CSI-SSB-ResourceSet, as described above. For a concrete example to understand, Q may be configured as 24. In this case, the measurement configurations and reports provided by the network can be applied to the remaining M = 64 - 24 = 40 measurements, while for the remaining Q = 24 measurements, the UE can determine what to measure and report, depending on the various embodiments, to capture, for example, unconfigured SSBs that have become stronger between. According to several further possible (but non-limiting) embodiments, the UE may be configured to measure up to 64 SSB indices configured by the network, and in addition, several other Q of the strongest L1 beam measurements (e.g., indices of unconfigured SSBs). When configured as proposed above, the UE can still meet the maximum UE capability to simultaneously measure up to 64 SSB indices as configured / required in accordance with the above standard.

[0111] In reporting, generally speaking, the UE may include a suitable (cell-specific) identifier to enable the serving DU to distinguish between L1 beam measurements of multiple different cells, and the cell identifier may be determined / designed to be associated with each prepared cell (e.g., PCI, or any other suitable identifier / ID available within the gNB or globally across the network). This has the advantage that the UE may be able to send only 3 bits for the cell identifier (or, in some cases, any other suitable number of bits depending on the total number of cells to be distinguished) instead of the usual / typical much longer cell- or network-specific identifier (e.g., 10 bits for PCI). Of course, depending on the various embodiments and / or requirements, generally speaking, any other suitable (existing or new) identifier (having a shorter length compared to the usual / typical cell identifier, such as PCI) may be considered (or proposed), as long as it is possible to use it to enable network nodes (e.g., CUs and DUs) and the UE to distinguish between L1 beam measurements of multiple different cells.

[0112] In a broad sense, this disclosure generally proposes three different possible exemplary methods for coordinating appropriate (cell-specific) identifiers (e.g., cell index or PCI, etc.) between UE, CU, and (serving DU and target DU), which will be described in more detail thereafter with reference to the drawings. Unless otherwise indicated, the same or similar reference numerals used in the drawings of this disclosure may refer to the same or similar elements. Similarly, the same or similar messages (and their contents) used in the drawings of this disclosure may refer to the same or similar messages (and their contents) unless otherwise indicated, and consequently, repeated explanations may be omitted for the sake of brevity.

[0113] First, Figure 4 schematically shows another example of a signaling / messaging flowchart according to some exemplary embodiments of the present disclosure.

[0114] In general, in the exemplary embodiment of Figure 4, it can be understood that the (source) DU is configured to determine a cell identifier (here, a cell index) to distinguish the L1 measurements of a cell. Thus, it is also the DU that is responsible for associating the PCI of the prepared target cell (or, for example, any other suitable cell identifier available within the gNB or globally across the network) with the cell index. Of course, in such a case, the DU would also need to provide the determined association between the cell index and the PCI to the CU, which can then send this association to the UE (and to other DUs as needed).

[0115] More specifically, in steps S401 and S402, the UE can report the measurement to the source / serving DU (DU1), and the DU (DU1) can then propagate such measurement report to the CU (similar to steps S101 and S102 in Figure 1).

[0116] Subsequently, based on the measurement report, the CU may determine in step S403 to identify a (target) cell (or a set of possible target cells) in DU2 (or, in some possible embodiments, even in DU1) and prepare it to enable L1 / 2 inter-cell mobility.

[0117] Similar to steps S103 and S104 or steps S105 and S106 in Figure 1, the CU may then request the preparation of the candidate target cell controlled by the DU2 by sending, for example, a UE context setup request message (or any other appropriate message), and in response, receive the configuration in a corresponding UE context setup response message (or any other appropriate message) containing a message container from the DU to the CU.

[0118] In step S406, the CU may send the PCI of the prepared target cell (e.g., received from the DU or obtained by the CU by any other suitable means) to the DU1. This information may also be sent from the CU to the DU1 in any suitable message (e.g., as part thereof), such as a CSI measurement configuration request message as exemplified in step S406.

[0119] When such a CSI measurement configuration request is received from the CU, the DU1 may be configured in step S407 to generate a CSI measurement configuration to support L1 / 2 inter-cell mobility. Specifically, as illustrated above, the DU1 may generate a configuration to instruct / configure the UE to report the N strongest L1 beam measurements of the prepared target cell without explicitly indicating the SSB / CSI-RS index configured by the upper layer, and to enable the UE to do so.

[0120] In addition, in this exemplary embodiment, DU1 also determines in step S408 the association between PCI (received from CU in step S406) and cell index (designed in a manner suitable for enabling the distinction of measurements of multiple different cells, as illustrated above). Depending on various embodiments and / or requirements, such associations may be determined by any suitable means. For example, a (predetermined or pre-configured) mapping function / algorithm or lookup table (LUT) may be used to map PCI (10 bits) to a suitable cell index (e.g., 3 bits, determined generally based on the number of cells to be distinguished). Of course, as can be understood and acknowledged by those skilled in the art, any other suitable means may be used, as long as the cell measurements can be adequately identified.

[0121] Once an association between the PCI and the cell index is created / generated, such association is propagated to the CU as shown in step S409. In some possible embodiments, for example, to support dynamic switching between prepared target cells (or between a target cell and the original source / serving cell), this association information may also be propagated further to the DU2 (and other appropriate DUs, if deemed necessary), as illustrated in step S410.

[0122] Subsequently, the CU generates an RRC reconstruction message (and so on) and sends it to the UE in step S411 (similar to step S108 in Figure 1). As illustrated above, such a configuration message may include CSI measurement-related configurations suitable for supporting L1 / 2 mobility functions. Furthermore, the association between PCI and cell index generated by the DU1 may also be communicated by the CU in this configuration message (or in any other suitable form). It may also be useful to note, though not explicitly shown in the drawings, but as can be understood and acknowledged by those skilled in the art, that a configuration for the UE to report the N strongest L1 beam measurements of a prepared target cell without explicitly indicating the SSB / CSI-RS index configured by the upper layer (in step S407) is also propagated from the DU1 to the CU (e.g., as part of a CSI measurement configuration response message or in any other suitable message) and then propagated from the CU to the UE (e.g., as part of an RRC reconstruction message or in any other suitable message).

[0123] The above process, in particular steps S403-S409, may be repeated for multiple target cells (e.g., PCell (P cell) and / or PSCell (PS cell)) prepared for L1 / 2 inter-cell mobility, thereby generating a list of associations between the PCI and cell index of the target cells, with one cell index associated with one target cell. The configurations of all prepared target cells may be integrated by the CU as a single collective measurement configuration and sent in a single RRC reconfiguration message, or the CU may send separate RRC reconfiguration messages encompassing each measurement configuration of the target cells whenever the CU prepares a target cell.

[0124] As a result, the UE can now begin reporting L1 beam measurements (e.g., periodically, aperiodically, etc.) as shown in step S412. At this point, the UE can report, along with the L1-RSRP, at least the cell index (for the DU to identify the corresponding target cell) and the SSB index to identify the corresponding beam. More specifically, in the CSI report (which includes the L1 beam measurements), the UE can report the SSB index detected by the physical layer instead of the SSB-RI, which generally refers to the working index (entry index) of the SSB configured in the CSI-SSB-ResourceSet configuration as illustrated above with reference to Figure 3. This SSB index is necessary because, in the proposed embodiment, the network does not specify a particular list of SSB indices to measure and therefore cannot use the SSB-RI (as used in conventional techniques).

[0125] Finally, as in step S111 in Figure 1, if it is determined that there is a target candidate cell with better radio link / beam measurements than that of the serving cell (for example, based on the determination that the L1-RSRP of the target beam measurement is greater than the L1-RSRP of the serving beam measurement, or based on any other appropriate criterion), DU1 may send an appropriate MAC CE (or L1 message) in step S413 to trigger a cell change / switch to the target candidate cell.

[0126] In some possible embodiments, the CSI report can be further enhanced to minimize the number of bits used to report the SSB index associated with the target cell index. For example, in an exemplary (non-limiting) example, a CU may request a DU (controlling the prepared target cell, e.g., DU2 in the example in Figure 4) to provide the number of supported RS indexes (e.g., SSB indexes) in the prepared target cell. This information, i.e., the number of SSB indexes for the target cell, can be sent to the CU as part of an exemplary UE context step response message (or in any other appropriate format), such as shown in step S405. This information is also propagated to the serving DU (i.e., DU1 in this example in Figure 4), and other appropriate target DUs and UEs as needed (as shown exemplary as part of steps S406, S410 and S411), which, based on such information, can derive the number of bits that may be allocated to report the SSB index of each prepared target cell (e.g., as shown in step S412).

[0127] Secondly, Figure 5 schematically illustrates another example of a signaling / messaging flowchart according to several other exemplary embodiments of the present disclosure. As mentioned above, the same or similar reference numerals or messages (and their contents) used in the drawings of the present disclosure may refer to the same or similar element messages (and their respective contents) unless otherwise indicated, and consequently, repeated descriptions may be omitted for brevity.

[0128] Broadly speaking, in the exemplary embodiment shown in Figure 4, it can be understood that the CU is configured to determine the cell index in order to distinguish the L1 measurements of the cells. Thus, it is also the CU that is responsible for associating the PCI (or any other cell-specific or network-specific cell identifier, as exemplified above) of the prepared target cells with their respective cell indexes. Of course, in such cases, the CU would need to provide the determined association between the cell index and PCI to the (source) DU and UE (and, if necessary, to other (target) DUs).

[0129] More specifically, as can be seen from the figures, the exemplary embodiment shown in Figure 5 is essentially the same as that shown in Figure 4, except that instead of DU1 being configured to associate PCI with cell index (step S408), CU is configured to determine the association between the PCI of the prepared target cell and its respective cell index (as illustrated in step S506 of Figure 5).

[0130] Here again, the above process may be repeated for multiple target cells (e.g., PCell (P cell) and / or PSCell (PS cell)) prepared for L1 / 2 inter-cell mobility, thereby generating a list of associations between the PCI and cell index of the target cells, with one cell index associated with one target cell. The configurations of all prepared target cells may be integrated by the CU as a single collective measurement configuration and sent in a single RRC reconfiguration message, or the CU may send separate RRC reconfiguration messages containing each measurement configuration of the target cells whenever the CU prepares a target cell.

[0131] Finally, Figure 6 schematically illustrates yet another example of a signaling / messaging flowchart according to some further exemplary embodiments of the present disclosure. As mentioned above, the same or similar reference numerals or messages (and their contents) used in the drawings of the present disclosure may refer to the same or similar element messages (and their respective contents) unless otherwise indicated, and consequently, repeated descriptions may be omitted for brevity.

[0132] Broadly speaking, in the exemplary embodiment of Figure 6, it can be understood that the CU is configured to determine the association of the PCI (or any other per-cell or per-network cell identifier) ​​of the prepared target cell. However, in this exemplary embodiment, instead of using the (newly introduced) cell index, a configuration identifier (ID) (similar to the cell index, generally shorter compared to other cell identifiers such as PCI) associated with the configuration of the prepared target cell is (re)used to identify the L1 beam measurements reported by the UE for the target cell. The configuration of the prepared target cell is used by the UE to perform the handover from the source cell to the target cell. Depending on the various embodiments and / or requirements, such configuration identifiers may be pre-existing, pre-configured, predetermined, or configured for the UE, as shown in step S611, etc., insofar as the network nodes (CU and DU) and the UE can, if applicable, use such configuration identifiers to identify or distinguish measurements of multiple different cells.

[0133] As a concrete example (but not to be understood as any kind of limitation), in an exemplary embodiment as shown in Figure 6, the CU may associate the PCI of a prepared target cell with a so-called “reconfiguration ID,” which itself is associated with the configuration of the target cell used by the UE to perform the handover from the source cell to the target cell, as shown in step S606. Thus, depending on the various embodiments, such “reconfiguration IDs” may have several different names, as can be understood and acknowledged by those skilled in the art. Since the CU may prepare multiple target cells for L1 / 2 central mobility (using steps S604 and S605), a different reconfiguration ID may be associated with each target cell configuration. When the UE receives a MAC CE command from the DU1, as shown in step S613, it applies one of the target cell configurations. The CU also sends the reconfiguration ID of the prepared target cell having a given PCI, along with the corresponding target cell configuration, to the UE in step S611. In this example, it can be assumed that, generally, the reconstruction ID itself may be sufficient for the UE to associate the measurement with each cell, and as a result, an explicit and complete association between PCI and the reconstruction ID may not be necessary. For example, the UE can decode the target cell configuration associated with the reconstruction ID in order to derive the PCI of the target cell. In this case, the PCI is not explicitly signaled by the CU in step S611, but is obtained by the UE by decoding the target cell configuration. However, in some other examples, it may be possible for the CU to send an explicit and complete association between PCI and the reconstruction ID in the RRC reconstruction message. On the other hand, when reporting the measurement in step S612, the UE may report the reconstruction ID along with the L1-RSRP measurement (and optionally also the SSB index for identifying the beam) instead of indicating the cell index (as is the case in the exemplary embodiments of Figures 4 and 5).Subsequently, such a reconfiguration ID can be used by DU1 (or any other appropriate DU as needed) to identify the corresponding cell to which this L1 measurement is associated (since such association, i.e., the association between PCI and the reconfiguration ID, has already been communicated by CU in step S607).

[0134] As described above, the process may be repeated for multiple target cells (e.g., PCell (P cell) and / or PSCell (PS cell)) prepared for L1 / 2 inter-cell mobility, thereby generating a list of associations between the cell configurations of the target cells and their cell identifiers, with one cell identifier associated with one target cell. All prepared target cell configurations may be integrated by the CU as a single collective measurement configuration and sent in a single RRC reconfiguration message, or the CU may send separate RRC reconfiguration messages containing each measurement configuration of the target cells whenever the CU prepares a target cell.

[0135] For completeness, please note that in any of the exemplary embodiments described above, with reference to Figures 4 to 6, in the case of releasing or replacing a target cell, the UE can generally be configured to release / or replace the cell index corresponding to the target cell being released or replaced.

[0136] Even though, in the exemplary embodiments shown in Figures 4-6, it can be assumed that the association between the (longer) PCI (or any other per-cell or per-network cell identifier) ​​and a suitable (shorter) identifier (such as either a cell index or reconfiguration ID) propagates between network nodes and UEs at specific timings / sequences, it should be noted that this is not necessarily always the case. Depending on the various embodiments and / or requirements, such an association between the PCI of a prepared cell and its cell index (or reconfiguration ID) can also be sent at a later (or even earlier) point in time, for example, when a cell change is triggered.

[0137] It should be understood that only examples of cell indexes or reconfiguration IDs are provided, but it should be further noted that, as those skilled in the art will understand and appreciate, any other suitable identifier may be used, insofar as it enables network nodes and UEs to identify and distinguish measurements of multiple different cells.

[0138] To summarize the above, when the network is configured as proposed above, it generally does not need to maintain a proper configuration of the SSB index for L1 / 2 inter-cell mobility. As a result, mobility failures caused by possible misconfigurations of the SSB index can be avoided, thereby saving the signaling overhead associated with RRC reconfiguration to configure / update the list of SSB indexes, and also reducing the signaling overhead associated with reporting PCI (10 bits) for each L1-RSRP.

[0139] According to another aspect of the present disclosure, the CU assigns a temporary dynamic mapping table to report cell ID + associated measurements. The table includes coding that is shorter in length than normal PCI to identify the measured cell and reduce signaling traffic, for example, in the following exemplary procedure.

[0140] The UE sends the L3 measurement of the (strongest) detected cell to the CU. The CU, taking into account load conditions, etc., selects several cells (e.g., eight) to be further measured by the UE, such as the eight strongest cells and / or the best available cells. The CU can report this to the DU for LLM. Each of the eight selected cells has its own physical cell identification PCI number, e.g., PC1, PC2, ..., PCI8. Each PCI is typically 10 bits long. This requires that the UE already sends 80 bits to identify the cell (+ associated measurement results sent by the UE).

[0141] For example, as a result of assigning a new cell ID solely for measurement purposes, signaling traffic is reduced, and if, for instance, eight cells are being measured, only three bits are needed to distinguish between the eight cells.

[0142] 001-PCI1

[0143] 010-PCI2

[0144] 100-PCI3

[0145] ...

[0146] 111-PCI8

[0147] This cell list can be updated by CU, for example, based on an L3 measurement report, to prepare new target cells and replace or delete target cells. For example, if PCI1-PCI5 should still be measured, but PCI6-8 need to be replaced by PCI9-11, a new updated assignment will be provided, for example, as follows:

[0148] 001-PCI1

[0149] 010-PCI2

[0150] 100-PCI3

[0151] ...

[0152] 101-PCI9

[0153] 110-PCI10

[0154] 111-PCI11

[0155] By using only 3 bits (instead of 10 bits) to identify the 8 cells to be measured (+ related measurement results sent by the UE), only 24 bits are required instead of the 80 bits that should be sent by the UE, thus significantly reducing signaling.

[0156] For example, if more than eight cells are measured, such as up to 16, four bits may be used for encoding.

[0157] If the UE wishes to report unconfigured / unprepared cells, it can use, for example, a standard PCI and aperiodic L1 or L3 measurement report.

[0158] According to another exemplary procedure, the UE sends L3 measurements of the (strongest) detected cells to the CU. The CU, taking into account load conditions, etc., selects several (e.g., eight) cells to be further measured by the UE, such as the eight strongest cells and / or the best available cells. The CU configures the UE to report the eight cells in a (predetermined) order, e.g., PCI1, PCI2, ..., PCI8. The UE then sends a measurement report with measurements related to PCI1 first, then PCI2, and so on. In this case, the DU (or CU) essentially knows from the received report which measurement refers to which cell. In this case, even a 3-bit cell identifier is not required. In this case, the UE is required to always report a predefined number of measurements for each prepared cell. Otherwise, the network would not know how to interpret the results.

[0159] To enable more flexible reporting of fluctuating numbers of measurements, the following variations of the procedure may be employed.

[0160] If the UE reports measurements for only seven cells, for example, unreported cells may be marked as "not measured" (e.g., by XXX), and thus no misinterpretation occurs on the receiving end. In this case, the (predefined) protocol of the report may include, for example, measure1 bit, measure2 bit, ... Reporting on the actual measurements of cell1, cell2 (not reported), cell3, ... may include the following:

[0161] 01010100111, XXXXXXXXXXX, 11001100110,...

[0162] XXXXXXXXXXX=A reserved bit used to indicate that no measurement is reported for cell2, which may be a predefined sequence, e.g., 00000000000, 11111111111, 10101010101, ... Alternatively, if no actual measurement is available, a previous measurement may be reported again.

[0163] Alternatively, an additional flag (1 bit) may be used to indicate whether or not actual measurements have been reported.

[0164] According to another exemplary procedure, the network associates the PCI of a prepared target cell with a cell identifier (as described above). The network configures the UE to report X L1 beam measurements of the prepared target cells, whose PCI is associated with a cell identifier in a predefined sequence, such as two beam measurements, X=2, for each cell in any predefined sequence indicated by the network, starting, for example, with the cell having the smallest cell identifier (or conversely, from the largest to the smallest), or in any predefined sequence indicated by the network. The DU implicitly derives the association between the reported L1 beam measurements and PCI using the predefined sequence to report the beam measurements. If the UE skips a measurement for one prepared cell, it can indicate this to the network using a flag or a predefined sequence, as described above.

[0165] Finally, nevertheless, in the exemplary embodiments illustrated above (see drawings), the messages communicated / exchanged between network components / elements may be thought to have specific / explicit names, but it should be noted that, as those skilled in the art can understand and comprehend, depending on the various embodiments (e.g., the underlying technology), these messages may have different names and / or be communicated / exchanged in different forms / formats.

[0166] According to some exemplary embodiments, corresponding methods are also provided that are suitable for being performed by the aforementioned devices (network elements / components), such as UE, CU, DU, etc.

[0167] While the characteristics of the above-described devices may not be explicitly described for the sake of brevity, it should be noted that they also correspond to the characteristics of the respective methods. The disclosures herein are expected to extend to the characteristics of such methods as well. In particular, these disclosures are understood to relate to methods for operating the above-described devices, and / or to the provision and / or arrangement of the respective elements of these devices.

[0168] Furthermore, according to some further exemplary embodiments, there are also provided which each device (for example, which performs a UE, CU, DU, etc. as described above) comprises at least one processing circuit and at least one memory for storing instructions to be executed by the processing circuit, and the at least one memory and instructions are configured such that at least one processing circuit causes each device to perform at least the respective steps described above.

[0169] Furthermore, according to several other exemplary embodiments, there are provided each apparatus (for example, one that performs the UE, CU, DU, etc., as described above) that comprises each means configured to perform at least each of the steps described above.

[0170] It should be noted that the examples of embodiments of this disclosure are applicable to a variety of different network configurations. In other words, the examples shown in the figures above, which are used as the basis for the above examples, are illustrative and in no way limit the disclosure. That is, additional existing and proposed novel functionalities available within the corresponding operating environments may be used in conjunction with the examples of embodiments of this disclosure, based on the defined principles.

[0171] The exemplary embodiments disclosed can be implemented in many ways using hardware and / or software configurations. For example, the disclosed embodiments may be implemented using hardware associated with dedicated hardware and / or software executable thereon. The components and / or elements in the drawings are illustrative and do not limit the scope of use or functionality of any hardware, software, firmware, embedded logic components, or combinations of two or more such components that implement a particular embodiment of this disclosure.

[0172] It should be further noted that this specification and drawings merely illustrate the principles of the disclosure. Those skilled in the art will be able to implement various configurations that embody the principles of the disclosure and fall within its spirit and scope, even if not expressly described or illustrated herein. Furthermore, all examples and embodiments outlined herein are expressly intended, in principle, for illustrative purposes only to assist the reader in understanding the principles of the proposed methods. Moreover, all statements herein providing the principles, aspects, and embodiments of the disclosure, as well as specific examples thereof, are intended to encompass their equivalents.

Claims

1. A first network node that supports at least one of the following: a central unit control plane (CU-CP) function or a Layer 3 protocol for a wireless access network, At least one processor, The system comprises at least one memory storing instructions, and when an instruction is executed by the at least one processor, it sends at least one instruction to the first network node. To decide to prepare a target cell of a third network node for lower layer mobility (LLM) performed at Layer 1 or Layer 2 with respect to a source cell of a second network node, wherein each of the second and third network nodes supports at least one of the Distributed Unit (DU) function or the Layer 2 protocol of the radio access network, To obtain an association between the cell identifier of the target cell and the first identifier, A configuration message including information indicating the association between the cell identifier of the target cell and the first identifier is sent to the user equipment (UE) serviced by the source cell. Have them do it, The first identifier is a first network node having a bit length shorter than the bit length of the cell identifier.

2. The first network node is, The first network node according to claim 1, further comprising sending a message to the third network node containing information indicating the association between the cell identifier of the target cell and the first identifier.

3. The first network node is, The first network node according to claim 1, further comprising receiving from the third network node information indicating the number of synchronous signal block (SSB) indices configured in the target cell.

4. The first network node is, The first network node according to claim 3, further comprising transmitting the information indicating the number of SSB indices configured in the target cell to at least one of the second network node, the third network node, or the UE.

5. The first network node according to claim 1, wherein the first identifier is a cell index for distinguishing beam measurements of a plurality of different cells.

6. Obtaining the association between the cell identifier of the target cell and the first identifier means that Sending a request message to the second network node, which includes information indicating the cell identifier of the target cell; Receiving a response message from the second network node that includes information indicating the association between the cell identifier and the cell index of the target cell. The first network node according to claim 5, including

7. Obtaining the association between the cell identifier of the target cell and the first identifier means that The first network node includes determining the association between the cell identifier and the cell index of the target cell, The first network node is, The first network node according to claim 5, further having it send a request message to the second network node, which includes information indicating the association between the cell identifier and the cell index of the target cell.

8. The first network node according to claim 1, wherein the first identifier is associated with the configuration of the prepared target cell used by the UE to perform a handover from the source cell, and is a configuration identifier for identifying the configuration.

9. Obtaining the association between the cell identifier of the target cell and the first identifier means that The first network node includes determining the association between the cell identifier and the configuration identifier of the target cell, The first network node is, The first network node according to claim 8, further having it send a request message to the second network node, which includes information indicating the association between the cell identifier and the configuration identifier of the target cell.

10. The first network node according to claim 1, wherein the configuration message further includes information indicating a measurement-related configuration.

11. The first network node according to claim 10, wherein the measurement-related configuration includes information for configuring the UE to report the N strongest beam measurements of the prepared target cell without referring to an SSB index or a channel state information reference signal (CSI-RS) index contained in the configuration message.

12. The first network node according to claim 10, wherein the measurement-related configuration includes information for configuring the UE to make its own decisions regarding the SSB index that the UE measures and reports.

13. The first network node according to claim 1, wherein the cell identifier is a physical cell identifier (PCI).

14. The first network node according to claim 1, wherein the bit length of the first identifier is 3 bits.

15. The first network node according to claim 1, wherein the first identifier is an identifier used solely for LLM measurement.

16. The first network node according to claim 1, wherein the first identifier is an identifier different from the cell identifier, and is an identifier obtained by abbreviating the cell identifier.

17. A second network node that supports at least one of the following: a distributed unit (DU) function or a Layer 2 protocol for a wireless access network, At least one processor, The system comprises at least one memory storing instructions, and when an instruction is executed by the at least one processor, it sends at least one instruction to the second network node. The objective is to obtain an association between a cell identifier of a target cell of a third network node supporting at least one of the DU function or the Layer 2 protocol of the radio access network, and a first identifier, wherein the target cell is prepared by the first network node, which supports at least one of the central unit control plane (CU-CP) function or the Layer 3 protocol of the radio access network, for lower layer mobility (LLM) to be performed at Layer 1 or Layer 2, with respect to the source cell of the second network node. Receiving a message from a user equipment (UE) serviced by the source cell, which includes information indicating a measurement report related to at least one beam of the target cell and the first identifier. Have them do it, The first identifier has a bit length shorter than the bit length of the cell identifier. The second network node.

18. The second network node described above is The second network node according to claim 17, further comprising receiving from the first network node information indicating the number of synchronization signal block (SSB) indices configured in the prepared target cell.

19. The second network node according to claim 17, wherein the first identifier is a cell index for distinguishing beam measurements of multiple different cells.

20. Obtaining the association between the cell identifier of the target cell and the first identifier means that Receiving a request message from the first network node that includes information indicating the cell identifier of the target cell, The second network node includes determining the association between the cell identifier and the cell index of the target cell, The second network node described above is The second network node according to claim 19, further comprising sending a response message to the first network node, which includes information indicating the association between the cell identifier and the cell index of the target cell.

21. Obtaining the association between the cell identifier of the target cell and the first identifier means that The second network node according to claim 19, comprising receiving a message from the first network node containing information indicating the association between the cell identifier and the cell index of the target cell.

22. The first identifier is associated with the configuration of the target cell sent by the first network node to configure the UE for handover to the target cell, and is a configuration identifier for identifying the configuration. Obtaining the association between the cell identifier of the target cell and the first identifier means that The second network node according to claim 17, comprising receiving a message from the first network node containing information indicating the association between the cell identifier and the configuration identifier of the target cell.

23. The second network node described above is To generate the measurement-related configuration which includes information for configuring the UE to report the N strongest beam measurements of the prepared target cell without referring to the SSB index or the channel state information reference signal, CSI-RS, or index included in the measurement-related configuration, A message containing information indicating the measurement-related configuration is sent to the first network node. A second network node according to claim 17, which is further subjected to the following.

24. The second network node described above is To generate a measurement-related configuration that includes information for configuring the UE to make its own decisions regarding the SSB index that the UE measures and reports, A message containing information indicating the measurement-related configuration is sent to the first network node. A second network node according to claim 17, which is further subjected to the following.

25. The second network node according to claim 17, wherein the message received from the UE further includes information indicating an index of an SSB detected by the UE for measurement of at least one beam of the target cell.

26. The second network node described above is The second network node according to claim 17, wherein the UE is further made to transmit a message containing information indicating an instruction to switch from the source cell to the target cell.

27. The second network node according to claim 17, wherein the cell identifier is a physical cell identifier (PCI).

28. The second network node according to claim 17, wherein the bit length of the first identifier is 3 bits.

29. The second network node according to claim 17, wherein the first identifier is an identifier used solely for LLM measurement.

30. The second network node according to claim 17, wherein the first identifier is an identifier different from the cell identifier, and is an identifier obtained by abbreviating the cell identifier.

31. A method for a first network node that supports at least one of the following: a central unit control plane (CU-CP) function or a Layer 3 protocol of a radio access network, The determination to prepare a target cell of a third network node for lower layer mobility (LLM) performed at Layer 1 or Layer 2 with respect to a source cell of a second network node, wherein each of the second and third network nodes supports at least one of the Distributed Unit (DU) function or the Layer 2 protocol of the radio access network, To obtain an association between the cell identifier of the target cell and the first identifier, A configuration message including information indicating the association between the cell identifier of the target cell and the first identifier is sent to the user equipment (UE) serviced by the source cell. Includes, The first identifier has a bit length shorter than the bit length of the cell identifier. method.

32. A method for a second network node that supports at least one of the following: a distributed unit (DU) function or a Layer 2 protocol for a wireless access network, The objective is to obtain an association between a cell identifier of a target cell of a third network node supporting at least one of the DU function or the Layer 2 protocol of the radio access network, and a first identifier, wherein the target cell is prepared by the first network, which supports at least one of the central unit control plane (CU-CP) function or the Layer 3 protocol of the radio access network, for lower layer mobility (LLM) to be performed at Layer 1 or Layer 2, with respect to a source cell of the second network node. Receiving a message from a user equipment (UE) serviced by the source cell, which includes information indicating a measurement report related to at least one beam of the target cell and the first identifier. Includes, The first identifier has a bit length shorter than the bit length of the cell identifier. method.

33. A computer program comprising instructions for causing a device to carry out the method described in claim 31.

34. A memory in the device that stores computer-readable instructions for performing the method described in claim 31.

35. A computer program comprising instructions for causing a device to carry out the method described in claim 32.

36. A memory in the device that stores computer-readable instructions for performing the method described in claim 32.

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