Radio access network node and method thereof

Abstract

According to the present invention, a first RAN node (1) receives a control message (201) from a second RAN node (2) indicating configuration information of a cell provided by the second RAN node (2). On the basis of the received configuration information, the first RAN node (1) recognizes a specific SSB associated with said cell that must be measured by user equipment (3) for the purpose of a direct handover to a specific bandwidth part (BWP) of said cell which differs from an initial BWP of said cell. This can contribute to, for instance, making it possible for a RAN node to find out a non-cell defining (NCD) SSB that can be used for the purpose of a direct handover to a non-initial BWP of a cell provided by another RAN node.

Description

[Technical Field]

[0001] The present disclosure relates to wireless communication systems, and more particularly to signaling between radio access network nodes. [Background technology]

[0002] The 3rd Generation Partnership Project (3GPP®) Release 17 supports Reduced Capability (RedCap) UEs (see, for example, Section 16.13 of 3GPP 2.0). RedCap UEs have reduced functionality compared to non-RedCap UEs, aiming for low complexity. RedCap UEs are required to support a maximum UE channel bandwidth of 20 MHz in FR1 (i.e., sub-6 GHz bands) and 100 MHz in FR2 (i.e., millimeter wave (mmWave) bands). However, Carrier Aggregation (CA), Multi-Radio Dual Connectivity (MR-DC), Dual Active Protocol Stack (DAPS), and Integrated Access and Backhaul (IAB) related features are not supported in RedCap UEs.

[0003] For example, RedCap UEs have a reduced or relaxed minimum number of UE reception (Rx) branches and a maximum number of downlink (DL) Multiple Input Multiple Output (MIMO) layers compared to non-RedCap UEs. In FR1, one DL MIMO layer is supported if one Rx branch is supported, and two DL MIMO layers are supported if two Rx branches are supported. In FR2, one or two DL MIMO layers can be supported, and two Rx branches are always supported. In FR1 and FR2, UE functions and corresponding capabilities related to more than two UE Rx branches or more than two DL MIMO layers, and UE functions and capabilities related to more than two UE Tx branches or more than two uplink (UL) MIMO layers are not supported by RedCap UEs.

[0004] RedCap UEs in Radio Resource Control (RRC)_IDLE and RRC_INACTIVE monitor paging only in the initial Bandwidth Part (BWP) (default or RedCap-specific) associated with the Cell Defining (CD) Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) and perform cell (re)selection and measurements in the CD-SSB. If a RedCap-specific initial UL BWP is configured, RedCap UEs in RRC_IDLE and RRC_INACTIVE must use only the RedCap-specific initial UL BWP to perform random access (Random Access Channel (RACH)).

[0005] A RedCap UE may be configured with multiple Non-Cell Defining (NCD) SSBs, provided that each BWP is configured with up to one SSB. In RRC_CONNECTED, if the active BWP does not contain a CD-SSB, an NCD-SSB may be configured for the RedCap UE to perform Radio Link Monitoring (RLM), Beam Failure Detection (BFD), and serving cell measurements.

[0006] An SSB consists of primary and secondary synchronization signals (PSS, SSS), each occupying one symbol and 127 subcarriers, and a Physical Broadcast Channel (PBCH) spanning three Orthogonal Frequency Division Multiplexing (OFDM) symbols and 240 subcarriers. CD-SSB is an SSB associated with Remaining Minimum System Information (RMSI). In other words, a CD-SSB is an SSB associated with System Information Block Type 1 (SIB1). To limit the frequency range that UEs should search for cell selection and cell reselection in RRC_IDLE or RRC_INACTIVE, a CD-SSB is always located in the synchronization raster. The synchronization raster is also called the SS raster or SSB raster. The synchronization raster occupies a predetermined (or fixed) frequency range within the NR channel bandwidth.

[0007] The following paragraphs provide a solution to the issue of NCD-SSB for RedCap UEs described in 3GPP TS 2013-03-29. When the active BWP of a RedCap UE is associated with NCD-SSB, it is up to the network to decide whether to perform serving cell measurements with NCD-SSB or CD-SSB. When a BWP is associated with NCD-SSB, a BWP-specific serving cell measurement object, i.e., servingCellMO, defined under BWP-DownlinkDedicated, can be configured. A RedCap UE uses this servingCellMO for serving cell measurements if it is configured for an active BWP; otherwise, it uses the legacy servingCellMO defined in ServingCellConfig. Although it is possible to configure CD-SSB and / or multiple NCD-SSB for serving cell measurements, the UE shall perform measurements using the configured serving cell measurement object of the active BWP associated with either CD-SSB or NCD-SSB.

[0008] From the Technical Specification Group (TSG) Radio Access Network (RAN) Working Group 2 (RAN2) signaling perspective, a BWP-specific servingCellMO can be configured under BWP-DownlinkDedicated. The SSB defined in this servingCellMO is the reference SSB used for serving cell measurements when the UE is in this active BWP. On the other hand, if this field is not present, the SSB defined by the servingCellMO under ServingCellConfig is the reference SSB used for serving cell measurements. This reference SSB is used to define intra-frequency measurements.

[0009] From the RAN2 perspective, direct handover to a specific Redcap BWP of the target cell associated with the NCD-SSB is supported, rather than to the initial BWP associated with the CD-SSB.

[0010] As described in Non-Patent Documents 3 and 4, 3GPP TSG-RAN has agreed that NCD-SSB is supported for RedCap UEs. In addition, as described in these documents, the applicability of NCD-SSB to non-RedCap UEs is being discussed. In the future, NCD-SSB in the Rel-17 RedCap Work Item (WI) may be applied to all UEs, including RedCap UEs and non-RedCap UEs.

[0011] As described in Non-Patent Document 5, during the Xn Setup procedure or the NG-RAN node Configuration Update procedure, a gNB can receive an Xn Application Protocol (XnAP) message including a Served Cell Information NR IE from another gNB. This allows the gNB to know a list of multiple MeasTiming instances for multiple SSBs configured in the served cell of the other gNB, and to know that the SSB described in the first MeasTiming instance of this list can be used for camping and Primary Cell (PCell) configuration (i.e., within spCellConfigCommon of the masterCellGroup). [Prior art documents] [Non-patent literature]

[0012] [Non-Patent Document 1] 3GPP TS 38.300 V17.1.0 (2022-06), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; NR and NG-RAN Overall Description; Stage 2 (Release 17), July 2022 [Non-patent document 2] RAN2, "LS on NCD-SSB issues for RedCap UE (R4-2207104)", R2-2206662, 3GPP TSG-RAN WG2 Meeting #118-e, May 9-20, 2022 [Non-patent document 3] vivo, "Discussion on NCD-SSB for non-RedCap UEs", RP-221275, 3GPP TSG-RAN Meeting #96, June 6-9, 2022 [Non-patent document 4] Vodafone, "NCD-SSB for all devices: proposed Way Forward", RP-221870, 3GPP TSG-RAN Meeting #96, Budapest, Hungary, June 6-9, 2022 [Non-Patent Document 5] 3GPP TS 38.423 V17.1.0 (2022-06), "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NG-RAN; Xn application protocol (XnAP) (Release 17)", June 2022 Summary of the Invention [Problem to be solved by the invention]

[0013] As mentioned above, 3GPP Release 17 will support direct handover to a BWP specific to RedCap UEs and associated with an NCD-SSB for handover of RedCap UEs from a source cell to a target cell. To enable this, the source gNB preferably knows the RedCap-specific NCD-SSB in the target cell or the RedCap-specific BWP associated with the RedCap-specific NCD-SSB. This is because the source RAN node needs to create and provide measurement objects to RedCap UEs in RRC_CONNECTED in the source cell so that these RedCap UEs can measure the RedCap-specific NCD-SSB within the RedCap-specific BWP of the target cell.

[0014] As mentioned above, in the current XnAP signaling specification (see, for example, Non-Patent Document 5), a gNB can know multiple MeasTiming lists for multiple SSBs configured in the served cells of other gNBs, and can know that the SSB described in the first MeasTiming instance of this list can be used for camping and PSCell configuration (i.e., in spCellConfigCommon of the masterCellGroup). In other words, a gNB can know that the SSB described in the first instance of the MeasTiming list provided by another gNB is a CD-SSB.

[0015] However, under the current XnAP signaling specifications, a gNB cannot know which of the remaining one or more SSBs indicated by the second or subsequent instances of the MeasTiming list provided by another gNB is an NCD-SSB specific to RedCap UEs. Alternatively, a gNB cannot know whether any of the SSBs in a cell provided by another gNB are specific to RedCap UEs. In other words, a gNB cannot know whether an SSB specific to RedCap UEs is configured in a cell provided by another gNB. In other words, a gNB cannot know the location of an SSB specific to RedCap UEs associated with a cell provided by another gNB.

[0016] As mentioned above, in the future, the NCD-SSB in 3GPP Release 17 RedCap WI may be applied to all UEs, including RedCap UEs and non-RedCap UEs. This may mean that in the future, direct handover to a specific BWP of a target cell associated with NCD-SSB will also be allowed for non-RedCap UEs, instead of the initial BWP of the target cell associated with CD-SSB.

[0017] However, under the current XnAP signaling specifications, a gNB cannot know whether any of the SSBs in a cell provided by another gNB is a specific NCD-SSB for a direct handover to a BWP different from the initial BWP. In other words, a gNB cannot know whether a specific NCD-SSB for a direct handover to a BWP different from the initial BWP is configured in a cell provided by another gNB. In other words, a gNB cannot know the location of a specific NCD-SSB for a direct handover to a BWP different from the initial BWP, which is associated with a cell provided by another gNB.

[0018] One of the objectives to be achieved by the embodiments disclosed in this specification is to provide an apparatus, a method, and a program that contribute to enabling a gNB or RAN node to know an available NCD-SSB for direct handover to a non-initial BWP of a cell provided by another gNB or RAN node. It should be noted that this objective is only one of multiple objectives to be achieved by multiple embodiments disclosed in this specification. Other objectives or problems and novel features will become apparent from the description of this specification or the accompanying drawings. [Means for solving the problem]

[0019] In a first aspect, a first RAN node includes at least one memory and at least one processor coupled to the at least one memory, the at least one processor configured to receive a control message from a second RAN node indicating configuration information of a cell provided by the second RAN node, and the at least one processor configured to recognize, based on the configuration information, a specific SSB associated with the cell that needs to be measured by a UE for direct handover to a specific BWP of the cell that differs from an initial BWP of the cell.

[0020] In a second aspect, a method performed by a first RAN node includes the following steps: (a) receiving a control message from a second RAN node indicating configuration information of a cell provided by the second RAN node; and (b) Recognizing, based on the configuration information, a specific SSB associated with the cell that needs to be measured by the UE for direct handover to a specific BWP of the cell that is different from the initial BWP of the cell.

[0021] In a third aspect, the second RAN node includes at least one memory and at least one processor coupled to the at least one memory, wherein the at least one processor is configured to send a control message to the first RAN node indicating configuration information of a cell provided by the second RAN node, the configuration information including one or more information elements or fields for indicating specific SSBs associated with the cell that need to be measured by the UE for direct handover to a specific BWP of the cell that differs from an initial BWP of the cell.

[0022] In a fourth aspect, a method performed by a second RAN node includes sending a control message to a first RAN node indicating configuration information of a cell provided by the second RAN node, the configuration information including one or more information elements or fields for indicating specific SSBs associated with the cell that need to be measured by a UE for direct handover to a specific BWP of the cell that differs from an initial BWP of the cell.

[0023] A fifth aspect is directed to a program, which includes a group of instructions (software code) that, when loaded into a computer, causes the computer to perform the method according to the second or fourth aspect. [Effects of the Invention]

[0024] According to the above-described aspects, an apparatus, a method, and a program can be provided that contribute to enabling a gNB or RAN node to know the NCD-SSBs available for direct handover to non-initial BWPs of cells provided by other gNBs or RAN nodes. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a diagram illustrating an example of the configuration of a wireless communication system according to an embodiment. [Figure 2] FIG. 2 is a sequence diagram illustrating an example of signaling between RAN nodes according to an embodiment. [Figure 3] FIG. 2 is a sequence diagram illustrating an example of signaling between RAN nodes according to an embodiment. [Figure 4] FIG. 1 is a conceptual diagram of a handover according to an embodiment. [Figure 5] 10 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. [Figure 6] 10 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. [Figure 7] FIG. 10 is a diagram illustrating an example of the format of a Served Cell Information NR information element according to an embodiment. [Figure 8] FIG. 10 is a diagram illustrating an example of the format of a Served Cell Information NR information element according to an embodiment. [Figure 9] FIG. 10 is a diagram illustrating an example of the format of a Served Cell Information NR information element according to an embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of the format of a Served Cell Information NR information element according to an embodiment. [Figure 11] FIG. 10 is a diagram illustrating an example of the format of a Served Cell Information NR information element according to an embodiment. [Figure 12] FIG. 10 is a diagram illustrating an example of the format of a Served Cell Information NR information element according to an embodiment. [Figure 13] FIG. 10 is a diagram illustrating an example of a format of a MeasurementTimingConfiguration message according to an embodiment. [Figure 14] FIG. 10 is a diagram illustrating an example of a format of a MeasurementTimingConfiguration message according to an embodiment. [Figure 15] FIG. 2 is a sequence diagram illustrating an example of signaling between RAN nodes according to an embodiment. [Figure 16]10 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. [Figure 17] 10 is a flowchart illustrating an example of an operation of a RAN node according to an embodiment. [Figure 18] FIG. 2 is a block diagram illustrating a configuration example of a RAN node according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0027] The multiple embodiments described below can be implemented independently or in appropriate combination. These multiple embodiments have different novel features. Therefore, these multiple embodiments contribute to solving different purposes or problems and to achieving different effects.

[0028] The following embodiments will be described with a focus on the 3GPP Long Term Evolution (LTE) system and the fifth generation mobile communication system (5G system). However, these embodiments may be applied to other wireless communication systems that support similar technologies (e.g., handover) to the 3GPP system. Note that the term LTE as used in this specification includes improvements and developments of LTE and LTE-Advanced to enable interworking with the 5G system, unless otherwise specified.

[0029] As used herein, depending on the context, "if" may be construed to mean "when," "at or around the time," "after," "upon," "in response to determining," "in accordance with a determination," or "in response to detecting." These expressions may be construed to have the same meaning, depending on the context.

[0030] First, the configurations and operations of multiple network elements common to multiple embodiments will be described. Figure 1 shows an example configuration of a wireless communication system according to multiple embodiments. In the example of Figure 1, the wireless communication system includes an NG-RAN node 1, an NG-RAN node 2, and a UE 3. Each element (network function) shown in Figure 1 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on the dedicated hardware, or as a virtualized function instantiated on an application platform.

[0031] The NG-RAN node 1 is deployed in the Radio Access Network (RAN) (i.e., NG-RAN). The NG-RAN node 1 may be a gNB or an ng-eNB. The ng-eNB provides E-UTRA user plane and control plane protocol termination to the UE and is connected to the 5G Core Network (5GC) via an NG interface. The NG-RAN node 1 may be a Central Unit (CU) (e.g., gNB-CU or eNB-CU) in a cloud RAN (C-RAN) deployment, or a combination of a CU and one or more Distributed Units (DUs) (e.g., gNB-DUs or eNB-DUs). The C-RAN is also referred to as a CU / DU split. Furthermore, the CU may include a Control Plane (CP) Unit (e.g., gNB-CU-CP) and one or more User Plane (UP) Units (e.g., gNB-CU-UP). Thus, NG-RAN node 1 may be a CU-CP or a combination of a CU-CP and a CU-UP. Similarly, NG-RAN node 2 may be a CU or a combination of a CU and one or more DUs. NG-RAN node 2 may be a CU-CP or a combination of a CU-CP and a CU-UP.

[0032] NG-RAN nodes 1 and 2 communicate with each other via a node-to-node interface (i.e., Xn interface) 101. The Xn interface 101 includes an Xn control plane (Xn-C) interface and an Xn user plane (Xn-U) interface. NG-RAN nodes 1 and 2 support the Xn Application Protocol (XnAP) for signaling procedures over the Xn-C interface. The transport network layer of the Xn-U interface is built on Internet Protocol (IP) transport, and General Packet Radio Service Tunneling Protocol User (GTP-U) over User Datagram Protocol (UDP) / IP is used to transport user plane Protocol Data Units (PDUs).

[0033] The UE 3 is connected to the NG-RAN node 1 via the air interface 102. The UE 3 may perform carrier aggregation (CA). Specifically, the UE 3 may simultaneously connect to multiple serving cells provided by the NG-RAN node 1. The multiple serving cells include a primary cell (PCell) and one or more secondary cells (SCells). The UE 3 may communicate with the NG-RAN node 1 using CA between the PCell and one or more SCells.

[0034] Furthermore, the UE 3 may be simultaneously connected to multiple NG-RAN nodes (i.e., a Master Node (MN) and a Secondary Node (SN)) for dual connectivity. In this case, the NG-RAN node 1 in FIG. 1 may be an MN (or an M-NG-RAN node) or an SN (or an S-NG-RAN node). When operating as an MN, the NG-RAN node 1 provides a Master Cell Group (MCG) to the UE 3. The MCG is a group of serving cells associated with (or provided to) the MN, and includes a Special Cell (SpCell) (i.e., a PCell) and, optionally, one or more SCells. On the other hand, when operating as an SN, the NG-RAN node 1 provides a Secondary Cell Group (SCG) to the UE 3. The SCG includes a Primary SCG Cell (PSCell) and, optionally, one or more SCells. The PSCell is a Special Cell (SpCell) of the SCG and supports Physical Uplink Control Channel (PUCCH) transmission and contention-based Random Access.

[0035] Similar to what is described with respect to NG-RAN node 1, NG-RAN node 2 may provide CA for UE 3 and may act as a MN or SN of the DC for UE 3.

[0036] Note that in some implementations, the UE 3 may be a RedCap UE. If the UE 3 is a RedCap UE, the UE 3 may not support the CA and DC described above.

[0037] UE3 supports handover from NG-RAN node 1 to NG-RAN node 2. If UE3 supports DC, the handover may be an inter-MN handover, a Master Node to gNB Change, or a gNB to Master Node Change. The handover may be a conditional handover. The handover may also be referred to as network-controlled (inter-cell) mobility of an RRC_CONNECTED UE.

[0038] First Embodiment This embodiment provides improved signaling between NG-RAN nodes. A configuration example of the wireless communication system according to this embodiment may be the same as the example shown in FIG.

[0039] Figure 2 shows an example of inter-RAN node signaling. In step 201, NG-RAN node 2 sends a control message to NG-RAN node 1 indicating configuration information of a cell provided by NG-RAN node 2. The control message may be an XnAP message. The XnAP message may be a message sent in any of the procedures not related to a specific UE (i.e., global procedures). More specifically, the XnAP message may be sent in the Xn Setup procedure or the NG-RAN node Configuration Update procedure. The purpose of the Xn Setup procedure is to exchange application-level configuration data required for two NG-RAN nodes to interoperate correctly over the Xn-C interface. The purpose of the NG-RAN node Configuration Update procedure is to update application-level configuration data required for two NG-RAN nodes to interoperate correctly over the Xn-C interface. The control message (XnAP message) in step 201 may be, for example, but not limited to, an XN SETUP REQUEST, an XN SETUP RESPONSE, an NG-RAN NODE CONFIGURATION UPDATE, or an NG-RAN NODE CONFIGURATION UPDATE ACKNOWLEDGE message.

[0040] The cell configuration information included in the control message of step 201 may include a Served Cell Information NR information element (IE). The Served Cell Information NR IE includes cell configuration information of an NR cell that a neighboring NG-RAN node 1 may need over the XnAP interface. The cell configuration information includes one or more information elements or fields for indicating specific SSBs associated with the cell that need to be measured by the UE for direct handover to a specific BWP of a cell that is different from the initial BWP of the cell. In one example, the cell configuration information includes one or more information elements or fields for indicating the location of specific SSBs associated with the cell that need to be measured by the UE for direct handover to a specific BWP of a cell that is different from the initial BWP of the cell. In other words, the cell configuration information includes one or more information elements or fields for indicating which of multiple associated SSBs configured for the cell is a specific SSB (or NCD-SSB) for direct handover to a BWP that is different from the initial BWP. Alternatively, the configuration information of the cell includes one or more information elements or fields for indicating whether a specific SSB (or NCD-SSB) for direct handover to a BWP different from the initial BWP is configured or associated with the cell. Alternatively, the configuration information of the cell includes one or more information elements or fields for indicating that a specific SSB (or NCD-SSB) for direct handover to a BWP different from the initial BWP is configured or available in the cell.

[0041] The initials BWP are associated with CD-SSB. SSB consists of PSS and SSS, each occupying one symbol and 127 subcarriers, and PBCH, spanning three OFDM symbols and 240 subcarriers. CD-SSB is an SSB associated with RMSI. In other words, CD-SSB is an SSB associated with SIB1. To limit the frequency range that UEs should search for cell selection and cell reselection in RRC_IDLE or RRC_INACTIVE, CD-SSB is always located in the synchronization raster. The synchronization raster is also called the SS raster or SSB raster. The synchronization raster occupies a predetermined (or fixed) frequency range within the NR channel bandwidth.

[0042] The initial BWP includes at least a DL BWP and may also include an UL BWP (if the serving cell is configured for uplink). The initial DL BWP is configured with a control resource set for the Common Search Space (i.e., Type0-PDCCH common search space). The initial BWP is the BWP that the UE first visits when accessing the serving cell (i.e., when transitioning from RRC_IDLE to RRC_CONNECTED).

[0043] A specific SSB that needs to be measured by a UE for direct handover to a specific BWP of a cell different from the initial BWP of the cell is associated with a specific BWP different from the initial BWP. In other words, a specific BWP that is different from the initial BWP and can be a target BWP of direct handover is associated with a specific SSB different from the CD-SSB. That is, this specific SSB is an NCD-SSB. The specific BWP is not associated with a CD-SSB but is associated with an NCD-SSB. In other words, the specific BWP is associated with an (NCD-)SSB but is not associated with an RMSI (or SIB1). The NCD-SSB and the specific BWP may be located outside the synchronization raster.

[0044] The above-mentioned specific BWP and specific SSB for direct handover to a non-initial BWP may be a BWP and SSB specific to RedCap UEs. A BWP specific to RedCap UEs may be referred to as a RedCap-specific BWP or a BWP for RedCap. A RedCap-specific BWP may be used by RedCap UEs as an active BWP, typically as a First Active BWP. The First Active BWP is the BWP that a UE should use from the time (or immediately after) radio connection establishment (RRC Connection Setup) is completed in a serving cell, or the BWP that a UE should use first when a serving cell (e.g., SCell) is activated. The First Active BWP is specified to the UE by the NG-RAN node through dedicated RRC signaling. An SSB specific to RedCap UEs may be referred to as a RedCap-specific SSB, a RedCap-specific NCD-SSB, an SSB for RedCap, or an NCD-SSB for RedCap.

[0045] FIG. 3 shows a variation of the inter-RAN node signaling shown in FIG. 2. Step 301 is similar to step 201 in FIG. 2. Specifically, in step 301, NG-RAN node 2 sends a control message to NG-RAN node 1 indicating configuration information of a cell served by NG-RAN node 2. The configuration information of the cell (e.g., Served Cell Information NR IE) includes one or more IEs or fields indicating an NCD-SSB specific to RedCap UEs. In one example, the configuration information of the cell includes one or more IEs or fields indicating the location of an NCD-SSB specific to RedCap UEs. In other words, the configuration information of the cell includes one or more information elements or fields for indicating which of multiple SSBs configured in or associated with the cell is a RedCap-specific NCD-SSB. Alternatively, the configuration information of the cell includes one or more information elements or fields for indicating whether a RedCap-specific SSB is configured in or associated with the cell. Alternatively, the cell configuration information includes one or more information elements or fields to indicate that RedCap specific SSB is configured or available in the cell.

[0046] FIG. 4 conceptually illustrates a handover 400 from a source cell 420 to a target cell 460. Here, it is assumed that the source cell is provided by NG-RAN node 1, and the target cell is provided by NG-RAN node 2. An initial BWP 422 for RedCap and a First Active BWP 424 for RedCap are configured in the source cell 420. The initial BWP 422 includes a CD-SSB 421. The First Active BWP 424 includes an NCD-SSB 423. Similarly, an initial BWP 462 for RedCap and a First Active BWP 464 for RedCap are configured in the target cell 460. The initial BWP 462 includes a CD-SSB 461. The First Active BWP 464 includes an NCD-SSB 463.

[0047] During handover 400, UE 3 moves directly to the RedCap-specific BWP 464 of target cell 460 that contains NCD-SSB 463, rather than to the initial BWP 462 of target cell 460 that contains CD-SSB 461. To enable this, when UE 3 is RRC_CONNECTED with source cell 420, UE 3 measures NCD-SSB 463 in the First Active BWP 464 for RedCap of target cell 460 while using First Active BWP 424. Source NG-RAN node 1 generates and provides a measurement object to UE 3, enabling UE 3 to measure NCD-SSB 463 of target cell 460. Source NG-RAN node 1 can generate the measurement object using configuration information (e.g., Served Cell Information NR IE) of target cell 460 provided by target NG-RAN node 2. The configuration information (eg, Served Cell Information NR IE) of the target cell 460 may be provided to the source NG-RAN node 1 via a control message in step 201 of FIG. 2 or step 301 of FIG.

[0048] The measurement object that enables the UE 3 to measure the NCD-SSB 463 of the target cell 460 is a serving cell measurement object specific to the RRC_CONNECTED UE 3. The NG-RAN node 1 provides a measurement configuration to the RRC_CONNECTED UE 3 in the source cell 420, thereby configuring the UE 3 to perform measurements. The measurement configuration includes a list of one or more measurement objects, a list of one or more reporting configurations, and a list of one or more measurement identities. Each measurement object (MeasObject) is an object on which the UE 3 must perform measurements. Each measurement object may indicate the frequency and timing position of the reference signals to be measured, as well as the subcarrier spacing. Each measurement object is identified by a measurement object identifier (MeasObjectId). Each reporting configuration may define the reporting criteria, reference signal type, and report format. Each reporting configuration is identified by a reporting configuration identifier (ReportConfigId). Each measurement identifier (MeasId) links one measurement object to one reporting configuration.

[0049] The NG-RAN node 1 can generate a measurement object for measuring the NCD-SSB 463 of the target cell 460 using the configuration information (e.g., Served Cell Information NR IE) of the target cell 460 provided by the target NG-RAN node 2. The NG-RAN node 1 can then include the measurement object in the measurement configuration provided to the UE 3. In addition, the NG-RAN node 1 can include a reporting configuration associated with the measurement object in the measurement configuration of the UE 3. This allows the NG-RAN node 1 to cause the UE 3 in RRC_CONNECTED status in the source cell 420 to measure the NCD-SSB 463 of the target cell 460 and receive a report on the measurement from the UE 3. Based on this report, the NG-RAN node 1 can determine and initiate a handover 400 to directly hand over the UE 3 to the RedCap-specific BWP 464 of the target cell 460.

[0050] Note that the configuration and use of BWPs shown in Fig. 4 are merely examples and can be modified as appropriate. For example, Fig. 4 shows that an initial BWP for RedCap is set in association with CD-SSB, and a First Active BWP for RedCap is set in association with NCD-SSB, in both the source cell 420 and the target cell 460. Alternatively, for example, an initial BWP for RedCap may also be set in association with NCD-SSB, in at least one of the source cell 420 and the target cell 460.

[0051] FIG. 5 illustrates an example of the operation of NG-RAN node 1. The second RAN node illustrated in FIG. 5 refers to NG-RAN node 2. In step 501, NG-RAN node 1 receives from NG-RAN node 2 a control message indicating configuration information of a cell provided by NG-RAN node 2. In step 502, NG-RAN node 1 recognizes, based on the received configuration information, a specific SSB associated with the cell that needs to be measured by UEs for direct handover to a specific BWP of the cell that is different from the initial BWP of the cell. In one example, NG-RAN node 1 recognizes, based on the received configuration information, the location of a specific SSB associated with the cell that needs to be measured by UEs for direct handover to a specific BWP of the cell that is different from the initial BWP of the cell. In other words, NG-RAN node 1 recognizes, based on the received configuration information, which of multiple SSBs configured or associated with the cell provided by NG-RAN node 2 is a specific SSB (or NCD-SSB) for direct handover to a BWP that is different from the initial BWP. Alternatively, the NG-RAN node 1 recognizes, based on the received configuration information, whether a specific SSB (or NCD-SSB) for direct handover to a BWP different from the initial BWP is configured or associated in a cell served by the NG-RAN node 2. Alternatively, the NG-RAN node 1 recognizes, based on the received configuration information, that a specific SSB (or NCD-SSB) for direct handover to a BWP different from the initial BWP is configured or available in a cell served by the NG-RAN node 2.

[0052] FIG. 6 shows a modification of the operation shown in FIG. 5. Step 601 is similar to step 501 in FIG. 5. Specifically, NG-RAN node 1 receives from NG-RAN node 2 a control message indicating configuration information of a cell served by NG-RAN node 2. In step 602, NG-RAN node 1 recognizes an NCD-SSB specific to RedCap UEs associated with the cell served by NG-RAN node 2 based on the received configuration information. In one example, NG-RAN node 1 recognizes the location of an NCD-SSB specific to RedCap UEs associated with the cell served by NG-RAN node 2 based on the received configuration information. In other words, NG-RAN node 1 recognizes which of multiple SSBs configured in or associated with the cell served by NG-RAN node 2 is a RedCap-specific NCD-SSB based on the received configuration information. Alternatively, NG-RAN node 1 recognizes whether a RedCap-specific SSB is configured in or associated with the cell served by NG-RAN node 2 based on the received configuration information. Alternatively, NG-RAN node 1 recognizes based on the received configuration information that RedCap-specific SSB is configured or available in the cell served by NG-RAN node 2.

[0053] Further details of the cell configuration information included in the control messages of step 201 of FIG. 2 and step 301 of FIG. 3 are described below. As already described, the cell configuration information (e.g., Served Cell Information NR IE) may include one or more information elements or fields for indicating the location of a specific NCD-SSB for direct handover to a non-initial BWP or for RedCap UEs. The location of a specific NCD-SSB includes the frequency location and time location of the radio resource on which the SSB is transmitted. In some implementations, multiple NCD-SSBs specific for direct handover to a non-initial BWP or for RedCap UEs may be configured in one cell. In this case, the cell configuration information (e.g., Served Cell Information NR IE) may include one or more information elements or fields for indicating the location of each of the multiple specific NCD-SSBs.

[0054] These one or more information elements or fields may be used by the NG-RAN node 1 to configure timing occasions for the UE 3 to measure the specific SSB. As described with reference to FIG. 4, the NG-RAN node 1 may provide a measurement object to a UE 3 that is RRC_CONNECTED in the cell of the NG-RAN node 1, causing the UE 3 to measure the NCD-SSB of a neighboring cell provided by the NG-RAN node 2. This may allow the NG-RAN node 1 to assist in direct handover of the UE 3 to a BWP of a neighboring cell that is not associated with a CD-SSB but is associated with an NCD-SSB. In other words, the NG-RAN node 1 may assist in direct handover of the UE 3 to a RedCap-specific BWP (e.g., RedCap-specific First Active BWP) associated with a RedCap-specific NCD-SSB in the neighboring cell.

[0055] Alternatively, the cell configuration information (e.g., Served Cell Information NR IE) may include one or more information elements or fields for indicating whether a specific NCD-SSB is configured or associated with the cell for direct handover to a non-initial BWP or for RedCap UEs. In other words, the cell configuration information may include one or more information elements or fields for indicating that a specific NCD-SSB is configured or available for direct handover to a non-initial BWP or for RedCap UEs. These one or more information elements or fields can be used by the NG-RAN node 1 to know that a specific NCD-SSB is configured or available in the cell of a neighboring NG-RAN node 2. If the NG-RAN node 1 determines that a specific NCD-SSB is configured in the cell of a neighboring NG-RAN node 2 based on the information elements or fields in the cell configuration information, the NG-RAN node 1 may recognize the location (e.g., frequency location and time location) of the specific NCD-SSB using a list of multiple measurement timing configuration (e.g., MeasTiming) instances included in the cell configuration information. For example, NG-RAN node 1 may recognize that a certain instance (e.g., the second instance, or the last instance) in the list of MeasTiming instances relates to a specific SSB for direct handover to RedCap or non-initial BWP.

[0056] In a first implementation, these one or more information elements or fields may be one or more XnAP information elements.

[0057] In a second implementation, these one or more information elements or fields may be included in an inter-node RRC message carried in an XnAP message. An inter-node RRC message is generally an RRC message sent between RAN nodes over an inter-node interface, such as an Xn interface or an X2 interface.

[0058] Specifically, in the second implementation, the one or more information elements or fields may include a list of multiple measurement timing configuration (e.g., MeasTiming) instances. Each measurement timing configuration instance in the list indicates a frequency and timing occasion at which a corresponding SSB is measured. In one example, at least one of the measurement timing configuration instances included in the list may indicate that the SSB indicated in that instance is the above-mentioned specific SSB or NCD-SSB. In another example, the one or more information elements or fields may further include an information element or field that specifies which instance in the measurement timing configuration list provides a configuration for the above-mentioned specific SSB or NCD-SSB.

[0059] 7 to 12 show examples of the format of the Served Cell Information NR IE according to the first implementation. The Served Cell Information NR IE can be included in an XN SETUP REQUEST, XN SETUP RESPONSE, NG-RAN NODE CONFIGURATION UPDATE, or NG-RAN NODE CONFIGURATION UPDATE ACKNOWLEDGE message.

[0060] The Served Cell Information NR IE specifies the served cell with the NR Physical Cell Identity (NR-PCI) IE and the NR Cell Global Identity (CGI) IE. In the example of Figure 7, the Served Cell Information NR IE may optionally include an NCD-SSB Configuration IE. Similarly, in the example of Figure 8, the Served Cell Information NR IE may optionally include an NCD-SSB Configuration List IE. That is, the NCD-SSB Configuration List IE in Figure 8 can specify multiple NCD-SSBs for one serving cell, up to a predetermined maximum number.

[0061] In the examples of Figures 7 and 8, the NCD-SSB Configuration IE and NCD-SSB Configuration List IE indicate the NCD-SSB(s) of the cell specified in the Served Cell Information NR IE. The NCD-SSB Configuration IE and NCD-SSB Configuration List IE include an SSB Frequency Info IE and may optionally include an SSB Transmission Periodicity IE and an SSB Transmission Timing Offset IE.

[0062] The SSB Frequency Info IE indicates the frequency location of the NCD-SSB. Specifically, it indicates the center frequency of the NCD-SSB.

[0063] The SSB Transmission Periodicity IE and SSB Transmission Timing Offset IE indicate the timing opportunity at which the SSB is transmitted. In other words, these IEs can be used by the UE to set the timing opportunity at which the SSB is measured. The SSB Transmission Periodicity IE indicates the periodicity of the NCD-SSB. The SSB Transmission Periodicity IE is included in the Served Cell Information NR IE only if the periodicity of the NCD-SSB is longer than that of the CD-SSB. If the SSB Transmission Periodicity IE is omitted (absent), this means that the periodicity of the NCD-SSB is the same as that of the CD-SSB. On the other hand, the SSB Transmission Timing Offset IE indicates the offset of the SSB transmission timing in half frames. If the SSB Transmission Timing Offset IE is omitted (absent), this means that the offset of the transmission timing of the NCD-SSB is the same as that of the CD-SSB.

[0064] In the example of Figure 9, the Served Cell Information NR IE can optionally include a RedCap Measurement Timing Configuration IE. The RedCap Measurement Timing Configuration IE contains a RedCap-specific MeasurementTimingConfiguration inter-node RRC message. This MeasurementTimingConfiguration message contains a list of MeasTiming instances. Each MeasTiming instance in the list indicates the frequency and timing occasion at which the corresponding SSB is measured. That is, the MeasurementTimingConfiguration message carried in the RedCap Measurement Timing Configuration IE provides measurement timing configuration for one or more RedCap-specific NCD-SSBs only.

[0065] In the example of FIG. 10, the Served Cell Information NR IE may optionally include an NCD-SSB Transmission Indication IE. This IE indicates whether a specific NCD-SSB is configured or associated in the cell for direct handover to a non-initial BWP or for RedCap UEs. Alternatively, this IE indicates that a specific NCD-SSB is configured or available in the cell for direct handover to a BWP different from the initial BWP. In the example of FIG. 10, the NCD-SSB Transmission Indication IE is of an enumerated type and indicates "activated." The NCD-SSB Transmission Indication IE may indicate "activated" or "deactivated." If the NG-RAN node 1 determines based on the NCD-SSB Transmission Indication IE in the Served Cell Information NR that a specific NCD-SSB is configured in the cell of a neighboring NG-RAN node 2, the NG-RAN node 1 may recognize the location (e.g., frequency location and time location) of the specific NCD-SSB using a list of multiple MeasTiming instances included in the Served Cell Information NR IE.

[0066] In the example of FIG. 11 , the Served Cell Information NR IE may optionally include an NCD-SSB Positions in Burst IE. This IE indicates whether a specific NCD-SSB is configured or associated in the cell for direct handover to a non-initial BWP or for RedCap UEs. Alternatively, this IE indicates that a specific NCD-SSB is configured or available in the cell for direct handover to a BWP different from the initial BWP. In addition, this IE indicates the time-domain location of NCD-SSB beams transmitted within one half-frame (i.e., one burst set). If NG-RAN node 1 determines that a specific NCD-SSB is configured in the cell of neighboring NG-RAN node 2 based on the NCD-SSB Positions in Burst IE in the Served Cell Information NR, it may recognize the location of the specific NCD-SSB using the list of multiple MeasTiming instances included in the Served Cell Information NR IE.

[0067] In the example of FIG. 12, the Served Cell Information NR IE can optionally include an NCD-SSB Positions in Burst List IE. This IE indicates whether one or more NCD-SSBs specific for direct handover to a non-initial BWP or for RedCap UEs are configured or associated with the cell. Alternatively, this IE indicates that one or more NCD-SSBs specific for direct handover to a BWP different from the initial BWP are configured or available in the cell. In addition, this IE includes an NCD-SSB Positions in Burst IE to indicate, for each NCD-SSB, the time-domain location of the NCD-SSB beams transmitted within one half-frame (i.e., one burst set). In addition, in the example of FIG. 12, the NCD-SSB Positions in Burst List IE includes an NR-PCI IE to indicate the PCI associated with each NCD-SSB. The NCD-SSB Positions in Burst List IE may also include an absoluteFrequencySSB IE to indicate the frequency location (e.g., center frequency) of each NCD-SSB. If the NG-RAN node 1 determines based on the NCD-SSB Positions in Burst List IE in the Served Cell Information NR that one or more specific NCD-SSBs are configured in the cell of a neighboring NG-RAN node 2, the NG-RAN node 1 may recognize the location of the one or more specific NCD-SSBs using a list of multiple MeasTiming instances included in the Served Cell Information NR IE.

[0068] The formats of the information elements shown in Figures 7 to 12 are exemplary and can be modified in various ways. The names of the IEs shown in Figures 7 to 12 are not limited to these. Each of the NCD-SSB Configuration IE, NCD-SSB Configuration List IE, and RedCap Measurement Timing Configuration IE may include one or more IEs other than those shown. For example, the NCD-SSB Configuration IE and NCD-SSB Configuration List IE may include an NCD-SSB Positions In Burst IE to indicate the time-domain positions of SSB beams transmitted within one half-frame (i.e., one burst set).

[0069] 13 and 14 show examples of the format of an inter-node RRC message according to the second implementation, specifically, a MeasurementTimingConfiguration message. In the example of FIG. 13, MeasTimingList (1301) defines a sequence of one or more MeasTiming instances. Each MeasTiming instance (1302) defines information necessary for a UE to measure an SSB. Specifically, each MeasTiming instance (1302) indicates a frequency allocation (i.e., center frequency), subcarrier spacing, and SSB Measurement Timing Configuration (SSB-MTC). The SSB-MTC defines the SSB periodicity and offset necessary for a UE to set a timing opportunity to measure the SSB.

[0070] Furthermore, in the example of Figure 13, each MeasTiming instance (1302) can optionally include an ncd-SSB-RedCap field (1303). In the example of Figure 13, the ncd-SSB-RedCap field (1303) is an enumerated type and indicates "true." If a MeasTiming instance (1302) includes the ncd-SSB-RedCap field (1303), it means that the SSB indicated by the instance is a RedCap-specific NCD-SSB.

[0071] In the example of Figure 14, MeasTimingList (1401) defines a sequence of one or more MeasTiming instances. Each MeasTiming instance (1402) defines the information necessary for the UE to measure the SSB. Although omitted in Figure 14, each MeasTiming instance (1402) indicates the frequency allocation (i.e., center frequency), subcarrier spacing, and SSB-MTC.

[0072] The campOnFirstSSB field (1403) is of Boolean type. The campOnFirstSSB field (1403) set to the value true indicates that the SSB listed or indicated in the first MeasTiming instance in the MeasTiming list (1401) can be used for camping and PCell configuration (i.e., in spCellConfigCommon of the masterCellGroup).

[0073] Furthermore, in the example of Figure 14, the MeasurementTimingConfiguration message includes a HandoverOnSecondSSB-RedCap field (1404). The HandoverOnSecondSSB-RedCap field (1404) is of Boolean type. A HandoverOnSecondSSB-RedCap field (1404) set to the value true indicates that the SSB listed or indicated in the second MeasTiming instance of the MeasTiming list (1401) is a RedCap-specific NCD-SSB.

[0074] The formats of the inter-node RRC messages described with reference to Figures 13 and 14 are examples and can be modified in various ways. For example, the name of the ncd-SSB-RedCap field (1303) in Figure 13 may be changed to something else, such as "ncd-SSB-supportHO" or "ncd-SSB-supportCampOn". The name of the HandoverOnSecondSSB-RedCap field (1404) in Figure 14 may be changed to something else, such as "HandoverOnSecondSSB" or "HandoverOnSecondSSB". The inter-node RRC message formats shown in Figure 13 or 14 or similar thereto may be used together with any of the new Xn information elements shown in Figures 10 to 12 or similar thereto.

[0075] By using the control messages described in this embodiment (e.g., step 201 in FIG. 2 and step 301 in FIG. 3), the following advantages can be obtained, for example: NG-RAN node 1 can know whether or not any of the SSBs in the cell served by NG-RAN node 2 is an NCD-SSB specific for a direct handover to a BWP different from the initial BWP. In other words, NG-RAN node 1 can know whether or not an NCD-SSB specific for a direct handover to a BWP different from the initial BWP is configured in the cell served by NG-RAN node 2. In other words, NG-RAN node 1 can know the location of an NCD-SSB specific for a direct handover to a BWP different from the initial BWP, which is associated with the cell served by NG-RAN node 2.

[0076] Alternatively, the NG-RAN node 1 can know which SSBs in the cell served by the NG-RAN node 2 are specific to RedCap UEs. In other words, the NG-RAN node 1 can know whether SSBs specific to RedCap UEs are configured in the cell served by the NG-RAN node 2. In other words, the NG-RAN node 1 can know the location of SSBs specific to RedCap UEs associated with the cell served by the NG-RAN node 2.

[0077] Alternatively, NG-RAN node 1 may know that a specific NCD-SSB for direct handover to a BWP different from the initial BWP is configured or available in the cell served by NG-RAN node 2. Alternatively, NG-RAN node 1 may know that a RedCap specific NCD-SSB is configured or available in the cell served by NG-RAN node 2.

[0078] <Second embodiment> This embodiment provides an improvement to the operation of an NG-RAN node when receiving a control message from another NG-RAN node. An example of the configuration of a wireless communication system according to this embodiment may be the same as the example shown in FIG.

[0079] Figure 15 shows an example of inter-RAN node signaling. In step 1501, NG-RAN node 2 sends an XnAP message to NG-RAN node 1, which includes configuration information of the cell provided by NG-RAN node 2 (i.e., Served Cell Information NR IE). The XnAP message may be, for example, but not limited to, an XN SETUP REQUEST, XN SETUP RESPONSE, NG-RAN NODE CONFIGURATION UPDATE, or NG-RAN NODE CONFIGURATION UPDATE ACKNOWLEDGE message. The Served Cell Information NR IE includes a RedCap Broadcast Information IE and a Measurement Timing Configuration IE. The RedCap Broadcast Information IE and the Measurement Timing Configuration IE may be the same as those included in the existing Served Cell Information NR IE. The Measurement Timing Configuration IE indicates a list of MeasTiming instances.

[0080] Figure 16 shows an example of the operation of NG-RAN node 1. The second RAN node depicted in Figure 16 refers to NG-RAN node 2. In step 1601, NG-RAN node 1 receives an XnAP message from NG-RAN node 2 indicating a Served Cell Information NR IE of a cell served by NG-RAN node 2. The Served Cell Information NR IE includes a RedCap Broadcast Information IE and a Measurement Timing Configuration IE.

[0081] In step 1602, NG-RAN node 1 uses the RedCap Broadcast Information IE together with the information in the Measurement Timing Configuration IE to determine that at least one of the one or more NCD-SSBs indicated in the list of MeasTiming instances is a RedCap-specific SSB. In other words, using the RedCap Broadcast Information IE together with the information in the Measurement Timing Configuration IE, NG-RAN node 1 implicitly knows the RedCap-specific SSB (or NCD-SSB) configured for the cell served by NG-RAN node 2. In one example, if the Served Cell Information NR IE includes the RedCap Broadcast Information IE, NG-RAN node 1 may recognize that a certain instance (e.g., the second instance or the last instance) in the list of MeasTiming instances relates to a RedCap-specific SSB.

[0082] Figure 17 shows another example of the operation of NG-RAN node 1. Step 1701 is similar to step 1601 in Figure 16. In step 1702, NG-RAN node 1 determines or detects that a RedCap Broadcast Information IE is included in the Served Cell Information NR IE and that the MeasTiming list in the Served Cell Information NR IE includes multiple instances. In this case, NG-RAN node 1 determines that at least one of the one or more NCD-SSBs in the list is a RedCap-specific SSB. In other words, NG-RAN node 1 implicitly knows the RedCap-specific SSB (or NCD-SSB) configured for the cell served by NG-RAN node 2. In one example, if the Served Cell Information NR IE includes a RedCap Broadcast Information IE, NG-RAN node 1 may recognize that a certain instance (e.g., the second instance or the last instance) in the list of MeasTiming instances relates to a RedCap-specific SSB.

[0083] According to the operation described in this embodiment, the NG-RAN node 1 can know whether an SSB specific to RedCap UEs is configured in a cell served by the NG-RAN node 2 based on the information contained in the existing Served Cell Information NR IE.

[0084] Next, configuration examples of the NG-RAN nodes 1 and 2 according to the above-described embodiments will be described below. Fig. 18 is a block diagram showing a configuration example of the NG-RAN node 1 according to the above-described embodiments. The NG-RAN node 2 may also have a configuration similar to the configuration shown in Fig. 18.

[0085] Referring to FIG. 18 , the NG-RAN node 1 includes a Radio Frequency (RF) transceiver 1801, a network interface 1803, a processor 1804, and a memory 1805. The RF transceiver 1801 performs analog RF signal processing for communication with UEs. The RF transceiver 1801 may include multiple transceivers. The RF transceiver 1801 is coupled to an antenna array 1802 and a processor 1804. The RF transceiver 1801 receives modulation symbol data from the processor 1804, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1802. The RF transceiver 1801 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1802 and provides the baseband receive signal to the processor 1804. The RF transceiver 1801 may include an analog beamformer circuit for beamforming. The analog beamformer circuit may include, for example, multiple phase shifters and multiple power amplifiers.

[0086] The network interface 1803 is used to communicate with network nodes (e.g., other RAN nodes, and control plane nodes and user plane nodes of the core network), and may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0087] The processor 1804 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. The processor 1804 may include multiple processors. For example, the processor 1804 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing.

[0088] For example, digital baseband signal processing by the processor 1804 may include signal processing of a Service Data Adaptation Protocol (SDAP) layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Medium Access Control (MAC) layer, and a Physical (PHY) layer. Control plane processing by the processor 1804 may also include processing of Non-Access Stratum (NAS) messages, RRC messages, Medium Access Control (MAC) Control Elements (CEs), and Downlink Control Information (DCI). Control plane processing by the processor 1804 may also include processing of application layer signaling protocols such as XnAP, FIAP, and NGAP.

[0089] The processor 1804 may include a digital beamformer module for beamforming, which may include a Multiple Input Multiple Output (MIMO) encoder and precoder.

[0090] The memory 1805 is configured by a combination of volatile memory and non-volatile memory. The volatile memory is, for example, Static Random Access Memory (SRAM), Dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is, for example, Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. The memory 1805 may include storage located remotely from the processor 1804. In this case, the processor 1804 may access the memory 1805 via the network interface 1803 or an I / O interface.

[0091] The memory 1805 may store one or more software modules (computer programs) 1806 including instructions and data for performing the processing by the NG-RAN node 1 described in the above-described embodiments. In some implementations, the processor 1804 may be configured to read and execute the software modules 1806 from the memory 1805 to perform the processing by the NG-RAN node 1 described in the above-described embodiments.

[0092] It should be noted that if the NG-RAN node 1 is a Central Unit (CU) (e.g., eNB-CU or gNB-CU) or a CU-CP, the NG-RAN node 1 may not include the RF transceiver 1801 (and the antenna array 1802).

[0093] As described with reference to FIG. 18 , each of the processors included in the NG-RAN nodes 1 and 2 according to the above-described embodiments can execute one or more programs including instructions for causing a computer to perform the algorithms described with reference to the drawings. The programs include instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The programs may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disk (DVD), Blu-ray® disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The programs may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0094] Furthermore, the above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications are possible.

[0095] For example, some or all of the above embodiments can be described as, but are not limited to, the following supplementary notes.

[0096] (Appendix 1) a first Radio Access Network (RAN) node, at least one memory; at least one processor coupled to the at least one memory; Equipped with The at least one processor: receiving a control message from a second RAN node indicating configuration information of a cell provided by the second RAN node; Based on the configuration information, recognize a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from the initial BWP of the cell; It is configured as follows: First RAN node. (Appendix 2) the configuration information includes one or more information elements or fields for indicating the location of the specific SSB; 1. The first RAN node of claim 1. (Appendix 3) the unique SSB includes a plurality of unique SSBs; the one or more information elements or fields indicating the location of each of the plurality of unique SSBs; 2. The first RAN node of claim 1. (Appendix 4) the one or more information elements or fields are used by the first RAN node to configure the UE with timing occasions for measuring the specific SSB. 4. The first RAN node of claim 2 or 3. (Appendix 5) the at least one processor is configured to recognize the location of the unique SSB based on the configuration information; 5. The first RAN node according to any one of Supplementary Note 1 to 4. (Appendix 6) the control message is an Xn Application Protocol (XnAP) message; the one or more information elements or fields are one or more XnAP information elements, 6. The first RAN node according to any one of Supplementary Note 2 to 5. (Appendix 7) the control message is an Xn Application Protocol (XnAP) message; the one or more information elements or fields are included in an inter-node Radio Resource Control (RRC) message carried in the control message; 6. The first RAN node according to any one of Supplementary Note 2 to 5. (Appendix 8) the one or more information elements or fields include a list of multiple MeasTiming instances; Each MeasTiming instance in the list indicates the frequency and timing occasion at which the corresponding SSB is measured; At least one MeasTiming instance included in the list indicates that the SSB indicated in that instance is the specific SSB; 7. The first RAN node of claim 7. (Appendix 9) the one or more information elements or fields include a list of multiple MeasTiming instances; Each MeasTiming instance in the list indicates the frequency and timing occasion at which the corresponding SSB is measured; The one or more information elements or fields further include an information element or field specifying which MeasTiming instance in the list provides the configuration for the particular SSB. 7. The first RAN node of claim 7. (Appendix 10) the configuration information includes one or more information elements or fields indicating whether the specific SSB is associated with or configured in the cell; 1. The first RAN node of claim 1. (Appendix 11) the control message is an Xn Application Protocol (XnAP) message; the one or more information elements or fields are one or more XnAP information elements, 11. The first RAN node of claim 10. (Appendix 12) the at least one processor is configured to recognize whether the specific SSB is associated with or configured in the cell based on the configuration information. 12. The first RAN node of claim 1, 10, or 11. (Appendix 13) the control message is an Xn Application Protocol (XnAP) message; The setting information includes a Served Cell Information (NR) information element, The Served Cell Information NR information element includes a RedCap Broadcast Information information element and a Measurement Timing Configuration information element, The Measurement Timing Configuration information element includes a list of one or more MeasTiming instances; the at least one processor is configured to use the RedCap Broadcast Information information element together with information in the Measurement Timing Configuration information element to determine that at least one of one or more Non-Cell Defining (NCD) SSBs indicated in the list is the specific SSB. 1. The first RAN node of claim 1. (Appendix 14) the control message is an Xn Application Protocol (XnAP) message; The setting information includes a Served Cell Information (NR) information element, The Served Cell Information NR information element includes a Measurement Timing Configuration information element, The Measurement Timing Configuration information element includes a list of one or more MeasTiming instances; Each MeasTiming instance in the list indicates the frequency and timing occasion at which the corresponding SSB is measured; The at least one processor is configured to determine that, if a RedCap Broadcast Information information element is included in the Served Cell Information NR information element and multiple MeasTiming instances are included in the list, at least one of one or more Non-Cell Defining (NCD) SSBs in the list is the specific SSB. 1. The first RAN node of claim 1. (Appendix 15) The location of the specific SSB includes a frequency location and a time location of the radio resource on which the specific SSB is transmitted. 6. The first RAN node according to any one of Supplementary Note 2 to 5. (Appendix 16) The unique SSB is a Non-Cell Defining (NCD) SSB that is not associated with an RMSI or SIB1. 16. The first RAN node according to any one of Supplementary Notes 1 to 15. (Appendix 17) The initial BWP is a BWP associated with a Cell Defining (CD) SSB to which Remaining Minimum System Information (RMSI) or System Information Block Type 1 (SIB1) is associated; 17. The first RAN node of claim 16. (Appendix 18) The CD-SSB is arranged in a predetermined synchronous raster; The NCD-SSB is not arranged in the synchronization raster; 18. The first RAN node of claim 17. (Appendix 19) The frequency location of the specific SSB is not included in the initial BWP, but is included in the specific BWP; 19. The first RAN node according to any one of Supplementary Notes 1 to 18. (Appendix 20) The specific SSB is a specific SSB for Reduced Capability (RedCap) UEs. 20. The first RAN node according to any one of Supplementary Notes 1 to 19. (Appendix 21) 1. A method performed by a first Radio Access Network (RAN) node, comprising: receiving a control message from a second RAN node indicating configuration information of a cell provided by the second RAN node; and Recognizing, based on the configuration information, a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from an initial BWP of the cell; A method for providing the above. (Appendix 22) 1. A program for causing a computer to perform a method for a first Radio Access Network (RAN) node, the method comprising: The method comprises: receiving a control message from a second RAN node indicating configuration information of a cell provided by the second RAN node; and Recognizing, based on the configuration information, a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from an initial BWP of the cell; A program that includes: (Appendix 23) a second Radio Access Network (RAN) node, at least one memory; at least one processor coupled to the at least one memory; Equipped with The at least one processor: configured to send a control message to the first RAN node indicating configuration information of a cell served by the second RAN node; The configuration information includes one or more information elements or fields for indicating a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from the initial BWP of the cell; Second RAN node. (Appendix 24) the one or more information elements or fields indicate the location of the specific SSB; 24. The second RAN node of claim 23. (Appendix 25) the unique SSB includes a plurality of unique SSBs; the one or more information elements or fields indicating the location of each of the plurality of unique SSBs; 25. The second RAN node of claim 24. (Appendix 26) the one or more information elements or fields are used by the first RAN node to configure timing occasions for measuring the specific SSBs in the UE. 26. The second RAN node according to any one of Supplementary Notes 23 to 25. (Appendix 27) the one or more information elements or fields are used by the first RAN node to identify the location of the specific SSB; 26. The second RAN node according to any one of Supplementary Notes 23 to 25. (Appendix 28) the control message is an Xn Application Protocol (XnAP) message; the one or more information elements or fields are one or more XnAP information elements, 28. The second RAN node according to any one of Supplementary Notes 23 to 27. (Appendix 29) the control message is an Xn Application Protocol (XnAP) message; the one or more information elements or fields are included in an inter-node Radio Resource Control (RRC) message carried in the control message; 29. The second RAN node according to any one of Supplementary Notes 23 to 28. (Appendix 30) the one or more information elements or fields include a list of multiple MeasTiming instances; Each MeasTiming instance in the list indicates the frequency and timing occasion at which the corresponding SSB is measured; At least one MeasTiming instance included in the list indicates that the SSB indicated in that instance is the specific SSB; 20. The second RAN node of claim 29. (Appendix 31) the one or more information elements or fields include a list of multiple MeasTiming instances; Each MeasTiming instance in the list indicates the frequency and timing occasion at which the corresponding SSB is measured; The one or more information elements or fields further include an information element or field specifying which MeasTiming instance in the list provides the configuration for the particular SSB. 20. The second RAN node of claim 29. (Appendix 32) The location of the specific SSB includes a frequency location and a time location of the radio resource on which the specific SSB is transmitted. 28. The second RAN node of claim 24, 25, or 27. (Appendix 33) the one or more information elements or fields indicating whether the specific SSB is associated with or configured in the cell; 24. The second RAN node of claim 23. (Appendix 34) the one or more information elements or fields are used by the first RAN node to recognize whether the specific SSB is associated with or configured in the cell; 34. The second RAN node of claim 23 or 33. (Appendix 35) the control message is an Xn Application Protocol (XnAP) message; the one or more information elements or fields are one or more XnAP information elements, 35. The second RAN node of claim 33 or 34. (Appendix 36) The unique SSB is a Non-Cell Defining (NCD) SSB that is not associated with an RMSI or SIB1. 36. The second RAN node according to any one of Supplementary Notes 23 to 35. (Appendix 37) The initial BWP is a BWP associated with a Cell Defining (CD) SSB to which Remaining Minimum System Information (RMSI) or System Information Block Type 1 (SIB1) is associated; 37. The second RAN node of claim 36. (Appendix 38) The CD-SSB is arranged in a predetermined synchronous raster; The NCD-SSB is not arranged in the synchronization raster; 38. The second RAN node of claim 37. (Appendix 39) The frequency location of the specific SSB is not included in the initial BWP, but is included in the specific BWP; 39. The second RAN node according to any one of Supplementary Notes 23 to 38. (Appendix 40) The specific SSB is a specific SSB for Reduced Capability (RedCap) UEs. 39. The second RAN node according to any one of Supplementary Notes 23 to 39. (Appendix 41) 1. A method performed by a second Radio Access Network (RAN) node, comprising: sending a control message to a first RAN node indicating configuration information of a cell served by the second RAN node; The configuration information includes one or more information elements or fields for indicating a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from the initial BWP of the cell; method. (Appendix 42) 1. A program for causing a computer to perform a method for a second Radio Access Network (RAN) node, the program comprising: The method comprises sending a control message to a first RAN node indicating configuration information of a cell served by the second RAN node; The configuration information includes one or more information elements or fields for indicating a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from the initial BWP of the cell; program.

[0097] This application claims priority based on Japanese Patent Application No. 2022-125116, filed on August 4, 2022, the disclosure of which is incorporated herein in its entirety. [Explanation of symbols]

[0098] 1, 2 NG-RAN nodes 3UE 1804 processor 1805 memory 1806 Module

Claims

1. a first Radio Access Network (RAN) node, means for receiving a control message from a second RAN node indicating configuration information of a cell provided by the second RAN node; means for recognizing, based on the configuration information, a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from an initial BWP of the cell; Equipped with First RAN node.

2. the configuration information includes one or more information elements or fields for indicating the location of the specific SSB; The first RAN node of claim 1.

3. the configuration information includes one or more information elements or fields indicating whether the specific SSB is associated with or configured in the cell; The first RAN node of claim 1.

4. the control message is an Xn Application Protocol (XnAP) message; The setting information includes a Served Cell Information (NR) information element, The Served Cell Information NR information element includes a RedCap Broadcast Information information element and a Measurement Timing Configuration information element, The Measurement Timing Configuration information element includes a list of one or more MeasTiming instances; the recognizing means is configured to use the RedCap Broadcast Information information element together with information in the Measurement Timing Configuration information element to determine that at least one of the one or more Non-Cell Defining (NCD) SSBs indicated in the list is the specific SSB. The first RAN node of claim 1.

5. the control message is an Xn Application Protocol (XnAP) message; The setting information includes a Served Cell Information (NR) information element, The Served Cell Information NR information element includes a Measurement Timing Configuration information element, The Measurement Timing Configuration information element includes a list of one or more MeasTiming instances; Each MeasTiming instance in the list indicates the frequency and timing occasion at which the corresponding SSB is measured; The recognizing means is configured to determine that, if a RedCap Broadcast Information information element is included in the Served Cell Information NR information element and multiple MeasTiming instances are included in the list, at least one of one or more Non-Cell Defining (NCD) SSBs in the list is the specific SSB. The first RAN node of claim 1.

6. The unique SSB is a Non-Cell Defining (NCD) SSB that is not associated with an RMSI or SIB1. A first RAN node according to any one of claims 1 to 5.

7. 1. A method performed by a first Radio Access Network (RAN) node, comprising: receiving a control message from a second RAN node indicating configuration information of a cell provided by the second RAN node; and Recognizing, based on the configuration information, a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from an initial BWP of the cell; A method for providing the above.

8. 1. A program for causing a computer to perform a method for a first Radio Access Network (RAN) node, the program comprising: The method comprises: receiving a control message from a second RAN node indicating configuration information of a cell provided by the second RAN node; and Recognizing, based on the configuration information, a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from an initial BWP of the cell; A program that includes:

9. a second Radio Access Network (RAN) node, means for sending a control message to a first RAN node indicating configuration information of a cell provided by the second RAN node; The configuration information includes one or more information elements or fields for indicating a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from the initial BWP of the cell; Second RAN node.

10. 1. A method performed by a second Radio Access Network (RAN) node, comprising: sending a control message to a first RAN node indicating configuration information of a cell served by the second RAN node; The configuration information includes one or more information elements or fields for indicating a specific Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB) associated with the cell that needs to be measured by a User Equipment (UE) for direct handover to a specific BWP of the cell that is different from the initial BWP of the cell; method.

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