Radio terminal and method thereof

Abstract

The invention provides a radio terminal and a method thereof. In a case where a downlink bandwidth part (BWP) is switched from a first BWP to a second BWP in a manner that does not change a cell-defining synchronization signal block (SSB), the radio terminal (12) continues to use a first SSB associated with the first BWP for radio link monitoring (RLM) measurements after the downlink BWP is switched to the second BWP if a reference signal type used for RLM is set to an SSB type. This enables the radio terminal to monitor a proper reference signal (RS) used for RLM measurements after a DL active BWP switch, for example.

Description

[0001] (This application is a divisional application of the application filed on August 14, 2018, with application number 2018800859543 and title "Radio Terminal and Method Thereof".) Technical Field

[0002] The present invention relates to radio communication systems, and more particularly to radio communication systems using one or more bandwidth portions configured within a carrier bandwidth. Background Technology

[0003] The 3rd Generation Partnership Project (3GPP) has been working on the standardization of fifth-generation mobile communication systems (5G) to make 5G a commercial reality in 2020 or later. 5G is expected to be achieved through continuous enhancements / evolutions of LTE and LTE-Advanced, as well as innovative enhancements / evolutions through the introduction of new 5G air interfaces (i.e., new Radio Access Technologies (RATs)). The new RATs support frequency bands higher than those supported by LTE / LTE-Advanced and their continued evolutions (e.g., 6 GHz or lower). For example, the new RATs support centimeter wave bands (10 GHz or higher) and millimeter wave bands (30 GHz or higher).

[0004] In this specification, the fifth-generation mobile communication system is referred to as a 5G system or a Next-Gen (NG) system. The new Radio Access Network (RAN) of the 5G system is referred to as New Radio (NR), 5G RAT, or NG RAT. The new Radio Access Network (RAN) of the 5G system is referred to as 5G-RAN or NextGen RAN (NG RAN). The new base station within the NG-RAN is referred to as NR NodeB (NR NB) or gNodeB (gNB). The new core network of the 5G system is referred to as 5G Core Network (5G-CN or 5GC) or NextGen Core (NG Core). Radio terminals capable of connecting to the 5G system (i.e., User Equipment (UE)) are referred to as 5G UE or NextGen UE (NG UE), or simply UE. As standardization progresses, the official names for the RAT, UE, radio access network, core network, network entities (nodes), and protocol layers used in the NG system will be determined in the future.

[0005] Unless otherwise stated, the term "LTE" as used in this specification includes LTE and enhanced / evolved LTE-Advanced to provide interoperability with 5G systems. The LTE and enhanced / evolved LTE-Advanced used for interoperability with 5G systems are referred to as LTE-Advanced Pro, LTE+, or enhanced LTE (eLTE). Furthermore, unless otherwise stated, terms related to LTE networks and logical entities as used in this specification (such as "Evolved Packet Core (EPC)," "Mobility Management Entity (MME)," "Serving Gateway (S-GW)," and "Packet Data Network (PDN) Gateway (P-GW)," etc.) include their enhancements / evolutions to provide interoperability with 5G systems. Enhanced EPC, enhanced MME, enhanced S-GW, and enhanced P-GW are referred to, for example, enhanced EPC (eEPC), enhanced MME (eMME), enhanced S-GW (eS-GW), and enhanced P-GW (eP-GW).

[0006] In LTE and LTE-Advanced, to achieve Quality of Service (QoS) and packet routing, bearers for each QoS level and for each PDN connection are used in both the RAN (i.e., Evolved Universal Terrestrial RAN (E-UTRAN)) and the core network (i.e., EPC). That is, in the bearer-based QoS (or bearer-specific QoS) concept, one or more Evolved Packet System (EPS) bearers are configured between the UE and the P-GW in the EPC, and multiple Service Data Streams (SDFs) with the same QoS level are transmitted via an EPS bearer that satisfies that QoS.

[0007] In contrast, regarding 5G systems, the discussion focuses on the use of radio bearers in NG-RAN but not in 5GC or at the interface between 5GC and NG-RAN. Specifically, PDU flows are defined instead of EPS bearers, and one or more SDFs are mapped to one or more PDU flows. The PDU flow between the 5G UE and the user plane terminal entity in the NG core (i.e., the entity corresponding to the P-GW in the EPC) corresponds to the EPS bearer in the EPS bearer-based QoS concept. PDU flows correspond to the finest granularity of packet forwarding and processing within the 5G system. That is, instead of the bearer-based QoS concept, the 5G system adopts a flow-based QoS (or flow-specific QoS) concept. In the flow-based QoS concept, QoS is processed for each PDU flow. The association between the 5G UE and the data network is called a "PDU session." The term "PDU session" corresponds to the term "PDN connection" in LTE and Advanced LTE. Multiple PDU flows can be configured within a single PDU session. The 3GPP specification defines a 5G QoS indicator (5QI) for 5G systems that corresponds to the QCI in LTE.

[0008] PDU flows are also referred to as "QoS flows." QoS flows represent the finest granularity of QoS treatment within a 5G system. User plane traffic within a PDU session that shares the same N3 tag value corresponds to a QoS flow. The N3 tag corresponds to the PDU flow ID mentioned above, and is also known as the QoS Flow Identifier (QFI) or Flow Identification Indicator (FII). There is at least a one-to-one relationship (i.e., a one-to-one mapping) between each of the 5QIs defined in the specification and the corresponding QFI with the same value (or number) as that 5QI.

[0009] Figure 1 This illustrates the basic architecture of a 5G system. The UE establishes one or more Signaling Radio Bearers (SRBs) and one or more Data Radio Bearers (DRBs) with the gNB. The 5GC and gNB establish the control plane interface and user plane interface used by the UE. The control plane interface between the 5GC and gNB (i.e., the RAN) is referred to as the N2 interface, NG2 interface, or NG-c interface, and is used for the transmission of Non-Access Stratum (NAS) information and control information (e.g., N2 AP information elements) between the 5GC and gNB. The user plane interface between the 5GC and gNB (i.e., the RAN) is referred to as the N3 interface, NG3 interface, or NG-u interface, and is used for the transmission of packets for one or more PDU streams within the UE's PDU session.

[0010] Notice, Figure 1 The architecture shown is just one of the 5G architecture options (or deployment schemes). Figure 1 The architecture shown is referred to as "Standalone NR (in the NextGen system)" or "Option 2". 3GPP further discusses the network architecture used for multi-connectivity operations employing E-UTRA and NR radio access technologies. A representative example of multi-connectivity operation is dual-connectivity (DC), where a primary node (MN) and a secondary node (SN) cooperate with each other and simultaneously communicate with a UE. Dual-connectivity operation using E-UTRA and NR radio access technologies is called Multi-RAT Dual-Connectivity (MR-DC). MR-DC is a dual connection between an E-UTRA node and an NR node.

[0011] In MR-DC, one of the E-UTRA node (i.e., eNB) and the NR node (i.e., gNB) operates as the primary node (MN), while the other operates as the secondary node (SN), and at least the MN is connected to the core network. The MN provides the UE with one or more primary cell groups (MCGs), while the SN provides the UE with one or more secondary cell groups (SCGs). MR-DC includes "MR-DC utilizing EPC" and "MR-DC utilizing 5GC".

[0012] MR-DC utilizing EPC includes E-UTRA-NR dual connectivity (EN-DC). In EN-DC, the UE connects to the eNB operating as the MN and the gNB operating as the SN. Furthermore, the eNB (i.e., the primary eNB) connects to the EPC, while the gNB (i.e., the secondary gNB) connects to the primary eNB via the X2 interface.

[0013] MR-DC utilizing 5GC includes NR-E-UTRA dual connectivity (NE-DC) and NG-RAN E-UTRA-NR dual connectivity (NG-EN-DC). In NE-DC, the UE connects to a gNB operating as an MN and an eNB operating as an SN. The gNB (i.e., the primary gNB) is connected to the 5GC, and the eNB (i.e., the secondary eNB) is connected to the primary gNB via the Xn interface. On the other hand, in NG-EN-DC, the UE connects to an eNB operating as an MN and a gNB operating as an SN. The eNB (i.e., the primary eNB) is connected to the 5GC, and the gNB (i.e., the secondary gNB) is connected to the primary eNB via the Xn interface.

[0014] Figure 2 , Figure 3 and Figure 4 The network structures for the three DC types (EN-DC, NE-DC, and NG-EN-DC) are shown respectively. Note that, although... Figure 2 The auxiliary gNB (SgNB) in EN-DC is also called en-gNB, and Figure 3 The auxiliary eNB (SeNB) in NE-DC and Figure 4 The primary eNB (MeNB) in the NG-EN-DC is also referred to as the ng-eNB, but in this specification, all three will be simply referred to as gNB or eNB. The 5G system also supports dual connectivity between two gNBs. In this specification, dual connectivity between two gNBs is referred to as NR-NR DC. Figure 5 The network structure of NR-NR DC is shown.

[0015] NR is expected to use different sets of radio parameters across multiple frequency bands. Each set of radio parameters is referred to as a "numerology." The OFDM digital schemes used in Orthogonal Frequency Division Multiplexing (OFDM) systems include, for example, subcarrier spacing, system bandwidth, transmit time interval (TTI) length, subframe duration, cyclic prefix length, and symbol duration. 5G systems support various types of services with different service requirements, including, for example, enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), and M2M communication with a large number of connections (e.g., massive machine-type communication (mMTC)). The choice of digital scheme depends on the service requirements.

[0016] In 5G systems, UEs and NR gNBs support the aggregation of multiple NR carriers with different digital schemes. 3GPP discusses the aggregation of multiple NR carriers (or NR cells) with different digital schemes through lower-layer aggregation (such as existing LTE carrier aggregation (CA)) or higher-layer aggregation (such as existing dual connectivity).

[0017] 5G NR supports channel bandwidths wider than LTE (e.g., hundreds of MHz). One channel bandwidth (i.e., BW) Channel Channel bandwidth is the radio frequency (RF) bandwidth that supports one NR carrier. Channel bandwidth is also known as system bandwidth. While LTE supports channel bandwidths up to 20MHz, 5G NR supports, for example, channel bandwidths up to 500MHz.

[0018] To effectively support multiple 5G services (such as broadband services like eMBB and narrowband services like the Internet of Things (IoT)), it is preferable to multiplex these services onto a single channel bandwidth. Furthermore, if each 5G UE needs to support transmission and reception within a transmission bandwidth corresponding to the entire channel bandwidth, this could hinder the implementation of lower-cost and lower-power UEs for narrowband IoT services. Therefore, 3GPP allows configuring one or more bandwidth portions (BWPs) within the carrier bandwidth (i.e., channel bandwidth or system bandwidth) of each NR component carrier. Multiple BWPs within an NR channel bandwidth can be used for different frequency division multiplexing (FDM) schemes using different digital schemes (e.g., subcarrier spacing (SCS)). The bandwidth portion is also referred to as the carrier bandwidth portion.

[0019] A bandwidth portion (BWP) is frequency-contiguous and comprises adjacent physical resource blocks (PRBs). The bandwidth of a BWP is at least as large as a synchronization signal (SS) / physical broadcast channel (PBCH) block. A BWP may or may not include SS / PBCH blocks (SSBs). BWP configurations include, for example, a digital scheme, frequency location, and bandwidth (e.g., the number of PRBs). To specify frequency locations, a common PRB index is used for downlink (DL) BWP configurations at least for Radio Resource Control (RRC) connected states. Specifically, the offset of the SSB to be accessed by the UE from PRB 0 to the lowest PRB is configured via upper-layer signaling. The reference point "PRB 0" is common to all UEs sharing the same wideband component carrier.

[0020] An SS / PBCH block includes the primary signals required by the idle UE, such as the NR synchronization signal (NR-SS) and the NR physical broadcast channel (NR-PBCH). The NR-SS is used by the UE for DL ​​synchronization. A reference signal (RS) is transmitted in the SS / PBCH block to enable the idle UE to perform radio resource management (RRM) measurements (e.g., RSRP measurements). This RS can be the NR-SS itself or an additional RS. The NR-PBCH broadcasts a portion of the minimum system information (SI) (e.g., the main information block (MIB)). The remaining minimum SI (RMSI) is transmitted on the physical downlink shared channel (PDSCH).

[0021] The network can transmit multiple SS / PBCH blocks within the channel bandwidth of a single wideband component carrier. In other words, SS / PBCH blocks can be transmitted across multiple BWPs within the channel bandwidth. In the first scheme, all SS / PBCH blocks within a wideband carrier are based on NR-SSs (e.g., primary SS (PSS) and secondary SS (SSS)) corresponding to the same physical layer cell identifier. In the second scheme, different SS / PBCH blocks within a wideband carrier can be based on NR-SSs corresponding to different physical layer cell identifiers.

[0022] From the UE's perspective, a cell is associated with an SS / PBCH block. Therefore, for the UE, each serving cell has a single associated SS / PBCH block in the frequency domain. Note that each serving cell is the primary cell (PCell) in carrier aggregation (CA) and dual connectivity (DC), the primary / secondary cell (PSCell) in DC, or the secondary cell (SCell) in both CA and DC. Such an SSB is called a cell-defined SS / PBCH block. The cell-defined SS / PBCH block has an associated RMSI. The cell-defined SS / PBCH block is used as the time reference or timing reference for the serving cell. Furthermore, the cell-defined SS / PBCH block is used for RRM measurements based on the SS / PBCH block (SSB). The cell-defined SS / PBCH block can be changed for a PCell / PSCell via "synchronous reconfiguration" (e.g., reconfiguration of radio resource configuration information using the RRC reconfiguration process without handover), while it can be changed for an SCell via "SCell release / addition".

[0023] One or more BWPs configured for each component carrier are semi-statically notified to the UE. Specifically, for each UE-specific serving cell, one or more DL BWPs and one or more ULBWPs can be configured for the UE via dedicated RRC messages. Furthermore, each BWP in the one or more BWPs configured for the UE can be activated and deactivated. The activation / deactivation of BWPs is determined not by the RRC layer but by lower layers (e.g., the Media Access Control (MAC) layer or the Physical (PHY) layer). Activated BWPs are referred to as active BWPs.

[0024] Active BWPs can be switched, for example, via downlink control information (DCI) (e.g., scheduling DCI) transmitted on the NR physical downlink control channel (PDCCH). In other words, the deactivation of the current active BWP and the activation of a new active BWP can be performed via DCI in the NR PDCCH. Therefore, the network can activate / deactivate BWPs based on, for example, the data rate or the digital scheme required by the service, and thereby dynamically switch the active BWP used by the UE. BWP activation / deactivation can be performed by the MAC control element (CE).

[0025] Figure 6 and Figure 7 This shows an example of BWP usage. Figure 6 In the example shown, the channel bandwidth of a component carrier is divided into BWP#1 and BWP#2, and these two BWPs are used in an FDM scheme employing different digital schemes (e.g., different subcarrier spacings). Figure 7 In the example shown, a narrowband BWP#1 is configured within the channel bandwidth of a component carrier, and a further narrowband BWP#2, narrower than BWP#1, is configured within BWP#1. When BWP#1 or BWP#2 is activated for the UE, the UE can reduce its power consumption by suppressing reception and transmission within the channel bandwidth other than the active BWP.

[0026] Non-patent documents 1-7 disclose the aforementioned BWP and cell definition SS / PBCH blocks.

[0027] Furthermore, 3GPP discusses the need for Radio Link Monitoring (RLM) related to the use of BWP (see Non-Patent Document 8). UEs in connected mode (i.e., RRC_CONNECTED) use the RLM procedure to measure the downlink radio quality of the serving cell to detect asynchrony (dissynchronization) and radio link failure (RLF).

[0028] Non-Patent Document 8 discloses the following: NR supports RLM only in PCell and PSCell. For a UE in connected mode, one or more BWPs can be configured semi-statically for each cell. The UE can switch between configured BWPs for a specific BWP used for communication with the gNB. This switching is performed over a short time scale (such as several scheduling intervals). This specific BWP is called the active BWP. The UE can only access one BWP at a time. The active BWP has at least a Channel State Information Reference Signal (CSI-RS) configured for RLM. The UE is configured with one RS type between CSI-RS and SS / PBCH blocks as the RS that needs to be monitored for RLM. Even if different types of RS (i.e., CSI-RS and NR-SS) are configured simultaneously in a BWP, only one RS type is selected for RLM, and the associated parameters of that RS type are used for RLM. It is discussed that when the active BWP of the DL is switched (or changed), the UE maintains the on-going L3 parameters related to RLM. In this situation, even if the DL active BWP is switched, the UE will not reset the L3 parameters related to RLM to their default values.

[0029] Existing technical documents

[0030] Non-patent literature

[0031] Non-patent literature 1: 3GPP R1-1711795, Ericsson, “On bandwidth parts and “RF” requirements”, TSG RAN1 NR Ad-Hoc#2, Qingdao, PRChina, June 2017

[0032] Non-patent literature 2: 3GPP R2-1707624, “LS on Bandwidth Part Operation in NR”, 3GPP TSG RAN WG2#99, Berlin, Germany, August 2017

[0033] Non-Patent Document 3: 3GPP R2-1710012, “LS on Further Agreements for Bandwidthpart Operation”, 3GPP TSG RAN WG2#99bis, Prague, Czech Republic, October 2017

[0034] Non-patent document 4: 3GPP R2-1710031, “Reply LS on multiple SSBs with a wideband carrier”, 3GPP TSG RAN WG2#99bis, Prague, Czech Republic, October 2017

[0035] Non-Patent Literature 5: 3GPP R2-1711640, ZTE Corporation, Sane Chips, “Initial discussion on the impacts of BWP on RAN2”, 3GPP TSG-RAN WG2 Meeting #99bis, Prague, Czech Republic, October 2017

[0036] Non-patent literature 6: 3GPP R2-1711969, Ericsson, “Text Proposal for L1 parameters for 38.331”, 3GPP TSG-RAN WG2#99bis, Prague, Czech Republic, October 2017

[0037] Non-patent literature 7: 3GPP R2-1709861, “LS on multiple SSBs within a wideband carrier”, 3GPP TSG RAN WG2#99, Berlin, Germany, August 2017

[0038] Non-Patent Document 8: 3GPP R2-1711404, Samsung, “RLM / RLF for bandwidth part”, 3GPP TSG RAN WG2#99bis, Prague, Czech Republic, October 2017 Summary of the Invention

[0039] The problem the invention aims to solve

[0040] As described above, Non-Patent Document 8 discloses that even when different types of RSs (i.e., CSI-RS and SS / PBCH blocks) are configured simultaneously in a BWP, only one RS type is selected for RLM, and the relevant parameters of that RS type are used for RLM. Non-Patent Document 8 also discloses that even when the DL active BWP is switched, the UE does not reset the L3 parameters related to RLM to their default values ​​in the example. However, there is a problem that when the DL active BWP is switched, it is unclear which RS the UE should monitor for the switched RLM. One of the objectives of the embodiments disclosed herein is to provide devices, methods, and procedures that help solve this problem. It should be noted that this objective is only one of the objectives of the embodiments disclosed herein. Other objectives or problems, as well as novel features, will become apparent from the following description and drawings.

[0041] Solution for solving the problem

[0042] In a first aspect, a radio terminal includes: a memory and at least one processor connected to the memory. The at least one processor is configured to: when switching a downlink bandwidth portion, i.e., a downlink BWP, from a first BWP to a second BWP without altering the cell-defined synchronization signal block (SSB), if the reference signal type used for radio link monitoring (RLM) is set to an SSB type, continue to perform RLM measurements using the first SSB associated with the first BWP after switching the downlink BWP to the second BWP.

[0043] In a second aspect, a method performed by a radio terminal includes: when switching a downlink bandwidth portion, i.e., a downlink BWP, from a first BWP to a second BWP without changing the cell definition synchronization signal block, i.e., the cell definition SSB, if the reference signal type used for radio link monitoring (RLM) is set to the SSB type, then after switching the downlink BWP to the second BWP, the first SSB associated with the first BWP is continued to be used for RLM measurements.

[0044] In a third aspect, a program includes instructions (software code) that, when loaded into a computer, cause the computer to perform the method described in the second aspect above.

[0045] The effects of the invention

[0046] Based on the above aspects, devices, methods, and procedures can be provided that allow radio terminals to monitor appropriate RS for RLM measurements after DL activity BWP handover. Attached Figure Description

[0047] Figure 1 This is a diagram illustrating the basic architecture of a 5G system;

[0048] Figure 2 This is a diagram showing the network structure of EN-DC;

[0049] Figure 3 This is a diagram showing the network structure of NE-DC;

[0050] Figure 4 This is a diagram showing the network structure of NG-EN-DC;

[0051] Figure 5 This is a diagram showing the network structure of NR-NR DC;

[0052] Figure 6 This is a diagram illustrating an example of the use of the Bandwidth Part (BWP);

[0053] Figure 7 This is a diagram illustrating an example of the use of the Bandwidth Part (BWP);

[0054] Figure 8 This is a diagram showing an example configuration of the BWP and SS / PBCH blocks;

[0055] Figure 9 This is a diagram showing an example configuration of the BWP and SS / PBCH blocks;

[0056] Figure 10 This is a diagram illustrating an example of the structure of a radio communication network according to several embodiments;

[0057] Figure 11 This is a flowchart illustrating an example of the operation of a radio terminal according to the first embodiment;

[0058] Figure 12 This is a flowchart illustrating an example of the operation of a radio terminal according to the first embodiment;

[0059] Figure 13 This is a sequence diagram illustrating an example of the operation of a radio terminal and a RAN node according to the first embodiment;

[0060] Figure 14 This is a flowchart illustrating an example of the operation of a radio terminal according to the second embodiment;

[0061] Figure 15 This is a flowchart illustrating an example of the operation of a radio terminal according to the second embodiment;

[0062] Figure 16 This is a sequence diagram illustrating an example of the operation of a radio terminal and a RAN node according to a second embodiment;

[0063] Figure 17 This is a sequence diagram illustrating an example of the operation of a radio terminal and a RAN node according to a third embodiment;

[0064] Figure 18 This is a block diagram illustrating an example structure of a RAN node according to some embodiments; and

[0065] Figure 19 This is a block diagram illustrating an example of the structure of a radio terminal according to some embodiments. Detailed Implementation

[0066] The specific embodiments are described in detail below with reference to the accompanying drawings. Throughout the drawings, the same reference numerals are used to denote the same or corresponding elements, and repeated descriptions will be omitted as needed for clarity.

[0067] The various embodiments described below can be used individually, or two or more embodiments can be appropriately combined with each other. These embodiments include novel features that differ from one another. Therefore, these embodiments help to achieve different purposes or solve different problems, and also help to obtain different advantages.

[0068] The following description of the embodiments focuses primarily on 3GPP 5G systems. However, these embodiments can be applied to other radio communication systems.

[0069] First, refer to Figure 8 and Figure 9 This section defines the terms used when a system bandwidth includes multiple BWPs. Figure 8 and Figure 9 This shows a configuration example for the BWP and SS / PBCH blocks. Figure 8 and Figure 9 In the example shown, one channel bandwidth includes three BWPs: BWP#1, BWP#2, and BWP#3. BWP#1 and BWP#2 include SS / PBCH blocks (SSB)#1 and SSB#2, respectively, while BWP#3 does not include any SS / PBCH blocks.

[0070] From a network perspective, as in existing LTE, the entire bandwidth of a component carrier (i.e., channel bandwidth or system bandwidth) corresponds to a cell. Figure 8 and Figure 9 In the example, the Physical Cell Identifier (PCI) associated with the cell corresponding to the channel bandwidth is "PCIx".

[0071] In this specification, a cell in a network viewpoint is defined as a "logical cell". Furthermore, the PCI associated with a cell in a network viewpoint (i.e., a logical cell) is defined as a base PCI. Note that a cell in a network viewpoint (i.e., a logical cell) can be associated with a cell identifier. In this case, the cell identifier of the cell in a network viewpoint (i.e., a logical cell) can be associated with the (sub)PCIs of multiple physical cells, as described later.

[0072] On the other hand, as mentioned above, from the UE's perspective, a cell is associated with an SS / PBCH block. In this specification, a cell from the UE's perspective is defined as a "physical cell." Furthermore, the PCI associated with a cell from the UE's perspective (i.e., a physical cell) is defined as a sub-PCI. Specifically, multiple BWPs that are included in the same system bandwidth and include their respective SS / PBCH blocks are multiple cells from the UE's perspective (i.e., multiple physical cells). The sub-PCIs of these cells from the UE's perspective (i.e., physical cells) are associated with a base PCI or a cell identifier of a cell from the network's perspective (i.e., a logical cell). Furthermore, a BWP that does not include any SS / PBCH block can be defined as a cell from the UE's perspective (i.e., a physical cell), or a group of BWPs that includes a BWP without an SS / PBCH block and a BWP with an SS / PBCH block referenced by the former can be defined as a cell from the UE's perspective (i.e., a physical cell). Note that, also from the network's perspective, the unit system bandwidth actually used by the network (e.g., a RAN node) to communicate with the UE is the cell from each UE's perspective (i.e., a physical cell).

[0073] exist Figure 8 In the example, the three BWPs support the same digital scheme (i.e., digital scheme #1), and all SS / PBCH blocks within the channel bandwidth (i.e., SSB#1 and SSB#2) are based on NR-SS corresponding to the same (sub)PCI (i.e., PCIx). Therefore, Figure 8 This corresponds to the first scheme described above regarding the transmission of multiple SS / PBCH blocks within a single channel bandwidth. To synchronize with BWP#3, which does not contain any SSBs, the UE monitors one of SSB#1 and SSB#2 transmitted in other BWPs. The SSB#1 or SSB#2 to be monitored is referred to as the reference SSB, and the UE can receive notification of the reference SSB's identifier (SSB index, such as SSB#1 or SSB#2) from the network.

[0074] exist Figure 9 In the examples, BWP#1 supports digital scheme #1, while BWP#2 and BWP#3 support digital scheme #2. The different SSB#1 and SSB#2 with different digital schemes are based on NR-SS corresponding to different (sub)PCIs (i.e., PCIx and PCIy). Therefore, Figure 9 This corresponds to the second scheme described above regarding the transmission of multiple SS / PBCH blocks within a single channel bandwidth. To synchronize with BWP#3, which does not include any SSBs, the UE monitors, for example, the SSB#2 of BWP#2, which supports the same digital scheme as BWP#3. Alternatively, to synchronize with BWP#3, which does not include any SSBs, the UE can monitor the SSB#1 of BWP#1, which supports a different digital scheme than BWP#3.

[0075] exist Figure 8 In the example, the sub-PCIs (i.e., PCIx and PCIx) of two UE-view cells (i.e., physical cells) are associated with the base PCI (i.e., PCIx) or cell identifier of a network-view cell (i.e., logical cell). On the other hand, in Figure 9 In the example, the sub-PCIs (i.e., PCIx and PCIy) of two UE view cells (i.e., physical cells) are associated with the base PCI (i.e., PCIx) or cell identifier of a network view cell (i.e., logical cell).

[0076] The network (e.g., a RAN node) can configure the UE using a BWP set that includes one or more BWPs. In other words, the UE receives configuration information (e.g., SSB index, SSB presence, reference SSB index, Layer 1 parameters) for one or more BWPs from the network. BWP sets can be configured separately for the downlink (DL) and uplink (UL). Thus, the BWP set can include the DL BWP set used by the DL and the UL BWP set used by the UL. Alternatively, UL BWPs and DL BWPs can be pre-associated with each other, and in this case, the BWP set can be shared by both DL and UL. The UE can activate k (k<=K) BWPs out of the K BWPs included in the (DL / UL) BWP set. In other words, for a given UE, up to K (DL / UL) BWPs can be activated at once. In the following description, for simplicity, it is assumed that one BWP is activated (i.e., k=1). However, note that this embodiment and subsequent embodiments can also be applied to the case of activating two or more (k>=2) BWPs at once.

[0077] Furthermore, the term "BWP group" is used in this specification. A BWP group is contained within a BWP set. A BWP group includes one or more BWPs, in which the active BWP can be changed via a DCI transmitted on the NR PDCCH. Within one or more BWPs included in the same BWP group, the active BWP can be changed without changing the cell definition SSB. Therefore, a BWP group can be defined as one or more BWPs associated with the same cell definition SSB. A BWP group may include one BWP containing the cell definition SSB (e.g., base BWP, initial BWP, or default BWP) and one or more other BWPs. Each BWP in one or more other BWPs that is not the base BWP (or initial BWP, default BWP) may or may not include an SSB. The UE may be explicitly notified (or configured) which SSB is the cell definition SSB. Alternatively, the UE may implicitly consider the cell definition SSB to be the SSB of the initial BWP when the UE was configured using the BWP group.

[0078] BWP groups can be configured separately for both the downlink (DL) and uplink (UL). Therefore, a BWP group can include the DL BWP group used by the DL and the UL BWP group used by the UL. Alternatively, UL BWPs and DL BWPs can be pre-associated with each other, and in this case, the BWP group can be shared by both the DL and UL.

[0079] exist Figure 8 In the example, the UE is configured using a set of BWPs including BWP#1 through BWP#3. Figure 8 In the example, the UE can monitor SSB#1 transmitted in BWP#1 to synchronize with BWP#3 (i.e., to achieve synchronization in BWP#3). In this case, BWP#1 and BWP#3 can correspond to one BWP group, while BWP#2 can correspond to another BWP group. Thus, a BWP set (BWP#1, BWP#2, and BWP#3) can include a first BWP group (BWP#1 and BWP#3) and a second BWP group (BWP#2). Alternatively, a BWP set (BWP#1, BWP#2, and BWP#3) can include a first BWP group (BWP#1) and a second BWP group (BWP#2 and BWP#3). Alternatively, a BWP set (BWP#1, BWP#2, and BWP#3) can correspond to one BWP group (BWP#1, #2, and #3). In this case, one of SSB#1 and SSB#2 is used as the cell definition SSB used by the UE.

[0080] Also in Figure 9In the example, the UE is configured using a set of BWPs including BWP#1 through BWP#3. In one example, BWP#1 with digitization scheme 1 may correspond to one BWP group, while BWP#2 and BWP#3 with digitization scheme 2 may correspond to another BWP group. Thus, a set of BWPs (BWP#1, BWP#2, and BWP#3) may include a first BWP group (BWP#1) and a second BWP group (BWP#2 and BWP#3). Note that, as mentioned above, BWPs with different digitization schemes may be included in one BWP group. Thus, in another example, a set of BWPs (BWP#1, #2, and #3) may include a first BWP group (BWP#1 and BWP#3) and a second BWP group (BWP#2). Alternatively, a set of BWPs (BWP#1, #2, and #3) may correspond to one BWP group (BWP#1, #2, and #3). In this case, one of SSB#1 and SSB#2 is used as the cell definition SSB used by the UE.

[0081] As mentioned earlier, BWP activation / deactivation can be performed by a lower layer (e.g., the Media Access Control (MAC) layer or the Physical (PHY) layer) rather than the RRC layer. A timer (e.g., a BWP inactivity timer in the MAC layer) can be used for DL ​​BWP activation / deactivation. The UE can switch the active BWP based on a timer set by the gNB. This timer can represent a time period or duration in subframes. For example, when the UE does not transmit or receive data within a predetermined time period in the active BWP (i.e., when the timer value expires), the UE switches the active BWP to a predetermined BWP (e.g., the default BWP or a BWP that includes the cell-defined SSB). This timer-based determination of active BWP changes can also be performed at the network level (e.g., the RAN node).

[0082] First Embodiment

[0083] Figure 10 Examples of the structure of a radio communication network according to several embodiments, including this embodiment, are shown. Figure 10 In the example, the radio communication network includes RAN node 11 and radio terminal (UE) 12. RAN node 11 is, for example, an eNB in ​​a gNB or MR-DC. RAN node 11 can be a central unit (CU) (e.g., gNB-CU) or a distributed unit (DU) (e.g., gNB-DU) in a cloud RAN (C-RAN) deployment. The central unit (CU) is also called a baseband unit (BBU) or a digital unit (DU). The distributed unit (DU) is also called a radio unit (RU), a remote radio headend (RRH), a remote radio equipment (RRE), or a transmit and receive point (TRP or TRxP).

[0084] UE 12 connects to RAN node 11 via air interface 1001. UE 12 can connect to multiple RAN nodes simultaneously to achieve dual connectivity. In connected mode, UE 12 can be semi-statically configured with one or more BWPs for each cell. UE 12 can switch its active BWP for communicating with RAN node 11 (e.g., MgNB) or other RAN nodes (e.g., SgNB) among the configured BWPs. This switching is completed within a short time (e.g., several scheduling intervals).

[0085] When UE 12 is in connected mode (e.g., NR RRC_CONNECTED), UE 12 performs an RLM procedure. During the RLM procedure, UE 12 performs RLM measurements. Specifically, UE 12 measures the downlink radio quality of the serving cell to detect asynchrony (dissynchronization) and radio link failure (RLF). UE 12 can connect to multiple RAN nodes simultaneously to achieve dual connectivity. In this case, UE 12 can perform RLM in both the PCell and PSCell simultaneously.

[0086] Radio quality can be, for example, RSRP, RSRQ, RSSI, or SINR, or any combination thereof. Furthermore, 5G NR employs a beam-based system where radio signals (data, control information, signaling, and RS) are beamformed. Therefore, in cell radio quality measurements, UE 12 first measures the RS beams transmitted in the target cell (i.e., BWP) (e.g., beamformed RS, precoded RS) (i.e., beam measurement) and obtains measurement results related to the RS beams (beam-level measurement results). Beam-level measurement results are also referred to as beam radio quality. UE 12 then derives the cell radio quality (cell measurement results) based on the beam-level measurement results. Hereinafter, the terms "measurement used by RLM (RLM measurement)," "measurement used by RRM (RRM measurement)," or simply "measurement," refer to measuring or deriving at least one of cell radio quality (cell quality) and beam radio quality (beam quality) based on the RS type represented by the RAN node or RS configuration information received from the RAN node. The measurement of beam quality corresponding to the RLM associated with cell quality is called beam monitoring (BM) or beam link monitoring (BLM). Similarly, radio link quality degradation based on the beam quality corresponding to the RLF associated with cell quality is called beam failure.

[0087] In an active BWP, at least the CSI-RS configured for RLM is transmitted. The active BWP may or may not contain an SS / PBCH block (SSB). In other words, RAN node 11 may or may not transmit NR-SS and PBCH in the active BWP. RAN node 11 indicates to UE 12 an RS type (CSI-RS or SSB (i.e., NR-SS)) as the RS to be measured for RLM. Even if different types of RS (i.e., CSI-RS and SSB) are transmitted simultaneously in a BWP, only one RS type is selected for RLM, and the measurement configuration (measurement parameters) associated with the selected RS type is used for RLM. The measurement configuration associated with the selected RS type may, for example, include the threshold "Q" defined in 3GPP standards TS 36.213 and TS 36.133. in ” and “ Q. out "Similar parameters. In this case, different RS types can be configured with thresholds "Q". in ” and “ Q. out "Quite different parameters."

[0088] RAN node 11 provides RLM configuration to UE 12. The RLM configuration includes the measurement configuration (measurement parameters) used by the RLM. These measurement configurations (measurement parameters) include, for example, a specified number of out-of-sync instances (e.g., N310 for PCell, N313 for PSCell), a specified number of in-sync instances (e.g., N311 for PCell, N314 for PSCell), and the expiration time (maximum time) of the RLF timer (e.g., T310 for PCell, T313 for PSCell). The specified number of out-of-sync instances is the number of consecutive "out-of-sync" representations received from the lower layer before the UE begins radio link self-recovery processing. The specified number of in-sync instances is the number of consecutive "synchronous" representations received from the lower layer before the UE determines that the radio link has been restored. The RLF timer is used to determine (or detect) RLF. The UE (e.g., the RRC layer) starts an RLF timer when it receives a specified number of consecutive out-of-synchronization (OOS) indications from the lower layer and stops the RLF timer when it receives a specified number of consecutive synchronized (IS) indications. The expiration time (maximum time) of the RLF timer is equivalent to the maximum time allowed for dynamic radio link recovery by the UE. The UE detects an RLF in response to the expiration of the RLF timer.

[0089] During the RLM process, UE 12 can evaluate the radio link quality for each radio frame. In this case, UE 12 can select the RS type (e.g., CSI-RS or SS / PBCH block) to be used for RLM for each radio frame for which the radio link quality is being evaluated. Optionally, UE 12 can select the radio link quality evaluation and the RS type to be used for RLM for each subframe, for each time slot, for each OFDM symbol, or for each TTI (rather than for each radio frame).

[0090] When the DL active BWP is changed from the first BWP to the second BWP without altering the cell definition SSB, UE 12 behaves as follows regarding RLM measurements. If the RS type used for RLM of the first BWP received by UE 12 is set to SSB type (i.e., NR-SS), then even after the DL BWP is switched to the second BWP, UE 12 continues to monitor the first SSB associated with the first BWP for RLM measurements. In other words, even if the second BWP includes an SSB, when instructing UE 12 to perform an SSB-based RLM measurement, UE 12 will not use that SSB in the second BWP for RLM measurements. In this case, UE 12 may choose not to measure the SSB in the second BWP, or UE 12 may measure the SSB for RLM. Hereinafter, the timing referred to as "when things change" can be radio frame-level timing, subframe-level timing, slot-level timing, or OFDM symbol-level timing.

[0091] The first SSB can be a cell-defined SSB associated with the first BWP. The first SSB can be included in the first BWP, or the first SSB can be included in other BWPs.

[0092] UE 12 can inherit and use the measurement configuration (e.g., measurement object) of the RLM used before the active BWP handover to continue using the first SSB for RLM measurements. Furthermore, UE 12 can also inherit and use the values ​​(or conditions) of RLM-related parameters used before the active BWP handover. In other words, UE 12 can continue the measurements of the first SSB used for RLM based on the measurement configuration and parameters (conditions) of the RLM used before the active BWP handover. Further, UE 12 can assume (consider) that the measurement configuration and parameters (conditions) of the RLM used before the active BWP handover are also used after the active BWP handover.

[0093] RLM-related parameters include, for example, the count values ​​of consecutive asynchronous representations, the count values ​​of consecutive synchronized representations, and the value of the RLF timer. RLM-related parameters may include synchronization thresholds and asynchronous thresholds. UE 12 compares the estimated DL radio link quality with the synchronization threshold and the asynchronous threshold to perform radio link monitoring (RLM). The synchronization threshold and the asynchronous threshold are each, for example, RSRP thresholds, and are represented by the block error rate (BLER) of the assumed PDCCH transmission from the serving cell. Specifically, for example, considering the transmission parameters used for asynchronous transmission and errors in the Physical Control Format Indicator Channel (PCFICH), the asynchronous threshold is defined as a level corresponding to a 10% BLER of the assumed PDCCH transmission. On the other hand, considering the transmission parameters used for synchronization and errors in the Physical Control Format Indicator Channel (PCFICH), the synchronization threshold is defined as a level corresponding to a 2% BLER of the assumed PDCCH transmission.

[0094] As described above, the measurement configuration used by RLM can include, for example, a specified number of asynchronous elements, a specified number of synchronous elements, and the expiration time (maximum time) of the RLF timer. The measurement configuration used by RLM can also include PDCCH / PCFICH transmission parameters for asynchronous and synchronous operations. PDCCH / PCFICH transmission parameters can include, for example, the DCI format, the number of control OFDM symbols, the aggregation level, the ratio of PDCCH RE energy to the average RS resource element (RE) energy, and the ratio of PCFICH RE energy to the average RS resource element (RE) energy. RS RE energy, PDCCH RE energy, and PCFICH RE energy represent the RS energy, PDCCH energy, and PCFICH energy for each RE, respectively. These PDCCH / PCFICH transmission parameters can be configured for each BWP, each SSB, or each CSI-RS. Alternatively or additionally, these PDCCH / PCFICH transmission parameters can be configured and used for each radio frame, each subframe, each time slot, each OFDM symbol, or each TTI.

[0095] Figure 11This is a flowchart illustrating process 1100, an example of an RLM-related operation performed by UE 12. In step 1101, UE 12 receives from RAN node 11 an indication to switch the active DL BWP from a first BWP to a second BWP without changing the cell definition SSB. For example, the indication could indicate the activation of the second BWP and could also indicate the deactivation of the first BWP. As previously explained, BWP activation / deactivation is performed via, for example, a DCI (e.g., a scheduling DCI) transmitted on the NR PDCCH.

[0096] In step 1102, UE 12 determines which RS type is used for the RLM of the first BWP prior to the DL active BWP handover. If UE 12 is configured with SSB-based RLM measurements, UE 12 continues RLM measurements in the first SSB associated with the first BWP even after the DL active BWP is handed over to the second BWP. In other words, if UE 12 has received the RS type used for the RLM of the first BWP set to SSB type (i.e., NR-SS), UE 12 continues to perform RLM measurements on the first SSB associated with the first BWP. Furthermore, UE 12 can use this measurement and measurement result as the measurement and measurement result used for RRM of neighboring cells (or neighboring BWPs).

[0097] Based on the above explanation, if UE 12 is configured with SSB-based RLM measurements for the first BWP, then when changing the DL active BWP from the first BWP to the second BWP without changing the cell definition SSB, UE 12 operates as follows. In other words, if the RS type of the RLM measurement received by UE 12 for the first BWP is set to SSB (i.e., NR-SS), then when switching the DL active BWP from the first BWP to the second BWP via NR PDCCH / DCI, UE 12 operates as follows. Specifically, UE 12 continues to measure the first SSB associated with the first BWP even after the DL BWP is switched to the second BWP. The first SSB can be the cell definition SSB associated with the first BWP. The first SSB can be included in the first BWP or other BWPs. Therefore, UE 12 can continue RLM based on the same first SSB even after the DL active BWP is switched.

[0098] Before and after switching the active BWP in a manner that does not alter the cell definition SSB, UE 12 does not change the RS (e.g., the first SSB) used for RLM measurements, thus allowing UE 12 to continuously measure cell radio quality. For example, even when dynamically switching active BWPs within a BWP group, UE 12 can stably measure cell radio quality, thereby appropriately understanding (detecting) radio quality degradation or improvement. Therefore, this control method is particularly effective for operations that switch active BWPs at relatively short time intervals.

[0099] On the other hand, if UE 12 is configured with CSI-RS-based RLM measurements, then when changing the DL active BWP from the first BWP to the second BWP without changing the cell definition SSB, UE 12 can operate as follows. In other words, if the RS type used by the RLM received by UE 12 is set to CSI-RS, then when switching the DL active BWP from the first BWP to the second BWP via NR PDCCH / DCI, UE 12 can operate as follows. Specifically, UE 12 can perform RLM measurements on the second CSI-RS in the second BWP, instead of the first CSI-RS in the first BWP. Although UE 12 changes the CSI-RS to be used for RLM, UE 12 can inherit and use the values ​​(or conditions) of the RLM-related parameters used before the active BWP handover. As mentioned above, RLM-related parameters may include the count value of continuous dissynchronization, the count value of continuous synchronization, and the value of the RLF timer. RLM-related parameters may include synchronization thresholds and dissynchronization thresholds. Furthermore, although UE 12 changes the CSI-RS to be used by the RLM, UE 12 can inherit and use at least a portion of the measurement configuration used by the RLM before the active BWP handover. As mentioned above, the measurement configuration used by the RLM may include a specified number of asynchronous operations, a specified number of synchronous operations, and the expiration time (maximum time) of the RLF timer. In addition, the measurement configuration used by the RLM may include PDCCH / PCFICH transmission parameters.

[0100] Figure 12This is a flowchart illustrating process 1200, another example of RLM-related operations performed by UE 12. The process in step 1201 is the same as that in step 1101. In step 1202, UE 12 determines which RS type was used for RLM of the first BWP before the DL active BWP handover. If UE 12 is configured for CSI-RS-based RLM measurement, then after the DL active BWP handover to the second BWP, UE 12 uses the second CSI-RS sent in the second BWP instead of the first CSI-RS sent in the first BWP for RLM measurement. Therefore, UE 12 performs RLM measurement on the second CSI-RS.

[0101] During a DL active BWP handover, UE 12 can perform RLM based on the radio quality of the serving cell (active BWP) by changing the RS (e.g., CSI-RS) to be used in the RLM to the RS transmitted in the DL active BWP after the handover. For example, in the case of a semi-static handover of an active BWP in a BWP group, UE 12 can appropriately measure the radio quality of the cell actually in use, thereby appropriately understanding (detecting) radio quality degradation or improvement. Therefore, this control method is particularly effective for operations that handover active BWPs at relatively long time intervals.

[0102] Based on the above explanation, it can be understood that in some implementations, when changing the DL active BWP from the first BWP to the second BWP without altering the cell definition SSB, UE 12 can operate as follows. Specifically, UE 12 determines whether to change the reference signal (RS) to be monitored for RLM after the DL active BWP handover, based on whether SSB-based RLM measurement or CSI-RS-based RLM measurement is configured for the first BWP. In other words, UE 12 determines whether to change the RS to be used for RLM measurement after the DL active BWP handover, based on whether the RS type used for RLM is SSB or CSI-RS. Therefore, when UE 12 receives an indication (DCI) on the NR PDCCH to switch the DL active BWP in the BWP group, UE 12 can appropriately change the RS to be used for RLM measurement without receiving an RRC message (e.g., RRC reconfiguration). In other words, RAN node 11 only needs to send the NR PDCCH, without sending an RRC message, to allow UE 12 to select the RS to be used for RLM measurement. This can reduce the amount of radio signaling (RRC signaling) and reduce the latency of changing the RRC layer configuration in UE 12.

[0103] Figure 13This diagram illustrates a sequence of processes 1300, which is an example of the operation of RAN node 11 and UE 12 according to this embodiment. UE RRC layer 121 and UE MAC layer 122 are included in the control plane protocol stack of UE 12. UE RRC layer 121 is a lower layer than UE NAS layer (not shown), and it provides radio resource control (RRC) and manages the RRC status of UE 12 (e.g., NR RRC_IDLE and NR RRC_CONNECTED). The RRC status indicates, for example, whether a radio connection (RRC connection) has been established between UE 12 and RAN node 11.

[0104] The UE RRC layer 121 receives one or more BWP configurations for each component carrier from the RAN node 11. For example, the RAN node 11 sends one or more BWP-related control information items (BWP configurations) for each component carrier to the UE RRC layer 121 via an RRC reconfiguration message. The one or more BWP configurations for each component carrier may, for example, include at least one of the following information elements (IEs):

[0105] - An information element representing one or more BWP indices associated with one or more downlink BWPs;

[0106] - An information element representing one or more BWP indices associated with one or more uplink BWPs;

[0107] - Information elements representing the carrier frequency (e.g., absolute radio frequency channel number (ARFCN)) associated with each BWP;

[0108] - Indicates whether each BWP contains information elements of the SS / PBCH block (SSB);

[0109] - Information element that represents a reference SSB associated with a BWP that does not contain an SSB, or a reference BWP that includes the reference SSB;

[0110] - Information elements representing the structure of the SSB transmitted in each BWP (e.g., SS sequence or PCI, SSB duration, digital scheme);

[0111] - An information element representing the offset from the base PRB (e.g., PRB0) to the lowest PRB of each SSB;

[0112] - Information elements representing the digital scheme configured for each BWP; and

[0113] - Information elements that represent the structure of a BWP set or BWP group (e.g., information related to the index of each BWP group and a list of BWP indices included in that BWP group).

[0114] In addition, the UE RRC layer 121 receives the measurement configuration (MeasConfig) used by the RLM of each serving cell from the RAN node 11. For example, the RAN node 11 sends the measurement configuration used by the RLM of each serving cell to the UE RRC layer 121 via an RRC reconfiguration message. The measurement configuration includes the measurement configuration used by the RLM (e.g., RS type).

[0115] Furthermore, the measurement configuration used by the RLM of each serving cell may include the aforementioned measurement configuration used by the RLM. One or more measurement configurations (measurement parameter sets) used by the RLM may be included in one or more corresponding BWP configurations. Optionally, the measurement configuration used by the RLM of each serving cell may be included in the DCI transmitted on the NR PDCCH or in the MAC CE.

[0116] The UE MAC layer 122 determines the activation / deactivation of one or more BWPs configured in UE 12. As described above, the handover of BWPs in a BWP group is performed, for example, via a DCI transmitted on the NR PDCCH. Furthermore, in this case, the deactivation of the active BWP before the handover and the activation of the active BWP after the handover can be performed via this DCI.

[0117] In step 1301, RAN node 11 sends a DCI (Distributed Control Message) for switching the active DL BWP to UE 12 on the NR PDCCH. This DCI triggers UE 12 to switch the active DL BWP. In step 1302, UE MAC layer 122 switches the active DL BWP in response to receiving the DCI from RAN node 11. In step 1303, UE MAC layer 122 notifies UE RRC layer 121 of the DL active BWP switch. The notification in step 1303 can occur before step 1302.

[0118] In step 1304, in response to receiving a notification from the lower layer (MAC layer 122) indicating a handover of the DL active BWP, the UE RRC layer 121 determines the RS type applicable to the DL active BWP before the handover. In other words, the UE RRC layer 121 determines whether the RS type used by the RLM is SSB type or CSI-RS type.

[0119] In step 1305, the UE RRC layer 121 modifies the RLM measurement based on which of the SSB type and CSI-RS type applies to the pre-handover DL active BWP. Specifically, if the RS type used for the RLM applicable to the pre-handover DL active BWP is SSB, the UE RRC layer 121 does not change the reference signal (i.e., SSB) to be used for the RLM measurement after the handover of the DL active BWP. Therefore, the UE RRC layer 121 performs RLM continuously based on the same SSB. On the other hand, if the RS type used for the RLM applicable to the pre-handover DL active BWP is CSI-RS, the UE RRC layer 121 performs RLM based on the CSI-RS included in the post-handover DL active BWP.

[0120] Note that in this embodiment, UE 12 can perform CSI measurements in addition to RLM measurements. CSI measurements include measuring the DL radio quality of the serving cell when UE 12 is in connected mode (e.g., NR RRC_CONNECTED) to send a report to RAN node 11 containing a channel quality indication (CQI) for at least one of scheduling and link adaptation. When switching the DL active BWP from the first BWP to the second BWP without changing the cell definition SSB, UE 12 can perform CSI measurements by monitoring the second CSI-RS in the second BWP instead of the first CSI-RS in the first BWP.

[0121] Furthermore, in the example above, the UE MAC layer 122 notifies the UE RRC layer 121 of the handover of the DL active BWP in response to receiving the DCI used for the handover of the DL active BWP via the NR PDCCH. However, instead of the UE MAC layer 122, the UE PHY layer, having received the DCI, can send the notification directly to the UE RRC layer 121 (and the UE MAC layer 122).

[0122] Second Embodiment

[0123] This embodiment provides an example of RLM measurements performed by a UE when switching a DL active BWP by changing the cell definition SSB. An example of the structure of the radio communication network according to this embodiment is provided. Figure 10 The structural example shown is the same.

[0124] In this embodiment, when the DL active BWP is changed from the first BWP to the second BWP by changing the cell definition SSB, the UE 12 behaves as follows regarding RLM measurements. If the RS type used for the RLM of the first BWP is set to the SSB type, the UE 12 suspends (or pauses) the use of the first SSB associated with the first BWP for RLM measurements. Therefore, the UE 12 suspends (or pauses) RLM based on the first SSB. Alternatively, if the RS type used for the RLM of the first BWP is set to the SSB type, the UE 12 can use the second SSB associated with the second BWP instead of the first SSB associated with the first BWP for RLM measurements.

[0125] Furthermore, in the event that RLM measurements are aborted (or suspended) using the first SSB associated with the first BWP, UE 12 can reset the values ​​(or conditions) of RLM-related parameters used before the DL active BWP switch to default values ​​(e.g., zero) or set values ​​(e.g., expiration values). RLM-related parameters may include count values ​​for continuous asynchrony, count values ​​for continuous synchronization, and values ​​of RLF timers.

[0126] When using SSBs for RLM as in this embodiment, there is a possibility that the DL radio quality may differ significantly between physical cells (BWPs) that are included in a single logical cell but have different cell definition SSBs. For example, when using physical cells (BWPs) with different cell definition SSBs within a single logical cell, there is a possibility that the frequency characteristics may differ significantly between these physical cells (BWPs) because the logical cell has a wider bandwidth (e.g., 400MHz). Alternatively, there is a possibility that the radio propagation characteristics may differ significantly between physical cells (BWPs) because different digital schemes (e.g., subcarrier spacing) are applied to these physical cells (BWPs). In other words, there is a possibility that the reception quality at UE 12 with the cell definition SSB after the DL active BWP handover may be significantly different from the reception quality with the cell definition SSB before the handover. Therefore, RLM after the DL active BWP handover is not expected to be optimal unless UE 12 changes the SSB to be used for RLM before and after the DL active BWP handover involving changes in the cell definition SSB. Therefore, UE 12 operates as described above to optimize RLM after DL active BWP handover.

[0127] Optionally, in the case of suspending (or pausing) the SSB used for monitoring RLM measurements, UE 12 can maintain (retain) the values ​​(or conditions) of the RLM-related parameters used before the DL active BWP handover without resetting them. UE 12 can then use the maintained (retained) values ​​of the RLM-related parameters when initiating RLM measurements in the second SSB associated with the second BWP after the handover. This is effective regardless of changes to the cell-defined SSB, provided that the frequency characteristics or propagation characteristics of the DL active BWP before and after the handover are the same or similar. RAN Node 11 can send information to UE 12 indicating whether to reset the values ​​of the RLM-related parameters (or whether to maintain their values ​​(or conditions)) when handing over the DL active BWP in a manner that changes the cell-defined SSB. This information can be sent from RAN Node 11 to UE 12 along with an instruction for handing over the DL active BWP.

[0128] Figure 14 This is a flowchart illustrating process 1400, an example of an RLM-related operation performed by UE 12. In step 1401, UE 12 receives from RAN node 11 an indication to switch the active DL BWP from a first BWP to a second BWP in the event of a change in the cell definition SSB. For example, the indication could indicate the activation of the second BWP and the deactivation of the first BWP. Since a change in the cell definition SSB is required, this indication can be sent from RAN node 11 to UE 12 via RRC signaling (e.g., an RRC reconfiguration message).

[0129] In step 1402, if UE 12 is configured with SSB-based RLM measurements, UE 12 stops RLM based on the first SSB associated with the first BWP. In step 1403, UE 12 resets the values ​​(or conditions) of the RLM-related parameters used before the DL active BWP handover to default values ​​(e.g., zero) or set values ​​(e.g., expired values). Step 1403 is not necessarily required.

[0130] Figure 15 This is a flowchart illustrating process 1500, which is another example of RLM-related operations performed by UE 12. The processes performed in steps 1501 to 1503 are the same as those in steps 1401 to 1403.

[0131] In step 1504, if UE 12 is configured with SSB-based RLM measurement, then UE 12 starts RLM based on the second SSB associated with the second BWP instead of the first SSB associated with the first BWP.

[0132] On the other hand, if the RS type used by RLM is set to CSI-RS type, then regardless of whether there is a change in the cell definition SSB, when the DL active BWP changes from the first BWP to the second BWP, UE 12 can operate as follows. Specifically, UE 12 can use the second CSI-RS in the second BWP instead of the first CSI-RS in the first BWP to perform RLM measurements. Although UE 12 changes the CSI-RS to be used by RLM, UE 12 can inherit and use the values ​​(or conditions) of the RLM-related parameters used before the DL active BWP handover. As mentioned above, RLM-related parameters may include the count value of continuous asynchrony representation, the count value of continuous synchronization representation, and the value of the RLF timer. RLM-related parameters may include synchronization thresholds and asynchrony thresholds.

[0133] Figure 16 This is a sequence diagram illustrating process 1600, which is an example of the operation of RAN node 11 and UE 12 according to this embodiment. UE RRC layer 121 and UE MAC layer 122 are included in the control plane protocol stack of UE 12.

[0134] In step 1601, RAN node 11 sends an RRC reconfiguration message for BWP reconfiguration to UE 12 (UE RRC layer 121). This BWP reconfiguration triggers UE 12 to change the cell definition SSB and switch the DL active BWP.

[0135] In step 1602, the UE RRC layer 121 instructs the UE MAC layer 122 to switch the DL active BWP. In step 1603, the UE MAC layer 122 switches the DL active BWP according to the instruction from the UE RRC layer 121. In this case, either the UE RRC layer 121 or the UE MAC layer 122 may instruct the UE PHY layer (not shown) to switch the DL active BWP, and the UE PHY layer may adjust its radio processing unit (e.g., RF) according to the instruction to receive the switched DL active BWP.

[0136] In step 1604, UE RRC 121 modifies RLM measurements based on changes in the cell definition SSB and the handover of the DL active BWP. Specifically, if the RS type used for the RLM applicable to the DL active BWP before handover is SSB type (i.e., NR-SS), then UE RRC layer 121 uses the SSB associated with the BWP after handover instead of the SSB associated with the DL active BWP before handover for RLM measurements. On the other hand, if the RS type used for the RLM applicable to the DL active BWP before handover is CSI-RS type, then UE RRC layer 121 uses the CSI-RS included in the DL active BWP after handover for RLM measurements.

[0137] Note that, according to this embodiment, UE 12 can also perform the RLM-related operations of the UE when switching DL active BWPs without changing the cell definition SSB, as described in the first embodiment. In other words, UE 12 can determine whether to continue using the first SSB associated with the first BWP for RLM measurements based on whether the handover of the (DL) active BWP from the first BWP to the second BWP involves a change in the cell definition SSB. Therefore, UE 12 can appropriately understand not only the radio quality in the (DL)BWP corresponding to the serving physical cell, but also the radio quality in the (DL)BWP that includes the cell definition SSB (i.e., the (DL)BWP that transmits the SSB). As mentioned above, the DLBWP that includes the cell definition SSB is the DL BWP representing one of the physical cells included in the logical cell. Therefore, by understanding the radio quality of the (DL)BWP that includes the cell definition SSB, UE 12 can determine whether the physical cell is suitable for staying. Furthermore, if no other (DL)BWP including a cell-defined SSB is present (or not configured) in the same logical cell, the (DL)BWP including the cell-defined SSB can be considered as representing the (DL)BWP of all BWPs included in the same logical cell. Therefore, by understanding the radio quality of the (DL)BWP including the cell-defined SSB, UE 12 can appropriately determine whether the logical cell is suitable for loitering.

[0138] Furthermore, in this embodiment, UE 12 can perform CSI measurements in addition to RLM measurements. When the DL active BWP is switched from the first BWP to the second BWP by changing the cell definition SSB, UE 12 can perform CSI measurements by monitoring the second CSI-RS in the second BWP instead of the first CSI-RS in the first BWP.

[0139] Third Embodiment

[0140] This embodiment provides a method for measurement configuration to handle the switching of active BWPs among multiple BWPs included in a BWP group. An example of the structure of a radio communication network according to this embodiment is provided. Figure 10 The structural example shown is the same. The method described in this embodiment can be used for RLM measurement, RRM measurement, and CSI measurement as described in the first and second embodiments.

[0141] In this embodiment, to handle the handover of active BWPs (without involving changes to the Cell Definition SSB) among multiple DL BWPs included in a DL BWP group, RAN node 11 provides a measurement configuration to UE 12 in advance via RRC signaling (e.g., RRC reconfiguration message). This measurement configuration can exchange (switch) the relationship between the serving cell (serving BWP, active BWP) and neighboring cells (non-serving BWP, neighboring BWP). When switching active BWPs among BWPs within a BWP group to communicate between UE 12 and RAN, UE 12 uses the previously received measurement configuration by exchanging the relationship between the serving cell (serving BWP, active BWP) and neighboring cells (non-serving BWP, neighboring BWP).

[0142] For example, in a BWP group comprising a first BWP and a second BWP, RAN node 11 provides UE 12 with a measurement configuration corresponding to the case where the first BWP is the serving cell (serving BWP) and the second BWP is a neighboring cell (neighboring BWP, non-serving BWP) via RRC signaling (e.g., RRC reconfiguration message). When the active BWP is the first BWP, UE 12 performs measurements (e.g., RLM measurements, RRM measurements, CSI measurements) based on this measurement configuration. Furthermore, when the active BWP switches from the first BWP to the second BWP, UE 12 uses the received measurement configuration by exchanging the relationships between the serving cell (serving BWP) and neighboring cells (neighboring BWP, non-serving BWP) in the measurement configuration.

[0143] According to this embodiment, RAN node 11 and UE 12 do not require RRC signaling to update the measurement configuration when switching active BWPs within a BWP group. Therefore, RAN node 11 and UE 12 can quickly update the measurement configuration in response to the switching of active BWPs within a BWP group, and thus can quickly start measurement operations based on the measurement configuration corresponding to the switched active BWP.

[0144] Figure 17This is a sequence diagram illustrating a process 1700 as an example of the operation of RAN node 11 and UE 12 according to this embodiment. In this example, it is assumed that the BWP group consists of BWP#1, which includes an SSB, and BWP#2, which does not include any SSB, and that UE 12 initially resides on BWP#1 (i.e., BWP#1 is the active BWP).

[0145] In step 1701, RAN node 11 sends an RRC reconfiguration message to UE 12. This RRC reconfiguration message includes measurement configurations corresponding to the case where BWP#1 is the serving cell (serving BWP) and BWP#2 is the neighboring cell (neighboring BWP).

[0146] UE 12 uses the measurement configuration received in step 1701 and performs measurements in BWP#1 (e.g., RLM measurement, CSI measurement, RRM measurement) and measurements in neighboring cells including BWP#2 (e.g., RRM measurement) (step 1702).

[0147] In step 1703, RAN node 11 sends control information (i.e., DCI on NR PDCCH) to UE 12 indicating that the active BWP is switching from BWP#1 to BWP#2. In response to receiving this control information (PDCCH / DCI), UE 12 switches the active BWP to BWP#2. Furthermore, during the switching of the active BWP, UE 12 uses the previously received (i.e., stored) measurement configuration by exchanging the relationship between the serving cell (serving BWP, active BWP) and neighboring cells (non-serving BWP, neighboring BWP) (step 1704). Specifically, UE 12 treats the serving cell (serving BWP) in the stored measurement configuration as BWP#2 and performs measurements based on at least a portion of this measurement configuration. In other words, UE 12 treats BWP#2 as the serving cell (serving BWP) and BWP#1 as the neighboring cell (neighboring BWP) and performs measurements based on at least a portion of the stored measurement configuration.

[0148] The measurements in step 1704 may include SSB-based measurements and CSI-RS-based measurements. If UE 12 is configured for SSB-based measurements, UE 12 can monitor the SSB in BWP#1 for RLM measurements. In this case, UE 12 can continue to use the SSB-based measurement configuration in the measurement configuration corresponding to BWP#1 for SSB-based measurements after the active BWP switches from BWP#1 to BWP#2. In other words, UE 12 can treat the serving cell (serving BWP) in the previously received (i.e., stored) measurement configuration as BWP#2 for CSI-RS-based measurements after the active BWP switches from BWP#1 to BWP#2. In other words, UE 12 treats BWP#2 as the serving cell (serving BWP) and BWP#1 as the neighboring cell (neighboring BWP), and performs measurements according to at least a portion of the stored measurement configuration.

[0149] Alternatively, in addition to the measurement configurations specific to BWP#1 and BWP#2, the measurement configurations for the carrier frequency (measObject) can be used together for measurements before and after the active BWP handover.

[0150] Alternatively, RAN node 11 can pre-send the "s-measure" configuration to the UE using measurement configuration. The s-measure is an RSRP threshold used to determine the start of neighbor cell measurements. When the serving cell's RSRP falls below the s-measure, UE 12 begins neighbor cell measurements. Furthermore, UE 12 can choose between SSB (i.e., ssb-rsrp) and CSI-RS (i.e., csi-rsrp), and in this case, RAN node 11 can indicate to UE 12 whether the s-measure is based on SSB or CSI-RS. UE 12 can determine the s-measure after the active BWP is switched from BWP#1 to BWP#2 by using the measurement value (e.g., SSB-based RSRP or CSI-RS-based RSRP) for the serving BWP after the handover (i.e., BWP#2). Optionally, UE 12 can determine the s-measure by using the measurement value for the serving BWP before the handover (i.e., BWP#1).

[0151] RAN node 11 can notify UE 12 in advance of the method for handling s-measurements after the handover of the active BWP (i.e., which of the measurements for the active BWP before the handover and the measurements for the active BWP after the handover should be used to determine the s-measurements after the handover of the active BWP). RAN node 11 can indicate the method for handling s-measurements after the handover of the active BWP in the measurement configuration or BWP set configuration information. Optionally, UE 12 can determine the RS type of the object to be measured after the handover of the active BWP based on the configuration of the RS type (e.g., SSB or CSI-RS) of the object to be measured before the handover of the active BWP. For example, if the RS type of the object to be measured before the handover of the active BWP is SSB, UE 12 can use the measurement value for SSB to determine the s-measurements after the handover of the active BWP. Note that UE 12 can measure the SSB in the active BWP before the handover if the active BWP after the handover does not include any SSB, or it can measure the SSB in the active BWP after the handover if the active BWP after the handover includes SSB.

[0152] For example, if the s-measurement in the measurement configuration defines the RSRP threshold of the RS (e.g., NR-SS) in the SSB, RAN node 11 can notify UE 12 in advance in step 1701 of the s-measurement to be used after the active BWP in the BWP group is switched. For example, if the new active BWP (e.g., active BWP#2) after the active BWP in the BWP group is switched does not include an SSB, RAN node 11 can pre-configure the RSRP threshold of the CSI-RS to be used for the s-measurement after the active BWP is switched. Optionally, if the s-measurement in the measurement configuration defines the RSRP threshold of the CSI-RS (and if the CSI-RS configuration in BWP#2 is sent from RAN node 11 to UE 12), UE 12 can continue to use the s-measurement configuration before the switch even after the active BWP is switched from BWP#1 to BWP#2.

[0153] The following provides a structural example of RAN node 11 and UE 12 according to the above embodiments. Figure 18 This is a block diagram illustrating an example structure of RAN node 11 according to the above embodiment. (See reference...) Figure 18RAN node 11 includes a radio frequency transceiver 1801, a network interface 1803, a processor 1804, and a memory 1805. The RF transceiver 1801 performs analog RF signal processing to communicate with the NG UE, including UE 12. 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 modulated symbol data from the processor 1804, generates a transmit RF signal, and supplies the transmit RF signal to the antenna array 1802. Furthermore, the RF transceiver 1801 generates a baseband receive signal based on the receive RF signal received by the antenna array 1802 and supplies the baseband receive signal to the processor 1804. The RF transceiver 1801 may include analog beamformer circuitry for beamforming. The analog beamformer circuitry includes, for example, multiple phase shifters and multiple power amplifiers.

[0154] Network interface 1803 is used to communicate with network nodes (e.g., the control and transport nodes of the NG Core). Network interface 1803 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 family.

[0155] Processor 1804 performs digital baseband signal processing (i.e., data plane processing) and control plane processing for radio communication. Processor 1804 may include multiple processors. Processor 1804 may include, for example, a modem processor (e.g., a digital signal processor (DSP)) for performing digital baseband signal processing and a protocol stack processor (e.g., a central processing unit (CPU) or microprocessor unit (MPU)) for performing control plane processing. Processor 1804 may include a digital beamformer module for beamforming. The digital beamformer module may include a multiple-input multiple-output (MIMO) encoder and a pre-encoder.

[0156] Memory 1805 comprises a combination of volatile and non-volatile memory. Volatile memory may be, for example, static random access memory (SRAM), dynamic RAM (DRAM), or any combination thereof. Non-volatile memory may be, for example, mask read-only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, hard disk drive, or any combination thereof. Memory 1805 may include memory configured separately from processor 1804. In this case, processor 1804 may access memory 1805 via network interface 1803 or an I / O interface (not shown).

[0157] Memory 1805 may store one or more software modules (computer programs) 1806, which include instructions and data for performing the processing of RAN node 11 as described in the above embodiments. In some implementations, processor 1804 may be configured to load software modules 1806 from memory 1805 and execute the loaded software modules to perform the processing of RAN node 11 as described in the above embodiments.

[0158] Note that if RAN node 11 is a gNB-CU, then RAN node 11 does not need to include RF transceiver 1801 (and antenna array 1802).

[0159] Figure 19 This is a block diagram illustrating an example of the structure of UE 12. A radio frequency (RF) transceiver 1901 performs analog RF signal processing to communicate with NR NB 1. RF transceiver 1901 may include multiple transceivers. The analog RF signal processing performed by RF transceiver 1901 includes up-conversion, down-conversion, and amplification. RF transceiver 1901 is coupled to antenna array 1902 and baseband processor 1903. RF transceiver 1901 receives modulated symbol data (or OFDM symbol data) from baseband processor 1903, generates a transmit RF signal, and supplies the transmit RF signal to antenna array 1902. Furthermore, RF transceiver 1901 generates a baseband receive signal based on the receive RF signal received by antenna array 1902 and supplies the baseband receive signal to baseband processor 1903. RF transceiver 1901 may include analog beamformer circuitry for beamforming. The analog beamformer circuitry includes, for example, multiple phase shifters and multiple power amplifiers.

[0160] The baseband processor 1903 performs digital baseband signal processing (i.e., data plane processing) and control plane processing for radio communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) generation / decomposition of transmission formats (i.e., transmission frames), (d) channel coding / decoding, (e) modulation (i.e., symbol mapping) / demodulation, and (f) generation of OFDM symbol data (i.e., baseband OFDM signals) using inverse fast Fourier transform (IFFT). On the other hand, control plane processing includes communication management at layers 1 (e.g., transmit power control), 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and 3 (e.g., signaling related to attachment, mobility, and call management).

[0161] The digital baseband signal processing performed by the baseband processor 1903 may include signal processing at layers such as the Serving Data Adaptation Protocol (SDAP) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, MAC layer, and PHY layer. Furthermore, the control plane processing performed by the baseband processor 1903 may include processing of Non-Access Stratum (NAS) protocols, RRC protocols, and MAC CE.

[0162] The baseband processor 1903 can perform MIMO coding and precoding for beamforming.

[0163] The baseband processor 1903 may include a modem processor (e.g., a DSP) for performing digital baseband signal processing and a protocol stack processor (e.g., a CPU or MPU) for performing control plane processing. In this case, the protocol stack processor for performing control plane processing may be integrated with the application processor 1904 described below.

[0164] Application processor 1904 is also referred to as CPU, MPU, microprocessor, or processor core. Application processor 1904 may include multiple processors (processor cores). Application processor 1904 loads system software programs (operating system (OS)) and various application programs (e.g., call applications, web browsers, email programs, camera operation applications, and music player applications) from memory 1906 or from other memory (not shown), and executes these programs, thereby providing the various functions of UE 12.

[0165] In some implementations, such as in Figure 19 As shown by the dashed line (1905), the baseband processor 1903 and application processor 1904 can be integrated on a single chip. In other words, the baseband processor 1903 and application processor 1904 can be implemented on a single system-on-a-chip (SoC) device 1905. SoC devices may be referred to as system-on-large-scale integration (LSI) or chipsets.

[0166] Memory 1906 is volatile memory, non-volatile memory, or a combination thereof. Memory 1906 may include multiple memory devices that are physically independent of each other. Volatile memory is, for example, SRAM, DRAM, or any combination thereof. Non-volatile memory is, for example, MROM, EEPROM, flash memory, hard disk drive, or any combination thereof. Memory 1906 may include external memory devices, for example, accessible from baseband processor 1903, application processor 1904, and SoC 1905. Memory 1906 may include internal memory devices integrated within baseband processor 1903, application processor 1904, or SoC 1905. Furthermore, memory 1906 may include memory in a Universal Integrated Circuit Card (UICC).

[0167] The memory 1906 may store one or more software modules (computer programs) 1907 including instructions and data for performing the processing of UE 12 as described in the above embodiments. In some implementations, the baseband processor 1903 or the application processor 1904 may load these software modules 1907 from the memory 1906 and execute the loaded software modules, thereby performing the processing of UE 12 as described in the above embodiments with reference to the accompanying drawings.

[0168] Note that the control plane processing and operation described in the above embodiments can be implemented by components other than the RF transceiver 1901 and the antenna array 1902, that is, by at least one of the memory 1906 of the storage software module 1907 and the baseband processor 1903 and the application processor 1904.

[0169] As referenced above Figure 17 and Figure 18 The processors included in RAN node 11 and UE 12 according to the above embodiments execute one or more programs including instructions for causing the computer to perform the algorithms described with reference to the accompanying drawings. Any type of non-transitory computer-readable medium can be used to store and provide the program to the computer. Non-transitory computer-readable media includes any type of tangible storage medium. Examples of non-transitory computer-readable media include: magnetic storage media (such as floppy disks, magnetic tapes, hard disk drives, etc.), opto-magnetic storage media (e.g., magneto-optical disks), compact disk read-only memory (CD-ROM), CD-R, CD-R / W, and semiconductor memory (such as mask ROM, programmable ROM (PROM), erasable PROM (EPROM), flash ROM, and random access memory (RAM), etc.). Any type of transient computer-readable medium can be used to provide the program to the computer. Examples of transient computer-readable media include electrical signals, optical signals, and electromagnetic waves. Transitory computer-readable media can provide the program to the computer via wired communication lines (e.g., electrical wires and optical fibers) or wireless communication lines.

[0170] Other embodiments

[0171] Each of the above embodiments can be used alone, or two or more embodiments can be appropriately combined with each other.

[0172] In the above embodiments, the switching of the active BWP is described using DCI transmitted on the NR PDCCH. However, note that the switching of the active BWP in the above embodiments can be performed by a MAC CE or a timer (e.g., a BWP inactivity timer).

[0173] The above embodiments are primarily based on the assumption that only one BWP is activated for each UE (i.e., one active BWP per UE). However, the methods described in the above embodiments can also be applied to situations where multiple BWPs are activated simultaneously for a UE. For example, there may be multiple active BWPs in a BWP set. Furthermore, there may be multiple active BWPs, each corresponding to a specific BWP group within a BWP set, or multiple active BWPs within a BWP group.

[0174] The 5G UE can be configured to measure beam quality in addition to cell quality and report it to the RAN node (e.g., gNB). In the above embodiment, UE 12 can perform RLM and beam monitoring in combination. If UE 12 detects a beam fault in an active BWP and then fails to perform beam recovery in that BWP (beam recovery failure), UE 12 can operate as follows. Specifically, if Layer 1 of UE 12 correctly detects the beam of another BWP (e.g., another BWP in a BWP group) contained in the same (physical) cell as the BWP, Layer 1 notifies Layers 2 and 3 of UE 12 of the success of beam recovery in that other BWP (beam recovery success). If Layer 3 of UE 12 has detected radio quality degradation in RLM but is still in the state before RLF detection, Layer 3 can stop the RLF timer and counter based on the notification from L1 and return to normal RLM operation.

[0175] The above embodiments are also applicable to MR-DC (e.g., EN-DC) and NR-NR DC. For example, an active BWP in an SCG can be switched via a DCI transmitted on an (NR)PDCCH. In this case, the RAN node (i.e., SN) operating the SCG can transmit the (NR)PDCCH in the active BWP of the SCG's DL, and the UE 12 can switch the active BWP of the DL according to any of the above embodiments in response to receiving the PDCCH (i.e., DCI). On the other hand, in the case of switching an active BWP in the SCG by changing the cell definition SSB, the RAN node (i.e., MN) operating the MCG can transmit an indication in the MCG cell (or the active BWP of the DL) for switching the active BWP in the SCG by changing the cell definition SSB. The UE 12 can switch the active BWP in the SCG according to any of the above embodiments in response to receiving the indication. For example, in NR-NR DC, the SgNB can send control information containing an active BWP handover indication to the primary gNB (MgNB) via an SN MODIFICATION REQUEST ACKNOWLEDGE message during SN modification. The MgNB can then send this control information to UE 12 via an RRC reconfiguration message. Optionally, in (NG-)EN-DC, the SgNB can send this control information to the primary eNB (MeNB) via an SN MODIFICATION REQUEST ACKNOWLEDGE message during SN modification. The MeNB can then send this control information to UE 12 via an RRC connection reconfiguration message. Optionally, the SgNB can directly send this control information to UE 12 via a signaling bearer in the SCG (e.g., SRB3).

[0176] Although the term "cell-defined SSB" is used in the above embodiments, it can also be referred to as a cell-representative SSB, as it represents an SSB that corresponds to a BWP (i.e., a physical cell) from the UE's perspective, or a group of BWPs that corresponds to a set of physical cells. Alternatively, a cell-defined SSB can be referred to as a cell-specific SSB, as it specifies the representative cell (physical cell) that includes the SSB. Furthermore, a cell-defined SSB can be referred to as a serving SSB, as it is the SSB that the UE monitors when camped on a BWP or group of BWPs that includes the SSB.

[0177] The sub-PCI described in the above embodiments can be associated with the BWP index.

[0178] The base BWP described in the above embodiments can be referred to as the default BWP, initial BWP, reference BWP, main BWP, anchor BWP, or primary BWP. Specifically, the BWP initially hosted by the UE when it first accesses the RAN node (i.e., when transitioning from idle mode to connected mode) can be referred to as the base BWP, default BWP, initial BWP, reference BWP, main BWP, anchor BWP, or primary BWP. Alternatively, a BWP that is not a base BWP among the multiple BWPs included within a system bandwidth can be referred to as a sub-BWP, secondary BWP, or slave BWP.

[0179] Furthermore, the above embodiments are merely examples of applications of the technical ideas obtained by the inventors. These technical ideas are not limited to the above embodiments, and various modifications can be made to them.

[0180] For example, all or part of the above embodiments may be described in, but not limited to, the following supplementary description.

[0181] (Supplementary Note 1)

[0182] A radio terminal, comprising:

[0183] Memory; and

[0184] At least one processor is connected to the memory.

[0185] The at least one processor is configured to: when switching the downlink bandwidth portion, i.e., the downlink BWP, from the first BWP to the second BWP without changing the cell definition synchronization signal block, i.e., the cell definition SSB, if the reference signal type used for radio link monitoring (RLM) is set to the SSB type, then after switching the downlink BWP to the second BWP, continue to use the first SSB associated with the first BWP for RLM measurements.

[0186] (Supplementary Note 2)

[0187] According to the radio terminal described in Supplementary Note 1, the at least one processor is configured to determine whether to change the reference signal to be used for RLM measurement after switching the downlink BWP, based on whether the reference signal type used by the RLM is the SSB type or the Channel State Information Reference Signal type, i.e., the CSI-RS type.

[0188] (Supplementary Explanation 3)

[0189] According to the radio terminal described in Supplementary Note 1 or 2, wherein the at least one processor is configured to: when the downlink BWP is switched from the first BWP to the second BWP without changing the cell definition SSB, if the reference signal type used by the RLM is set to the channel state information reference signal type, i.e., the CSI-RS type, then the second CSI-RS in the second BWP is used instead of the first CSI-RS in the first BWP to perform the RLM measurement.

[0190] (Supplementary Note 4)

[0191] According to any one of Supplementary Explanations 1 to 3, the radio terminal wherein,

[0192] The at least one processor is configured to inherit parameters related to the RLM when switching the downlink BWP from the first BWP to the second BWP without changing the cell definition SSB.

[0193] The parameters include the count value of a timer that is activated to determine radio link failure (RLF) when a specified number of consecutive asynchronys occur.

[0194] (Supplementary Note 5)

[0195] According to any one of Supplementary Notes 1 to 4, the radio terminal wherein the at least one processor is configured to perform CSI measurements using a second CSI-RS in the second BWP instead of a first CSI-RS in the first BWP when the downlink BWP is switched from the first BWP to the second BWP without changing the cell definition SSB.

[0196] (Supplementary Note 6)

[0197] According to any one of Supplementary Notes 1 to 5, in the radio terminal, wherein the at least one processor is configured to: when instructing to switch the downlink BWP from the first BWP to the second BWP in a manner that changes the cell definition SSB, if the reference signal type used by the RLM is set to the SSB type, then suspend the use of the first SSB associated with the first BWP for the RLM measurement.

[0198] (Supplementary Note 7)

[0199] According to any one of Supplementary Notes 1 to 6, in the radio terminal, wherein the at least one processor is configured to: when instructing to switch the downlink BWP from the first BWP to the second BWP in a manner that changes the cell definition SSB, if the reference signal type used by the RLM is set to the SSB type, then use the second SSB associated with the second BWP instead of the first SSB associated with the first BWP to perform the RLM measurement.

[0200] (Supplementary Note 8)

[0201] According to any one of Supplementary Notes 1 to 7, in the radio terminal, the at least one processor is configured to determine whether to continue using the first SSB associated with the first BWP for the RLM measurement based on whether the handover of the downlink BWP from the first BWP to the second BWP involves a change in the cell definition SSB.

[0202] (Supplementary Note 9)

[0203] According to any one of Supplementary Explanations 6 to 8, the radio terminal wherein...

[0204] The at least one processor is configured to: upon instructing a switch of the downlink BWP from the first BWP to the second BWP in a manner that changes the cell definition SSB, if the reference signal type used by the RLM is set to the SSB type, reset parameters related to the RLM, and

[0205] The parameters include the count value of a timer that is activated to determine radio link failure (RLF) when a specified number of consecutive asynchronys occur.

[0206] (Supplementary Note 10)

[0207] According to any one of Supplementary Notes 1 to 7, the radio terminal wherein the RLM measurement includes measuring the downlink radio quality of the serving cell when the radio terminal is in connected mode, in order to detect asynchrony and radio link failure, i.e., RLF.

[0208] (Supplementary Note 11)

[0209] According to the radio terminal described in Supplementary Note 5, the CSI measurement includes measuring the downlink radio quality of the serving cell when the radio terminal is in connected mode, in order to send a report to the radio access network node containing a channel quality indication, i.e., CQI, for use in scheduling and link adaptation.

[0210] (Supplementary Note 12)

[0211] A method performed by a radio terminal, the method comprising: when switching a downlink bandwidth portion, i.e., a downlink BWP, from a first BWP to a second BWP without changing the cell definition synchronization signal block, i.e., the cell definition SSB, if the reference signal type used for radio link monitoring (RLM) is set to the SSB type, then after switching the downlink BWP to the second BWP, continuing to use the first SSB associated with the first BWP for RLM measurements.

[0212] (Supplementary Note 13)

[0213] The method described in Supplementary Note 12 further includes: determining whether to change the reference signal used for RLM measurement after switching the downlink BWP, based on whether the reference signal type used by the RLM is the SSB type or the channel state information reference signal type, i.e., the CSI-RS type.

[0214] (Supplementary Note 14)

[0215] The method described according to Supplementary Note 12 or 13 further includes: when the downlink BWP is switched from the first BWP to the second BWP without changing the cell definition SSB, if the reference signal type used by the RLM is set to the channel state information reference signal type, i.e., the CSI-RS type, then the second CSI-RS in the second BWP is used instead of the first CSI-RS in the first BWP to perform the RLM measurement.

[0216] (Supplementary Note 15)

[0217] The method according to any one of Supplementary Notes 12 to 14 further includes: when switching the downlink BWP from the first BWP to the second BWP without changing the cell definition SSB, inheriting parameters related to the RLM, wherein...

[0218] The parameters include the count value of a timer that is activated to determine radio link failure (RLF) when a specified number of consecutive asynchronys occur.

[0219] (Supplementary Note 16)

[0220] The method according to any one of Supplementary Notes 12 to 15 further includes: when the downlink BWP is switched from the first BWP to the second BWP without changing the cell definition SSB, using the second CSI-RS in the second BWP instead of the first CSI-RS in the first BWP to perform CSI measurements.

[0221] (Supplementary Note 17)

[0222] The method according to any one of Supplementary Notes 12 to 16 further includes: when the downlink BWP is switched from the first BWP to the second BWP in a manner that changes the cell definition SSB, if the reference signal type used by the RLM is set to the SSB type, then the RLM measurement using the first SSB associated with the first BWP is stopped.

[0223] (Supplementary Note 18)

[0224] The method according to any one of Supplementary Notes 12 to 17 further includes: when the downlink BWP is switched from the first BWP to the second BWP in a manner that changes the cell definition SSB, if the reference signal type used by the RLM is set to the SSB type, then the second SSB associated with the second BWP is used instead of the first SSB associated with the first BWP to perform the RLM measurement.

[0225] (Supplementary Note 19)

[0226] The method according to any one of Supplementary Notes 12 to 18 further includes: determining whether to continue using the first SSB associated with the first BWP for the RLM measurement based on whether the handover of the downlink BWP from the first BWP to the second BWP involves a change in the cell definition SSB.

[0227] (Supplementary Note 20)

[0228] The method according to any one of Supplementary Notes 17 to 19 further includes: when instructing to switch the downlink BWP from the first BWP to the second BWP in a manner that changes the cell definition SSB, if the reference signal type used by the RLM is set to the SSB type, resetting the parameters associated with the RLM, wherein,

[0229] The parameters include the count value of a timer that is activated to determine radio link failure (RLF) when a specified number of consecutive asynchronys occur.

[0230] (Supplementary Note 21)

[0231] According to any one of Supplementary Notes 12 to 20, the method wherein the RLM measurement includes measuring the downlink radio quality of the serving cell when the radio terminal is in connected mode, in order to detect asynchrony and radio link failure, i.e., RLF.

[0232] (Supplementary Note 22)

[0233] According to the method described in Supplementary Note 16, the CSI measurement includes measuring the downlink radio quality of the serving cell when the radio terminal is in connected mode, in order to send a report to the radio access network node containing a channel quality indication, i.e., CQI, for use in scheduling and link adaptation.

[0234] (Supplementary Note 23)

[0235] A non-transitory computer-readable medium storing a program for enabling a computer to perform a method of radio terminal operation, wherein the method includes: when switching a downlink bandwidth portion, i.e., a downlink BWP, from a first BWP to a second BWP without changing the cell-defined synchronization signal block, i.e., the cell-defined SSB, if the reference signal type used for radio link monitoring (RLM) is set to the SSB type, then after switching the downlink BWP to the second BWP, continuing to perform RLM measurements using the first SSB associated with the first BWP.

[0236] This application is based on and claims priority to Japanese Patent Application 2017-218040, filed on November 13, 2017, the entire contents of which are incorporated herein by reference.

[0237] List of reference numerals

[0238] 11RAN nodes

[0239] 12UE

[0240] 1804 processor

[0241] 1805 memory

[0242] 1903 Baseband Processor

[0243] 1904 Application Processor

[0244] 1906 Memory

Claims

1. A radio terminal, comprising: Memory; as well as At least one processor, which is connected to the memory and is configured to: Receive the first BWP configuration for the initial bandwidth portion, i.e., the initial BWP; Receive the second BWP configuration for the second BWP; and When the active BWP is the initial BWP, radio link monitoring (RLM) is performed on the initial BWP based on the synchronization signal (SS) / physical broadcast channel (PBCH) block associated with the initial BWP, where the synchronization signal / physical broadcast channel block is the SSB. The RLM based on the SSB is configured for use in the second BWP.

2. The radio terminal according to claim 1, wherein, The initial BWP overlaps with the second BWP.

3. The radio terminal according to claim 2, wherein, The initial BWP partially overlaps with the second BWP.

4. The radio terminal according to claim 1, wherein, The at least one processor is configured to receive SSB configuration, and The SSB is configured by the SSB configuration.

5. The radio terminal according to claim 1, wherein, The at least one processor is configured to receive the first BWP configuration and the second BWP configuration in the same message.

6. The radio terminal according to claim 1, wherein, The at least one processor is also configured to switch the active BWP from the initial BWP to the second BWP.

7. The radio terminal according to claim 1, wherein, The SSB is the cell definition SSB.

8. The radio terminal according to claim 1, wherein, The SSB is associated with the Remaining Minimal System Information (RMSI).

9. The radio terminal according to claim 1, wherein, The at least one processor is also configured to perform the RLM in the second BWP based on the SSB when the active BWP is the second BWP.

10. A method for using a base station, the method comprising: Send the first BWP configuration for the initial bandwidth portion, i.e., the initial BWP, to the radio terminal; as well as Send the second BWP configuration for the second BWP to the radio terminal. When the active BWP is the initial BWP, radio link monitoring (RLM) is performed on the initial BWP based on the synchronization signal (SS) / physical broadcast channel (PBCH) block associated with the initial BWP, where the synchronization signal / physical broadcast channel block is the SSB. The RLM based on the SSB is configured for use in the second BWP.

11. A method for using a radio terminal, the method comprising: Receive the first BWP configuration for the initial bandwidth portion, i.e., the initial BWP; Receive the second BWP configuration for the second BWP; as well as When the active BWP is the initial BWP, radio link monitoring (RLM) is performed on the initial BWP based on the synchronization signal (SS) / physical broadcast channel (PBCH) block associated with the initial BWP, where the synchronization signal / physical broadcast channel block is the SSB. The RLM based on the SSB is configured for the second BWP.

12. The method according to claim 11, wherein, The initial BWP overlaps with the second BWP.

13. The method according to claim 12, wherein, The initial BWP partially overlaps with the second BWP.

14. The method of claim 11, further comprising: Receive SSB configuration, The SSB is configured by the SSB configuration.

15. The method according to claim 11, wherein, The first BWP configuration and the second BWP configuration are received in the same message.

16. The method of claim 11, further comprising switching the active BWP from the initial BWP to the second BWP.

17. The method according to claim 11, wherein, The SSB is the cell definition SSB.

18. The method according to claim 11, wherein, The SSB is associated with the Remaining Minimal System Information (RMSI).

19. The method of claim 11, further comprising: When the active BWP is the second BWP, the RLM is performed in the second BWP based on the SSB.

20. A non-transitory computer-readable storage medium storing a program for causing a computer to perform processing, said processing comprising: Receive the first BWP configuration for the initial bandwidth portion, i.e., the initial BWP; Receive the second BWP configuration for the second BWP; as well as When the active BWP is the initial BWP, radio link monitoring (RLM) is performed on the initial BWP based on the synchronization signal (SS) / physical broadcast channel (PBCH) block associated with the initial BWP, where the synchronization signal / physical broadcast channel block is the SSB. The RLM based on the SSB is configured for the second BWP.

21. The non-transitory computer-readable storage medium according to claim 20, wherein, The initial BWP overlaps with the second BWP.

22. The non-transitory computer-readable storage medium according to claim 21, wherein, The initial BWP partially overlaps with the second BWP.

23. The non-transitory computer-readable storage medium according to claim 20, wherein, The process also includes: Receive SSB configuration, The SSB is configured by the SSB configuration.

24. The non-transitory computer-readable storage medium according to claim 20, wherein, The first BWP configuration and the second BWP configuration are received in the same message.

25. The non-transitory computer-readable storage medium according to claim 20, wherein, The process also includes switching the active BWP from the initial BWP to the second BWP.

26. The non-transitory computer-readable storage medium according to claim 20, wherein, The SSB is the cell definition SSB.

27. The non-transitory computer-readable storage medium according to claim 20, wherein, The SSB is associated with the Remaining Minimal System Information (RMSI).

28. The non-transitory computer-readable storage medium according to claim 20, wherein, The process further includes: when the active BWP is the second BWP, performing the RLM in the second BWP based on the SSB.

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