Central unit, distributed unit, base station, and methods thereof

Abstract

To allow a central unit of a base station to know a wireless terminal that stays in an active bandwidth part (BWP) in which a Common Search Space (CSS) is not set.SOLUTION: A central unit (1) of a base station sends a message containing an information element indicating system information to a distributed unit (2) of the base station. As a reply to the message, the central unit (1) receives a list from the distributed unit (2). The list indicates a terminal device that needs to be notified of the system information by dedicated signaling.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, and more particularly to the use of one or more bandwidth parts configured within one carrier bandwidth.

Background Art

[0002] The 3rd Generation Partnership Project (3GPP (registered trademark)) is standardizing the 5th generation mobile communication system (5G) for introduction after 2020. 5G is realized by a combination of continuous enhancement / evolution of LTE and LTE-Advanced and innovative enhancement / evolution by introducing a new 5G air interface (new Radio Access Technology (RAT)). The new RAT supports, for example, frequency bands higher than those targeted by the continuous development of LTE / LTE-Advanced (e.g., below 6 GHz), such as centimeter wave bands of 10 GHz or higher and millimeter wave bands of 30 GHz or higher.

[0003] In this specification, the 5th generation mobile communication system is referred to as 5G System, or Next Generation (NextGen) System (NG System). The new RAT for 5G System is referred to as New Radio (NR), 5G RAT, or NG RAT. The new Radio Access Network (RAN) for 5G System is referred to as NextGen RAN (NG-RAN) or 5G-RAN. The new base station in NG-RAN is referred to as gNodeB (gNB). The new core network for 5G System is referred to as 5G Core Network (5GC) or NextGen Core (NG Core). The wireless terminal (User Equipment (UE)) connected to 5G System is referred to as 5G UE, NextGen UE (NG-UE), or simply UE.

[0004] As used herein, the term "LTE" includes, unless otherwise specified, the improvements and developments of LTE and LTE-Advanced for enabling interworking with the 5G System. The improvements and developments of LTE and LTE-Advanced for interworking with the 5G System are referred to as LTE-Advanced Pro, LTE+, or enhanced LTE (eLTE). Further, terms related to LTE network or logical entities such as "Evolved Packet Core (EPC)", "Mobility Management Entity (MME)", "Serving Gateway (S-GW)", and "Packet Data Network (PDN) Gateway (P-GW)" used herein include, unless otherwise specified, these improvements and developments for enabling interworking with the 5G System. The improved EPC, MME, S-GW, and P-GW are referred to as, for example, enhanced EPC (eEPC), enhanced MME (eMME), enhanced S-GW (eS-GW), and enhanced P-GW (eP-GW).

[0005] In LTE and LTE-Advanced, for Quality of Service (QoS) and packet routing, bearers for each QoS class and 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 per-bearer QoS) concept, one or more Evolved Packet System (EPS) bearers are established between the UE and the P-GW in the EPC, and multiple Service Data Flows (SDFs) having the same QoS class are transferred through one EPS bearer that satisfies these QoSs.

[0006] In contrast, in the 5G System, although radio bearers may be used in the NG-RAN, bearers are not used in the interfaces within the 5GC and between the 5GC and the NG-RAN. Specifically, QoS flows are defined instead of EPS bearers, and one or more SDFs are mapped to one or more QoS flows. The QoS flow between the 5G UE and the user plane termination 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. The QoS flow corresponds to the finest granularity of packet forwarding and treatment within the 5G system. That is, the 5G System adopts the Flow-based QoS (or per-flow QoS) concept instead of the Bearer-based QoS concept. In the Flow-based QoS concept, QoS is handled on a per-QoS flow basis. The association between the 5G UE and the data network is called a PDU session. The PDU session is a term corresponding to the PDN connection in LTE and LTE-Advanced. Multiple QoS flows can be configured within one PDU session. The 3GPP specifications define the 5G QoS Indicator (5QI) corresponding to the LTE QCI for the 5G System.

[0007] Figure 1 shows the basic architecture of a 5G system. The architecture shown in Figure 1 is an architecture called "Standalone NR (in NextGen System)" or "Option 2". The UE establishes one or more Signalling Radio Bearers (SRBs) and one or more Data Radio Bearers (DRBs) with the gNB. The 5GC and the gNB establish a control plane interface and a user plane interface for the UE. The control plane interface between the 5GC and the gNB (i.e., the RAN) is called the NG-c interface and is used for the transfer of Non-Access Stratum (NAS) information and control information between the 5GC and the gNB (e.g., N2 AP Information Element). The user plane interface between the 5GC and the gNB (i.e., the RAN) is called the NG-u interface and is used for the transfer of packets of one or more QoS flows within the PDU session of the UE.

[0008] NR supports the use of different sets of radio parameters in multiple frequency bands. Each set of radio parameters is called "numerology". For an Orthogonal Frequency Division Multiplexing (OFDM) system, OFDM numerology includes, for example, subcarrier spacing, system bandwidth, Transmission Time Interval (TTI) length, subframe duration, Cyclic prefix length, and symbol duration. The 5G system supports various types of services with different service requirements, such as enhanced Mobile Broad Band (eMBB), Ultra Reliable and Low Latency Communication (URLLC), and massive Machine Type Communication (mMTC). The selection of numerology depends on the service requirements.

[0009] NR supports wider channel bandwidths (e.g., 100s of MHz) compared to that of LTE. One channel bandwidth (i.e., BW Channel ) is the radio frequency (RF) bandwidth that supports one NR carrier. The channel bandwidth is also called the system bandwidth. While LTE supports channel bandwidths up to 20 MHz, 5G NR supports channel bandwidths up to 500 MHz, for example.

[0010] To efficiently support multiple 5G services, such as broadband services like eMBB and narrowband services like Internet of Things (IoT), it is preferable that these multiple services can be multiplexed on one channel bandwidth. Further, if all 5G UEs have to support transmission and reception with a transmission bandwidth corresponding to the entire channel bandwidth, this may prevent low cost and low power consumption of UEs for narrowband IoT services. Therefore, 3GPP allows one or more bandwidth parts (BWPs) to be configured within the carrier bandwidth (i.e., channel bandwidth or system bandwidth) of each NR component carrier. A bandwidth part is also called a carrier bandwidth part. Multiple BWPs may be used for frequency division multiplexing (FDM) of different numerologies (e.g., subcarrier spacing (SCS)). For example, multiple BWPs may have different SCSs and different bandwidths.

[0011] Figures 2 and 3 show examples of the use of BWPs. In the example shown in Figure 2, the channel bandwidth of one component carrier is divided into BWP #1 and BWP #2, and these two BWPs are used for FDM of different numerologies (e.g., different subcarrier spacings). In the example shown in Figure 3, a narrowband BWP #1 is arranged within the channel bandwidth of one component carrier, and a BWP #2 that is narrower than BWP #1 is further arranged. When BWP #1 or BWP #2 is activated for a UE, the UE can reduce power consumption by not performing reception and transmission outside the active BWP (but within the channel bandwidth).

[0012] One bandwidth part (BWP) is frequency-consecutive and is composed of contiguous physical resource blocks (PRBs). The bandwidth of one BWP is at least the same size as the synchronization signal (SS) / physical broadcast channel (PBCH) block bandwidth. The BWP may or may not include the SS / PBCH block (SSB).

[0013] BWP configuration includes, for example, numerology, frequency location, and bandwidth (e.g., the number of PRBs). To specify the frequency location, a common PRB indexing is used at least for downlink (DL) BWP configuration in the Radio Resource Control (RRC) connected state. Specifically, the offset from PRB 0 to the lowest PRB of the SSB accessed by the UE is set by higher layer signaling. The reference point “PRB 0” is common to all UEs sharing the same wideband component carrier.

[0014] One SS / PBCH block contains primary signals necessary for idle UEs, such as NR synchronization signals (NR-SS) and NR physical broadcast channel (NR-PBCH). The NR-SS is used by the UE to obtain DL synchronization. A Reference Signal (RS) is transmitted in the SS / PBCH block to enable Radio Resource Management (RRM) measurements (e.g., RSRP measurement) for idle UEs. The RS may be the NR-SS itself or an additional RS. The NR-PBCH broadcasts a part of the Minimum System Information (e.g., Master Information Block (MIB)). The remaining minimum SI (RMSI) is transmitted on the Physical Downlink Shared Channel (PDSCH).

[0015] The network can transmit multiple SS / PBCH blocks within the channel bandwidth of one wideband component carrier. In other words, the SS / PBCH blocks may be transmitted in multiple BWPs within the channel bandwidth. In the first scenario, all SS / PBCH blocks within one wideband carrier are based on the NR-SS (e.g., primary SS (PSS) and secondary SS (SSS)) corresponding to the same physical-layer cell identity. In the second scenario, different SS / PBCH blocks within one wideband carrier may be based on the NR-SS corresponding to different physical-layer cell identities.

[0016] From the perspective of the UE, a cell is associated with one SS / PBCH block. Therefore, for the UE, each serving cell has one associated SS / PBCH block (single associated SS / PBCH block) in terms of frequency. Note that each serving cell is a primary cell (PCell) in carrier aggregation (CA) and dual connectivity (DC), a primary secondary cell (PSCell) in DC, or a secondary cell (SCell) in CA and DC. Such an SSB is called a cell defining SS / PBCH block. The cell defining SS / PBCH block has the associated RMSI. The cell defining SS / PBCH block serves as the time reference or timing reference of the serving cell. Also, the cell defining SS / PBCH block is used for SS / PBCH block (SSB) based RRM Measurements. The cell defining SS / PBCH block can be changed by "synchronous reconfiguration" (e.g., reconfiguration of radio resource setting information without handover using the RRC Reconfiguration procedure) for the PCell / PSCell and by "SCell release / add" for the SCell.

[0017] One or more BWP configurations for each component carrier are semi-statically signaled to the UE. Specifically, for each UE-specific serving cell, one or more DL BWPs (e.g., up to 4 DL BWPs) and one or more UL BWPs (e.g., up to 4 UL BWPs) can be configured for the UE by dedicated RRC messages. One or more DL BWPs and one or more UL BWPs configured for the UE are referred to as “DL BWP set” and “UL BWP set”, respectively.

[0018] Each of one or more BWPs (i.e., BWP set) configured for the UE can be activated and deactivated. An activated BWP is called an “active BWP”. That is, the UE receives signals on one or more active DL BWPs of the configured DL BWP set at a given time. Similarly, the UE transmits signals on one or more active UL BWPs of the configured UL BWP set at a given time. Note that in the current specification, only one DL BWP and only one UL BWP are activated at a given time.

[0019] The activation / deactivation of a BWP is determined by a lower layer (e.g., Physical (PHY) layer or Medium Access Control (MAC) layer), rather than the RRC layer. The switching of an active BWP is performed, for example, by 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 may be performed by the DCI of the NR PDCCH. The network can activate / deactivate a BWP, for example, according to the data rate or according to the numerology required by the service, and can dynamically switch the active BWP for the UE.

[0020] The BWP where the UE first stays (i.e., the initial active BWP) when accessing each serving cell (i.e., when transitioning from the Idle mode to the Connected mode) is called the "initial BWP". The initial BWP includes at least a DL BWP and may also include a UL BWP (if the serving cell is configured for the uplink). The initial BWP may be called the default BWP, reference BWP, primary BWP, anchor BWP, or master BWP. The set of BWPs configured for the UE always includes the initial BWP.

[0021] The initial BWP always configures the Common Search Space. For BWPs other than the initial BWP, the Common Search Space may or may not be configured. Note that the Common Search Space is a subset of the resources (i.e., PDCCH Search Space) for blind decoding performed by the UE to search for PDCCH data (i.e., DCI). In the 5G system, similar to LTE, the PDCCH Search Space includes the Common Search Space and the UE-specific Search Space. The UE-specific search space is individually configured for each UE via RRC signaling. On the other hand, all UEs accessing the serving cell know the extent or range of the Common Search Space. The NR Common Search Space is used to broadcast system information and paging, and random access channel (RACH) response, etc. The NR Common Search Space includes the "Type0-PDCCH common search space". In the Type0-PDCCH common search space, PDCCH (i.e., DCI) scrambled by the System Information Radio Network Temporary Identifier (SI-RNTI) is transmitted to enable the UE to receive System Information Block Type 1 (SIB1).

[0022] In 3GPP, it is being considered that if the active DL BWP of the UE does not have a Common Search Space (CSS) configured, the UE may not need to receive system information updates (SI updates) via broadcast (see, for example, Non-Patent Document 1). In this case, the network (NG-RAN) may send the updated SI to the UE staying in the active DL BWP without a configured Common Search Space via dedicated signaling (e.g., RRC Reconfiguration message).

[0023] Subsequently, the cloud RAN (C-RAN) deployment of NG-RAN will be described. FIG. 4 is a diagram showing the overall architecture of NG-RAN (see Non-Patent Document 2). NG-RAN is composed of a set of gNBs connected to the 5GC via the NG interface. The gNBs can be connected via the Xn interface. As shown in FIG. 4, a gNB may be composed of a gNB Central Unit (gNB-CU) and one or more gNB Distributed Units (gNB-DUs). The gNB-CU and the gNB-DU are connected via the F1 interface. The gNB-CU is a logical node that hosts the RRC, Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) protocols of the gNB (or the RRC and PDCP protocols of the gNB). The gNB-DU is a logical node that hosts the Radio Link Control (RLC), MAC, and PHY layers of the gNB.

Prior Art Documents

Non-Patent Documents

[0024]

Non-Patent Document 1

[0025] The inventors considered the case where the gNB-CU transmits SI updates to the UE via dedicated signaling. The gNB-CU transmits the updated SI to UEs staying in the active DL BWP where the Common Search Space is not configured via dedicated signaling. Therefore, it is preferable that the gNB-CU can know the UEs staying in the active DL BWP where the Common Search Space is not configured.

[0026] However, as described above, the change of the active BWP is performed, for example, by the DCI of the NR PDCCH. Therefore, in some implementations, the gNB-DU may determine the active BWP change and send the DCI for the active BWP change to the UE. In this case, the gNB-CU may not know which of the DL BWP sets configured for the UE is the active DL BWP. In other words, the gNB-CU may not know the active DL BWP of each UE. In addition to this, in some implementations, the gNB-DU may determine whether to set the Common Search Space for a non-initial BWP. In this case, the gNB-CU may not know whether the Common Search Space is set for each non-initial BWP included in the DL BWP set configured for the UE.

[0027] Therefore, the gNB-CU may not be able to know the UEs staying in the active DL BWP where the Common Search Space is not set. In addition to or instead of sending the SI update, for other purposes or uses, it may be preferable for the gNB-CU to be able to know the UEs staying in the active DL BWP where the Common Search Space is not set.

[0028] One of the objectives to be achieved by the embodiments disclosed in this specification is to provide an apparatus, a method, and a program that contribute to enabling a central unit (e.g., gNB-CU) of a base station (e.g., gNB) to know a radio terminal (e.g., UEs) staying in an active bandwidth part where the Common Search Space is not set. It should be noted that this objective is only one of the multiple objectives to be achieved by the multiple embodiments disclosed in this specification. Other objectives or problems and novel features will be clarified from the description of this specification or the attached drawings.

Means for Solving the Problems

[0029] In the first aspect, the distributed unit of the base station includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to transmit at least one terminal list to the central unit of the base station. The at least one terminal list indicates at least one of the following: (a) A plurality of wireless terminals for which a Common Search Space is not set in each activated downlink Bandwidth Part (BWP); (b) A plurality of wireless terminals for which a Search Space (SS) for receiving at least system information is not set in each activated downlink BWP; (c) A plurality of wireless terminals that need to receive updated system information via individual signaling for each wireless terminal; (d) A plurality of wireless terminals for which each activated downlink BWP is a non-initial downlink BWP; and (e) A plurality of wireless terminals that are receiving on each downlink BWP.

[0030] In the second aspect, the central unit of the base station includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to receive at least one terminal list from the distributed unit of the base station. The at least one terminal list is the same as that in the first aspect.

[0031] In the third aspect, the method in the distributed unit of the base station includes transmitting at least one terminal list to the central unit of the base station. The at least one terminal list is the same as that in the first aspect.

[0032] In a fourth aspect, the method in the central unit of the base station includes receiving at least one terminal list from the distributed unit of the base station. The at least one terminal list is the same as that in the first aspect.

[0033] In a fifth aspect, the distributed unit of the base station includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to transmit a message including an information element indicating a change in the activated downlink Bandwidth Part (BWP) of the wireless terminal to the central unit of the base station.

[0034] In a sixth aspect, the central unit of the base station includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to receive a message including an information element indicating a change in the activated downlink BWP of the wireless terminal from the distributed unit of the base station.

[0035] In a seventh aspect, the method in the distributed unit of the base station includes transmitting a message including an information element indicating a change in the activated downlink BWP of the wireless terminal to the central unit of the base station.

[0036] In an eighth aspect, the method in the central unit of the base station includes receiving a message including an information element indicating a change in the activated downlink BWP of the wireless terminal from the distributed unit of the base station.

[0037] In a ninth aspect, the program includes a set of instructions (software code) for causing a computer to perform the method according to the third, fourth, seventh, or eighth aspect described above when loaded into the computer.

Advantages of the Invention

[0038] According to the above aspect, it is possible to provide an apparatus, a method, and a program that contribute to enabling a central unit (e.g., gNB-CU) of a base station (e.g., gNB) to know a radio terminal (e.g., UEs) staying in an active bandwidth part for which a Common Search Space is not set.

Brief Description of Drawings

[0039]

Figure 1

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DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted as necessary for clarity of explanation.

[0041] The plurality of embodiments described below can be implemented independently or in appropriate combination. These embodiments have different novel features from each other. Therefore, these embodiments contribute to solving different purposes or problems and to achieving different effects.

[0042] The plurality of embodiments shown below are mainly described with respect to the 3GPP 5G system. However, these embodiments may be applied to other wireless communication systems.

[0043] <First Embodiment> FIG. 5 shows a configuration example of a wireless communication network according to this embodiment. The wireless communication network according to this embodiment includes a gNB Central Unit (gNB-CU) 1 and one or more gNB Distributed Units (gNB-DUs) 2. The gNB-CU 1 and each gNB-DU 2 are connected by an interface 501. The interface 501 is an F1 interface. The UE 3 is connected to at least one gNB-DU 2 via at least one air interface 502.

[0044] As shown in FIG. 6, the gNB-CU 1 may include a Control Plane (CP) Unit (gNB-CU-CP) 11 and one or more User Plane (UP) Units (gNB-CU-UP) 12. In this case, the gNB-CU-CP 11 is connected to the gNB-CU-UP 12 via a control plane interface 601 (i.e., an E1 interface). Further, the gNB-CU-CP 11 is connected to the gNB-DU 2 via a control plane interface 602 (i.e., an F1-C interface). The gNB-CU-UP 12 is connected to the gNB-DU 2 via a user plane interface 603 (i.e., an F1-U interface).

[0045] The gNB-CU1 may be a logical node that hosts the RRC, SDAP, and PDCP protocols of the gNB (or the RRC and PDCP protocols of the gNB). The gNB-DU2 may be a logical node that hosts the RLC, MAC, and PHY layers of the gNB. In such a functional configuration, the gNB-DU2 may determine the BWP set configured for the UE3 and notify the related gNB-CU1 of the configuration of the BWP set for the UE3. Further, the gNB-DU2 may determine the (first) active BWP(s) of the UE3 and notify the related gNB-CU1 of this. Alternatively, the gNB-CU1 may determine the BWP set configured for the UE3 and notify the related gNB-DU2 of the configuration of the BWP set for the UE3. Further or alternatively, the gNB-CU1 may determine the (first) active BWP(s) of the UE3 and notify the related gNB-DU2 of this. In any of these cases, the gNB-DU2 may change the active BWP(s) of the UE3. That is, the gNB-DU2 may determine the activation / deactivation of the BWP(s). Further, the gNB-DU2 may notify the gNB-CU1 of the information of the BWP(s) after the change. The information of the BWP(s) after the change may be, for example, information indicating whether each BWP is activated or deactivated, or information indicating the difference from the information of the BWP(s) before the change.

[0046] Figure 7 shows a process 700 which is an example of signaling between the gNB-CU1 and the gNB-DU2. In step 701, the gNB-DU2 transmits an F1 Application Protocol message. The name of the message may be, but is not limited to, for example, a BWP INFORMATION message. The message includes at least one terminal list (i.e., UE list). The at least one UE list indicates at least one of the following: (a) UEs for which no Common Search Space (CSS) is configured in each active DL BWP; (b) UEs that do not have a Search Space (SS) configured to receive at least SI in each active DL BWP; (c) UEs that need to receive updated SI via per-UE individual signaling (or UEs for which updated SI needs to be sent via per-UE individual signaling, or UEs for which gNB-CU1 needs to send updated SI via per-UE individual signaling); (d) UEs for which each active DL BWP is a non-initial DL BWP; and (e) UEs that are receiving on each DL BWP.

[0047] By receiving from gNB-DU2 a UE list indicating UEs that do not have CSS configured in each active DL BWP, gNB-CU1 can know the UEs staying in the active DL BWP without CSS configured. This enables gNB-CU1 to determine, for example, UEs that require the transmission of updated SI via individual signaling (e.g., RRC Reconfiguration message). In other words, this enables gNB-DU2 to inform gNB-CU1 of the UEs that require the transmission of updated SI via individual signaling. The UE list is useful, for example, for an implementation where gNB-DU2 decides whether to configure CSS for non-initial BWPs. The UE list may be a list of UEs staying in the active DL BWP without CSS configured. gNB-DU2 may select UEs that are receiving on the active DL BWP without CSS configured from among the UEs that are RRC_Connected in its cell and send the list of the selected UEs to gNB-CU1.

[0048] Alternatively or in addition, gNB-DU2 may send a list of UEs for which a Search Space (SS) (SI-SS) for receiving at least SI in each active DL BWP is not configured to gNB-CU1. Thereby, gNB-CU1 can know the UEs staying in the active DL BWP for which the SI-SS is not configured. Note that the SI-SS may be included in the CSS or may be included in the UE specific Search Space (USS).

[0049] By receiving from gNB-DU2 a UE list indicating UEs that need to receive updated SI via per-UE individual signaling, gNB-CU1 can directly know such UEs. This enables gNB-CU1, for example, to determine UEs that require transmission of updated SI via individual signaling. The UE list is useful, for example, for an implementation where gNB-DU2 decides whether to configure CSS in a non-initial BWP. gNB-DU2 may select UEs that are receiving in an active DL BWP for which CSS is not configured from among the UEs that are RRC_Connected in its cell and send a list of the selected UEs to gNB-CU1.

[0050] By receiving from gNB-DU2 a UE list indicating UEs for which each active DL BWP is a non-initial DL BWP, gNB-CU1 can know the UEs staying in the non-initial DL BWP. This enables gNB-CU1, for example, to determine UEs that require transmission of updated SI via individual signaling. The UE list is useful, for example, for an implementation where gNB-CU1 decides whether to set CSS for the non-initial BWP and instructs gNB-DU2 to set CSS for the non-initial BWP. Further, the UE list is also useful for an implementation where gNB-DU2 decides whether to set CSS for the non-initial BWP. In this implementation, gNB-CU1 may further refer to other information (e.g., Cell Group Configuration (CG-Config or CellGroupConfig)) to know whether CSS is set for each non-initial BWP. gNB-DU2 may select UEs that are being received on a non-initial active DL BWP from among the UEs that are RRC_Connected in its cell and send a list of the selected UEs to gNB-CU1.

[0051] By receiving from gNB-DU2 a UE list indicating UEs being received on each DL BWP (i.e., a list of UEs for each DL BWP), gNB-CU1 can know the UEs staying on each DL BWP (i.e., UEs for which their active DL BWP is each DL BWP). This enables gNB-CU1, for example, to determine UEs that require transmission of updated SI via individual signaling. The UE list is useful, for example, for an implementation where gNB-DU2 decides whether to set CSS for the non-initial BWP. In this implementation, gNB-CU1 may further refer to other information (e.g., CG-Config or CellGroupConfig) to know whether CSS is set for each non-initial BWP.

[0052] Specifically, during the UE Context Setup procedure, gNB-CU1 may examine the content of the CellGroupConfig IE in the DU to CU RRC Information IE in the F1AP: UE Context Setup Response message received from gNB-DU2. gNB-DU2 can include information related to the Common Search Space in the "CellGroupConfig" IE. Therefore, by examining the CellGroupConfig IE, gNB-CU1 can determine whether the CSS has been set by gNB-DU2 for each non-initial BWP.

[0053] Furthermore, the UE list is also useful for the implementation where gNB-CU1 determines whether to set the CSS for the non-initial BWP and instructs gNB-DU2 to set the CSS for the non-initial BWP.

[0054] These UE lists may utilize any identifier for distinguishing UEs. For example, the identifier used to distinguish UEs within the UE list may be the Cell RNTI (C-RNTI), the gNB-CU UE F1AP ID, the gNB-DU UE F1AP ID, or a pair of the gNB-CU UE F1AP ID and the gNB-DU UE F1AP ID. The C-RNTI uniquely identifies a UE (or the UE's RRC connection) within a cell for scheduling. The gNB-CU UE F1AP ID uniquely identifies the UE association on the F1 interface within gNB-CU1. The gNB-DU UE F1AP ID uniquely identifies the UE association on the F1 interface within gNB-DU2.

[0055] In some implementations, in response to receiving from gNB-CU1 a first control message (i.e., an F1AP message) that includes a System Information Update Notification, gNB-DU2 may send to gNB-CU1 a second control message (i.e., an F1AP message) that includes the UE list described above. The System Information Update Notification indicates that the system information will be updated in the next modification period. This contributes to promptly informing gNB-CU1 from gNB-DU2 that there are UEs that require transmission by individual signaling of the updated SI when the SI is updated by gNB-CU1. Note that the system information may be, for example, a warning notification message of the Public Warning System (PWS), or a warning notification message of the Earthquake and Tsunami Warning System (ETWS) (e.g., ETWS primary notification, ETWS secondary notification, or both).

[0056] This first control message may be a SYSTEM INFORMATION DELIVERY COMMAND message. In response to receiving the SYSTEM INFORMATION DELIVERY COMMAND message, gNB-DU2 broadcasts the requested system information in the CSS. Further, in this embodiment, gNB-DU2 sends to gNB-CU1 a second control message that includes the UE list described above. The name of this second control message is not limited to this, and may be, for example, a SYSTEM INFORMATION DELIVERY CONFIRM message.

[0057] FIG. 8 shows a process 800 which is an example of signaling between gNB-CU1 and gNB-DU2. In step 801, gNB-CU1 sends a SYSTEM INFORMATION DELIVERY COMMAND message including a system information update notification to gNB-DU2. In step 802, in response to receiving the SYSTEM INFORMATION DELIVERY COMMAND message, gNB-DU2 sends a SYSTEM INFORMATION DELIVERY CONFIRM message including the above-mentioned UE list to gNB-CU1.

[0058] Furthermore or alternatively, in response to determining by itself the update of system information, gNB-DU2 may send the above-mentioned UE list to gNB-CU1. This contributes to promptly informing gNB-CU1 from gNB-DU2 that there are UEs that require transmission by individual signaling of the updated SI during SI update by gNB-DU2.

[0059] Furthermore or alternatively, in response to receiving a request for the UE list from gNB-CU1, gNB-DU2 may send the above-mentioned UE list to gNB-CU1. This enables gNB-CU1 to know at a given time that there are UEs that require transmission by individual signaling of the updated SI.

[0060] As can be understood from the above description, in this embodiment, gNB-DU2 is configured to send at least one UE list to gNB-CU1. The at least one UE list indicates at least one of the following: (a) UEs for which a Common Search Space (CSS) is not set in each active DL BWP; (b) UEs for which a Search Space (SS) for receiving at least SI is not set in each active DL BWP; (c) UEs that need to receive updated SI via per-UE individual signaling (or UEs for which updated SI needs to be sent via per-UE individual signaling, or UEs for which gNB-CU1 needs to send updated SI via per-UE individual signaling); (d) UEs for which each active DL BWP is a non-initial DL BWP; and (e) UEs that are receiving on each DL BWP. This helps gNB-CU1 to know UEs staying on an active DL BWP with CSS not configured. For example, gNB-CU1 can determine UEs that need updated SI to be sent via individual signaling (e.g., RRC Reconfiguration message) by referring to this UE list.

[0061] <Second Embodiment> This embodiment provides details regarding signaling for sending updated SI. The configuration example of the wireless communication network according to this embodiment is the same as the example shown in FIGS. 5 and 6.

[0062] FIG. 9 shows a procedure 900 which is an example of signaling for sending updated SI. In step 901, gNB-DU2 instructs UE3 via PDCCH (i.e., DCI) to change the active DL BWP to a non-initial DL BWP with CSS not configured. In step 902, UE3 stays on the non-initial DL BWP with CSS not configured and operates to receive signals on the non-initial DL BWP.

[0063] Steps 903 and 904 are the same as steps 801 and 802 shown in FIG. 8. That is, in step 903, gNB-CU1 sends a SYSTEM INFORMATION DELIVERY COMMAND message including a system information update notification to gNB-DU2. In step 904, in response to receiving the SYSTEM INFORMATION DELIVERY COMMAND message, gNB-DU2 sends a SYSTEM INFORMATION DELIVERY CONFIRM message including the UE list described in the first embodiment to gNB-CU1.

[0064] In step 905, after receiving the UE list, gNB-CU1 sends the updated SI to one or more UEs3 via per-UE individual signaling (e.g., RRC Reconfiguration message). Specifically, gNB-CU1 refers to the received UE list to identify the UEs staying in the active DL BWP without CSS configured and determines the UEs that require the transmission of the updated SI via individual signaling. The RRC Reconfiguration message including the updated SI is carried from gNB-CU1 to gNB-DU2 on the F1 interface by the DL RRC MESSAGE TRANSFER message and then sent to UE3 by gNB-DU2.

[0065] In step 906, UE3 sends an RRC Reconfiguration Complete message to gNB-CU1. The RRC Reconfiguration Complete message is carried from gNB-DU2 to gNB-CU1 on the F1 interface by the UL RRC MESSAGE TRANSFER message.

[0066] According to the procedure of FIG. 9, gNB-CU1 can determine UEs staying in the active DL BWP with CSS not configured, and can send SI updated via individual signaling to these UEs.

[0067] <The Third Embodiment> This embodiment provides details regarding the F1AP message for carrying the UE list described in the first embodiment. The configuration example of the wireless communication network according to this embodiment is the same as the examples shown in FIGS. 5 and 6.

[0068] FIG. 10 shows an example of the format of an F1AP message (e.g., BWP INFORMATION message) for carrying the UE list described in the first embodiment. The message shown in FIG. 10 is sent from gNB-DU2 to gNB-CU1. The F1AP message (e.g., BWP INFORMATION message) shown in FIG. 10 includes a BWP list indicating all (DL) BWPs. The BWP list includes a UE list (or UE ID list) for each (DL) BWP. In the example of FIG. 10, the UE list (or UE ID list) uses C-RNTI to distinguish UEs. The UE list (or UE ID list) may use other identifiers (e.g., gNB-CU UE F1AP ID or gNB-DU UE F1AP ID) instead of C-RNTI.

[0069] The F1AP message shown in FIG. 10 enables gNB-DU2 to provide gNB-CU1 with a UE list (i.e., a list of UEs for each DL BWP) indicating the UEs received on each DL BWP.

[0070] <The Fourth Embodiment> The configuration example of the wireless communication network according to this embodiment is the same as the examples shown in FIGS. 5 and 6. In the first to third embodiments, an example in which gNB-DU2 provides a UE list to gNB-CU1 was shown. These examples described in the first to third embodiments use non-UE associated procedure or signaling to send the UE list from gNB-DU2 to gNB-CU1. Therefore, the first to third embodiments have the advantage of being able to reduce the number of signaling between gNB-CU1 and gNB-DU2 compared to the method using UE associated procedure or signaling.

[0071] However, in some implementations, gNB-DU2 may notify gNB-CU1 of the change of the active DL BWP of UE3 using UE associated procedure or signaling. In this embodiment, gNB-DU2 sends a message indicating the change of the active DL BWP of UE3 to gNB-CU1. In response to the change of the active DL BWP of UE3, gNB-DU2 may send a message indicating the change of the active DL BWP of UE3 to gNB-CU1. After the change of the active DL BWP of UE3, gNB-DU2 may send a message indicating the change of the active DL BWP of UE3 to gNB-CU1. Specifically, gNB-DU2 may notify gNB-CU1 that the active DL BWP of UE3 has been changed from the initial BWP to a non-initial DL BWP (especially a non-initial DL BWP without CSS). Thereby, gNB-CU1 can know the UEs staying in the active DL BWP for which CSS is not set. This enables gNB-CU1 to determine, for example, the UEs that require the transmission of updated SI via individual signaling.

[0072] In some implementations, when gNB-DU2 changes (or switches) the active DL BWP of UE3, in the UE Context Modification Required procedure initiated by gNB-DU2, gNB-DU2 may send a message containing an information element indicating the change (or switching) of the active DL BWP of UE3 to gNB-CU1. Specifically, in response to changing the active DL BWP of UE3 from the initial BWP to a non-initial DL BWP (especially a non-initial DL BWP without CSS), gNB-DU2 may send a message containing the said information element to gNB-CU1. gNB-DU2 may include the said information element in the F1AP: UE CONTEXT MODIFICATION REQUIRED message.

[0073] The said information element may be a BOOLEAN data type variable indicating whether the active DL BWP of UE3 has been changed from the initial DL BWP to a non-initial DL BWP. Alternatively, the said information element may be an ENUMERATED type variable indicating that the active DL BWP of UE3 has no CSS. Alternatively, the said information element may be an INTEGER type variable indicating the identifier (e.g., BWP ID) of the active DL BWP of UE3.

[0074] Figure 11 shows procedure 1100 which is an example of the signaling according to this embodiment. In step 1101, gNB-DU2 sends a UE CONTEXT MODIFICATION REQUIRED message. The said message includes the information element described in this embodiment.

[0075] FIG. 12 shows an example of the format of an F1 message including the information elements described in this embodiment. The UE CONTEXT MODIFICATION REQUIRED message shown in FIG. 12 is sent from the gNB-DU2 to the gNB-CU1 to request modification of the UE context. The UE CONTEXT MODIFICATION REQUIRED message shown in FIG. 12 includes a UE switch to BWP information element (IE). As described above, the "UE switch to BWP" IE may be a BOOLEAN data type variable indicating whether the active DL BWP of UE3 has been changed from the DL BWP to the non-initial DL BWP. Alternatively, the "UE switch to BWP" IE may be an ENUMERATED type variable indicating that the active DL BWP of UE3 does not have CSS.

[0076] The UE CONTEXT MODIFICATION REQUIRED message in FIG. 12 may include a BWP-ID information element (IE) instead of the "UE switch to BWP" IE. The "BWP-ID" IE may be an INTEGER type variable indicating the identifier (e.g., BWP ID) of the active DL BWP of UE3.

[0077] Next, a configuration example of the gNB-CU1 and gNB-DU2 according to the above-described plurality of embodiments will be described below. FIG. 13 is a block diagram showing a configuration example of the gNB-CU1 according to the above-described embodiment. Note that the configurations of the gNB-CU-CP11 and gNB-CU-UP12 may be the same as those shown in FIG. 13. Referring to FIG. 13, the gNB-CU1 includes a network interface 1301, a processor 1302, and a memory 1303. The network interface 1301 is used to communicate with network nodes (e.g., gNB-DU2 and control plane (CP) nodes and user plane (UP) nodes in the 5GC). The network interface 1301 may include a plurality of interfaces. The network interface 1301 may include, for example, an optical fiber interface for CU-DU communication and a network interface compliant with the IEEE 802.3 series.

[0078] The processor 1302 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. The processor 1302 may include a plurality of processors. For example, the processor 1302 may include a modem processor (e.g., Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., Central Processing Unit (CPU) or Micro Processing Unit (MPU)) that performs control plane processing.

[0079] The memory 1303 is composed of a combination of volatile memory and non-volatile memory. The volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM) or a combination thereof. The non-volatile memory is Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. The memory 1303 may include storage located away from the processor 1302. In this case, the processor 1302 may access the memory 1303 via the network interface 1301 or an I / O interface (not shown).

[0080] The memory 1303 may store one or more software modules (computer programs) 1304 containing instruction groups and data for performing the processing by the gNB-CU1 described in the above-described embodiments. In some implementations, the processor 1302 may be configured to perform the processing of the gNB-CU1 described in the above embodiments by reading and executing the one or more software modules 1304 from the memory 1303.

[0081] FIG. 14 is a block diagram showing a configuration example of the gNB-DU2 according to the above-described embodiment. Referring to FIG. 14, the gNB-DU2 includes a Radio Frequency transceiver 1401, a network interface 1403, a processor 1404, and a memory 1405. The RF transceiver 1401 performs analog RF signal processing to communicate with NG UEs. The RF transceiver 1401 may include a plurality of transceivers. The RF transceiver 1401 is coupled to the antenna array 1402 and the processor 1404. The RF transceiver 1401 receives modulation symbol data from the processor 1404, generates a transmission RF signal, and supplies the transmission RF signal to the antenna array 1402. Also, the RF transceiver 1401 generates a baseband reception signal based on the reception RF signal received by the antenna array 1402 and supplies this to the processor 1404. The RF transceiver 1401 may include an analog beamformer circuit for beamforming. The analog beamformer circuit includes, for example, a plurality of phase shifters and a plurality of power amplifiers.

[0082] The network interface 1403 is used to communicate with network nodes (e.g., gNB-CU1, gNB-CU-CP11, gNB-CU-UP12). The network interface 1403 may include a plurality of interfaces. The network interface 1403 may include, for example, at least one of an optical fiber interface for CU-DU communication and a network interface compliant with IEEE 802.3 series.

[0083] Processor 1404 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Processor 1404 may include a plurality of processors. For example, Processor 1404 may include a modem processor (e.g., DSP) that performs digital baseband signal processing and a protocol stack processor (e.g., CPU or MPU) that performs control plane processing. Processor 1404 may include a digital beamformer module for beamforming. The digital beamformer module may include a Multiple Input Multiple Output (MIMO) encoder and a precoder.

[0084] Memory 1405 is composed of a combination of volatile memory and non-volatile memory. The volatile memory is, for example, SRAM, DRAM, or a combination thereof. The non-volatile memory is MROM, EEPROM, flash memory, or a hard disk drive, or any combination thereof. Memory 1405 may include storage located away from Processor 1404. In this case, Processor 1404 may access Memory 1405 via Network Interface 1403 or an I / O interface not shown.

[0085] Memory 1405 may store one or more software modules (computer programs) 1406 including instruction groups and data for performing the processing by gNB-DU2 described in the above-described embodiments. In some implementations, Processor 1404 may be configured to perform the processing of gNB-DU2 described in the above-described embodiments by reading and executing the one or more software modules 1406 from Memory 1405.

[0086] As described with reference to FIGS. 13 and 14, each of the processors included in the gNB-CU1 and gNB-DU2 according to the above-described embodiments executes one or more programs including a set of instructions for causing a computer to perform the algorithms described with reference to the drawings. This program is stored using various types of non-transitory computer readable media and can be supplied to a computer. The non-transitory computer readable media include various types of tangible storage media. Examples of the non-transitory computer readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), Compact Disc Read Only Memory (CD-ROM), CD-R, CD-R / W, and semiconductor memories (e.g., mask ROM, Programmable ROM (PROM), Erasable PROM (EPROM), flash ROM, Random Access Memory (RAM)). Also, the program may be supplied to a computer by various types of transitory computer readable media. Examples of the transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer readable media can supply the program to a computer via a wired communication path such as electric wires and optical fibers, or a wireless communication path.

[0087] <Other Embodiments> The above-described embodiment shows an example in which the gNB-CU1 uses the UE list received from the gNB-DU2 to determine UEs that require transmission of updated SI via individual signaling. However, the gNB-CU1 may use the UE list received from the gNB-DU2 for other purposes.

[0088] The signaling between the gNB-CU1 and the gNB-DU2 described in the above embodiments may be performed between the gNB-CU-CP11 and the gNB-DU2.

[0089] Furthermore, the above-described embodiments are merely examples regarding the application of the technical idea obtained by the present inventor. That is, the technical idea is not limited to only the above-described embodiments, and it goes without saying that various modifications are possible.

[0090] For example, part or all of the above embodiments may be described as follows in the appended claims, but are not limited thereto.

[0091] (Appendix 1) A distributed unit of a base station, at least one memory, at least one processor coupled to the at least one memory, comprising, the at least one processor is configured to transmit at least one terminal list to a central unit of the base station, the at least one terminal list a plurality of radio terminals in which a Common Search Space is not set in each activated downlink Bandwidth Part (BWP); a plurality of radio terminals in which a Search Space (SS) for receiving at least system information is not set in each activated downlink BWP; a plurality of radio terminals that need to receive updated system information via individual signaling for each radio terminal; a plurality of radio terminals in which each activated downlink BWP is a non-initial downlink BWP; and a plurality of radio terminals receiving on each downlink BWP; indicating at least one of a distributed unit.

[0092] (Appendix 2) In response to receiving, from the central unit, a first control message including a system information update notification, the at least one processor is configured to transmit the at least one terminal list to the central unit. The distributed unit according to Supplementary Note 1.

[0093] (Supplementary Note 3) The first control message is a SYSTEM INFORMATION DELIVERY COMMAND message. The distributed unit according to Supplementary Note 2.

[0094] (Supplementary Note 4) In response to determining an update of system information, the at least one processor is configured to transmit the at least one terminal list to the central unit. The distributed unit according to any one of Supplementary Notes 1 to 3.

[0095] (Supplementary Note 5) In response to receiving a request from the central unit, the at least one processor is configured to transmit the at least one terminal list to the central unit. The distributed unit according to any one of Supplementary Notes 1 to 4.

[0096] (Supplementary Note 6) The at least one terminal list indicates a plurality of wireless terminals for which a Common Search Space is not set in each activated downlink BWP. The distributed unit according to any one of Supplementary Notes 1 to 5.

[0097] (Supplementary Note 7) The at least one terminal list indicates a plurality of wireless terminals for which a Search Space (SS) for receiving at least system information is not set in each activated downlink BWP. The distributed unit according to any one of Supplementary Notes 1 to 5.

[0098] (Appendix 8) The at least one terminal list indicates a plurality of wireless terminals for which each activated downlink BWP is a non-initial downlink BWP. The distributed unit according to any one of Appendices 1 to 5.

[0099] (Appendix 9) The at least one terminal list includes a per-BWP terminal list for indicating a plurality of wireless terminals receiving on each downlink BWP. The distributed unit according to any one of Appendices 1 to 5.

[0100] (Appendix 10) A central unit of a base station, including at least one memory, at least one processor coupled to the at least one memory, and the at least one processor is configured to receive at least one terminal list from a distributed unit of the base station, the at least one terminal list is a plurality of wireless terminals for which no Common Search Space (CSS) is set in each activated downlink Bandwidth Part (BWP); a plurality of wireless terminals for which no Search Space (SS) for receiving at least system information is set in each activated downlink BWP; a plurality of wireless terminals that need to receive updated system information via per-terminal individual signaling; a plurality of wireless terminals for which each activated downlink BWP is a non-initial downlink BWP; and a plurality of wireless terminals receiving on each downlink BWP; indicating at least one of Central unit.

[0101] (Appendix 11) The at least one processor is configured to send a first control message including a system information update notification to the distributed unit, The first control message causes the distributed unit to send the at least one terminal list to the central unit, The central unit according to Appendix 10.

[0102] (Appendix 12) The first control message is a SYSTEM INFORMATION DELIVERY COMMAND message, The central unit according to Appendix 11.

[0103] (Appendix 13) The at least one processor is configured to send a request for the at least one terminal list to the distributed unit, The central unit according to any one of Appendices 10 to 12.

[0104] (Appendix 14) After receiving the at least one terminal list, the at least one processor is configured to send updated system information to one or more wireless terminals via individual signaling for each wireless terminal, The central unit according to any one of Appendices 10 to 13.

[0105] (Appendix 15) The at least one terminal list indicates a plurality of wireless terminals for which a Common Search Space (CSS) is not set in each activated downlink BWP, The central unit according to any one of Appendices 10 to 14.

[0106] (Appendix 16) The at least one terminal list indicates a plurality of wireless terminals for which a Search Space (SS) for receiving at least system information is not set in each activated downlink BWP, The central unit according to any one of Appendices 10 to 14.

[0107] (Appendix 17) The at least one terminal list indicates a plurality of wireless terminals for which each activated downlink BWP is a non-initial downlink BWP. The central unit according to any one of Appendices 10 to 14.

[0108] (Appendix 18) The at least one terminal list includes a per-BWP terminal list for indicating a plurality of wireless terminals receiving on each downlink BWP. The central unit according to any one of Appendices 10 to 14.

[0109] (Appendix 19) A method in a distributed unit of a base station, comprising: transmitting at least one terminal list to a central unit of the base station, wherein the at least one terminal list includes a plurality of wireless terminals for which no Common Search Space (CSS) is configured in each activated downlink Bandwidth Part (BWP); a plurality of wireless terminals for which no Search Space (SS) for receiving at least system information is configured in each activated downlink BWP; a plurality of wireless terminals that need to receive updated system information via per-terminal individual signaling; a plurality of wireless terminals for which each activated downlink BWP is a non-initial downlink BWP; and a plurality of wireless terminals receiving on each downlink BWP; and indicates at least one of them. Method.

[0110] (Appendix 20) A method in a central unit of a base station, comprising: comprising receiving at least one terminal list from a distributed unit of the base station; wherein the at least one terminal list includes a plurality of radio terminals for which a Common Search Space is not configured in each activated downlink Bandwidth Part (BWP); a plurality of radio terminals for which a Search Space (SS) for receiving at least system information is not configured in each activated downlink BWP; a plurality of radio terminals that need to receive updated system information via individual signaling for each radio terminal; a plurality of radio terminals for which each activated downlink BWP is a non-initial downlink BWP; and a plurality of radio terminals that are receiving on each downlink BWP; indicating at least one of a method.

[0111] (Appendix 21) A program for causing a computer to perform a method in a distributed unit of a base station, wherein the method comprises transmitting at least one terminal list to a central unit of the base station, wherein the at least one terminal list includes a plurality of radio terminals for which a Common Search Space is not configured in each activated downlink Bandwidth Part (BWP); a plurality of radio terminals for which a Search Space (SS) for receiving at least system information is not configured in each activated downlink BWP; a plurality of radio terminals that need to receive updated system information via individual signaling for each radio terminal; a plurality of radio terminals for which each activated downlink BWP is a non-initial downlink BWP; and a plurality of radio terminals that are receiving on each downlink BWP; indicating at least one of a program.

[0112] (Appendix 22) A program for causing a computer to perform a method in a central unit of a base station, The method includes receiving at least one terminal list from a distributed unit of the base station, The at least one terminal list includes a plurality of radio terminals for which a Common Search Space is not set in each active downlink Bandwidth Part (BWP); a plurality of radio terminals for which a Search Space (SS) for receiving at least system information is not set in each active downlink BWP; a plurality of radio terminals that need to receive updated system information via individual signaling for each radio terminal; a plurality of radio terminals for which each active downlink BWP is a non-initial downlink BWP; and a plurality of radio terminals receiving on each downlink BWP; indicating at least one of them, Program.

[0113] (Appendix 23) A distributed unit of a base station, including at least one memory, at least one processor coupled to the at least one memory, and comprising The at least one processor is configured to transmit a message including an information element indicating a change in an active downlink Bandwidth Part (BWP) of a radio terminal to a central unit of the base station. Distributed unit.

[0114] (Appendix 24) The at least one processor is configured to transmit the message to a central unit of the base station in response to a change in an active downlink BWP of the radio terminal. The dispersion unit described in Supplementary Note 23.

[0115] (Supplementary Note 25) The information element indicates whether the activated downlink BWP of the wireless terminal has been changed from the initial downlink BWP to a non-initial downlink BWP. The dispersion unit described in Supplementary Note 23 or 24.

[0116] (Supplementary Note 26) The information element indicates that the activated downlink BWP of the wireless terminal does not have a Common Search Space. The dispersion unit described in Supplementary Note 23 or 24.

[0117] (Supplementary Note 27) The information element indicates the identifier of the changed activated downlink BW of the wireless terminal. The dispersion unit described in Supplementary Note 23 or 24.

[0118] (Supplementary Note 28) A central unit of a base station, at least one memory, at least one processor coupled to the at least one memory, comprising The at least one processor is configured to receive, from the dispersion unit of the base station, a message including an information element indicating a change in the activated downlink BWP of a wireless terminal. Central unit.

[0119] (Supplementary Note 29) The information element indicates whether the activated downlink BWP of the wireless terminal has been changed from the initial downlink BWP to a non-initial downlink BWP. The central unit described in Supplementary Note 28.

[0120] (Supplementary Note 30) The information element indicates that the activated downlink BWP of the wireless terminal does not have a Common Search Space. The central unit according to Appendix 28.

[0121] (Appendix 31) The information element indicates the identifier of the changed activated downlink BW of the wireless terminal. The central unit according to Appendix 28.

[0122] (Appendix 32) The at least one processor is configured to transmit updated system information to the wireless terminal via per-wireless-terminal individual signaling after receiving the information element. The central unit according to any one of Appendices 28 to 31.

[0123] (Appendix 33) A method in a distributed unit of a base station, comprising: transmitting a message including an information element indicating a change in the activated downlink Bandwidth Part (BWP) of a wireless terminal to a central unit of the base station. Method.

[0124] (Appendix 34) A method in a central unit of a base station, comprising: receiving a message including an information element indicating a change in the activated downlink BWP of a wireless terminal from a distributed unit of the base station. Method.

[0125] This application claims priority based on Japanese Patent Application No. 2018-150709 filed on August 9, 2018, and incorporates the entire disclosure thereof herein.

Explanation of Signs

[0126] 1 gNB-CU 2 gNB-DU 3 UE 11 gNB-CU-CP 12 gNB-CU-UP 1302 Processor 1303 Memory 1304 Modules 1404 Processor 1405 Memory 1406 Modules

Claims

1. A method in a central unit (CU) communicating with a distributed unit (DU) of a base station, comprising: sending a first message to the DU; receiving, as a response to the first message, a second message including a list from the DU, the list indicating terminal devices that need to transmit system information by individual signaling.

2. The first message includes information for updating the system information. The method according to claim 1.

3. Sending a third message including the system information to the DU, wherein the system information is included in a Radio Resource Control (RRC) message. The method according to claim 1 or 2.

4. The base station is a gNB. The method according to any one of claims 1 to 3.

5. The system information is notified via a Physical Downlink Shared Channel (PDSCH). The method according to any one of claims 1 to 4.

6. The list includes a gNB-CU UE F1AP ID. The method according to any one of claims 1 to 4.

7. Each of the first message and the second message is an F1AP message. The method according to any one of claims 1 to 5.

8. A method in a distributed unit (DU) communicating with a central unit (CU) of a base station, comprising: receiving a first message from the CU; sending, as a response to the first message, a second message including a list to the CU, the list indicating terminal devices that need to transmit system information by individual signaling. Method.

9. The first message includes information for updating the system information. The method according to claim 8.

10. Receiving a third message including the system information from the CU, wherein the system information is included in a Radio Resource Control (RRC) message, and transmitting the RRC message including the system information to the terminal device. The method according to claim 8 or 9.

11. The base station is a gNB. The method according to any one of claims 8 to 10.

12. The system information is notified via a Physical Downlink Shared Channel (PDSCH). The method according to any one of claims 8 to 11.

13. The list includes a gNB-CU UE F1AP ID. The method according to any one of claims 8 to 12.

14. Each of the first message and the second message is an F1AP message. The method according to any one of claims 8 to 13.

15. A method for a base station including a distributed unit (DU) and a central unit (CU), wherein the CU transmits a first message to the DU, and the DU transmits, as a response to the first message, a second message including a list to the CU, the list indicating terminal devices for which system information needs to be transmitted by individual signaling. Method.

16. A central unit (CU) communicating with a distributed unit (DU) of a base station, comprising transmission means for transmitting a first message to the DU, and reception means for receiving, as a response to the first message, a second message including a list from the DU, the central unit, wherein the list indicates terminal devices for which system information needs to be transmitted by individual signaling.

17. The first message includes information for updating the system information. The central unit according to claim 16.

18. A distributed unit (DU) communicating with a central unit (CU) of a base station, comprising reception means for receiving a first message from the CU, and transmission means for transmitting a second message including a list to the CU, the distributed unit, wherein the list indicates terminal devices for which system information needs to be transmitted by individual signaling.

19. The first message includes information for updating the system information. The distributed unit according to claim 18.

20. A base station including a distributed unit (DU) and a central unit (CU), comprising transmission means for the CU to transmit a first message to the DU, and for the DU to transmit, as a response to the first message, a second message including a list to the CU, wherein the list indicates terminal devices for which system information needs to be transmitted by individual signaling. Base station.

21. The first message includes information for updating the system information. The base station according to claim 20.

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