Terminal, communication method and integrated circuit

Abstract

This base station is provided with: a control circuit which determines a disposition method for a downlink control channel signal in at least one among a first period before a timing based on a carrier sense and a second period after the timing based on the carrier sense on the basis of information about at least one among the number of times a downlink control channel signal is blind-decoded and the number of resources for channel estimation; and a transmission circuit which transmits the downlink control channel signal on the basis of the determined disposition method.

Description

[Technical Field]

[0001] The present disclosure relates to a base station, a terminal, a transmission method, and a reception method. [Background technology]

[0002] The 3rd Generation Partnership Project (3GPP) has completed the Release 15 NR (New Radio access technology) specification for the realization of 5G (5th Generation mobile communication systems). NR supports functions that realize Ultra Reliable and Low Latency Communication (URLLC) in addition to high speed and large capacity, which are the basic requirements for enhanced Mobile Broadband (eMBB) (see, for example, Non-Patent Documents 1-4). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS 38.211 V15.7.0, "NR; Physical channels and modulation (Release 15)," September 2019 [Non-patent document 2] 3GPP TS 38.212 V15.7.0, "NR; Multiplexing and channel coding (Release 15)," September 2019 [Non-patent document 3] 3GPP TS 38.213 V15.7.0, "NR; Physical layer procedure for control (Release 15)," September 2019 [Non-patent document 4] 3GPP TS 38.214 V15.7.0, "NR; Physical layer procedures for data (Release 15)," September 2019 Summary of the Invention

[0004] However, methods for transmitting downlink signals in unlicensed bands have not been fully studied.

[0005] Non-limiting examples of the present disclosure contribute to providing a base station, a terminal, a transmission method, and a reception method that can improve the transmission efficiency of downlink signals in unlicensed bands.

[0006] A terminal according to one embodiment of the present disclosure includes a control circuit that determines a placement method for a downlink control channel signal in at least one of a first period before a timing based on carrier sense and a second period after a timing based on carrier sense, based on information regarding at least one of the number of blind decodings for the downlink control channel signal and the number of resources for channel estimation, and a transmission circuit that transmits the downlink control channel signal based on the determined placement method.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0008] According to an embodiment of the present disclosure, it is possible to improve the transmission efficiency of downlink signals in unlicensed bands.

[0009] Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features. [Brief explanation of the drawings]

[0010] [Figure 1] Diagram of an example architecture of a 3GPP NR system [Figure 2] Schematic diagram showing functional separation between NG-RAN and 5GC [Figure 3] Sequence diagram of RRC connection setup / reconfiguration procedure [Figure 4] Schematic diagram showing usage scenarios for enhanced Mobile BroadBand (eMBB), massive Machine Type Communications (mMTC), and Ultra Reliable and Low Latency Communications (URLLC). [Figure 5] Block diagram illustrating an exemplary 5G system architecture for a non-roaming scenario [Figure 6] A diagram showing an example of the maximum number of blind detections (BDs) and the maximum number of control channel elements (CCEs). [Figure 7] An example of the phases in downlink (DL) burst detection [Figure 8] A diagram showing an example of CORESET and synchronization signal (SS) allocation in multiple subbands. [Figure 9] A diagram showing an example of PDCCH monitoring occasion settings [Figure 10] Block diagram showing a partial configuration of a base station [Figure 11] Block diagram showing part of the terminal configuration [Figure 12] Block diagram showing the configuration of a base station [Figure 13] Block diagram showing the terminal configuration [Figure 14] A sequence diagram showing an example of the operation of a base station and a terminal. [Figure 15] FIG. 10 is a diagram showing an example of PDCCH monitoring occasion configuration according to determination method 1 of embodiment 1. [Figure 16] FIG. 10 is a diagram showing an example of PDCCH monitoring occasion setting according to a modification of determination method 1 of embodiment 1. [Figure 17] FIG. 10 is a diagram showing an example of PDCCH monitoring occasion setting according to determination method 2 of embodiment 1. [Figure 18] FIG. 10 shows an example of PDCCH monitoring occasion configuration according to embodiment 2. [Figure 19] FIG. 10 shows an example of PDCCH monitoring occasion configuration according to embodiment 3. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] <5G NR system architecture and protocol stack> 3GPP is working on the next release of fifth-generation cellular technology (also known as 5G), which includes the development of New Radio Access Technology (NR) operating in the frequency range up to 100 GHz. The first version of the 5G standard was completed in late 2017, allowing for the prototyping and commercial deployment of 5G NR-compliant devices (e.g., smartphones).

[0013] For example, the system architecture assumes a Next Generation Radio Access Network (NG-RAN) with gNBs. The gNBs provide UE-side termination of NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocols. The gNBs are connected to each other via an Xn interface. The gNBs are also connected to a Next Generation Core (NGC) via a Next Generation (NG) interface, more specifically to an Access and Mobility Management Function (AMF) (e.g., a specific core entity that performs AMF) via an NG-C interface, and to a User Plane Function (UPF) (e.g., a specific core entity that performs UPF) via an NG-U interface. The NG-RAN architecture is shown in Figure 1 (see, for example, 3GPP TS 38.300 v15.6.0, section 4).

[0014] The NR user plane protocol stack (see, for example, 3GPP TS 38.300, section 4.4.1) includes the Packet Data Convergence Protocol (PDCP) sublayer (see, for example, TS 38.300, section 6.4), the Radio Link Control (RLC) sublayer (see, for example, TS 38.300, section 6.3), and the Medium Access Control (MAC) sublayer (see, for example, TS 38.300, section 6.2), which are terminated on the network side at the gNB. A new Access Stratum (AS) sublayer (Service Data Adaptation Protocol (SDAP)) has also been introduced on top of PDCP (see, for example, 3GPP TS 38.300, section 6.5). A control plane protocol stack has also been defined for NR (see, for example, TS 38.300, section 4.4.2). An overview of Layer 2 functions is given in Section 6 of TS 38.300. The functions of the PDCP sublayer, RLC sublayer, and MAC sublayer are listed in clauses 6.4, 6.3, and 6.2 of TS 38.300, respectively. The functions of the RRC layer are listed in clause 7 of TS 38.300.

[0015] For example, the Medium-Access-Control layer handles logical channel multiplexing and scheduling and scheduling-related functions, including handling various numerologies.

[0016] For example, the physical layer (PHY) is responsible for coding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals to appropriate physical time-frequency resources. The physical layer also handles mapping of transport channels to physical channels. The physical layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for transmitting a specific transport channel, and each transport channel is mapped to a corresponding physical channel. For example, physical channels include the Physical Random Access Channel (PRACH), the Physical Uplink Shared Channel (PUSCH), and the Physical Uplink Control Channel (PUCCH) as uplink physical channels, and the Physical Downlink Shared Channel (PDSCH), the Physical Downlink Control Channel (PDCCH), and the Physical Broadcast Channel (PBCH) as downlink physical channels.

[0017] NR use cases / deployment scenarios may include enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communication (mMTC), which have diverse requirements in terms of data rate, latency, and coverage. For example, eMBB is expected to support peak data rates (20 Gbps in the downlink and 10 Gbps in the uplink) and effective (user-experienced) data rates that are approximately three times higher than those offered by IMT-Advanced. For URLLC, on the other hand, more stringent requirements are placed on ultra-low latency (0.5 ms for user plane latency in both UL and DL) and high reliability (1-10 ms within 1 ms). -5Finally, mMTC is preferably designed for high connection density (1,000,000 devices / km in urban environments). 2 ), wide coverage in adverse environments, and extremely long battery life (15 years) for low-cost devices may be desired.

[0018] Therefore, OFDM numerology (e.g., subcarrier spacing, OFDM symbol length, cyclic prefix (CP) length, number of symbols per scheduling interval) suitable for one use case may not be valid for another use case. For example, low-latency services may preferably require a shorter symbol length (and therefore a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also called TTI) than mMTC services. Furthermore, deployment scenarios with large channel delay spreads may preferably require a longer CP length than scenarios with small delay spreads. Subcarrier spacing may be optimized accordingly to maintain similar CP overhead. NR may support one or more subcarrier spacing values. Correspondingly, subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, etc. are currently considered. The symbol length T u and the subcarrier spacing Δf is given by the formula Δf=1 / T u Similar to LTE systems, the term "resource element" can be used to mean the smallest resource unit consisting of one subcarrier for the length of one OFDM / SC-FDMA symbol.

[0019] In the new radio system 5G-NR, a resource grid of subcarriers and OFDM symbols is defined for each numerology and each carrier in the uplink and downlink. Each element of the resource grid is called a resource element and is specified based on a frequency index in the frequency domain and a symbol position in the time domain (see 3GPP TS 38.211 v15.6.0).

[0020] <Functional separation between NG-RAN and 5GC in 5G NR> Figure 2 shows the functional separation between NG-RAN and 5GC. The logical node of NG-RAN is gNB or ng-eNB. 5GC has logical nodes AMF, UPF, and SMF.

[0021] For example, the gNB and ng-eNB host the following main functions: - Radio Resource Management functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, dynamic allocation (scheduling) of resources to UEs in both uplink and downlink; - IP header compression, encryption, and integrity protection of data; - AMF selection at UE attach time if routing to the AMF cannot be determined from the information provided by the UE; - Routing of user plane data towards UPF; - Routing of control plane information towards AMF; - Setting up and tearing down connections; - scheduling and sending of paging messages; - Scheduling and transmission of system broadcast information (originating from AMF or Operation, Admission, Maintenance (OAM) Function); - Configuring measurements and measurement reporting for mobility and scheduling; - Transport level packet marking in the uplink; - Session management; - Network slicing support; - QoS flow management and mapping to data radio bearers; - Support for UEs in RRC_INACTIVE state; - NAS message delivery function; - Sharing of radio access networks; - Dual connectivity; - Close cooperation between NR and E-UTRA.

[0022] The Access and Mobility Management Function (AMF) hosts the following main functions: - Ability to terminate Non-Access Stratum (NAS) signaling; - NAS signaling security; - Access Stratum (AS) security control; - 3GPP Core Network (CN) inter-node signaling for mobility between access networks; - Reachability to idle mode UEs (including control and execution of paging retransmissions); - Managing the registration area; - Support for intra-system and inter-system mobility; - Access authentication; - Access authorization, including checking roaming privileges; - Mobility management control (subscription and policy); - Network slicing support; - Selection of Session Management Function (SMF).

[0023] Additionally, the User Plane Function (UPF) hosts the following main functions: - Anchor points for intra-RAT / inter-RAT mobility (if applicable); - External PDU (Protocol Data Unit) session points for interconnection with data networks; - Packet routing and forwarding; - Packet inspection and enforcement of policy rules in the user plane part; - Reporting of traffic usage; - Uplink classifier to support routing of traffic flows to the data network; - Branching Point to support multi-homed PDU session; - QoS processing for the user plane (e.g., packet filtering, gating, UL / DL rate enforcement); - Verification of uplink traffic (mapping to QoS flows of SDF); - Buffering of downlink packets and triggering function for downlink data notification.

[0024] Finally, the Session Management Function (SMF) hosts the following main functions: - Session management; - Assignment and management of IP addresses for the UE; - Selection and control of UPF; - Configuration function of traffic steering in the User Plane Function (UPF) to route traffic to the appropriate destination; - Enforcement of control part policies and QoS; - Notification of downlink data.

[0025] <Procedures for setup and reconfiguration of RRC connection> Figure 3 shows some of the interactions between the UE, gNB, and AMF (5GC entities) when the UE transitions from RRC_IDLE to RRC_CONNECTED in the NAS part (see TS 38.300 v15.6.0).

[0026] RRC is a higher layer signaling protocol used to configure the UE and the gNB. With this transition, the AMF prepares UE context data (including, for example, PDU session context, security keys, UE radio capabilities, and UE security capabilities) and sends it to the gNB with an INITIAL CONTEXT SETUP REQUEST. The gNB then activates AS security together with the UE. This is done by the gNB sending a SecurityModeCommand message to the UE, and the UE responding with a SecurityModeComplete message. The gNB then sends an RRCReconfiguration message to the UE, and upon receiving an RRCReconfigurationComplete from the UE, the gNB reconfigures the UE to set up a Signaling Radio Bearer 2 (SRB2) and a Data Radio Bearer (DRB). For signaling-only connections, the RRCReconfiguration steps are omitted because SRB2 and DRB are not set up. Finally, the gNB notifies the AMF that the setup procedure is complete with an INITIAL CONTEXT SETUP RESPONSE.

[0027] Therefore, the present disclosure provides a 5th Generation Core (5GC) entity (e.g., AMF, SMF, etc.) that includes: control circuitry that, in operation, establishes a Next Generation (NG) connection with a gNodeB; and a transmitter that, in operation, transmits an initial context setup message to the gNodeB via the NG connection so that a signaling radio bearer between the gNodeB and a user equipment (UE) is set up. Specifically, the gNodeB transmits Radio Resource Control (RRC) signaling that includes a resource allocation configuration information element (IE) to the UE via the signaling radio bearer. Then, the UE performs uplink transmission or downlink reception based on the resource allocation configuration.

[0028] <IMT usage scenarios from 2020 onwards> Figure 4 illustrates some use cases for 5G NR. The 3rd Generation Partnership Project New Radio (3GPP NR) is considering three use cases envisioned by IMT-2020 to support a wide variety of services and applications. The first phase of specifications for enhanced mobile broadband (eMBB) has been completed. Current and future work includes standardization for ultra-reliable and low-latency communications (URLLC) and massive machine-type communications (mMTC), in addition to expanding support for eMBB. Figure 4 illustrates some example use scenarios envisioned for IMT beyond 2020 (see, for example, ITU-R M.2083 Figure 2).

[0029] URLLC use cases have stringent performance requirements, such as throughput, latency, and availability. URLLC use cases are envisioned as one of the enabling technologies for future applications, such as wireless control of industrial production or manufacturing processes, remote medical surgery, automated power transmission and distribution in smart grids, and road safety. URLLC's ultra-high reliability is supported by identifying technologies that meet the requirements set by TR 38.913. Key requirements for NR URLLC in Release 15 include a target user plane latency of 0.5 ms on the uplink (UL) and 0.5 ms on the downlink (DL). The overall URLLC requirement for a single packet transmission is a block error rate (BLER) of 1E-5 for a 32-byte packet size at a user plane latency of 1 ms.

[0030] From a physical layer perspective, reliability can be improved in many possible ways. Current reliability improvement room includes defining a separate CQI table for URLLC, more compact DCI formats, PDCCH repetition, etc. However, this room can be expanded to achieve ultra-high reliability as NR (with respect to the key requirements of NR URLLC) becomes more stable and developed. Specific use cases for NR URLLC in Release 15 include augmented reality / virtual reality (AR / VR), e-health, e-safety, and mission-critical applications.

[0031] Additionally, technology enhancements targeted by NR URLLC aim to improve latency and reliability. Technology enhancements for latency improvement include configurable numerology, non-slot-based scheduling with flexible mapping, grant-free (configured grant) uplink, slot-level repetition in the data channel, and preemption in the downlink. Preemption means that a transmission with previously allocated resources is stopped and the allocated resources are used for another transmission with a later requested lower latency / higher priority requirement. Thus, a previously allowed transmission is preempted by a later transmission. Preemption is applicable regardless of the specific service type. For example, a transmission of service type A (URLLC) may be preempted by a transmission of service type B (eMBB, etc.). Technology enhancements for reliability improvement include dedicated CQI / MCS tables for a target BLER of 1E-5.

[0032] The use case for massive machine-type communication (mMTC) is characterized by a very large number of connected devices that typically transmit relatively small amounts of data that are not sensitive to latency. These devices are required to be low cost and have very long battery life. From an NR perspective, using very narrow bandwidth portions is one solution that saves power and allows for long battery life from the UE perspective.

[0033] As mentioned above, the scope of reliability improvement in NR is expected to be broader. One of the key requirements for all cases, for example for URLLC and mMTC, is high or ultra-high reliability. Several mechanisms can improve reliability from a radio perspective and a network perspective. Generally, there are two to three key areas that can help improve reliability. These areas include compact control channel information, data channel / control channel repetition, and diversity in the frequency, time, and / or spatial domains. These areas are generally applicable to reliability improvement regardless of the specific communication scenario.

[0034] Further use cases with more stringent requirements are envisioned for NR URLLC, such as factory automation, transportation, and power distribution. The stringent requirements include high reliability (10 -6 reliability up to a certain level), high availability, packet size up to 256 bytes, time synchronization up to a few microseconds (depending on the use case, the value can be 1 microsecond or a few microseconds depending on the frequency range and low latency in the 0.5ms-1ms range (e.g., a targeted latency of 0.5ms on the user plane)).

[0035] Furthermore, for NR URLLC, several technical enhancements may be available from the perspective of the physical layer. These technical enhancements include enhancements to the Physical Downlink Control Channel (PDCCH) related to compact DCI, repetition of the PDCCH, and increased monitoring of the PDCCH. Also, the enhancement of UCI (Uplink Control Information) is related to the enhancement of enhanced HARQ (Hybrid Automatic Repeat Request) and CSI feedback. Additionally, there may be enhancements to the PUSCH related to mini-slot level hopping, and enhancements to retransmission / repetition. The term "mini-slot" refers to a Transmission Time Interval (TTI) that contains fewer symbols than a slot (a slot has 14 symbols).

[0036] <QoS Control> The QoS (Quality of Service) model of 5G is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (GBR: Guaranteed Bit Rate QoS flow) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flow). Therefore, at the NAS level, a QoS flow is the finest granularity of QoS differentiation in a PDU session. A QoS flow is identified within a PDU session by a QoS Flow ID (QFI: QoS Flow ID) that is carried in an encapsulation header via the NG-U interface.

[0037] For each UE, the 5GC establishes one or more PDU sessions. For each UE, the NG-RAN establishes at least one Data Radio Bearer (DRB) for each PDU session, e.g., as shown above with reference to Figure 3. Additional DRBs for the QoS flows of that PDU session can be configured later (when this is up to the NG-RAN). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in the UE and the 5GC associate UL and DL packets with QoS flows, while AS-level mapping rules in the UE and the NG-RAN associate UL and DL QoS flows with DRBs.

[0038] Figure 5 shows the 5G NR non-roaming reference architecture (see TS 23.501 v16.1.0, section 4.23). An Application Function (AF) (e.g., an external application server hosting 5G services, as illustrated in Figure 4) interacts with the 3GPP core network to provide services. For example, it accesses a Network Exposure Function (NEF) to support applications that affect traffic routing, or interacts with a policy framework (see Policy Control Function (PCF)) for policy control (e.g., QoS control). Based on the operator's deployment, Application Functions that are considered trusted by the operator can interact directly with the relevant Network Functions. Application Functions that are not authorized by the operator to directly access Network Functions interact with the relevant Network Functions using the external exposure framework via the NEF.

[0039] Figure 5 further illustrates further functional units of the 5G architecture, namely, Network Slice Selection Function (NSSF), Network Repository Function (NRF), Unified Data Management (UDM), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), and Data Network (DN, e.g., operator-provided services, Internet access, or third-party services). All or part of the core network functions and application services may be deployed and run in a cloud computing environment.

[0040] Therefore, the present disclosure provides an application server (e.g., an AF in a 5G architecture) comprising: a transmitter that, in operation, sends a request including QoS requirements for at least one of a URLLC service, an eMMB service, and an mMTC service to at least one of 5GC functions (e.g., an NEF, an AMF, an SMF, a PCF, an UPF, etc.) to establish a PDU session including a radio bearer between a gNodeB and a UE according to the QoS requirements; and a control circuit that, in operation, performs a service using the established PDU session.

[0041] In Release 15 NR, for example, the number of downlink control channels (e.g., PDCCHs: Physical Downlink Control Channels) that can be blind decoded (or also referred to as monitoring) in one slot and the number of control channel elements (CCEs) that can be channel estimated in the PDCCHs are defined for a terminal (also referred to as user equipment (UE)). The number of PDCCHs that can be blind decoded in one slot is also referred to as the "maximum number of blind decoding attempts" or the "maximum number of BDs." The number of CCEs that can be channel estimated in the PDCCH is also referred to as the "maximum number of CCEs." A base station (e.g., also referred to as a gNB) transmits PDCCHs based on, for example, the number of BDs or the number of CCEs allocated to each terminal.

[0042] In addition, Release 16 NR is considering NR-Unlicensed (NR-U), which performs communication based on the NR radio access scheme in unlicensed frequency bands (also called unlicensed bands). In unlicensed frequency bands, each device performs carrier sense (also called Listen Before Talk (LBT)) to check whether other systems or terminals are using the radio channel before transmission. In NR-U, whether transmission is possible is determined based on the result of the LBT, for example, so a procedure is being considered for a terminal to detect the start of transmission of a series of downlink data (e.g., downlink burst (DL burst)). For example, in Release 16 NR, detection of DL bursts based on PDCCH is being considered.

[0043] [Maximum number of BDs and CCEs] For example, the maximum number of BDs and the maximum number of CCEs in non-carrier aggregation (CC) mode can be defined as shown in Fig. 6 (see, for example, Non-Patent Document 3). The maximum number of BDs and the maximum number of CCEs shown in Fig. 6 indicate values for each terminal and each slot, for example.

[0044] In Release 15 NR, for example, a PDCCH candidate exceeding the maximum number of BDs or the maximum number of CCEs (in other words, the upper limit) shown in Fig. 6 may be configured in a terminal. In this case, a "dropping rule" (in other words, a rule for not allocating PDCCH candidates and PDCCH monitoring occasions) is defined as one method for setting the actual PDCCH candidate to a number equal to or less than the maximum number of BDs or the maximum number of CCEs shown in Fig. 6.

[0045] Note that a "PDCCH candidate" indicates a candidate for a terminal to receive a PDCCH. For example, a PDCCH monitoring occasion (or a PDCCH reception opportunity) indicates a frequency resource and a time resource of a PDCCH candidate.

[0046] In the dropping rule, for example, the following provisions may be applied: - PDCCH candidates and PDCCH monitoring occasions in the common search space (CSS) are not dropped. - In a UE-specific search space (USS), if the configured PDCCH candidates exceed the maximum number of BDs or the minimum number of CCEs, the search spaces are dropped in descending order of search space identification number (e.g., called search space ID (SS ID)) (in other words, resources are not allocated). - The dropping rule is not applied to the secondary cell. In other words, the dropping rule is applied to the primary cell.

[0047] [DL burst detection] For example, the following three phases are discussed for DL burst detection: Figure 7 shows an example of the three phases. Phase A: Before DL burst detection Phase B: After DL burst detection and before reaching the slot boundary (slot #0 in Figure 7) (partial slot) Phase C: After DL burst detection and reaching the slot boundary (slot #0 in Figure 7) (full slot)

[0048] For example, the use of a Group common PDCCH (GC-PDCCH) is being considered for DL burst detection. A base station transmits the GC-PDCCH, for example, at the beginning of a DL burst, and a terminal detects the GC-PDCCH at a configured PDCCH monitoring occasion. If the terminal successfully detects the GC-PDCCH, it recognizes the transmission of a DL burst (in other words, detects a DL burst). Note that it is being considered that the GC-PDCCH includes information such as an LBT subband (also called an LBT bandwidth) available to the base station or a slot format within the channel occupancy time (COT).

[0049] [CORESET and Search space] In Release 15 NR, for example, the following provisions are made regarding the number of control resource sets (CORESETs) or search spaces (SSs), which are areas to which downlink control channels can be assigned to terminals. CORESET: 3 (per bandwidth part (BWP)) SS: 10 pieces (per BWP)

[0050] For example, let us say that the bandwidth of the BWP is 80 MHz, and the bandwidth of the band (e.g., called the LBT subband) in which the terminal (or base station) performs carrier sensing (e.g., LBT) is 20 MHz. For example, if there are four LBT subbands in the BWP and a CORESET is allocated to each LBT subband (in other words, if an individual CORESET is allocated to each LBT subband), the number of CORESETs configured in the terminal will be four, which exceeds the specified number (3) above.

[0051] Therefore, in NR-U, it has been agreed that if a CORESET is placed so as to fit within an LBT subband (in other words, closed), the same CORESET and SSs associated with the CORESET can be placed in multiple subbands, regardless of the above specified number (e.g., three).

[0052] FIG. 8 shows an example in which the same CORESET and SS are allocated to each of a plurality of (for example, four) LBT subbands.

[0053] [Maximum number of BDs and CCEs and SS] As described above, in NR-U, it is agreed that the same CORESET and SS can be allocated to each of multiple subbands.

[0054] In addition, in NR-U, it has been agreed that the maximum number of BDs and the maximum number of CCEs specified in Release 15 NR will not be increased in order to reduce the complexity of UE implementation. On the other hand, for example, assuming a situation in which an LBT subband becomes unavailable due to an LBT failure (e.g., referred to as an LBT failure), an SS may be configured for each of multiple LBT subbands.

[0055] Under the above-described limitations on the maximum number of BDs and the maximum number of CCEs, the efficiency of PDCCH candidate arrangement may be reduced when configuring SSs for each of a plurality of LBT subbands.

[0056] FIG. 9 shows an example of setting PDCCH monitoring occasions.

[0057] In the example shown in FIG. 9, the maximum number of BDs configured in a terminal is 44. Note that, for simplicity of explanation, FIG. 9 takes the maximum number of BDs into consideration, but does not take the maximum number of CCEs into consideration. In the following explanation, the expression "taking... into consideration" may be replaced with "based on..." or "using...", and the expression "not taking... into consideration" may be replaced with "not based on..." or "not using...". Also, FIG. 9 describes four LBT subbands (e.g., LBT subbands #0 to #3) as an example, but the number of LBT subbands is not limited to four and may be any other number. Also, in FIG. 9, PDCCH monitoring occasions equivalent to the number of BDs=11 are configured for each of subbands #0 to #3.

[0058] For example, in Fig. 9(a), the LBT for subbands #0 to #2 fails, and subband #3 is available. Also, in Fig. 9(b), the LBT for subbands #0 to #3 is available.

[0059] For example, in the case of Figure 9(a), the number of BDs in the PDCCH monitoring occasions (e.g., SS#1 in subband #3) valid for the terminal is 11. In Figure 9(a), the number of BDs (11) set for the terminal is less than the maximum number of BDs (e.g., 44). Therefore, in Figure 9(a), depending on the SS settings, it is possible to place an SS other than SS#1 in subband #3 for the terminal and transmit and receive PDCCH.

[0060] On the other hand, for example, in the case of Figure 9(b), the number of BDs in the PDCCH monitoring occasions (for example, SS#1 in each of subbands #0 to #3) valid for the terminal is 44. In Figure 9(b), the number of BDs (44 times) set for the terminal reaches the maximum number of BDs (for example, 44 times). Therefore, in Figure 9(b), it is not possible to further configure SSs other than SS#1 for the terminal.

[0061] In NR, for example, PDCCHs of different types or uses are associated with each SS, and the efficiency of PDCCH transmission and reception is improved by using SSs according to their uses. However, for example, in the example shown in Figure 9(b), multiple SSs cannot be allocated to each LBT subband, and the efficiency of PDCCH allocation may not be improved.

[0062] As described above, there is room for further study on the method of transmitting PDCCHs in DL burst detection in NR-U. Therefore, in one embodiment of the present disclosure, a method for improving the efficiency of DL burst detection and PDCCH transmission in NR-U will be described.

[0063] (Embodiment 1) [Communication System Overview] A communication system according to one embodiment of the present disclosure includes, for example, a base station 100 (e.g., gNB) shown in FIGS. 10 and 12, and a terminal 200 (e.g., UE) shown in FIGS. 11 and 13.

[0064] Fig. 10 is a block diagram showing a configuration example of a part of a base station 100 according to an embodiment of the present disclosure. In the base station 100 shown in Fig. 10, the scheduling unit 104 determines a downlink control channel signal allocation method (in other words, a PDCCH monitoring occasion) in at least one of a first period (e.g., Phase A) before timing based on carrier sensing (e.g., LBT) (in other words, DL burst detection timing in the terminal 200) and a second period (e.g., Phase B or Phase C) after the timing based on the carrier sensing, based on information on at least one of the number of BDs for the downlink control channel signal and the number of resources (e.g., the number of CCEs) for channel estimation. The transmitting unit 108 transmits the downlink control channel signal based on the determined allocation method.

[0065] Fig. 11 is a block diagram showing a configuration example of a portion of terminal 200 according to an embodiment of the present disclosure. In terminal 200 shown in Fig. 11, reception control unit 205 determines a reception opportunity (e.g., PDCCH monitoring occasion) for a downlink control channel signal in at least one of a first period (e.g., Phase A) before the detection timing of a downlink burst (DL burst) and a second period (e.g., Phase B or Phase C) after the detection timing, based on information on at least one of the maximum number of BDs for a downlink control channel signal and the number of resources (e.g., the number of CCEs) for channel estimation. Reception unit 201 receives the downlink control channel signal at the determined reception opportunity.

[0066] [Base station configuration] 12 is a block diagram showing an example configuration of a base station 100 according to an embodiment of the present disclosure. In FIG. 12, the base station 100 includes a receiving unit 101, a demodulating and decoding unit 102, a channel state estimating unit 103, a scheduling unit 104, a control information storing unit 105, a data and control information generating unit 106, an encoding and modulating unit 107, and a transmitting unit 108.

[0067] The receiving unit 101 receives a signal transmitted from the terminal 200 via an antenna, performs reception processing such as down-conversion or A / D conversion on the received signal, and outputs the received signal after reception processing to the demodulation and decoding unit 102 and the channel state estimation unit 103.

[0068] Demodulation and decoding section 102 demodulates and decodes the received signal input from receiving section 101 and outputs the decoded result to scheduling section 104 .

[0069] The channel state estimation unit 103 estimates the channel state (in other words, carrier sense or LBT) based on the received signal input from the receiving unit 101. For example, the channel state estimation unit 103 may determine whether the channel state is busy or idle. The channel state estimation unit 103 outputs information indicating the determined channel state to the scheduling unit 104.

[0070] Scheduling section 104 generates, for example, information relating to the configuration of a PDCCH for terminal 200 (hereinafter referred to as PDCCH configuration information), and outputs this information to control information holding section 105. Furthermore, scheduling section 104 outputs signaling information including the PDCCH configuration information to data / control information generating section 106.

[0071] Furthermore, scheduling section 104 may, for example, schedule (e.g., allocate) a PDCCH to each terminal 200. For example, scheduling section 104 may determine (in other words, decide) a PDCCH monitoring occasion for each terminal 200 in each phase of a DL burst (e.g., phases A, B, and C shown in FIG. 7 ) based on information indicating the channel state received as input from channel state estimation section 103, and schedule a PDCCH for terminal 200 based on the determination result. Based on the scheduling result, scheduling section 104 instructs data and control information generation section 106 to generate data or control information. Furthermore, scheduling section 104 outputs scheduling information including the scheduling result to coding and modulation section 107.

[0072] Furthermore, the scheduling unit 104 may instruct the data and control information generating unit 106 to generate data or control information based on the decoding result input from the demodulation and decoding unit 102, for example.

[0073] For example, the PDCCH configuration information may include configuration information such as CORESET configuration or SS configuration.

[0074] The control information holding unit 105 holds, for example, control information (including, for example, PDCCH setting information) input from the scheduling unit 104. The control information holding unit 105 may output the held information to each component of the base station 100 (for example, the scheduling unit 104) as necessary.

[0075] The data and control information generating unit 106 generates data or control information in accordance with instructions from the scheduling unit 104, and outputs a signal including the generated data or control information to the coding and modulation unit 107. The control information may include, for example, signaling information input from the scheduling unit 104.

[0076] The coding and modulation unit 107 codes and modulates the signal input from the data and control information generation unit 106, for example, based on the scheduling information input from the scheduling unit 104, and outputs the modulated signal (symbol sequence) to the transmission unit 108.

[0077] Transmitting section 108 performs transmission processing such as D / A conversion, up-conversion, or amplification on the signal input from encoding and modulation section 107, and transmits the radio signal obtained by the transmission processing to terminal 200 from an antenna.

[0078] [Device configuration] 13 is a block diagram showing an example configuration of terminal 200 according to one embodiment of the present disclosure. In FIG. 13, terminal 200 includes receiving section 201, demodulating and decoding section 202, DL transmission detecting section 203, control information retaining section 204, reception control section 205, transmission control section 206, data generating section 207, coding and modulation section 208, and transmitting section 209.

[0079] The receiving unit 201 performs receiving processing such as down-conversion or A / D conversion on a signal received via an antenna, and outputs the received signal to the demodulation and decoding unit 202 .

[0080] The demodulation and decoding unit 202 demodulates and decodes the data or control information included in the received signal input from the receiving unit 201, and outputs the decoded result to the transmission control unit 206. Also, for example, the demodulation and decoding unit 202 outputs the signaling information included in the decoded result to the control information holding unit 204.

[0081] Furthermore, for example, the demodulation and decoding unit 202 demodulates and decodes the PDCCH included in the received signal based on information input from the reception control unit 205, and outputs the decoded PDCCH result to the DL transmission detection unit 203.

[0082] DL transmission detection section 203 detects DL bursts based on the decoding result of the PDCCH input from demodulation and decoding section 202. DL transmission detection section 203 outputs DL burst information indicating the DL burst detection result to reception control section 205. The DL burst information may include, for example, LBT information indicating resources (e.g., LBT subbands) available to terminal 200, or information such as the channel occupancy time (COT) length.

[0083] The control information storage unit 204 stores signaling information (e.g., PDCCH setting information) input from the demodulation and decoding unit 202, and outputs the stored information to each component (e.g., the reception control unit 205 or the transmission control unit 206) as necessary.

[0084] The reception control unit 205 determines a PDCCH monitoring occasion based on the DL burst information input from the DL transmission detection unit 203 and the PDCCH setting information input from the control information storage unit 204. The reception control unit 205 outputs PDCCH monitoring occasion information indicating the determination result to the demodulation and decoding unit 202.

[0085] The transmission control unit 206 instructs the data generation unit 207 to generate data based on the decoding result input from the demodulation and decoding unit 202 and the information input from the control information holding unit 204 .

[0086] Data generation section 207 generates transmission data (for example, PUSCH) based on a data generation instruction inputted from transmission control section 206 and outputs this to coding and modulation section 208 .

[0087] The coding and modulation unit 208 codes and modulates the transmission data input from the data generation unit 207 and outputs the modulated signal to the transmission unit 209 .

[0088] The transmitter 209 performs transmission processing such as D / A conversion, up-conversion, or amplification on the signal input from the encoder / modulator 208, and transmits the radio signal obtained by the transmission processing from an antenna to the base station 100.

[0089] [Operations of Base Station 100 and Terminal 200] An example of the operation of base station 100 and terminal 200 having the above configuration will be described.

[0090] FIG. 14 is a sequence diagram showing an example of the operation of base station 100 and terminal 200. In FIG.

[0091] Base station 100 performs, for example, channel state estimation (for example, carrier sense or LBT) (ST101).

[0092] Base station 100 configures a PDCCH monitoring occasion for terminal 200 (ST102). For example, base station 100 may configure a PDCCH monitoring occasion for terminal 200 based on the result of channel state estimation (e.g., busy state or idle state), information on the LBT subband configured for terminal 200, or information such as the number of BDs or the number of CCEs configured for terminal 200.

[0093] Base station 100 transmits a downlink signal to terminal 200 (ST103). The downlink signal may include, for example, DL burst information, PDCCH setting information, or a PDCCH signal (including, for example, scheduling information). These pieces of information may be included in the same signal or in different signals. For example, DL burst information may be included in a group common PDCCH (GC-PDCCH). Furthermore, PDCCH setting information may be included in signaling information.

[0094] Terminal 200 performs DL burst detection, for example, based on a signal (for example, GC-PDCCH) transmitted from base station 100 (ST104).

[0095] Terminal 200 configures a PDCCH monitoring occasion for terminal 200 (ST105). For example, terminal 200 may configure a PDCCH monitoring occasion for terminal 200 based on the DL burst detection result, information on the LBT subband configured in terminal 200, or information such as the number of BDs or the number of CCEs configured in terminal 200.

[0096] Terminal 200 receives (for example, blindly decodes) a PDCCH addressed to terminal 200, for example, in a configured PDCCH monitoring occasion (ST106). The PDCCH may include, for example, information on resources scheduled (in other words, allocated) for terminal 200.

[0097] Base station 100 and terminal 200 communicate data (for example, uplink data or downlink data) based on the resources allocated to terminal 200 (ST107).

[0098] [Method for determining PDCCH monitoring occasion] The following describes an example of a method for determining a PDCCH monitoring occasion in scheduling section 104 of base station 100. Furthermore, reception control section 205 of terminal 200 may determine a PDCCH monitoring occasion based on the same determination method as scheduling section 104.

[0099] <Decision method 1> In determination method 1, when the number of BDs or the number of CCEs set in terminal 200 exceeds a threshold (for example, an upper limit value such as the maximum number of BDs or the maximum number of CCEs), base station 100 determines a search space (SS) to be allocated to resources based on the priority of the LBT subband. For example, base station 100 drops SS based on the priority of each LBT subband. In other words, base station 100 sets the number of BDs or the number of CCEs set in terminal 200 to be equal to or less than the threshold by dropping SS for each LBT subband.

[0100] The dropping rule for dropping SS for each LBT subband may be applied in addition to the dropping rule defined in Release 15 NR, for example.

[0101] For example, in the dropping rule according to decision method 1, SSs are dropped first in descending order of SS ID. In other words, in the dropping rule, SSs are allocated to resources in ascending order of SS ID.

[0102] Next, for example, when there are multiple SSs with the same SS ID, if the number of BDs or the number of CCEs for each SS exceeds a threshold (for example, the maximum number of BDs or the maximum number of CCEs), base station 100 performs dropping of the SSs based on the priority of the LBT subband. For example, base station 100 may drop SSs in order of decreasing LBT subband priority. In other words, base station 100 may allocate SSs to resources in order of decreasing LBT subband priority.

[0103] FIG. 15 shows an example of operation according to the determination method 1.

[0104] 15, for simplicity of explanation, the number of BDs is taken into consideration, but the number of CCEs is not. For example, base station 100 may determine an SS based on the dropping rule according to determination method 1 not only when the number of BDs set in terminal 200 exceeds the maximum number of BDs, but also when at least one of the number of BDs and the number of CCEs exceeds a threshold (for example, either the maximum number of BDs or the maximum number of CCEs).

[0105] In the example shown in FIG. 15, the maximum number of BDs set in the terminal 200 is 44.

[0106] 15 illustrates an example in which four LBT subbands (e.g., LBT subbands #0 to #3) are used, but the number of LBT subbands is not limited to four and may be other numbers. Also, in FIG. 15, the priority of the LBT subbands is highest for both SS #1 and SS #2, in the order of subband #0, #1, #2, and #3 (in other words, subband #0 has the highest priority and subband #3 has the lowest priority). Also, in FIG. 15, for example, of the SSs (e.g., SS #1 and SS #2) set for each subband, SS #1 has a lower ID than SS #2, so SS #1 is allocated to resources with priority over SS #2.

[0107] Also, the number of BDs in an SS allocated to each subband is set to 8. However, the number of BDs in an SS is not limited to 8, and may be set to another number.

[0108] For example, FIG. 15(a) shows a state in which four LBT subbands, subbands #0 to #3, are available for terminal 200 as a result of the LBT.

[0109] 15(a), for SS#1, which has a higher priority than SS#2, if SS#1 is allocated to each of LBT subbands#0 to #3, the number of BDs set in terminal 200 will be 32, which is less than the maximum number of BDs (44). Therefore, SS#1 is allocated to the resources of each of the available LBT subbands#0 to #3 (in other words, it is not dropped).

[0110] 15(a), with respect to SS#2, which has a lower priority than SS#1, if SS#2 is allocated to each of LBT subbands#0 to #3 in addition to SS#1, the number of BDs set in terminal 200 will be 64, exceeding the maximum number of BDs (44). Therefore, base station 100, for example, allocates SS#2 to resources in subband #0 based on the priorities of subbands #0 to #3, and drops SS#2 in subbands #1, #2, and #3. With this dropping, the number of BDs set in terminal 200 will be 40, which is less than the maximum number of BDs (44).

[0111] On the other hand, FIG. 15(b) shows a state in which, as a result of the LBT, three LBT subbands, subbands #1 to #3, are available for terminal 200, but subband #0 is unavailable due to an LBT failure.

[0112] In FIG. 15(b), base station 100 can count the number of BDs for terminal 200 by excluding the number of BDs (for example, 16) of SSs set in unavailable subband #0, for example.

[0113] 15(b), for SS#1, which has a higher priority than SS#2, if SS#1 is allocated to each of LBT subbands#1 to #3, the number of BDs set in terminal 200 will be 24, which is less than the maximum number of BDs (44). Therefore, SS#1 is allocated to the resources of each of the available LBT subbands#1 to #3 (in other words, it is not dropped).

[0114] 15(b), with respect to SS#2, which has a lower priority than SS#1, if SS#2 is allocated to each of subbands#1 to #3 in addition to SS#1, the number of BDs configured for terminal 200 will be 48, exceeding the maximum number of BDs (44). Therefore, base station 100 allocates SS#2 to resources in subbands #1 and #2 based on the priorities of subbands #1 to #3, and drops SS#2 in subband #3. With this dropping, the number of BDs configured for terminal 200 will be 40, which is less than the maximum number of BDs (44).

[0115] Here, if the dropping rule according to determination method 1 is not applied (for example, in the case of the dropping rule defined in Release 15 NR), in both cases of Fig. 15(a) and Fig. 15(b), SS#1 is allocated to resources in each LBT subband, and SS#2 is dropped. In other words, the same SS (for example, SS#2) set in multiple LBT subbands is not allocated to resources in any of the multiple LBT subbands.

[0116] In contrast, according to determination method 1, SS#2 is allocated to resources of subband#0 in FIG. 15(a), and to resources of subband#1 and #2 in FIG. 15(b). In other words, with determination method 1, whether the same SS (e.g., SS#2) set in multiple LBT subbands is allocated to resources or dropped is determined based on the priority among the multiple LBT subbands. For example, as shown in FIGS. 15(a) and 15(b), SS#2 set in each LBT subband may be allocated to resources in some LBT subbands and dropped in the remaining LBT subbands. This dropping rule allows base station 100 to increase the number of SSs set for terminal 200, thereby improving the transmission and reception efficiency of PDCCH.

[0117] For example, when applying the dropping rule according to determination method 1 to Phase A shown in Fig. 7, it may be applied to all LBT subbands (e.g., similar to Fig. 15(a)). Also, when applying the dropping rule according to determination method 1 to Phase B and Phase C shown in Fig. 7, it may be applied to all LBT subbands (e.g., similar to Fig. 15(a)), or it may be applied to LBT subbands available to terminal 200 based on the LBT result (e.g., similar to Fig. 15(b)).

[0118] When the dropping rule according to determination method 1 is applied to all LBT subbands (for example, when applied in Phase A), the SS placement does not change depending on the LBT result. This can simplify the SS determination process in base station 100, the PDCCH scheduling, or the reception operation in terminal 200.

[0119] Furthermore, when the dropping rule according to determination method 1 is applied to LBT subbands available to terminal 200 (for example, Phase B or C), depending on the LBT determination, for example, unavailable LBT subbands can be excluded from the count of the number of BDs, so that the number of PDCCH candidates actually placed can be increased and resource utilization efficiency can be improved.

[0120] In addition, in determination method 1, the priority of the LBT subband may be notified from base station 100 to terminal 200 by signaling information, or may be defined in specifications (or standards). For example, the priority of the LBT subband may be set such that the lower the subband number, the higher the priority, or may be set randomly for each terminal 200.

[0121] Furthermore, the priority of the LBT subband may be different for each SS. By using different LBT subband priorities for each SS, for example, the SSs are more likely to be allocated to different LBT subbands, and the possibility of PDCCH resources colliding (in other words, blocking) between SSs in PDCCH monitoring occasions can be reduced.

[0122] Furthermore, the priority of the LBT subband may differ between terminals 200. By using a different priority of the LBT subband for each terminal 200, for example, the LBT subband in which the PDCCH is arranged is likely to differ between terminals 200, and therefore, the possibility of collision (in other words, blocking) of PDCCH monitoring occasions between terminals 200 can be reduced.

[0123] 15 has been described in which an SS is set for each LBT subband, an SS does not have to be set for each LBT subband set in terminal 200, and may be set for some of the LBT subbands. Even in this case, base station 100 may determine dropping based on the priority of some of the LBT subbands.

[0124] In this way, according to determination method 1, by applying a dropping rule based on the priority of the LBT subband, the number of SSs that can be allocated to the LBT subband (in other words, PDCCH monitoring occasions) increases, and resource utilization efficiency can be improved.

[0125] [Variation of Determination Method 1] In the determination method 1, for example, a method for determining the priority of the LBT subband after determining the SS ID has been described. In other words, when there are multiple SSs with the same SS ID, if the number of BDs or the number of CCEs exceeds a threshold (for example, the maximum number of BDs or the maximum number of CCEs), the SSs are dropped in descending order of priority based on the priority of the LBT subband. However, the method is not limited to this.

[0126] For example, in a variation of determination method 1, a method may be applied in which the order of determining the SS ID and determining the priority of the LBT subband in the above method is reversed. In other words, a method in which the SS ID is determined after determining the priority of the LBT subband may be used. For example, base station 100 may first drop SSs in ascending order of LBT subband priority, and when there are multiple SSs in the same LBT subband, drop SSs in descending order of SS ID.

[0127] Fig. 16 shows an example of operation according to a variation of determination method 1. Note that the conditions in Fig. 16 (e.g., the maximum number of BDs, the number of BDs for each SS, the number of LBT subbands, the priority of the LBT subbands, or the LBT result) are the same as those in the example in Fig. 15.

[0128] In FIG. 16(a), base station 100 first allocates SSs to LBT subband resources in descending order of LBT subband priority (e.g., subband #0, #1, #2, #3). In FIG. 16(a), for example, if both SS #1 and SS #2 are allocated to subband #2, the number of BDs set for terminal 200 will be 48, exceeding the maximum number of BDs (44). Therefore, base station 100 allocates SS #1 with a low SS ID (high priority SS) to resources in subband #2 and drops SS #2 with a high SS ID. As a result of this dropping, the number of BDs set for terminal 200 will be 40, which is less than the maximum number of BDs (44). Note that in FIG. 16(a), both SS #1 and SS #2 in subband #3 with a low priority are dropped.

[0129] In the case of Fig. 16(b), SSs are allocated to the resources of each LBT subband in the same procedure as in the case of Fig. 16(a). In the case of Fig. 16(b), SS#2 in subband#3 is dropped.

[0130] In this way, even in a method in which the order of determining the SS ID and the priority of the LBT subband is reversed from that of Determination Method 1, as in the modified example of Determination Method 1, the number of SSs that can be allocated to the LBT subband (in other words, PDCCH monitoring occasions) increases, thereby improving resource utilization efficiency. Furthermore, in the modified example of Determination Method 1, this dropping rule makes it possible, for example, to perform scheduling that concentrates PDCCH monitoring occasions on some LBT subbands compared to Determination Method 1.

[0131] The above describes the modified example of determination method 1.

[0132] Note that dropping is not limited to SS-based dropping, and dropping may be PDCCH candidate-based dropping. For example, priority may be assigned to aggregation levels (ALs), and SSs may be allocated in descending order of priority to ALs until the maximum number of BDs or the maximum number of CCEs is reached. This SS allocation allows PDCCH candidates to be allocated with finer granularity. This increases the number of PDCCH monitoring occasions, improving resource utilization efficiency.

[0133] Furthermore, dropping in units of PDCCH candidates may be applied in conjunction with, for example, the priority of the LBT subband. For example, when applying the dropping rule according to the above-described determination method 1, dropping in units of PDCCH candidates may be performed instead of dropping in units of SSs. Alternatively, the priority of LBT subbands may not be applied, and dropping in units of PDCCH candidates may be applied to all LBT subbands. When dropping in units of PDCCH candidates is applied to all LBT subbands, for example, base station 100 may perform SS allocation based on SS ID determination, and then, if there are multiple SSs with the same SS ID, perform SS dropping for all LBT subbands based on the priority of AL. This dropping, for example, makes it possible to schedule PDCCH candidates and PDCCH monitoring occasions in a distributed manner among LBT subbands, thereby reducing the possibility of collisions between PDCCH monitoring occasions.

[0134] <Decision method 2> In determination method 2, when the number of LBT subbands for which PDCCH monitoring occasions are set exceeds a threshold (for example, the maximum number of LBT subbands), base station 100 determines the SS to allocate to resources based on the priority of the LBT subbands. For example, base station 100 drops the SS based on the priority of each LBT subband.

[0135] Dropping, which drops SS for each LBT subband based on the number of LBT subbands, may be applied, for example, before application of the dropping rule defined in Release 15 NR.

[0136] For example, in dropping according to determination method 2, if the number of LBT subbands set in terminal 200 exceeds a threshold (for example, the maximum number of LBT subbands), base station 100 drops SSs based on the priority of the LBT subbands. For example, base station 100 may drop SSs set in LBT subbands in ascending order of LBT subband priority. In other words, base station 100 may allocate SSs set in LBT subbands to resources in descending order of LBT subband priority.

[0137] After dropping based on the number of LBT subbands according to determination method 2, base station 100 may drop SSs in descending order of SS ID, similar to Release 15 NR, if the number of BDs or the number of CCEs in each SS exceeds a threshold (e.g., the maximum number of BDs or the maximum number of CCEs), for example.

[0138] FIG. 17 shows an example of operation according to the determination method 2.

[0139] 17, for simplicity of explanation, the number of BDs is taken into consideration, but the number of CCEs is not. For example, base station 100 may determine an SS based on the dropping rule according to determination method 2 not only when the number of BDs set in terminal 200 exceeds the maximum number of BDs, but also when at least one of the number of BDs and the number of CCEs exceeds a threshold (for example, either the maximum number of BDs or the maximum number of CCEs).

[0140] 17 illustrates an example in which four LBT subbands (e.g., LBT subbands #0 to #3) are used, but the number of LBT subbands is not limited to four and may be any other number. Also, in FIG. 17, the priority of the LBT subbands is highest in the order of subbands #0, #1, #2, and #3 for both SS #1 and SS #2 (in other words, subband #0 has the highest priority and subband #3 has the lowest priority).

[0141] In the example shown in FIG. 17, the maximum number of LBT subbands set in terminal 200 is two for both SS#1 and SS#2.

[0142] Also, the number of BDs in an SS allocated to each subband is set to 8. However, the number of BDs in an SS is not limited to 8, and may be set to another number.

[0143] For example, FIG. 17(a) shows a state in which four LBT subbands, subbands #0 to #3, are available for terminal 200 as a result of the LBT.

[0144] 17(a), the number of LBT subbands set for both SS#1 and SS#2 exceeds the maximum number of LBT subbands (2). Therefore, base station 100 allocates SS#1 and SS#2 to resources in subbands #0 and #1 based on the priorities of subbands #0 to #3, and drops SS#1 and SS#2 in subbands #2 and #3. As a result of this dropping, the number of BDs set for terminal 200 becomes 32, which is less than the maximum number of BDs (44).

[0145] On the other hand, FIG. 17(b) shows a state in which, as a result of the LBT, three LBT subbands, subbands #1 to #3, are available for terminal 200, but subband #0 is unavailable due to an LBT failure.

[0146] 17(b), the number of LBT subbands set for both SS#1 and SS#2 exceeds the maximum number of LBT subbands (2). Therefore, base station 100 allocates SS#1 and SS#2 to resources in subbands #1 and #2 based on the priorities of subbands #1 to #3, and drops SS#1 and SS#2 in subband #3. As a result of this dropping, the number of BDs set for terminal 200 becomes 32, which is less than the maximum number of BDs (44).

[0147] 17(a) and 17(b), the base station 100 may apply, for example, a Release 15 NR dropping rule (e.g., dropping based on the number of BDs or the number of CCEs) after dropping the SS based on the maximum number of LBT subbands.

[0148] For example, when applying the dropping rule according to determination method 2 to Phase A shown in Fig. 7, it may be applied to all LBT subbands (e.g., similar to Fig. 17(a)). Also, when applying the dropping rule according to determination method 2 to Phase B and Phase C shown in Fig. 7, it may be applied to all LBT subbands (e.g., similar to Fig. 17(a)), or may be applied to LBT subbands available to terminal 200 (e.g., similar to Fig. 17(b)).

[0149] When the dropping rule according to determination method 2 is applied to all LBT subbands (for example, when applied in Phase A), the SS placement does not change depending on the LBT result. This can simplify the SS determination process in base station 100, the PDCCH scheduling, or the reception operation in terminal 200.

[0150] Furthermore, when the dropping rule according to determination method 2 is applied to the LBT subbands available to terminal 200 (for example, Phase B or C), for example, unavailable LBT subbands can be excluded depending on the LBT determination, so that the number of PDCCH candidates that are actually allocated can be increased and resource utilization efficiency can be improved.

[0151] Furthermore, in determination method 2, at least one of the maximum number of LBT subbands and the priority of the LBT subbands may be notified from base station 100 to terminal 200 by signaling information, or may be defined in specifications (or standards). For example, the priority of the LBT subbands may be set such that the lower the subband number, the higher the priority, or may be set randomly for each terminal 200.

[0152] Furthermore, at least one of the maximum number of LBT subbands and the priority may be different for each SS. Using different maximum numbers of LBT subbands and priorities for each SS makes it easier for SSs to be allocated to different LBT subbands, and reduces the possibility of PDCCH resources colliding (in other words, blocking) PDCCH monitoring occasions between SSs.

[0153] Furthermore, at least one of the maximum number of LBT subbands and the priority may differ between terminals 200. By using a different maximum number of LBT subbands and priority for each terminal 200, for example, the LBT subbands in which PDCCHs are allocated are likely to differ between terminals 200, and therefore, the possibility of collision (in other words, blocking) of PDCCH monitoring occasions between terminals 200 can be reduced.

[0154] Furthermore, the dropping rule according to determination method 2 may be applied to the CSS, unlike the dropping rule of Release 15 NR (e.g., a dropping rule based on the maximum number of BDs or the maximum number of CCEs). In the dropping rule of Release 15 NR, for example, whether or not an SS is dropped is determined based on the number of BDs or the number of CCEs for each UE. The count of the number of BDs or the number of CCEs is, for example, the sum of the CSS and the USS. Therefore, for example, in a dropping rule that drops the SS including the CSS, whether or not the CSS is dropped may differ for each UE.

[0155] Here, it is assumed that the CSS is shared and used between UEs. If whether or not the CSS is dropped differs for each UE, a situation may occur in which a PDCCH transmitted in the CSS is received by some UEs but not by other UEs. In this situation, it is assumed that the scheduling of the base station 100 becomes complicated. Therefore, for example, it is unlikely that the dropping rule of Release 15 NR will be applied to the CSS.

[0156] On the other hand, when transmitting a DL burst, LBT subbands available to terminal 200 are notified from base station 100 to terminal 200, and therefore the dropping rule according to determination method 2 can determine SS allocation (in other words, SS dropping) based on the number of LBT subbands available to terminal 200. Therefore, in determination method 2, for example, by matching the maximum number of LBT subbands and the priority settings of LBT subbands between terminals 200, it becomes possible to determine SS (e.g., CSS) dropping between terminals 200 using the same determination criteria. Therefore, the dropping rule according to determination method 2 can also be applied to CSS.

[0157] 17 has described a case where an SS is set for each LBT subband, but an SS does not have to be set for each LBT subband set in terminal 200, and may be set for some of the LBT subbands. Even in this case, base station 100 may determine dropping based on the number and priority of some of the LBT subbands.

[0158] In this way, according to determination method 2, by applying a dropping rule based on the number and priority of LBT subbands, the number of SSs that can be allocated to LBT subbands (in other words, PDCCH monitoring occasions) increases, and resource utilization efficiency can be improved.

[0159] Determination methods 1 and 2 have been described above.

[0160] In the present embodiment, base station 100 and terminal 200 determine the setting of a PDCCH monitoring occasion in each LBT subband (in other words, a PDCCH arrangement method in base station 100) based on the priority of the LBT subband (frequency resource) set in terminal 200. This setting allows base station 100 and terminal 200 to set a PDCCH monitoring occasion (for example, parameters such as SS or the number of BDs and the number of CCEs) for each of a plurality of LBT subbands, thereby improving the efficiency of PDCCH arrangement.

[0161] Furthermore, in the present embodiment, base station 100 and terminal 200 determine a PDCCH monitoring occasion (in other words, a PDCCH allocation method) in at least one of Phase A (the period before the DL burst detection timing), Phase B, and Phase C (the periods after the DL burst detection timing), based on information related to at least one of the maximum number of BDs and the maximum number of CCEs, for example. For example, base station 100 and terminal 200 determine an LBT subband in which to set the PDCCH monitoring occasion according to each phase of DL burst detection, and determine the setting of the PDCCH monitoring occasion in the determined LBT subband. This setting allows base station 100 and terminal 200 to set a PDCCH monitoring occasion suitable for each phase of DL burst detection, thereby improving the efficiency of PDCCH allocation.

[0162] Therefore, according to this embodiment, for example, it is possible to improve the transmission efficiency of DL signals in NR-U.

[0163] (Embodiment 2) It is assumed that the desired PDCCH monitoring occasion arrangement differs in each phase (for example, Phases A, B, and C shown in FIG. 7) related to DL burst detection.

[0164] For example, since Phase A is a period before DL burst detection, whether each LBT subband is available for use depends on the LBT result. Therefore, in Phase A, PDCCH monitoring occasions may be allocated to all LBT subbands. Furthermore, in order to start transmission earlier in Phase A, it is desirable that the granularity of PDCCH monitoring occasions in the time domain be finer (in other words, that PDCCH monitoring occasions be allocated at short intervals).

[0165] On the other hand, for example, since Phase C is a period after DL burst detection, PDCCH monitoring occasions do not need to be allocated to all LBT subbands. Also, in Phase C, if PDSCH does not need to be scheduled at short intervals, the granularity of PDCCH monitoring occasions in the time domain may be coarse.

[0166] Furthermore, dynamic switching of PDCCH monitoring occasions may complicate the scheduling process in the base station or the reception process in the terminal.

[0167] Therefore, in this embodiment, a method for dynamically switching PDCCH monitoring occasions while suppressing the complexity of the scheduling process in the base station and the reception process in the terminal will be described.

[0168] [Base station and terminal configuration] The configurations of a base station and a terminal according to the present embodiment may be the same as the configurations of base station 100 and terminal 200 according to the first embodiment.

[0169] Scheduling section 104 of base station 100 according to this embodiment determines the PDCCH monitoring stage based on, for example, the phase in DL burst detection. Furthermore, scheduling section 104 changes a method for determining the PDCCH monitoring occasion in the LBT subband based on the determined PDCCH monitoring stage. Then, scheduling section 104 determines the PDCCH monitoring occasion (for example, SS) in each LBT subband based on, for example, the method for determining the PDCCH monitoring occasion.

[0170] The "PDCCH monitoring stage" is, for example, a period in which each phase in DL burst detection is classified based on a method for determining the PDCCH monitoring occasion. For example, for Phases A, B, and C shown in Fig. 7, Phases A and B may be classified as "PDCCH monitoring stage 1," and Phase C may be classified as "PDCCH monitoring stage 2." For example, the PDCCH monitoring stage may be in slot units (slots #0 and #1 in Fig. 7).

[0171] Similar to scheduling section 104, reception control section 205 of terminal 200 according to this embodiment determines the PDCCH monitoring stage based on the phase in DL burst detection, and changes the method for determining the PDCCH monitoring occasion in the LBT subband based on the determined PDCCH monitoring stage.

[0172] [Method for determining PDCCH monitoring occasion] The following describes an example of a method for determining a PDCCH monitoring occasion in scheduling section 104 of base station 100. Furthermore, reception control section 205 of terminal 200 may determine a PDCCH monitoring occasion based on the same determination method as scheduling section 104.

[0173] In the following, as an example, as described above, base station 100 classifies Phases into two PDCCH monitoring stages from the viewpoint of switching PDCCH monitoring occasions. For example, base station 100 classifies Phase A and Phase B into PDCCH monitoring stage 1 (hereinafter also referred to as "Stage 1"), and classifies Phase C into PDCCH monitoring stage 2 (hereinafter also referred to as "Stage 2"). In other words, Phase A and Phase B included in the same slot as Phase A are classified into Stage 1, and Phase C included in a different slot from Phase A is classified into Stage 2. Note that "classifying" may be interpreted as "associating" or "associating" interchangeably.

[0174] FIG. 18 shows an example of setting PDCCH monitoring occasions according to the present embodiment.

[0175] In FIG. 18, as an example, four LBT subbands (for example, subbands #0, #1, #2, and #3) are set.

[0176] 18 shows, as an example, a case in which terminal 200 detects a DL burst transmitted in subbands #3 and #4 at symbol #4 of slot #0. Therefore, in FIG. 18, the period from symbol #0 to #3 of slot #0 corresponds to Phase A, the period from symbol #4 to symbol #13 of slot #0 corresponds to Phase B, and the period from slot #1 onwards (for example, the period from symbol #0 to #13 of slot #1) corresponds to Phase C. Also, in FIG. 18, as described above, Phase A and Phase B (for example, slot #0) are classified as Stage 1, and Phase C (for example, slot #1) is classified as Stage 2.

[0177] In the example of FIG. 18, it is assumed that no available LBT subbands other than subbands #2 and #3 will be added in the period after symbol #4 of slot #0 (for example, until the end of Phase B).

[0178] In Stage 1, for example, if a PDCCH monitoring occasion is set in an LBT subband (for example, subbands #0 to #3 in FIG. 18) in which a DL burst can be transmitted, base station 100 allocates the PDCCH monitoring occasion.

[0179] On the other hand, in Stage 2, base station 100 allocates PDCCH monitoring occasions in LBT subbands where DL bursts are transmitted (e.g., subbands #2 and #3 in FIG. 18), and does not allocate PDCCH monitoring occasions in LBT subbands where DL bursts are not transmitted (e.g., subbands #0 and #1 in FIG. 18).

[0180] Furthermore, in Stage 1, even in Phase B (in other words, DL burst detection has been completed in at least some subbands), the same PDCCH monitoring occasion as in Phase A (in other words, before DL burst detection) is allocated. Here, in Phase B, DL burst has already been transmitted in at least one LBT subband. However, in Phase B, DL burst may not be transmitted in all LBT subbands. In this case, terminal 200 continues monitoring the PDCCH even in LBT subbands in which DL burst is not transmitted in Phase B. For example, in FIG. 18, during Stage 1, PDCCH monitoring occasions are valid in subbands #0 and #1, regardless of Phase A and Phase B.

[0181] In this way, the same PDCCH monitoring occasions as in Phase A (in other words, before DL burst detection) are allocated in Phase B. By setting these PDCCH monitoring occasions, for example, when an LBT subband that was unavailable near the beginning of Phase B becomes available in the middle of Phase B, terminal 200 can add an LBT subband to use, thereby improving resource utilization efficiency.

[0182] Furthermore, in Stage 1, PDCCH monitoring occasions are allocated to each LBT subband, so that terminal 200 can perform DL burst detection no matter which LBT subband becomes available.

[0183] Furthermore, the number of BDs in the PDCCH monitoring occasion allocated to each symbol of each subband may be set to, for example, 1. This setting of the number of BDs can suppress an increase in the number of BDs in the frequency domain and increase the number of BDs in the time domain, allowing for finer setting of the granularity of the PDCCH monitoring occasion in the time domain. For example, in FIG. 18, in Stage 1, the PDCCH monitoring occasion is allocated every two symbols.

[0184] Also, for example, a similar (for example, the same) payload size may be set between the GC-PDCCH used for DL burr detection and the PDCCH used for PDSCH scheduling, etc. By setting this payload size, for example, terminal 200 can receive both the GC-PDCCH and the PDCCH in one BD.

[0185] In this way, the same PDCCH monitoring occasion is set in Phase A and Phase B included in Stage 1 corresponding to one slot, so that, for example, the scheduling process in base station 100 or the receiving process in terminal 200 can be prevented from becoming complicated.

[0186] Furthermore, in Stage 2, PDCCH monitoring occasions are placed in LBT subbands where DL bursts are detected (e.g., subbands #2 and #3 in FIG. 18), and PDCCH monitoring occasions are not placed in LBT subbands where DL bursts are not detected (e.g., subbands #0 and #1 in FIG. 18).

[0187] With this arrangement, in Stage 2, for example, PDCCH monitoring occasions are not allocated to LBT subbands other than the LBT subband in which the DL burst is transmitted, and therefore the number of BDs or CCEs can be reduced.

[0188] Furthermore, an arrangement of PDCCH monitoring occasions may be configured in Stage 2 that is different from that in Stage 1. For example, as shown in Fig. 18, in Stage 2, one PDCCH monitoring occasion in the time domain may be arranged per slot. For example, as shown in Fig. 18, PDCCH monitoring occasions may be arranged dispersedly in the time domain in Stage 1, whereas PDCCH monitoring occasions may be arranged concentratedly in the time domain in Stage 2. Furthermore, for example, in the example shown in Fig. 18, in each subband, PDCCH monitoring occasions set in Stage 2 are arranged in a wider range in the frequency domain than PDCCH monitoring occasions set in Stage 1.

[0189] Also, as shown in FIG. 18, for example, during a period of Stage 1, allocation of the PDCCH monitoring occasion set for Stage 1 continues regardless of whether a DL burst is detected (in other words, the Phase). In other words, during a period of Stage 1, the PDCCH monitoring occasion is not switched. For example, as shown in FIG. 18, the PDCCH monitoring occasion may be switched between Stage 1 and Stage 2 (in other words, between slots). This switching can reduce the number of times the PDCCH monitoring occasion is switched.

[0190] In this embodiment, base station 100 and terminal 200 thus determine a PDCCH monitoring occasion (in other words, a PDCCH placement method) in at least one of Phase A (the period before the DL burst detection timing), Phase B, and Phase C (the periods after the DL burst detection timing), based on information relating to at least one of the maximum number of BDs and the maximum number of CCEs, for example.

[0191] For example, in this embodiment, the same PDCCH monitoring occasion allocation (in other words, PDCCH arrangement method) is set for Phase A and Phase B of Stage 1. Also, different PDCCH monitoring occasion allocations are set for Stage 1 (for example, Phase A and Phase B) and Stage 2 (for example, (Phase C)). Also, for example, between Stage 1 and Stage 2, the presence or absence of PDCCH monitoring occasions in the LBT subband where no DL burst is transmitted is switched.

[0192] By configuring these PDCCH monitoring occasions, for example, the PDCCH monitoring occasions can be switched in time resource units (for example, in slot units). In other words, the PDCCH monitoring occasions are not switched midway through one slot, which makes it possible to suppress, for example, the complexity of the scheduling process in base station 100 or the reception process in terminal 200. Furthermore, according to the present embodiment, it is possible to allocate PDCCH monitoring occasions according to, for example, each phase in DL burst detection.

[0193] Note that the arrangement of PDCCH monitoring occasions in each stage shown in Fig. 18 is an example and is not limited to the example shown in Fig. 18. For example, the number of BDs for PDCCH monitoring occasions arranged in each symbol of Stage 1 is not limited to one, but may be multiple. Furthermore, for example, at least one of the symbol positions and number of symbols at which PDCCH monitoring occasions are arranged in Stage 1 and Stage 2 is not limited to the example shown in Fig. 18, and may be other positions or other numbers.

[0194] (Embodiment 3) For example, to switch the PDCCH monitoring occasion, configuration information of CORESET and SS may be prepared in a number corresponding to the number of allocation patterns of the PDCCH monitoring occasion. Then, the PDCCH monitoring occasion may be switched by switching the configuration information of CORESET and SS. However, as mentioned above, there is a limit to the number of configurable CORESETs and SSs. Therefore, there is room for consideration of a method for switching the PDCCH monitoring occasion while suppressing an increase in the number of CORESETs and SSs.

[0195] [Base station and terminal configuration] The configurations of the base station and terminal according to the present embodiment may be the same as those of base station 100 and terminal 200 according to the first embodiment, respectively.

[0196] The scheduling unit 104 of the base station 100 according to this embodiment switches the applied dropping rule depending on, for example, the current Phase. The scheduling unit 104 may perform dropping determination for the SS based on, for example, the switched dropping rule.

[0197] Reception control section 205 of terminal 200 according to this embodiment switches the applied dropping rule depending on the current Phase, similar to scheduling section 104. Reception control section 205 performs dropping determination for the SS, for example, based on the switched dropping rule.

[0198] [Method for determining PDCCH monitoring occasion] The following describes an example of a method for determining a PDCCH monitoring occasion in scheduling section 104 of base station 100. Furthermore, reception control section 205 of terminal 200 may determine a PDCCH monitoring occasion based on the same determination method as scheduling section 104.

[0199] In the present embodiment, base station 100 switches the dropping rule to be applied (in other words, the rule for not setting the PDCCH monitoring occasion) depending on, for example, the phase (for example, Phase A, Phase B, or Phase C) in DL burst detection. For example, a different dropping rule may be applied to each phase. By applying this dropping rule, it becomes possible to set the PDCCH monitoring occasion depending on the phase.

[0200] FIG. 19 shows an example of setting PDCCH monitoring occasions according to the present embodiment.

[0201] Figure 19(a) shows an example of a state when a PDCCH monitoring occasion is set. In Figure 19(a), a PDCCH monitoring occasion (e.g., SS or BD) is set every two symbols (e.g., even-numbered symbols) in each LBT subband. Also, the number of PDCCH candidates for the PDCCH monitoring occasion in each symbol of each LBT subband is 11 (in other words, the number of BDs is 11).

[0202] FIG. 19(b) shows an example of setting PDCCH monitoring occasions in Phase A.

[0203] In the configuration of Figure 19(a), 11 PDCCH candidates (in other words, 11 BDs) are configured in the PDCCH monitoring occasion in each symbol of each LBT subband, whereas in Figure 19(b), 1 PDCCH candidate (in other words, 1 BD) is configured. In other words, in Figure 19(b), of the 11 PDCCH candidates, 10 PDCCH candidates are dropped, and 1 PDCCH candidate is configured.

[0204] For example, any of the following methods (1) to (3) may be applied to the dropping rule in FIG. 19(b).

[0205] (1) Among the PDCCH candidates of a certain AL, PDCCH candidates other than one PDCCH candidate and PDCCH monitoring occasions are dropped. As a method for selecting one PDCCH candidate, for example, the first PDCCH candidate may be selected, a PDCCH candidate may be selected at random, a PDCCH candidate may be designated by signaling, or a PDCCH candidate may be selected by another method.

[0206] (2) Priority is assigned based on the AL of the PDCCH candidate and the PDCCH candidate number within the AL, and if the number of BDs or the number of CCEs set in terminal 200 exceeds a threshold (e.g., the maximum number of BDs or the maximum number of CCEs), the PDCCH candidate and PDCCH monitoring occasion are dropped.

[0207] For example, when ALs 1, 2, and 4 are configured, a rule is assumed in which higher priority is assigned to ALs 2, 4, and 1 in that order, and within the same AL, higher priority is assigned to the PDCCH candidate with the lowest PDCCH number. Note that the PDCCH candidate number may correspond to ms,nCI in Section 10.1 of Non-Patent Document 3, for example. In the example shown in FIG. 19(b), when the maximum value of CCEs is 56 CCEs, there are 4 subbands × 7 symbols × 2 CCEs = 56 CCEs, so one PDCCH candidate for AL 2 is allocated in the PDCCH monitoring occasions for each even-numbered symbol in each LBT subband, and PDCCH candidates and PDCCH monitoring occasions for ALs different from AL 2 are dropped.

[0208] (3) PDCCH candidate and PDCCH monitoring occasion are dropped based on SS ID. In the example shown in Fig. 19(b), assuming that 11 BDs are configured separately as SS ID #1 (number of BDs = 1) and SS ID #2 (number of BDs = 10), when dropping based on SS ID is performed in Phase A, a PDCCH candidate for SS ID #1 is placed in the PDCCH monitoring occasion for each even-numbered symbol of each LBT subband, and the PDCCH candidate and PDCCH monitoring occasion for SS ID #2 are dropped.

[0209] FIG. 19(c) shows an example of setting PDCCH monitoring occasions in Phase C.

[0210] In FIG. 19(c), for example, in each LBT subband, the PDCCH candidate and PDCCH monitoring occasion of symbols #2 to #12 are dropped, and the PDCCH candidate and PDCCH monitoring occasion of symbol #0 are set.

[0211] For example, either of the following methods (4) or (5) may be applied to the dropping rule in FIG. 19(c).

[0212] (4) PDCCH candidates and PDCCH monitoring occasions are arranged in order from the first symbol in a slot, and if the number of BDs or the number of CCEs set in terminal 200 exceeds a threshold (for example, the maximum number of BDs or the maximum number of CCEs), the remaining PDCCH candidates and PDCCH monitoring occasions are dropped. In the example shown in FIG. 19(c), when a PDCCH candidate and a PDCCH monitoring occasion are arranged in symbol #0, the number of BDs reaches the maximum number of BDs (44 times), and therefore PDCCH candidates and PDCCH monitoring occasions in symbols other than symbol #0 are dropped.

[0213] (5) PDCCH candidate and PDCCH monitoring occasion are dropped based on SS ID. In the example shown in Fig. 19(c), assuming that SS ID #1 (11 BDs) is set for symbol #0 and SS ID #2 (11 BDs) is set for another symbol different from symbol #0, when dropping based on SS ID is performed in Phase C, PDCCH candidate and PDCCH monitoring occasion for symbol #0 are arranged, and PDCCH candidate and PDCCH monitoring occasion for another symbol different from symbol #0 are dropped.

[0214] In this way, according to the present embodiment, by applying different dropping rules to each phase, it is possible to set different PDCCH allocations in each phase.

[0215] In the example shown in Fig. 19, the dropping rules for Phase A and Phase C have been described, but the present invention is not limited to this, and different dropping rules may be applied to any phase. Also, for example, different dropping rules may be applied to each "PDCCH monitoring stage" defined in the second embodiment.

[0216] Furthermore, the association between the phase and the dropping rule may be notified from base station 100 to terminal 200 by signaling information, or may be defined in a specification (or standard), for example.

[0217] In this way, base station 100 and terminal 200 determine a PDCCH monitoring occasion (in other words, a PDCCH placement method) in at least one of Phase A (the period before the DL burst detection timing), Phase B, and Phase C (the period after the DL burst detection timing), based on information regarding at least one of the maximum number of BDs and the maximum number of CCEs, for example.

[0218] For example, in the present embodiment, base station 100 and terminal 200 set a dropping rule (in other words, a rule that determines resources on which PDCCH is not allocated) for each phase in DL burst detection or for each PDCCH monitoring stage (in other words, slot). In other words, a different dropping rule is set depending on the phase or stage. This setting allows base station 100 and terminal 200 to set the PDCCH allocation according to each phase or stage. Also, for example, when the same CORESET and SS are set, the PDCCH allocation can be changed by changing the dropping rule. Therefore, the present embodiment can reduce the number of CORESET / SS settings compared to, for example, a method of changing the PDCCH allocation by setting different CORESETs and SSs.

[0219] An embodiment of the present disclosure has been described above.

[0220] (Other embodiments) In each of the above embodiments, the statement "PDCCH candidate and PDCCH monitoring occasion are dropped" may be read as "PDCCH candidate and PDCCH monitoring occasion are not arranged (mapped)." Similarly, the statement "PDCCH candidate and PDCCH monitoring occasion are not dropped" may be read as "PDCCH candidate and PDCCH monitoring occasion are arranged (mapped)." Furthermore, even when the statement "PDCCH candidate and PDCCH monitoring occasion are dropped," for example, when multiple PDCCH candidates are configured for the same PDCCH monitoring occasion (time, frequency resource), the PDCCH monitoring occasion may not be dropped.

[0221] Furthermore, in the above-described embodiments, the downlink control channel for transmitting the control signal is not limited to the PDCCH, and may be a control channel with another name.

[0222] In the above embodiments, the unit of time resource (or unit time interval) is not limited to slot or symbol, and may be other time resource unit (e.g., subframe, frame, minislot, etc.). Furthermore, the unit of frequency resource is not limited to subband, and may be other frequency resource unit (e.g., resource block (PRB: Physical Resource Block), RB group (RBG), BWP, subcarrier, resource element group (REG), etc.).

[0223] Furthermore, the above embodiments may be applied in combination.

[0224] The present disclosure can be realized by software, hardware, or software linked to hardware. Each functional block used in the description of the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit, and each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may be called an IC, system LSI, super LSI, or ultra LSI.

[0225] The integrated circuit method is not limited to LSI, but may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0226] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology can be used to integrate functional blocks. The application of biotechnology is also a possibility.

[0227] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a wireless transceiver and processing / control circuitry. The wireless transceiver may include a receiver and a transmitter, or both functions. The wireless transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0228] Communications equipment is not limited to portable or mobile equipment, but also includes non-portable or fixed equipment, devices, and systems of any kind, such as smart home devices (such as appliances, lighting equipment, smart meters or metering devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0229] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0230] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0231] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0232] A base station according to one embodiment of the present disclosure includes a control circuit that determines an allocation method for a downlink control channel signal in at least one of a first period before a timing based on carrier sense and a second period after a timing based on carrier sense, based on information regarding at least one of the number of blind decodings for the downlink control channel signal and the number of resources for channel estimation, and a transmission circuit that transmits the downlink control channel signal based on the determined allocation method.

[0233] In one embodiment of the present disclosure, the allocation method is based on the priority of multiple frequency resources.

[0234] In one embodiment of the present disclosure, the allocation method is based on the priority of the plurality of frequency resources during the first period, and based on the priority of at least one frequency resource among the plurality of frequency resources based on the carrier sense during the second period.

[0235] In one embodiment of the present disclosure, the allocation method does not allocate the downlink control channel signal based on the priority when at least one of the number of blind decoding attempts and the number of resources exceeds a threshold.

[0236] In an embodiment of the present disclosure, the same allocation method is set for the first period and a period of the second period that is included in the same unit time interval as the first period.

[0237] In one embodiment of the present disclosure, an allocation method different from the allocation method in the first period is set for a period of the second period that is included in a unit time interval different from that of the first period.

[0238] In one embodiment of the present disclosure, the control circuit sets the allocation method, which includes a rule for determining resources in which the downlink control channel signal is not allocated, to each of the first period and the second period, or sets it for each unit time interval.

[0239] A terminal according to one embodiment of the present disclosure includes a control circuit that determines a reception opportunity for a downlink control channel signal in at least one of a first period before a detection timing of a downlink burst and a second period after the detection timing based on information regarding at least one of the number of blind decoding attempts for the downlink control channel signal and the number of resources for channel estimation, and a receiving circuit that receives the downlink control channel signal at the determined reception opportunity.

[0240] In a transmission method according to one embodiment of the present disclosure, a base station determines a placement method for the downlink control channel signal in at least one of a first period before a timing based on carrier sense and a second period after a timing based on carrier sense, based on information regarding at least one of the number of blind decodings for the downlink control channel signal and the number of resources for channel estimation, and transmits the downlink control channel signal based on the determined placement method.

[0241] In a receiving method according to one embodiment of the present disclosure, a terminal determines a reception opportunity for the downlink control channel signal in at least one of a first period before the detection timing of a downlink burst and a second period after the detection timing, based on information regarding at least one of the number of blind decoding attempts for the downlink control channel signal and the number of resources for channel estimation, and receives the downlink control channel signal at the determined reception opportunity.

[0242] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2019-184566, filed on October 7, 2019, are incorporated herein by reference in their entirety. [Industrial Applicability]

[0243] One embodiment of the present disclosure is useful in wireless communication systems. [Explanation of symbols]

[0244] 100 base stations 101,201 Receiver 102,202 Demodulation and decoding section 103 Channel State Estimation Unit 104 Scheduling Department 105,204 Control information storage unit 106 Data and control information generation unit 107,208 Encoding and Modulation Section 108,209 Transmitter 200 devices 203 DL transmission detection unit 205 Reception control section 206 Transmission control section 207 Data Generation Unit

Claims

1. a control circuit that determines a first plurality of search spaces for a downlink control channel and a second plurality of search spaces different from the first plurality of search spaces; a receiver for receiving the downlink control channel in an unlicensed frequency band; the receiver receives the downlink control channel based on the first plurality of search spaces in a first period including a period before detection of a signal transmitted from a base station and a period before a slot boundary after detection of the signal, and receives the downlink control channel based on the second plurality of search spaces in a second period that is a period after the slot boundary after detection of the signal; When switching from the first plurality of search spaces to the second plurality of search spaces, the first plurality of search spaces are maintained until a slot boundary, and at the slot boundary, the first plurality of search spaces are switched to the second plurality of search spaces. Terminal.

2. Only one of the first plurality of search spaces or the second plurality of search spaces is used within the slot. The terminal according to claim 1 .

3. The second plurality of search spaces are arranged in a wider frequency range than the first plurality of search spaces. The terminal according to claim 1 .

4. determining a first plurality of search spaces for a downlink control channel and a second plurality of search spaces different from the first plurality of search spaces; receiving the downlink control channel in an unlicensed frequency band; receiving the downlink control channel based on the first plurality of search spaces in a first period including a period before detection of a signal transmitted from a base station and a period before a slot boundary after detection of the signal; and receiving the downlink control channel based on the second plurality of search spaces in a second period that is a period after the slot boundary after detection of the signal; When switching from the first plurality of search spaces to the second plurality of search spaces, the first plurality of search spaces are maintained until a slot boundary, and at the slot boundary, the first plurality of search spaces are switched to the second plurality of search spaces. Communication method.

5. Only one of the first plurality of search spaces or the second plurality of search spaces is used within the slot. The communication method according to claim 4.

6. The second plurality of search spaces are arranged in a wider frequency range than the first plurality of search spaces. The communication method according to claim 4.

7. determining a first plurality of search spaces for a downlink control channel and a second plurality of search spaces different from the first plurality of search spaces; receiving the downlink control channel in an unlicensed frequency band; receiving the downlink control channel based on the first plurality of search spaces in a first period including a period before detection of a signal transmitted from a base station and a period before a slot boundary after detection of the signal; and receiving the downlink control channel based on the second plurality of search spaces in a second period that is a period after the slot boundary after detection of the signal; When switching from the first plurality of search spaces to the second plurality of search spaces, the first plurality of search spaces are maintained until a slot boundary, and at the slot boundary, the first plurality of search spaces are switched to the second plurality of search spaces. Integrated circuit.

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