Terminal, wireless communication method, and base station

Abstract

A terminal according to one embodiment of the present disclosure includes: a receiving unit for receiving an initial transmission of downlink (DL) data scheduled and multicast based on first downlink control information (DCI); and a control unit for controlling, based on a decoding result of the initial transmission, reception of a retransmission of the DL data scheduled and unicast based on a second DCI. According to one embodiment of the present disclosure, HARQ-ACK corresponding to a multicast PDSCH can be appropriately transmitted.

Description

Technical Field

[0001] The present disclosure relates to a terminal, a wireless communication method, and a base station in a next-generation mobile communication system. Background Art

[0002] In the Universal Mobile Telecommunications System (UMTS) network, Long Term Evolution (LTE) has been standardized to achieve even higher data rates and lower latency (Non-Patent Document 1). Furthermore, LTE-Advanced (3GPP Rel. 10-14) has been standardized to further enhance the capacity and sophistication of LTE (Third Generation Partnership Project (3GPP) Releases (Rel.) 8 and 9).

[0003] Successor systems to LTE (e.g., also known as the fifth generation mobile communication system (5G), 5G+ (plus), the sixth generation mobile communication system (6G), New Radio (NR), 3GPP Rel. 15 and later, etc.) are also being studied.

[0004] Prior art literature

[0005] Non-patent literature

[0006] Non-Patent Document 1: 3GPP TS 36.300 V8.12.0 “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall Description; Stage 2 (Release 8)”, April 2010 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In future wireless communication systems (e.g., NR), it is envisioned that multiple user terminals (UEs) will communicate in an ultra-high-density and high-traffic environment.

[0009] In NR, it is assumed that in such an environment, multiple UEs receive the same PDSCH simultaneously while utilizing multicast.

[0010] However, in the NR specifications to date, the retransmission method of HARQ-ACK corresponding to the PDSCH using UE multicast has not been fully studied. If this method cannot be properly controlled, there is a concern that system performance such as reduced throughput will be reduced.

[0011] Therefore, one of the objects of the present disclosure is to provide a terminal, a wireless communication method, and a base station that appropriately transmit HARQ-ACK corresponding to a multicast PDSCH.

[0012] Means for solving problems

[0013] A terminal involved in one embodiment of the present disclosure comprises: a receiving unit for receiving an initial transmission of downlink (DL) data scheduled and multicast based on a first downlink control information (DCI); and a control unit for controlling the reception of a retransmission of the DL data scheduled and unicast based on a second DCI based on a decoding result of the initial transmission.

[0014] Effects of the Invention

[0015] According to one embodiment of the present disclosure, HARQ-ACK corresponding to a multicast PDSCH can be appropriately transmitted. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a diagram showing an example of a retransmission procedure of a multicast PDSCH.

[0017] Figure 2 This is a diagram showing another example of the retransmission procedure of the multicast PDSCH.

[0018] Figure 3A-3C This is a diagram showing an example of resource indication based on DCI for initial transmission of a multicast PDSCH and retransmission of a multicast PDSCH.

[0019] Figures 4A-4C This is a diagram showing an example of a method for determining HARQ feedback timing / HARQ-ACK transmission resources for initial transmission of a multicast PDSCH and retransmission of a multicast PDSCH.

[0020] Figure 5This is a diagram showing an example of a retransmission procedure of a multicast PDSCH.

[0021] Figure 6 This is a diagram showing an example of a retransmission procedure of a multicast PDSCH.

[0022] Figure 7 This is a diagram showing an example of the reception timing of DCI that schedules retransmission of a multicast PDSCH.

[0023] Figure 8 This is a diagram showing an example of the reception timing of DCI that schedules retransmission of a multicast PDSCH.

[0024] Figure 9 This is a diagram showing an example of repeated transmission of a multicast PDSCH.

[0025] Figure 10 This is a diagram showing an example of repeated transmission of a multicast PDSCH.

[0026] Figure 11 This is a diagram showing an example of repeated transmission of a multicast PDSCH.

[0027] Figure 12 This is a diagram showing an example of HARQ-ACK transmission for repeated transmission of a multicast PDSCH.

[0028] Figure 13 This is a diagram showing an example of HARQ-ACK transmission for repeated transmission of a multicast PDSCH.

[0029] Figure 14 This is a diagram showing an example of a higher layer parameter reference for unicast DCI and multicast DCI.

[0030] Figure 15 This is a diagram showing an example of a schematic configuration of a wireless communication system according to one embodiment.

[0031] Figure 16 This is a diagram showing an example of the configuration of a base station according to one embodiment.

[0032] Figure 17 This is a diagram showing an example of the configuration of a user terminal according to one embodiment.

[0033] Figure 18 This is a diagram showing an example of the hardware configuration of a base station and a user terminal according to one embodiment. DETAILED DESCRIPTION

[0034] (TCI, spatial relationship, QCL)

[0035] In NR, research is being conducted on: reception processing (e.g., at least one of reception, demapping, demodulation, and decoding) and transmission processing (e.g., at least one of transmission, mapping, precoding, modulation, and coding) in the UE based on the transmission configuration indication state (TCI state) of the control signal and at least one of the channels (hereinafter referred to as signal / channel).

[0036] The TCI state may also indicate the state of a signal / channel applied to a downlink. A state equivalent to the TCI state applied to a signal / channel applied to an uplink may also be expressed as a spatial relation.

[0037] The TCI status refers to information related to Quasi-Co-Location (QCL) of signals / channels, and may also be referred to as spatial reception parameters, spatial relationship information, etc. The TCI status may be set for each channel or each signal in the UE.

[0038] In addition, in the present disclosure, TCI state can also be replaced with at least one of DL TCI state, UL TCI state, unified TCI state, default TCI state, spatial relationship, default spatial relationship, QCL, QCL relationship, QCL assumption, and QCL type.

[0039] QCL is an indicator that represents the statistical properties of a signal / channel. For example, the fact that a signal / channel is in a QCL relationship with another signal / channel may mean that at least one of the Doppler shift, Doppler spread, average delay, delay spread, or spatial parameters (e.g., spatial Rx parameters) can be assumed to be the same among these different signals / channels (at least one of these is QCL).

[0040] In addition, the spatial reception parameter may also correspond to the UE's receive beam (e.g., receive analog beam), and the beam may also be determined based on spatial QCL. The QCL (or at least one element of QCL) in this disclosure may also be replaced with sQCL (spatial QCL).

[0041] QCLs can also be specified in multiple types (QCL types). For example, four QCL types AD can be set that can assume the same parameters (or parameter sets) but with different parameters. The following represents the parameters (also referred to as QCL parameters):

[0042] QCL Type A (QCL-A): Doppler shift, Doppler spread, average delay, and delay spread,

[0043] QCL type B (QCL-B): Doppler shift and Doppler spread,

[0044] QCL type C (QCL-C): Doppler shift and average delay,

[0045] QCL type D (QCL-D): spatial reception parameters.

[0046] The UE's assumption that a specific Control Resource Set (CORESET), channel, or reference signal has a specific QCL (e.g., QCL type D) relationship with other CORESETs, channels, or reference signals may also be referred to as a QCL assumption.

[0047] The UE may also determine at least one of the transmit beam (Tx beam) and receive beam (Rx beam) of the signal / channel based on the TCI status or QCL assumption of the signal / channel.

[0048] The TCI status may also be information related to the QCL of the target channel (in other words, the reference signal (RS) used for the channel) and other signals (for example, other RS). The TCI status may also be set (indicated) through higher layer signaling, physical layer signaling, or a combination thereof.

[0049] In the present disclosure, the higher layer signaling may be, for example, any one of Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling, broadcast information, etc., or a combination thereof.

[0050] MAC signaling may also use, for example, MAC Control Element (MAC CE) and MAC Protocol Data Unit (MAC PDU). Broadcast information may also include, for example, Master Information Block (MIB), System Information Block (SIB), minimum system information (Remaining Minimum System Information (RMSI)), and Other System Information (OSI).

[0051] The physical layer signaling may also be, for example, downlink control information (DCI).

[0052] The channel for which the TCI state or spatial relationship is set (specified) may be, for example, at least one of a downlink shared channel (Physical Downlink Shared Channel (PDSCH)), a downlink control channel (Physical Downlink Control Channel (PDCCH)), an uplink shared channel (Physical Uplink Shared Channel (PUSCH)), and an uplink control channel (Physical Uplink Control Channel (PUCCH)).

[0053] In addition, the RS that has a QCL relationship with the channel may be, for example, at least one of a synchronization signal block (Synchronization Signal Block (SSB)), a channel state information reference signal (Channel State Information Reference Signal (CSI-RS)), a measurement reference signal (Sounding Reference Signal (SRS)), a tracking CSI-RS (also called a tracking reference signal (TRS)), and a QCL detection reference signal (also called QRS).

[0054] The SSB is a signal block that includes at least one of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a broadcast channel (physical broadcast channel (PBCH)). The SSB may also be referred to as an SS / PBCH block.

[0055] The TCI state information element (RRC's "TCI-state IE") set through high-layer signaling may also include one or more QCL information ("QCL-Info"). The QCL information may also include at least one of information related to the RS that forms a QCL relationship (RS relationship information) and information indicating the QCL type (QCL type information). The RS relationship information may also include information such as the RS index (for example, SSB index, non-zero-power CSI-RS (Non-Zero-Power (NZP) CSI-RS) resource ID (Identifier)), the index of the cell where the RS is located, and the index of the bandwidth part (Bandwidth Part (BWP)) where the RS is located.

[0056] In Rel.15NR, as a TCI state of at least one of PDCCH and PDSCH, both QCL type A RS and QCL type D RS, or only QCL type A RS can be set to the UE.

[0057] When TRS is configured as the RS of QCL Type A, it is assumed that the TRS is different from the demodulation reference signal (DMRS) of PDCCH or PDSCH, and the same TRS is transmitted periodically for a long time. The UE can measure the TRS and calculate the average delay, delay spread, etc.

[0058] A UE in which the TRS is configured as a QCL Type A RS in the TCI state of the DMRS of a PDCCH or PDSCH can assume that the DMRS of the PDCCH or PDSCH has the same QCL Type A parameters (average delay, delay spread, etc.) as those of the TRS. Therefore, the Type A parameters (average delay, delay spread, etc.) of the DMRS of the PDCCH or PDSCH can be calculated based on the measurement results of the TRS. When performing channel estimation for at least one of the PDCCH and PDSCH, the UE can use the measurement results of the TRS to perform more accurate channel estimation.

[0059] A UE configured with a QCL type D RS can determine a UE reception beam (spatial domain reception filter, UE spatial domain reception filter) using the QCL type D RS.

[0060] The RS of QCL type X in the TCI state may also mean an RS that has a QCL type X relationship with a certain channel / signal (DMRS), and the RS may also be referred to as a QCL source of QCL type X in the TCI state.

[0061] (Default TCI status / default spatial relationship / default PL-RS)

[0062] In RRC connected mode, in both cases where the TCI information in the DCI (higher layer parameter TCI-PresentInDCI) is set to "valid (enabled)" and when the TCI information in the DCI is not set, if the time offset between the reception of the DL DCI (DCI that schedules the PDSCH) and the corresponding PDSCH (the PDSCH scheduled by the DCI) is less than a threshold (timeDurationForQCL) (applicable condition, first condition), then in the case of non-cross-carrier scheduling, the TCI state of the PDSCH (default TCI state) may be the TCI state of the lowest CORESET ID in the latest timeslot within the active DL BWP of the CC (for the specific UL signal). Otherwise, the TCI state of the DSCH (default TCI state) may be the TCI state of the lowest TCI state ID of the PDSCH within the active DL BWP of the scheduled CC.

[0063] In Rel. 15, separate MAC CEs are required for activating / deactivating the PUCCH spatial relationship and activating / deactivating the SRS spatial relationship. The PUSCH spatial relationship follows the SRS spatial relationship.

[0064] In Rel. 16, at least one of the MAC CE for activation / deactivation of the PUCCH spatial relationship and the MAC CE for activation / deactivation of the SRS spatial relationship may not be used.

[0065] In FR2, if both the spatial relationship and PL-RS for the PUCCH are not configured (application condition, second condition), the default assumption of the spatial relationship and PL-RS (default spatial relationship and default PL-RS) is applied to the PUCCH. In FR2, if both the spatial relationship and PL-RS for the SRS (SRS resources for the SRS, or SRS resources corresponding to the SRI in DCI format 0_1 ​​scheduling the PUSCH) are not configured (application condition, second condition), the default assumption of the spatial relationship and PL-RS (default spatial relationship and default PL-RS) is applied to the PUSCH and SRS scheduled in DCI format 0_1.

[0066] If a CORESET is configured within the active DL BWP on the CC, the default spatial relationship and default PL-RS may also be the TCI state or QCL assumption of the CORESET with the lowest CORESET ID within the active DL BWP. If a CORESET is not configured within the active DL BWP on the CC, the default spatial relationship and default PL-RS may also be the activated TCI state with the lowest ID of the PDSCH within the active DL BWP.

[0067] In Rel.15, the spatial relationship of the PUSCH scheduled using DCI format 0_0 follows the spatial relationship of the PUCCH resource with the lowest PUCCH resource ID in the activated spatial relationship of the PUCCH on the same CC. Even if no PUCCH is transmitted on an SCell, the network needs to update the PUCCH spatial relationship on all SCells.

[0068] In Rel. 16, PUCCH configuration is not required for PUSCHs scheduled using DCI format 0_0. For PUSCHs scheduled using DCI format 0_0, if there is no activated PUCCH spatial relation or no PUCCH resources on the activated UL BWP within the CC (application condition, second condition), the default spatial relation and default PL-RS are applied to the PUSCH.

[0069] (NR multicast / broadcast)

[0070] In NR up to Rel. 16, the transmission of at least one of a signal and a channel (hereinafter referred to as a signal / channel) from the network to the user equipment terminal (UE) is essentially unicast transmission. In this case, it is assumed that each UE uses multiple reception opportunities (reception timings) corresponding to multiple beams (or panels) of the network to receive the same downlink (DL) data signal / channel (e.g., downlink shared channel (PDSCH)) transmitted from the network to multiple UEs.

[0071] Furthermore, in ultra-high-density and high-traffic environments, such as those in stadiums, where a large number of UEs are geographically densely packed, it is assumed that multiple UEs simultaneously receive the same signal / channel. In this case, multiple UEs are located in the same area, and each UE receives the same signal / channel. Therefore, while unicast reception of this signal / channel by each UE can ensure communication reliability, it is believed that resource utilization efficiency is reduced.

[0072] On the other hand, there are also use cases where the same DL data signal / channel is multicast (broadcast) to multiple UEs (e.g., televisions, radios, etc.) However, in this use case, the NW does not confirm the reception of the DL data signal / channel by each UE, making it difficult to ensure reliability.

[0073] Therefore, the inventors of the present invention have come up with a method for receiving downlink control information (DCI) of a UE that schedules a PDSCH that utilizes multicast, and a method for sending delivery confirmation information corresponding to the PDSCH that utilizes multicast (for example, also known as Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK) information, HARQ-ACK, ACK / NACK, etc.).

[0074] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The wireless communication methods according to the various embodiments may be applied individually or in combination.

[0075] (Wireless Communication Method)

[0076] Multicast / broadcast can also be configured from the NW to multiple UEs. This multicast / broadcast configuration can also be performed using higher layer signaling.

[0077] A UE configured for multicast / broadcast can also receive a PDSCH scheduled by DCI (PDCCH), which is blindly detected (received) in at least one of the downlink control channel (PDCCH) monitoring opportunities, search spaces, and control resource sets (CORESETs) corresponding to multicast / broadcast. This PDSCH can also be called a PDSCH utilizing multicast.

[0078] Furthermore, a UE configured with multicast / broadcast may use the PUCCH or PUSCH to transmit HARQ-ACK / NACK for the PDSCH utilizing multicast.

[0079] This HARQ-ACK / NACK may be transmitted as a 1-bit HARQ-ACK / NACK for each transport block (TB) / codeword (CW) of a PDSCH using multicast, or as a 1-bit HARQ-ACK / NACK for each of multiple TBs / CWs.

[0080] In the present disclosure, multicast can also be replaced with broadcast (broadcast information). In addition, PDSCH using multicast can also be replaced with PDSCH common to multiple UEs, common PDSCH, shared PDSCH, multicast PDSCH, broadcast (notification) PDSCH, etc.

[0081] In the present disclosure, A / B may also mean at least one of A and B.

[0082] In the present disclosure, PUCCH / PUSCH resources for HARQ-ACK transmission corresponding to the multicast PDSCH may also be simply referred to as HARQ-ACK transmission resources.

[0083] In the present disclosure, each of the multiple UEs may also be referred to as each UE, or simply referred to as UE.

[0084] In the present disclosure, a new DCI format dedicated to multicast PDSCH may also be specified. When a multicast PDSCH is scheduled using a DCI format dedicated to multicast PDSCH, the UE may also report UE capability information (UE Capability) related to support for this DCI format to the network (NW, e.g., gNB). In this case, the number of DCI size combinations (payload size, number of bits) increases, the number of blind DCI detections performed by the UE increases, and the complexity of UE operations increases. Therefore, only UEs that support this DCI format may monitor this DCI format.

[0085] In the present disclosure, multicast PDSCH may also be replaced with reception opportunity, opportunity, downlink (DL) data, data, transport block (TB), codeword (CW), PDSCH, multicast PUSCH, PUSCH, etc.

[0086] Multiple DCIs may each schedule one or more multicast PDSCHs (reception opportunities). The same DL data may also be transmitted to multiple UEs in each of one or more multicast PDSCHs. In the present disclosure, each of the multiple DCIs may also be referred to as a UE-specific DCI.

[0087] One DCI using QCL#x may also schedule DL data with QCL#x' for multiple UEs.

[0088] DCI detected in a (corresponding) PDCCH monitoring opportunity associated with a certain QCL may also schedule DL data in a reception opportunity associated with the QCL.

[0089] PDCCH monitoring in multiple DCIs may also follow at least one of the following PDCCH monitoring methods 1 to 3.

[0090] [PDCCH Monitoring Method 1]

[0091] A plurality of DCIs may be transmitted (received) in the common search space or the group common search space. The UE may select a PDCCH monitoring opportunity corresponding to a QCL configured / indicated for PDCCH use for DCI reception.

[0092] [PDCCH Monitoring Method 2]

[0093] A common search space or a group common search space may be configured for each of the multiple QCLs. The UE may select the search space corresponding to the QCL configured / indicated for PDCCH use for DCI reception.

[0094] [PDCCH monitoring method 3]

[0095] A common CORESET or a group-common CORESET may be configured for each of the plurality of QCLs. The UE may select the search space corresponding to the QCL configured / indicated for PDCCH use for DCI reception.

[0096] The UE detects DCI by monitoring the group scheduling search space configured as a common search space or a group common search space.

[0097] The search space for group scheduling may also be different depending on the QCL assumption. For example, the search space for group scheduling may have different time domain resources (symbols, time slots, etc.) depending on the QCL assumption.

[0098] The UE may also assume that the same DL data is scheduled in each PDCCH monitoring opportunity (DCI in each PDCCH monitoring opportunity) within the group scheduling search space.

[0099] The UE may also be configured with a search space for group scheduling through higher layer signaling.

[0100] In the present disclosure, UE-specific (or dedicated) DCI can be scrambled by a cyclic redundancy check (CRC) using a UE-specific Radio Network Temporary Identifier (RNTI) (e.g., a cell (C-)RNTI) or by a CRC using a UE-common RNTI. Furthermore, UE-specific DCI can also be scrambled by a CRC using a RNTI dedicated to multicast / broadcast scheduling.

[0101] One DCI for multiple UEs may also schedule DL data for the multiple UEs. One DCI may also schedule the same DL data in more than one multicast PDSCH. In the present disclosure, the one DCI may also be referred to as UE-common DCI.

[0102] DCI can be sent in both the common search space and the group common search space. The PDCCH monitoring timing for DCI can also vary depending on the QCL used in the UE. The UE can also select the PDCCH monitoring timing based on multiple QCL assumptions.

[0103] One DL data item may be a codeword (CW) or a transport block (TB). The same DL data item may have the same size (eg, transport block size (TBS)) or different sizes.

[0104] It is also conceivable that the base station does not use multiple beams to simultaneously transmit DL data.

[0105] In the present disclosure, DCI that is common to multiple UEs (UE-common) can be CRC-scrambled using either a UE-specific RNTI (e.g., C-RNTI) or a UE-common RNTI. In addition, UE-specific DCI can also be CRC-scrambled using a RNTI dedicated to multicast / broadcast scheduling.

[0106] In the present disclosure, the search space dedicated to multicast / broadcast scheduling may be a search space for group scheduling set as a common search space or a group common search space.

[0107] <First embodiment>

[0108] The multicast PDSCH may not be retransmitted. In other words, the NW may not retransmit the multicast PDSCH regardless of the success or failure of the multicast PDSCH reception processing (e.g., demodulation and decoding) by multiple UEs. In this case, the UE may also assume that the multicast PDSCH is not retransmitted and perform the multicast PDSCH reception processing.

[0109] In the case where multicast PDSCH is not retransmitted, regarding the new data indicator (NDI) contained in the downlink control information (DCI) (scheduling DCI, for example, DCI formats 1_0, 1_1) that schedules the multicast PDSCH, the UE can either assume that the value of the NDI field is a certain value (for example, 1) or ignore the value of the NDI field. In this case, the UE can also determine that the multicast PDSCH is initially transmitted (initial transmission) based on the certain value (for example, 1). In addition, the UE can also receive the multicast PDSCH regardless of the value of the NDI field (without using the value of the NDI field).

[0110] Furthermore, when multicast PDSCH retransmission is not performed and multicast is configured for multiple UEs using higher-layer signaling, the scheduling DCI for the multicast PDSCH may not include the NDI field. In other words, when multicast is configured using higher-layer signaling, multiple UEs may receive scheduling DCI for the multicast PDSCH that does not include the NDI field.

[0111] Furthermore, the NDI field may not exist in the DCI format dedicated to the multicast PDSCH. In other words, multiple UEs may receive the multicast PDSCH scheduled using the DCI format dedicated to the multicast PDSCH that does not include the NDI field.

[0112] Furthermore, DCI scrambled with a dedicated RNTI for multicast scheduling may not include the NDI field. In other words, when the DCI for scheduling multicast PDSCH is scrambled with a dedicated RNTI for multicast scheduling, multiple UEs may receive multicast PDSCH scheduled using this DCI format that does not include the NDI field.

[0113] At this time, the DCI scrambled by the RNTI other than the RNTI dedicated to multicast scheduling may have a structure including the NDI field or a structure not including the NDI field.

[0114] When the multicast PDSCH is not retransmitted, the multiple UEs may not transmit HARQ-ACK (at least one of ACK and NACK) for the multicast PDSCH.

[0115] As described above, according to the first embodiment, it is possible to reduce PUCCH / PUSCH resources for HARQ-ACK transmission and power consumption of UE when multicast PDSCH is transmitted.

[0116] <Second embodiment>

[0117] Multicast PDSCH can also be retransmitted using multicast / broadcast. In other words, the network can send a single piece of data via the multicast PDSCH, and if reception processing (e.g., demodulation or decoding) of any of the multicast PDSCHs by multiple UEs fails, the single piece of data can be retransmitted using multicast / broadcast. In this case, the UE can also assume that the data sent using the initial multicast PDSCH transmission is being retransmitted using multicast / broadcast, and then receive the multicast PDSCH.

[0118] In addition, in the present disclosure, a multicast PDSCH that is retransmitted using multicast / broadcast may also be simply referred to as a retransmission multicast PDSCH.

[0119] Furthermore, in the present disclosure, the initially transmitted multicast PDSCH may be replaced by the first multicast PDSCH, the initially transmitted multicast PDSCH, etc. The retransmitted multicast PDSCH may be replaced by the second multicast PDSCH.

[0120] In addition, in the present disclosure, the scheduling DCI for initially transmitting a multicast PDSCH may also be referred to as the first DCI. In addition, in the present disclosure, the scheduling DCI for retransmitting a multicast PDSCH may also be referred to as the second DCI. The first DCI and the second DCI may also be different DCIs.

[0121] In the present disclosure, each of the first DCI and the second DCI may be a UE-specific DCI or a DCI common to multiple UEs.

[0122] In the present disclosure, the search space used to monitor UE-specific DCI may be either a common search space or a UE-specific search space. In addition, the search space used to monitor UE-specific DCI may also be a search space dedicated to multicast / broadcast scheduling (or a control resource set (CORESET)).

[0123] In the present disclosure, the search space used to monitor UE-common DCI may be either a common search space or a UE-specific search space. In addition, the search space used to monitor UE-common DCI may also be a search space dedicated to multicast / broadcast scheduling (or a control resource set (CORESET)).

[0124] In the present disclosure, UE-specific DCI can be scrambled by a cyclic redundancy check (CRC) using either a UE-specific RNTI (e.g., cell (C-) RNTI) or a UE-common RNTI. Furthermore, UE-specific DCI can also be scrambled by a CRC using a RNTI dedicated to multicast / broadcast scheduling.

[0125] In the present disclosure, UE-common DCI may be CRC-scrambled using either a UE-specific RNTI (e.g., C-RNTI) or a UE-common RNTI. The UE-common RNTI may also be a newly defined RNTI. In addition, UE-specific DCI may also be CRC-scrambled using a RNTI dedicated to multicast / broadcast scheduling.

[0126] Implementation Method 2-1

[0127] The following describes a case where the retransmission of the multicast PDSCH is scheduled using the second DCI.

[0128] When a multicast PDSCH retransmission is scheduled using a second DCI, the first DCI and the second DCI may also be associated. For example, at least one of the DCI format, RNTI, control channel element (CCE) index / aggregation level of the PDCCH carrying the DCI, and search space / control resource set (CORESET) of the first DCI and the second DCI may be common.

[0129] In addition, the NDI fields of the first DCI and the second DCI may also be restricted to certain values. In this case, the value of the NDI field of the first DCI may also be N (for example, 1). In addition, the value of the NDI field of the second DCI may also be M (for example, 0). The value of the NDI field of the first DCI and the value of the NDI field of the second DCI may also be different from each other.

[0130] Figure 1 This is a diagram showing an example of a retransmission process of a multicast PDSCH. Figure 1In the process, multiple UEs (UE1 and UE2) receive multicast PDSCH1 scheduled by DCI1. The multicast PDSCH1 is a PDSCH that carries DL data (which may also be referred to as data). UE1 that successfully receives and processes the PDSCH1 uses PUCCH1 to send a positive response (HARQ-ACK, or ACK for short), and UE2 that fails to receive and process the PDSCH uses PUCCH2 to send a negative response (HARQ-NACK, or NACK for short). Thereafter, the UE receives PDSCH2 that is scheduled by DCI2 and utilizes multicast. The multicast PDSCH2 is a PDSCH that carries the same data as the data carried by multicast PDSCH1.

[0131] in addition, Figure 1 The number of UEs, the number of DCI, PDSCH, PUCCH resources, and the time / frequency allocation positions shown are just examples and are not limited to these examples. Figure 1 The DCI1 and DCI2 in the UE may be either UE-common DCI or UE-specific DCI. In addition, the HARQ-ACK transmission resources for the multicast PDSCH may be either UE-common HARQ-ACK transmission resources or PUSCH resources.

[0132] In the following figures shown in this disclosure, the first transmission multicast PDSCH and the retransmission multicast PDSCH may be PDSCHs carrying the same DL data. In addition, the repeated transmission of the multicast PDSCH may be multicast PDSCHs carrying the same DL data.

[0133] A UE that successfully receives a multicast PDSCH (a UE that has sent an ACK for the multicast PDSCH) may not be requested to monitor the second DCI. In addition, a UE that successfully receives a multicast PDSCH may not be requested to retransmit the multicast PDSCH reception or send HARQ-ACK information for the multicast PDSCH.

[0134] In this case, the UE may not send a HARQ-ACK for the retransmitted multicast PDSCH. Furthermore, the UE may send an ACK for the retransmitted multicast PDSCH regardless of the reception result of the retransmitted multicast PDSCH. This can avoid HARQ-ACK reception errors at the NW.

[0135] A UE that has failed in receiving the multicast PDSCH (a UE that has transmitted a NACK for the multicast PDSCH) may monitor the second DCI and receive the retransmitted multicast PDSCH.

[0136] In this case, the UE may also transmit an ACK / NACK based on the reception result of the retransmitted multicast PDSCH. Furthermore, if the predefined / set upper limit for the number of multicast PDSCH retransmissions is reached, ACK / NACK transmission for the multicast PDSCH may not be performed. The upper limit for the number of multicast PDSCH retransmissions may be predefined in the specification or configured for the UE via higher-layer signaling.

[0137] Implementation Method 2-2

[0138] Hereinafter, a case will be described in which the retransmission of the multicast PDSCH is scheduled by using the DCI (first DCI) for scheduling the initial transmission of the multicast PDSCH.

[0139] When a retransmitted multicast PDSCH is transmitted using multicast, the DCI (first DCI) that schedules the initial multicast PDSCH can also schedule the retransmitted multicast PDSCH. In other words, the UE can receive both the initial multicast PDSCH and the retransmitted multicast PDSCH scheduled by a single scheduling DCI. This reduces the overhead of receiving the scheduling DCI for the retransmitted multicast PDSCH.

[0140] In this case, the UE may transmit HARQ-ACK information for the initial transmission multicast PDSCH regardless of the reception result of the initial transmission multicast PDSCH, or may not transmit HARQ-ACK information for the initial transmission multicast PDSCH.

[0141] In addition, in the present disclosure, the retransmission multicast PDSCH may be sent once or multiple times. Furthermore, the upper limit (maximum number) of the number of retransmissions of the multicast PDSCH may be pre-specified in the specification, set to the UE via higher-layer signaling, or reported to the NW via UE capability information (UE Capability).

[0142] In this case, the value of the NDI field included in the first DCI may be a certain value (e.g., 1). Furthermore, when multicast is configured for multiple UEs, the UE may assume (replace) the value of the NDI field included in the first DCI with a certain value (e.g., 1) and receive the multicast PDSCH. Furthermore, the value of the NDI field included in the first DCI may not exist.

[0143] Figure 2 FIG. 1 is a diagram showing another example of the retransmission process of the multicast PDSCH. Figure 2 In , multiple UEs (UE1 and UE2) receive the multicast PDSCH1 scheduled by DCI1. Figure 2In the example, UE1 that successfully receives PDSCH1 uses PUCCH1 to send a positive response (HARQ-ACK, or simply ACK). UE2 that fails to receive PDSCH1 uses PUCCH2 to send a negative response (HARQ-NACK, or simply NACK). However, ACK / NACK does not need to be sent. Thereafter, the UE receives PDSCH2 scheduled by DCI1 and using multicast.

[0144] in addition, Figure 2 The number of UEs, the number of DCI, PDSCH, PUCCH resources, and the time / frequency allocation positions shown are just examples and are not limited to these examples. Figure 2 The DCI1 in the UE may be either UE-common DCI or UE-specific DCI. In addition, the HARQ-ACK transmission resources for the multicast PDSCH may be either UE-common HARQ-ACK transmission resources or PUSCH resources.

[0145] A UE that has successfully received the multicast PDSCH (a UE that has transmitted ACK for the multicast PDSCH) may not be requested to retransmit the reception of the multicast PDSCH, nor may it transmit HARQ-ACK information for the multicast PDSCH.

[0146] In this case, the UE may not transmit HARQ-ACK for the retransmission multicast PDSCH. Alternatively, the UE may transmit ACK for the retransmission multicast PDSCH regardless of the reception result of the retransmission multicast PDSCH.

[0147] A UE that has failed in receiving the multicast PDSCH (a UE that has transmitted a NACK for the multicast PDSCH) may also receive the retransmitted multicast PDSCH.

[0148] In this case, the UE may also transmit an ACK / NACK based on the reception result of the retransmitted multicast PDSCH. Furthermore, if the predefined / set upper limit for the number of multicast PDSCH retransmissions is reached, ACK / NACK transmission for the multicast PDSCH may not be performed. The upper limit for the number of multicast PDSCH retransmissions may be predefined in the specification or configured for the UE via higher-layer signaling.

[0149] The following describes resource indication for retransmission of the multicast PDSCH based on the scheduling DCI for the initial transmission of the multicast PDSCH. The UE may receive information on resources for retransmission of the multicast PDSCH included in the scheduling DCI for the initial transmission of the multicast PDSCH.

[0150] When the scheduling DCI for initially transmitting the multicast PDSCH is used to schedule the retransmission of the multicast PDSCH, the DCI field for indicating the resources of the multicast PDSCH may also be extended.

[0151] Specifically, a correspondence (table) between the DCI code point and at least one of the time domain resource allocation (TDRA) and frequency domain resource allocation (FDRA) of the multicast PDSCH, applied in each of the initial transmission of the multicast PDSCH and the retransmission of the multicast PDSCH, is notified / specified to the UE. The UE may also determine the resources for the initial transmission / retransmission of the multicast PDSCH based on the DCI code point included in the scheduling DCI. This correspondence (table) may be pre-specified in the specification or notified to the UE via higher-layer signaling.

[0152] Figure 3A This is a diagram showing an example of resource indication based on DCI for initial transmission of multicast PDSCH and retransmission of multicast PDSCH. Figure 3A In the DCI field, the table for determining the resources for the first multicast PDSCH transmission (DCI field 1) and the table for determining the resources for the retransmission multicast PDSCH (DCI field 2) are notified / set to the UE. The UE uses the PDSCH resources with the value corresponding to the first DCI code point notified by the scheduling DCI among the PDSCH resources indicated by DCI field 1 to receive the first multicast PDSCH transmission. In addition, the UE uses the PDSCH resources with the value corresponding to the second DCI code point notified by the scheduling DCI among the PDSCH resources indicated by DCI field 2 to receive the retransmission multicast PDSCH. The value corresponding to each DCI code point can also be associated with the TDRA / FDRA field of the multicast PDSCH.

[0153] in addition, Figure 3A The tables shown are merely examples, and the DCI code points and the values ​​corresponding to the code points are not limited thereto.

[0154] Furthermore, when scheduling a retransmission of a multicast PDSCH using the scheduling DCI for the initial multicast PDSCH, the DCI field used to indicate the resources for the multicast PDSCH can be extended. In other words, the UE can receive both the initial and retransmission multicast PDSCH using the resources for the initial and retransmission multicast PDSCHs corresponding to a single DCI code point.

[0155] Specifically, the correspondence (table) between the DCI code points and the TDRA / FDRA fields of the multicast PDSCH used in the initial transmission and retransmission of the multicast PDSCH is notified / specified to the UE. The UE can also determine the resources for the initial transmission and retransmission of the multicast PDSCH based on a DCI code point included in the scheduling DCI. In this case, the time / frequency resources for the initial transmission and retransmission of the multicast PDSCH can be the same or different.

[0156] Figure 3B This is a diagram showing an example of resource indication based on DCI for initial transmission of multicast PDSCH and retransmission of multicast PDSCH. Figure 3B In the DCI field 1, a table (DCI field 1) for determining the resources for the initial and retransmission multicast PDSCH is notified / configured to the UE. The UE receives the initial and retransmission multicast PDSCH using the PDSCH resources indicated in DCI field 1 that correspond to the DCI code point notified via the scheduling DCI. The values ​​corresponding to each DCI code point may also be associated with the TDRA / FDRA fields of the multicast PDSCH.

[0157] in addition, Figure 3B The tables shown are merely examples, and the DCI code points and the values ​​corresponding to the code points are not limited thereto.

[0158] In addition, when using the scheduling DCI for the initial transmission of the multicast PDSCH to schedule the retransmission of the multicast PDSCH, the UE can also determine the time / frequency resources for the retransmission of the multicast PDSCH based on the offset value relative to the time / frequency resources for the initial transmission of the multicast PDSCH notified (set) through the scheduling DCI.

[0159] The offset value may be pre-defined in the specification or may be notified to the UE via higher layer signaling.

[0160] Figure 3C This figure shows an example of DCI-based resource indication for the initial transmission of multicast PDSCH and the retransmission of multicast PDSCH. The UE is notified / specified of the time offset value (K) from the initial transmission of multicast PDSCH (multicast PDSCH1) resources to the retransmission of multicast PDSCH (multicast PDSCH2) resources, and receives the retransmission of multicast PDSCH based on this offset value. Figure 3C In the case of multicast PDSCH1, the UE receives multicast PDSCH2 using the same frequency resources as multicast PDSCH1 after K time slots from the multicast PDSCH1 resource.

[0161] in addition, Figure 3CThe example shown is merely an example, and the time offset may be expressed in slots / symbols as the time from the start or end of the initial transmission of the multicast PDSCH resource to the start or end of the retransmission of the multicast PDSCH resource.

[0162] In addition, Figure 3C The example shown shows a case where the time offset is notified / set to the UE, but the frequency offset may be notified / set to the UE, or both the time offset and the frequency offset may be notified / set to the UE.

[0163] The frequency offset may also be a value from the minimum / maximum / average physical resource block (PRB) of the initial transmission multicast PDSCH resource to the minimum / maximum / average PRB of the retransmission multicast PDSCH resource.

[0164] When multiple retransmission multicast PDSCHs are configured, the time / frequency offset value of each retransmission multicast PDSCH resource relative to the initial transmission multicast PDSCH resource may also be notified / set to the UE. Furthermore, when multiple retransmission multicast PDSCHs are configured, the time / frequency offset value of the retransmission multicast PDSCH resource relative to the previous multicast PDSCH resource may also be notified / set to the UE. In this case, the offset value may be either a single value or a specific number (e.g., the number of configured retransmission multicast PDSCHs) notified / set to the UE.

[0165] The following method is described: using the scheduling DCI for the initial transmission of the multicast PDSCH to indicate at least one of the timing from PDSCH to HARQ feedback (PDSCH-to-HARQ_feedback timing indicator, HARQ feedback timing) and the resources for HARQ-ACK transmission when scheduling the retransmission of the multicast PDSCH.

[0166] When scheduling retransmission of a multicast PDSCH using the scheduling DCI for the initial multicast PDSCH transmission, the scheduling DCI may include specific fields (HARQ feedback timing indicator field / other fields). The other fields may be fields for indicating HARQ-ACK transmission resources.

[0167] Specifically, a correspondence (table) between the DCI code point of a specific field and the HARQ feedback timing / HARQ-ACK transmission resources for the multicast PDSCH, applied in each of the initial transmission and retransmission of the multicast PDSCH, can also be notified / specified to the UE, and the HARQ feedback timing / HARQ-ACK transmission resources for the initial transmission / retransmission of the multicast PDSCH are determined based on the DCI code point included in the scheduling DCI. This correspondence (table) can be pre-specified in the specification or notified to the UE through higher-layer signaling.

[0168] Figure 4A This is a diagram showing an example of a method for determining HARQ feedback timing / HARQ-ACK transmission resources for initial multicast PDSCH transmission and retransmission multicast PDSCH. Figure 4A In the DCI, a table (DCI field 1) for determining HARQ feedback timing / HARQ-ACK sending resources for the initial transmission of HARQ-ACK for multicast PDSCH and a table (DCI field 2) for determining HARQ feedback timing / HARQ-ACK sending resources for retransmission of multicast PDSCH are notified / set to the UE.

[0169] exist Figure 4A In the HARQ feedback timing / HARQ-ACK transmission resources indicated by DCI field 1, the UE uses the HARQ feedback timing / HARQ-ACK transmission resources corresponding to the first DCI code point notified by the scheduling DCI to transmit HARQ-ACK for the initial transmission of the multicast PDSCH. In addition, the UE uses the HARQ feedback timing / HARQ-ACK transmission resources corresponding to the second DCI code point notified by the scheduling DCI among the HARQ feedback timing / HARQ-ACK transmission resources indicated by DCI field 2 to transmit HARQ-ACK for the retransmission of the multicast PDSCH. The value corresponding to each DCI code point may also be associated with the HARQ feedback timing / HARQ-ACK transmission resources for the initial transmission / retransmission of the multicast PDSCH.

[0170] in addition, Figure 4A The tables shown are merely examples, and the DCI code points and the values ​​corresponding to the code points are not limited thereto.

[0171] Furthermore, when scheduling a retransmission of a multicast PDSCH using the scheduling DCI for the initial transmission of the multicast PDSCH, the scheduling DCI may also include a DCI field for indicating the HARQ feedback timing and HARQ-ACK transmission resources for the multicast PDSCH. In other words, the UE may use the HARQ feedback timing and HARQ-ACK transmission resources for the initial transmission of the multicast PDSCH and the retransmission of the multicast PDSCH, which correspond to a single DCI code point, to transmit HARQ-ACK for the initial and retransmission multicast PDSCHs.

[0172] Specifically, the correspondence (table) between the DCI code points applied in the initial transmission of the multicast PDSCH and the HARQ feedback timing / HARQ-ACK transmission resources for the HARQ-ACK for the multicast PDSCH is notified / specified to the UE. The UE may also determine the HARQ feedback timing / HARQ-ACK transmission resources for the HARQ-ACK for the initial transmission and the retransmission of the multicast PDSCH based on a DCI code point included in the scheduling DCI. In this case, the HARQ feedback timing / HARQ-ACK transmission resources for the HARQ-ACK for the initial transmission of the multicast PDSCH and the retransmission of the multicast PDSCH may be the same or different.

[0173] Figure 4B This is a diagram showing an example of a method for determining HARQ feedback timing / HARQ-ACK transmission resources for initial multicast PDSCH transmission and retransmission multicast PDSCH. Figure 4B In the DCI field 1, a table (DCI field 1) for determining HARQ feedback timing / HARQ-ACK transmission resources for initial and retransmission multicast PDSCHs is notified / configured to the UE. The UE uses the HARQ feedback timing / HARQ-ACK transmission resources corresponding to the DCI code points notified by the scheduling DCI, among the HARQ feedback timing / HARQ-ACK transmission resources indicated in DCI field 1, to transmit HARQ-ACK for initial and retransmission multicast PDSCHs. The values ​​corresponding to each DCI code point may also be associated with the HARQ feedback timing / HARQ-ACK transmission resources for HARQ-ACK for the multicast PDSCH.

[0174] in addition, Figure 4B The tables shown are merely examples, and the DCI code points and the values ​​corresponding to the code points are not limited thereto.

[0175] In addition, when using the scheduling DCI for the initial transmission of the multicast PDSCH to schedule the retransmission of the multicast PDSCH, the UE can also determine the HARQ-ACK transmission resources for the retransmission of the multicast PDSCH based on the offset value relative to the HARQ-ACK transmission resources for the initial transmission of the multicast PDSCH notified (set) through the scheduling DCI.

[0176] The offset value may be pre-defined in the specification or may be notified to the UE via higher layer signaling.

[0177] Figure 4C This is a diagram showing an example of a method for determining HARQ-ACK transmission resources for the initial transmission of multicast PDSCH and retransmission of multicast PDSCH. The UE is notified / specified of a time offset value (K) from the HARQ-ACK transmission resources (PUCCH1) for the initial transmission of multicast PDSCH to the HARQ-ACK transmission resources (PUCCH2) for the retransmission of multicast PDSCH, and transmits HARQ-ACK for the initial transmission and retransmission of multicast PDSCH based on the offset value. Figure 4C In the example, the UE starts from PUCCH1 and sends PUCCH2 using the same frequency resources as PUCCH1 after K time slots.

[0178] in addition, Figure 4C The example shown is just an example, and the time offset can also be expressed by time slots / code symbols as the time from the start or end of the HARQ-ACK transmission resources for the initial transmission of the multicast PDSCH to the start or end of the HARQ-ACK transmission resources for the retransmission of the multicast PDSCH.

[0179] In addition, Figure 4C The example shown shows a case where the time offset is notified / set to the UE, but the frequency offset may be notified / set to the UE, or both the time offset and the frequency offset may be notified / set to the UE.

[0180] The frequency offset may be a value from the minimum / maximum / average PRB of HARQ-ACK transmission resources for the initial transmission of the multicast PDSCH to the minimum / maximum / average PRB of HARQ-ACK transmission resources for the retransmission of the multicast PDSCH.

[0181] In the case where multiple retransmission multicast PDSCHs are set, the time / frequency offset value of the HARQ-ACK transmission resources of each retransmission multicast PDSCH relative to the HARQ-ACK transmission resources of the initial multicast PDSCH can also be notified / set to the UE. In addition, in the case where multiple retransmission multicast PDSCHs are set, the time / frequency offset value of the HARQ-ACK transmission resources of the retransmission multicast PDSCH relative to the HARQ-ACK transmission resources of the previous multicast PDSCH can also be notified / set to the UE. In this case, the offset value can be either one or a certain number (for example, the number of retransmission multicast PDSCHs set) is notified / set to the UE.

[0182] As described above, according to the second embodiment, even when the number of UEs that need to retransmit the multicast PDSCH is large, retransmission can be performed using fewer PDSCH resources, thereby improving resource utilization efficiency.

[0183] <Third embodiment>

[0184] Multicast PDSCH can also be retransmitted using unicast. In other words, the network can send a single data item via the multicast PDSCH. If reception processing (e.g., demodulation or decoding) fails for any of the multicast PDSCHs at multiple UEs, the data item can be retransmitted using unicast. In this case, the UE can also assume that the multicast PDSCH is being retransmitted using unicast and perform reception processing on the multicast PDSCH.

[0185] In addition, in the present disclosure, unicast may also mean that the data is transmitted exclusively by the UE according to the method specified in Rel.15 and Rel.16.

[0186] In this embodiment, the first DCI and the second DCI may also be restricted. For example, the first DCI may be a DCI dedicated to multicast / broadcast, a DCI in a DCI format dedicated to multicast / broadcast, or a DCI scrambled by CRC using a RNTI dedicated to multicast / broadcast. In addition, the second DCI may be a DCI used in unicast (specified in Rel.15 / 16), a DCI in a DCI format used in unicast, or a DCI scrambled by CRC using a RNTI used in unicast. In addition, the second DCI may be a DCI dedicated to multicast / broadcast, a DCI in a DCI format dedicated to multicast / broadcast, or a DCI scrambled by CRC using a RNTI dedicated to multicast / broadcast.

[0187] In the present disclosure, the DCI format for multicast may be at least one of a DCI format dedicated to multicast / broadcast and a DCI format applied to DCI scrambled by CRC using a RNTI dedicated to multicast / broadcast.

[0188] Furthermore, in the present disclosure, the DCI for unicast may be at least one of DCI to which the DCI format specified in Rel. 15 / 16 is applied and DCI scrambled by CRC using the RNTI specified in Rel. 15 / 16.

[0189] In addition, for example, between the first DCI and the second DCI, at least one of the DCI format, RNTI, control channel element (CCE) index / aggregation level of the PDCCH carrying the DCI, and search space / control resource set (CORESET) may also be associated with each other.

[0190] In addition, the NDI fields of the first DCI and the second DCI may also be restricted to certain values. In this case, the value of the NDI field of the first DCI may also be N (for example, 1). In addition, the value of the NDI field of the second DCI may also be M (for example, 0). The value of the NDI field of the first DCI and the value of the NDI field of the second DCI may also be different from each other.

[0191] Figure 5 This is a diagram showing an example of a retransmission process of a multicast PDSCH. Figure 5 In the example, multiple UEs (UE1 and UE2) receive multicast PDSCH1 scheduled via DCI1. UE1 that successfully receives PDSCH1 sends an ACK using PUCCH1, while UE2 that fails to receive PDSCH1 sends a NACK using PUCCH2. Subsequently, the UEs receive unicast PDSCH2 scheduled via DCI2.

[0192] in addition, Figure 5 The number of UEs, the number of DCI, PDSCH, PUCCH resources, and the time / frequency allocation positions shown are just examples and are not limited to these examples. Figure 5 The DCI1 and DCI2 in the UE may be either UE-common DCI or UE-specific DCI. In addition, the HARQ-ACK transmission resources for the multicast PDSCH may be either UE-common HARQ-ACK transmission resources or PUSCH resources.

[0193] The first DCI and the second DCI may also be applied to different DCI formats. Specifically, the first DCI may also be applied to a DCI format for multicast / broadcast. In addition, the second DCI may also be applied to a DCI format for unicast.

[0194] Alternatively, the first DCI format may be a DCI format specified in Rel. 15 / 16. In this case, the UE may replace specific fields included in the DCI format specified in Rel. 15 / 16 with multicast parameters and receive the multicast PDSCH.

[0195] At this time, when the HARQ process ID contained in the first DCI and the second DCI is the same and the value of the NDI field is different (or the same), the UE can also determine that the initial multicast PDSCH scheduled by the first DCI and the retransmission multicast PDSCH scheduled by the second DCI carry the same data.

[0196] Furthermore, the same (common) DCI format may be applied to the first DCI and the second DCI. Specifically, the first DCI and the second DCI may also be applied to a DCI format for multicast / broadcast.

[0197] At this time, when the HARQ process ID contained in the first DCI and the second DCI is the same and the value of the NDI field is different (or the same), the UE can also determine that the initial multicast PDSCH scheduled by the first DCI and the retransmission multicast PDSCH scheduled by the second DCI carry the same data.

[0198] In this case, a field may be defined / configured in the multicast / broadcast DCI to notify the UE whether the DCI schedules a multicast PDSCH or a unicast PDSCH.

[0199] This field may also be the first bit of the DCI for multicast / broadcast, and the UE may use subsequent bits as a field for unicast or a field for multicast based on the first bit.

[0200] In this case, the UE may also implicitly determine whether the DCI for multicast / broadcast is for scheduling multicast PDSCH or unicast PDSCH based on a specific field value included in the DCI and a rule applied to the specific field value.

[0201] By making the DCI formats used in the first DCI and the second DCI the same, UEs that do not need to receive the retransmitted multicast PDSCH (for example, UEs that successfully received the initially transmitted multicast PDSCH) do not receive the retransmitted multicast PDSCH, thereby suppressing overhead.

[0202] Regardless of the differences between the first DCI and the second DCI, UE-specific / UE-common retransmission DCI resources (at least one of search space, CORESET, and monitoring opportunity) may be configured for the UE. The UE may monitor the second DCI using these retransmission DCI resources.

[0203] A UE that successfully receives a multicast PDSCH (a UE that has sent an ACK for the multicast PDSCH) may not be requested to monitor the second DCI. In addition, a UE that successfully receives a multicast PDSCH may not be requested to retransmit the multicast PDSCH reception or send HARQ-ACK information for the multicast PDSCH.

[0204] In this case, the UE may not transmit HARQ-ACK information for the retransmission multicast PDSCH. Alternatively, the UE may transmit HARQ-ACK information indicating ACK for the retransmission multicast PDSCH regardless of the reception result of the retransmission multicast PDSCH.

[0205] A UE that has failed in receiving the multicast PDSCH (a UE that has transmitted a NACK for the multicast PDSCH) may monitor the second DCI and receive the retransmitted multicast PDSCH.

[0206] In this case, the UE may also transmit an ACK / NACK based on the reception result of the retransmitted multicast PDSCH. Furthermore, if the upper limit (maximum number) of multicast PDSCH retransmissions is reached, ACK / NACK transmission for the multicast PDSCH may not be performed. The upper limit of the multicast PDSCH retransmissions may be predefined in the specification or configured for the UE via higher-layer signaling.

[0207] As described above, according to the third embodiment, even when the number of UEs that need to retransmit the multicast PDSCH is small, the NW can perform the minimum required data transmission, thereby improving resource utilization efficiency.

[0208] <Fourth embodiment>

[0209] When the second to third embodiments are applied, it is assumed that the DCI (second DCI) for scheduling the retransmission of the multicast PDSCH is notified before the determination (HARQ determination) of the reception processing result of the first transmission of the multicast PDSCH is made ( Figure 6 ). In this case, at the time of receiving the second DCI, the NW and the UE cannot identify whether the initially transmitted multicast PDSCH is correctly received by the UE.

[0210] Furthermore, if the second DCI is always received after the transmission of the HARQ-ACK corresponding to the initial transmission of the multicast PDSCH, there is a possibility that the delay until the retransmission is completed will increase.

[0211] Hereinafter, in this embodiment, a method of controlling the appropriate reception timing of the second DCI will be described.

[0212] The UE may also assume that the second DCI is transmitted after a specific time. Specifically, the UE may also receive (or may assume that it receives) the second DCI after a specific time after receiving the multicast PDSCH that was initially transmitted.

[0213] The specific moment may also be determined based on the HARQ-ACK processing time. The specific moment may also be the moment after the multicast PDSCH is received and the HARQ-ACK processing time has elapsed. In the present disclosure, the HARQ-ACK processing time may also be the minimum time from PDSCH reception to HARQ transmission (PDSCH to HARQ transmission). The HARQ-ACK processing time may be specified in the specification, set through higher-layer signaling, or reported from the UE through UE capability information.

[0214] In addition, the specific time can be an integer multiple (M times) of a certain time resource (e.g., a symbol, a time slot, a sub-time slot) or Tms (T is an arbitrary value). The values ​​M and T can also be determined based on the HARQ-ACK processing time. In addition, the above values ​​M and T can be pre-specified in the specification, set to the UE through higher-layer signaling, or reported to the NW through the UE capability information (UE Capability) of the UE.

[0215] This makes it possible to control the retransmission of the multicast PDSCH by the UE in consideration of HARQ-ACK detection of the initial transmission of the multicast PDSCH.

[0216] In addition, in the present disclosure, the specific time may also be a time / offset notified separately via higher layer signaling. In addition, the specific time may also be a time obtained by adding / subtracting the time / offset notified via higher layer signaling to the above HARQ-ACK processing time.

[0217] Figure 7 : is a diagram showing an example of the reception timing of the DCI for scheduling the retransmission of the multicast PDSCH. Figure 7In the example, multiple UEs receive the first-transmission multicast PDSCH (multicast PDSCH1) scheduled by DCI1. Thereafter, the UEs receive the retransmission multicast PDSCH (multicast PDSCH2) scheduled by DCI2.

[0218] exist Figure 7 In the embodiment, the UE receives DCI2 after the HARQ-ACK processing time of the multicast PDSCH 1. In other words, the UE does not assume that the DCI2 is received before the HARQ-ACK processing time of the multicast PDSCH 1.

[0219] in addition, Figure 7 The number of DCI, PDSCH, and PUCCH resources and their time / frequency allocation positions shown are just examples and are not limited to these examples. Figure 7 The DCI1 and DCI2 can be either UE-common DCI or UE-specific DCI.

[0220] The UE may also switch the monitoring (reception, detection) operation of the second DCI based on whether the monitoring period of the second DCI is before or after a specific time. Alternatively, the specific time may be HARQ processing time. In addition, the DCI monitoring period may be replaced by a DCI measurement time, a DCI detection time, a search space / CORESET / monitoring opportunity set for monitoring DCI, a DCI reception period, etc.

[0221] If the second DCI is received before a specific time, the UE may measure the second DCI and perform blind detection. If the second DCI is received after a specific time, the UE may determine whether to perform blind detection of the second DCI based on the reception processing result of the initial multicast PDSCH transmission.

[0222] In this case, the UE may not perform blind detection of the second DCI if the reception processing of the first multicast PDSCH is successful, and may perform blind detection of the second DCI if the reception processing of the first multicast PDSCH fails ( Figure 8 ).

[0223] In addition, Figure 8 In the example shown, the UE can also be notified of DCI1 resources (at least one of the search space, CORESET, and monitoring opportunity) and DCI2 resources through higher-layer signaling. This allows the UE to recognize that the DCI resources for initial transmission and the DCI resources for retransmission are different, and can appropriately control the reception of the DCI for initial transmission / retransmission.

[0224] As described above, according to the fourth embodiment, it is possible to flexibly control the reception of the retransmission multicast PDSCH by the UE regardless of the reception timing of the DCI that schedules the retransmission multicast PDSCH.

[0225] <Fifth embodiment>

[0226] In this embodiment, a case where repeated transmission (repetition) of multicast PDSCH is performed using one DCI will be described.

[0227] In this embodiment, the HARQ process IDs of the multicast PDSCHs may be the same. In addition, the redundancy versions (RVs) of the multicast PDSCHs may be the same or may be changed based on a specific rule.

[0228] The number of repetitions of the multicast PDSCH may be pre-specified in the specification, notified (set) to the UE via higher-layer signaling, or reported to the NW via the UE's UE capability information (UE Capability). Furthermore, the UE may use the configured value for the repetition number of the multicast PDSCH if it is configured by the NW, or use a specific value (e.g., 4) if it is not configured by the NW.

[0229] Figure 9 : is a diagram showing an example of repeated transmission of multicast PDSCH. Figure 9 In the UE, the UE receives the repeated transmission of the multicast PDSCH (multicast PDSCH1-4) scheduled by one scheduling DCI (DCI1). Figure 9 In , the number of repetitions of multicast PDSCH is 4.

[0230] in addition, Figure 9 The number of iterations, the number of DCI and PDSCH resources, and the time / frequency allocation positions shown are just examples and are not limited to these examples. Figure 9 The DCI1 in the figure is shown as UE-common DCI, but it can also be UE-specific DCI.

[0231] In the repeated transmission of the multicast PDSCH, the frequency resources of each multicast PDSCH may be different. By using different frequency resources for each multicast PDSCH, a frequency diversity effect can be obtained.

[0232] Multiple candidates for the time / frequency resources of each multicast PDSCH may also be configured for the UE via higher-layer signaling. The UE may then determine the time / frequency resources of each multicast PDSCH from among these multiple candidates based on specific fields (e.g., TDRA / FDRA fields) included in the scheduling DCI for the multicast PDSCH.

[0233] Furthermore, a time / frequency offset value relative to the time / frequency resource of a specific multicast PDSCH among multiple multicast PDSCHs is notified to the UE, and the UE may determine the time / frequency resource of a multicast PDSCH other than the specific multicast PDSCH based on the offset value. The scheduling DCI may also indicate the time / frequency resource of the specific multicast PDSCH.

[0234] Note that the specific multicast PDSCH may be the multicast PDSCH that is transmitted first among a plurality of multicast PDSCHs, or may be the multicast PDSCH that is transmitted previously among a plurality of multicast PDSCHs.

[0235] Figure 10 : is a diagram showing an example of repeated transmission of multicast PDSCH. Figure 10 In the UE, the UE receives the repeated transmissions (multicast PDSCH1-4) of the multicast PDSCH scheduled by one scheduling DCI (DCI1). Figure 10 In , the number of repetitions of multicast PDSCH is 4.

[0236] exist Figure 10 In the example shown, a frequency offset value relative to a previous multicast PDSCH is notified to the UE, and the UE receives multiple multicast PDSCHs based on the offset value.

[0237] in addition, Figure 10 The number of iterations, the number of DCI and PDSCH resources, and the time / frequency allocation positions shown are just examples and are not limited to these examples. Figure 10 The DCI1 in the figure is shown as UE-common DCI, but it can also be UE-specific DCI.

[0238] During repeated transmission of a multicast PDSCH, the TCI state applied to each multicast PDSCH can be different. In other words, the UE can use different spatial domain filters to receive each multicast PDSCH. By applying different TCI states to each multicast PDSCH, spatial diversity can be achieved.

[0239] Multiple candidates for the TCI state to be applied in each multicast PDSCH can also be set to the UE through higher layer signaling. The UE can then determine the TCI state to be applied in each multicast PDSCH from these multiple candidates based on a specific field included in the scheduling DCI of the multicast PDSCH.

[0240] Furthermore, the UE may determine the TCI state to be applied in each multicast PDSCH based on specific rules (beam cycle, beam period). The list of multiple TCI states used for beam cycle can be pre-defined in the specification or notified (set) to the UE via higher-layer signaling. Furthermore, the TCI state to be applied in the initial multicast PDSCH (initial TCI state) can also be notified to the UE.

[0241] The beam cycle (beam period) can also be a list of multiple TCI states cyclically applied to multiple signals / channels (e.g., PDSCH).

[0242] Figure 11 : is a diagram showing an example of repeated transmission of multicast PDSCH. Figure 11 In the UE, the UE receives the repeated transmissions (multicast PDSCH1-4) of the multicast PDSCH scheduled by one scheduling DCI (DCI1). Figure 11 In , the number of repetitions of multicast PDSCH is 4.

[0243] exist Figure 11 In the example shown, the UE is configured with TCI states #1, #2, #3, and #4 as beams, and is notified to apply TCI state #1 to the initial multicast PDSCH. Based on this cycle and the initial TCI state, the UE receives multiple multicast PDSCHs.

[0244] in addition, Figure 11 The number of iterations, the number of DCI and PDSCH resources, the time / frequency allocation position, the TCI state, the cycle of the TCI state, and the initial TCI state shown are just examples and are not limited to these examples. Figure 11 The DCI1 in the figure is shown as UE-common DCI, but it can also be UE-specific DCI.

[0245] The following describes the transmission of HARQ-ACK by the UE in response to repeated transmission of the multicast PDSCH.

[0246] The UE may not send HARQ-ACK for repeated transmission of the multicast PDSCH.

[0247] In addition, the UE may also send HARQ-ACK for repeated transmissions of the multicast PDSCH.

[0248] For example, the UE may use a single HARQ-ACK transmission PUCCH / PUSCH resource to send HARQ-ACK for repeated transmissions of a multicast PDSCH. In this case, the UE may send an ACK if at least one of the multicast PDSCHs is successfully received. Furthermore, the UE may send a NACK if all of the multicast PDSCHs fail to be received.

[0249] In this case, the PUCCH / PUSCH resources for HARQ-ACK transmission may be allocated after the last symbol of the last multicast PDSCH.

[0250] Figure 12 This is a diagram showing an example of HARQ-ACK transmission for repeated transmission of a multicast PDSCH. Figure 12 The scheduling DCI and the structure of each multicast PDSCH are shown in FIG. Figure 9 The UE uses the PUCCH resources to send HARQ-ACK (ACK / NACK) for the repeated transmission of the multicast PDSCH.

[0251] in addition, Figure 12 The number of iterations, the number of DCI, PDSCH, and PUCCH resources, and the time / frequency allocation positions shown are just examples and are not limited to these examples. Figure 12 The DCI2 in FIG is respectively shown as a UE-common DCI, but it can also be a UE-specific DCI. Figure 12 The resources used for sending HARQ-ACK are PUCCH resources, but can also be PUSCH resources.

[0252] Furthermore, for example, the UE may transmit HARQ-ACK for the repeatedly transmitted multicast PDSCH using PUCCH / PUSCH resources for HARQ-ACK transmission configured for each multicast PDSCH.

[0253] In this case, the UE may perform reception processing on each multicast PDSCH and transmit an ACK corresponding to the first multicast PDSCH for which reception processing has been successfully performed, using the HARQ-ACK transmission resources corresponding to the multicast PDSCH.

[0254] Alternatively, the UE may perform reception processing on each multicast PDSCH and not transmit the HARQ-ACK corresponding to the multicast PDSCH for which reception processing failed. Alternatively, the UE may perform reception processing on each multicast PDSCH and transmit a NACK corresponding to the multicast PDSCH for which reception processing failed, using the HARQ-ACK transmission resources corresponding to the multicast PDSCH.

[0255] If at least one multicast PDSCH is successfully received, the UE may not transmit HARQ-ACK for the multicast PDSCH received after the first successfully received multicast PDSCH, thereby avoiding unnecessary power consumption of the UE.

[0256] Furthermore, if at least one multicast PDSCH is successfully received, the UE can also send an ACK for subsequent multicast PDSCHs, regardless of the reception results of subsequent multicast PDSCHs received after the initial successfully received multicast PDSCH. This avoids errors caused by the network and improves communication reliability.

[0257] Furthermore, if reception processing of at least one multicast PDSCH is successful, the UE may transmit ACKs for subsequent multicast PDSCHs a specific number of times, regardless of the reception processing results of subsequent multicast PDSCHs. The number of ACK transmissions may be the sum N of the number of ACK transmissions for the initial successfully received multicast PDSCH and the number of ACK transmissions for subsequent multicast PDSCHs.

[0258] This value N may be defined in advance in the specification, may be notified (set) to the UE through higher layer signaling, or may be a value reported to the NW through the UE capability information (UE Capability) of the UE.

[0259] In addition, a specific RV value may also be applied to the multicast PDSCH. In addition, a specific RV value may also be applied to at least the initially received multicast PDSCH. The specific RV value may also be a self-decodable (Self-decodable) RV. The self-decodable RV may also be a specific RV (for example, RV=0, 3). The UE receives the multicast PDSCH to which the self-decodable RV is applied, thereby increasing the probability of being able to decode based on the PUSCH to which the RV is applied. For example, the specific RV value may be either 0 or 0 and 3.

[0260] Figure 13 This is a diagram showing an example of HARQ-ACK transmission for repeated transmission of a multicast PDSCH. Figure 13 The scheduling DCI and the structure of each multicast PDSCH are shown in FIG. Figure 9 The UE uses the PUCCH resources corresponding to each multicast PDSCH to transmit HARQ-ACK (ACK / NACK) for the repeated transmission of the multicast PDSCH. For multicast PDSCHs 1-4, PUCCHs 1-4 are the corresponding HARQ-ACK transmission resources.

[0261] exist Figure 13 In the example shown, a UE fails to receive multicast PDSCH1. The UE does not send (or may send) a HARQ-ACK (NACK) corresponding to multicast PDSCH1. Subsequently, the UE successfully receives multicast PDSCH1. The UE uses PUCCH2 to send a HARQ-ACK (ACK) corresponding to multicast PDSCH2.

[0262] Furthermore, the UE transmits (or may not transmit) ACK corresponding to each of multicast PDSCHs 3 and 4, regardless of the reception processing results of multicast PDSCHs 3 and 4 received after multicast PDSCH 2.

[0263] in addition, Figure 13 The number of iterations, the number of DCI, PDSCH, and PUCCH resources, and the time / frequency allocation positions shown are just examples and are not limited to these examples. Figure 13 The DCI1 in FIG is respectively shown as a UE-common DCI, but it can also be a UE-specific DCI. Figure 13 The resources used for sending HARQ-ACK are PUCCH resources, but can also be PUSCH resources.

[0264] The following describes the spatial domain filter (UL beam, UL spatial relation) applied to the transmission of HARQ-ACK corresponding to the multicast PDSCH. Furthermore, the method for determining the spatial domain filter described below can also be applied to the HARQ-ACK of at least one of the first to fourth embodiments described above.

[0265] In the case where the UE uses one HARQ-ACK transmission PUCCH / PUSCH resource to send HARQ-ACK for repeated transmission of multicast PDSCH ( Figure 12 In the case shown in the example above, the UE may also use a specific spatial domain filter (UL beam) to send the HARQ-ACK.

[0266] This spatial domain filter may also be notified (set, indicated) to the UE using at least one of higher layer signaling (e.g., RRC signaling), MAC signaling, and physical layer signaling (e.g., DCI). That is, the UE may also use at least one of the spatial domain filters indicated by the configured PUSCH / PUCCH spatial relationship information (Spatial Relation Information (SRI)) or the spatial domain filters corresponding to the spatial relationship of the PUSCH / PUCCH to transmit HARQ-ACK for the repeatedly transmitted multicast PDSCH.

[0267] Furthermore, the specific spatial domain filter may be a spatial domain filter corresponding to a default spatial relationship specified in Rel. 16.

[0268] Furthermore, the specific domain filter may also be a spatial domain filter corresponding to the spatial domain filter (DL beam) applied to multiple multicast PDSCHs. In this case, the spatial domain filter applied to the repeatedly transmitted HARQ-ACK for the multicast PDSCH may also be the spatial domain filter applied to the first received multicast PDSCH. Furthermore, the spatial domain filter applied to the repeatedly transmitted HARQ-ACK for the multicast PDSCH may also be the spatial domain filter applied to the last received multicast PDSCH.

[0269] In addition, for example, when the UE uses the HARQ-ACK transmission PUCCH / PUSCH resources configured for each multicast PDSCH to transmit HARQ-ACK for repeated transmission of the multicast PDSCH ( Figure 13 In the case shown in the example above, the UE may also use a specific spatial domain filter (UL beam) to send each HARQ-ACK.

[0270] A specific spatial domain filter will be described below. However, the specific spatial domain filter applied to each HARQ-ACK may be common to each HARQ-ACK or may be determined individually for each HARQ-ACK.

[0271] This spatial domain filter may also be notified (set, indicated) to the UE using at least one of higher layer signaling (e.g., RRC signaling), MAC signaling, and physical layer signaling (e.g., DCI). That is, the UE may also use at least one of the spatial domain filter indicated by the configured PUSCH / PUCCH SRI or the spatial domain filter corresponding to the spatial relationship of the PUSCH / PUCCH to transmit HARQ-ACK for the repeatedly transmitted multicast PDSCH.

[0272] Furthermore, the specific spatial domain filter may be a spatial domain filter corresponding to a default spatial relationship specified in Rel. 16.

[0273] Furthermore, the specific domain filter may also be a spatial domain filter corresponding to a spatial domain filter (DL beam) commonly applied to multiple multicast PDSCHs. In this case, the spatial domain filter applied to the repeatedly transmitted HARQ-ACK for the multicast PDSCH may also be the spatial domain filter applied to the first received multicast PDSCH. Furthermore, the spatial domain filter applied to the repeatedly transmitted HARQ-ACK for the multicast PDSCH may also be the spatial domain filter applied to the last received multicast PDSCH.

[0274] Furthermore, the specific domain filter may be a spatial domain filter (DL beam) applied to each multicast PDSCH corresponding to each HARQ-ACK.

[0275] Alternatively, the specific domain filter may be the spatial domain filter corresponding to the spatial domain filter (DL beam) of the multicast PDSCH that was successfully received. In this case, the UE may also apply the spatial domain filter corresponding to the spatial domain filter of the successfully received multicast PDSCH to the HARQ-ACK transmission for subsequent multicast PDSCHs.

[0276] As described above, according to the fifth embodiment, low delay and low PDCCH overhead can be achieved, and highly reliable multicast PDSCH reception can be performed.

[0277] <Sixth embodiment>

[0278] Regarding at least one parameter included in a higher layer (RRC) parameter (at least one of the PDSCH configuration (PDSCH-Config), the PUCCH configuration (PUCCH-Config), and the PUSCH configuration (PUSCH-Config)), the unicast parameter and the multicast parameter may be separately notified to the UE. For example, the UE may receive the unicast parameter and the multicast parameter for TDRA and FDRA included in the PDSCH configuration, respectively.

[0279] In addition, this embodiment can also be applied to at least one of the first to fifth embodiments described above.

[0280] In addition, the high-level parameters in the present disclosure may also be replaced by a high-level parameter list, a high-level parameter set, a high-level parameter table, etc.

[0281] In addition, the UE may assume that the DCI reference detected in the resources for multicast (e.g., CORESET, search space, monitoring opportunity) is set as the higher-layer parameter for multicast, or may assume that other DCI references are set as the higher-layer parameter for unicast.

[0282] Furthermore, the UE may assume that the DCI reference to which the DCI format for multicast is applied is set as a higher layer parameter for multicast, or may assume that other DCI references are set as higher layer parameters for unicast.

[0283] In addition, the UE may assume that the DCI reference scrambled by the CRC using the RNTI for multicast is set as a higher layer parameter for multicast, or may assume that other DCI references are set as higher layer parameters for unicast.

[0284] Figure 14 This is a diagram showing an example of a higher layer parameter reference for unicast DCI and multicast DCI. Figure 14 In the example, the UE assumes that the DCI reference for unicast is set as the higher layer parameter list for unicast, and assumes that the DCI reference for multicast is set as the higher layer parameter list for multicast.

[0285] (Wireless Communication System)

[0286] The following describes a configuration of a wireless communication system according to an embodiment of the present disclosure. In this wireless communication system, communication is performed using any one of the wireless communication methods according to the above-described embodiments of the present disclosure or a combination thereof.

[0287] Figure 15 This figure shows an example of a schematic configuration of a wireless communication system according to one embodiment. The wireless communication system 1 may also be a system that implements communication using Long Term Evolution (LTE) standardized by the Third Generation Partnership Project (3GPP) or the fifth generation mobile communication system New Radio (5G NR).

[0288] In addition, the wireless communication system 1 can also support dual connectivity (Multi-RAT Dual Connectivity (MR-DC)) between multiple radio access technologies (Radio Access Technology (RAT)). MR-DC can also include dual connectivity between LTE (Evolved Universal Terrestrial Radio Access (E-UTRA)) and NR (E-UTRA-NR Dual Connectivity (EN-DC)), dual connectivity between NR and LTE (NR-E-UTRA Dual Connectivity (NR-E-UTRA Dual Connectivity (NE-DC)), etc.

[0289] In EN-DC, the LTE (E-UTRA) base station (eNB) is the master node (MN), and the NR base station (gNB) is the secondary node (SN). In NE-DC, the NR base station (gNB) is the MN, and the LTE (E-UTRA) base station (eNB) is the SN.

[0290] The wireless communication system 1 can also support dual connectivity between multiple base stations within the same RAT (for example, dual connectivity (NR-NR Dual Connectivity (NN-DC)) where both MN and SN are NR base stations (gNB)).

[0291] The wireless communication system 1 may also include a base station 11 that forms a macrocell C1 with relatively wide coverage, and base stations 12 (12a-12c) that are deployed within the macrocell C1 and form small cells C2 that are narrower than the macrocell C1. User terminals 20 may also be located within at least one of the cells. The configuration and number of cells and user terminals 20 are not limited to those shown in the figure. Hereinafter, when not distinguishing between base stations 11 and 12, they are collectively referred to as base stations 10.

[0292] The user terminal 20 may be connected to at least one of the multiple base stations 10. The user terminal 20 may utilize at least one of carrier aggregation (CA) using multiple component carriers (CCs) and dual connectivity (DC).

[0293] Each CC may also be included in at least one of the first frequency band (Frequency Range 1 (FR1)) and the second frequency band (Frequency Range 2 (FR2)). The macro cell C1 may also be included in FR1, and the small cell C2 may also be included in FR2. For example, FR1 may be a frequency band below 6 GHz (below 6 GHz (sub-6 GHz)), and FR2 may be a frequency band higher than 24 GHz (above-24 GHz). In addition, the frequency bands and definitions of FR1 and FR2 are not limited to these. For example, FR1 may also be equivalent to a frequency band higher than FR2.

[0294] Furthermore, the user terminal 20 may perform communication using at least one of time division duplex (TDD) and frequency division duplex (FDD) in each CC.

[0295] Multiple base stations 10 can also be connected by wired (for example, optical fiber based on Common Public Radio Interface (CPRI)), X2 interface, etc.) or wireless (for example, NR communication). For example, when NR communication is used as a backhaul between base stations 11 and 12, the base station 11 equivalent to the upper station can also be called an integrated access backhaul (IAB) donor, and the base station 12 equivalent to the relay station (relay) can also be called an IAB node.

[0296] The base station 10 may also be connected to the core network 30 via other base stations 10 or directly. The core network 30 may also include, for example, at least one of an Evolved Packet Core (EPC), a 5G Core Network (5GCN), and a Next Generation Core (NGC).

[0297] The user terminal 20 may also be a terminal that supports at least one of communication methods such as LTE, LTE-A, and 5G.

[0298] In the wireless communication system 1, a radio access scheme based on orthogonal frequency division multiplexing (OFDM) may be used. For example, in at least one of the downlink (DL) and uplink (UL), cyclic prefix OFDM (CP-OFDM), discrete Fourier transform spread OFDM (DFT-s-OFDM), orthogonal frequency division multiple access (OFDMA), or single carrier frequency division multiple access (SC-FDMA) may be used.

[0299] The radio access scheme may also be referred to as a waveform. In addition, in the wireless communication system 1, other radio access schemes (for example, other single-carrier transmission schemes, other multi-carrier transmission schemes) may be used as the UL and DL radio access schemes.

[0300] In each user terminal 20, as a downlink channel, a shared downlink shared channel (Physical Downlink Shared Channel (PDSCH)), a broadcast channel (Physical Broadcast Channel (PBCH)), a downlink control channel (Physical Downlink Control Channel (PDCCH)), etc. can also be used in the wireless communication system 1.

[0301] In addition, in the wireless communication system 1, as uplink channels, an uplink shared channel (Physical Uplink Shared Channel (PUSCH)) shared by each user terminal 20, an uplink control channel (Physical Uplink Control Channel (PUCCH)), a random access channel (Physical Random Access Channel (PRACH)), etc. can also be used.

[0302] User data, higher-layer control information, and system information blocks (SIBs) are transmitted via the PDSCH. User data, higher-layer control information, and the like can also be transmitted via the PUSCH. Furthermore, the Master Information Block (MIB) can also be transmitted via the PBCH.

[0303] Lower layer control information may also be transmitted via the PDCCH. The lower layer control information may include, for example, downlink control information (Downlink Control Information (DCI)) including scheduling information for at least one of the PDSCH and the PUSCH.

[0304] In addition, the DCI that schedules the PDSCH may also be referred to as DL allocation, DL DCI, etc., and the DCI that schedules the PUSCH may also be referred to as UL grant, UL DCI, etc. In addition, the PDSCH may also be replaced by DL data, and the PUSCH may also be replaced by UL data.

[0305] In PDCCH detection, a control resource set (CORESET) and a search space can also be used. A CORESET corresponds to the resources for searching for DCI. A search space corresponds to the search area and search method for PDCCH candidates. A CORESET can also be associated with one or more search spaces. The UE can also monitor the CORESET associated with a search space based on the search space settings.

[0306] A search space may also correspond to PDCCH candidates corresponding to one or more aggregation levels. One or more search spaces may also be referred to as a search space set. In addition, the terms "search space," "search space set," "search space setting," "search space set setting," "CORESET," and "CORESET setting" in this disclosure may be used interchangeably.

[0307] Uplink control information (uplink control information (UCI)) including at least one of channel state information (CSI), delivery confirmation information (e.g., also known as hybrid automatic repeat request confirmation (HARQ-ACK), ACK / NACK, etc.), and scheduling request (SR) can also be transmitted via the PUCCH. The random access preamble used to establish a connection with a cell can also be transmitted via the PRACH.

[0308] In the present disclosure, downlink, uplink, etc. may be expressed without the word "link." Furthermore, various channels may be expressed without the word "physical" at the beginning.

[0309] In the wireless communication system 1, a synchronization signal (Synchronization Signal (SS)), a downlink reference signal (Downlink Reference Signal (DL-RS)), etc. can also be transmitted. As DL-RS, in the wireless communication system 1, a cell-specific reference signal (Cell-specific Reference Signal (CRS)), a channel state information reference signal (Channel State Information Reference Signal (CSI-RS)), a demodulation reference signal (DeModulation Reference Signal (DMRS)), a positioning reference signal (Positioning Reference Signal (PRS)), a phase tracking reference signal (Phase Tracking Reference Signal (PTRS)), etc. can also be transmitted.

[0310] For example, a synchronization signal may be at least one of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). A signal block containing SSs (PSS, SSS) and PBCHs (and DMRS for PBCHs) may also be referred to as an SS / PBCH block or an SS block (SSB). Furthermore, SSs and SSBs may also be referred to as reference signals.

[0311] In addition, in the wireless communication system 1, as an uplink reference signal (Uplink Reference Signal (UL-RS)), a measurement reference signal (Sounding Reference Signal (SRS)), a demodulation reference signal (DMRS), etc. can also be transmitted. In addition, DMRS can also be called a user terminal specific reference signal (UE-specific Reference Signal).

[0312] (Base Station)

[0313] Figure 16 This figure shows an example of the configuration of a base station according to one embodiment. The base station 10 includes a control unit 110, a transmitting / receiving unit 120, a transmitting / receiving antenna 130, and a transmission path interface (transmission line interface) 140. Furthermore, more than one of each of the control unit 110, the transmitting / receiving unit 120, the transmitting / receiving antenna 130, and the transmission path interface 140 may be provided.

[0314] In addition, in this example, the functional blocks of the characteristic parts of this embodiment are mainly shown, and it is also assumed that the base station 10 also has other functional blocks required for wireless communication. Part of the processing of each unit described below may also be omitted.

[0315] The control unit 110 controls the entire base station 10. The control unit 110 can be composed of a controller, a control circuit, and the like that are described based on common knowledge in the technical field to which this disclosure relates.

[0316] The control unit 110 may also control signal generation, scheduling (e.g., resource allocation, mapping), etc. It may also control transmission and reception, measurement, etc., using the transmission and reception unit 120, the transmission and reception antennas 130, and the transmission path interface 140. The control unit 110 may also generate data, control information, sequences, etc. to be transmitted as signals, and forward them to the transmission and reception unit 120. The control unit 110 may also perform call processing (setting up, releasing, etc.) of communication channels, manage the status of the base station 10, manage radio resources, etc.

[0317] The transceiver unit 120 may also include a baseband unit 121, a radio frequency (RF) unit 122, and a measurement unit 123. The baseband unit 121 may also include a transmission processing unit 1211 and a reception processing unit 1212. The transceiver unit 120 may include a transmitter / receiver, an RF circuit, a baseband circuit, a filter, a phase shifter (phase shifter), a measurement circuit, a transceiver circuit, and the like, which are described based on common knowledge in the technical fields involved in this disclosure.

[0318] The transmitting and receiving unit 120 may be configured as an integrated transmitting and receiving unit or may be configured as a transmitting unit and a receiving unit. The transmitting unit may also be configured as a transmitting processing unit 1211 and an RF unit 122. The receiving unit may also be configured as a receiving processing unit 1212, an RF unit 122, and a measuring unit 123.

[0319] The transmitting and receiving antenna 130 can be formed of an antenna described based on common knowledge in the technical field to which this disclosure relates, such as an array antenna.

[0320] The transmitting and receiving unit 120 may also transmit the aforementioned downlink channel, synchronization signal, downlink reference signal, etc. The transmitting and receiving unit 120 may also receive the aforementioned uplink channel, uplink reference signal, etc.

[0321] The transmitting and receiving unit 120 may also use digital beamforming (eg, precoding), analog beamforming (eg, phase rotation), etc. to form at least one of a transmit beam and a receive beam.

[0322] The sending and receiving unit 120 (sending processing unit 1211) can also perform processing on the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (RLC) layer (for example, RLC retransmission control), the Medium Access Control (MAC) layer (for example, HARQ retransmission control), etc. on the data and control information obtained from the control unit 110 to generate a bit string to be sent.

[0323] The transmitting and receiving unit 120 (transmitting processing unit 1211) can also perform channel coding (which may also include error correction coding), modulation, mapping, filter processing (filtering processing), discrete Fourier transform (DFT) processing (as needed), inverse fast Fourier transform (IFFT) processing), precoding, digital-to-analog conversion and other transmission processing on the bit string to be sent, and output a baseband signal.

[0324] The transmitting and receiving unit 120 (RF unit 122 ) may also perform modulation, filter processing, amplification, etc. on the baseband signal to a radio frequency band, and transmit the signal in the radio frequency band via the transmitting and receiving antenna 130 .

[0325] On the other hand, the transmitting and receiving unit 120 (RF unit 122 ) may also perform amplification, filter processing, and demodulation into a baseband signal on the radio frequency band signal received by the transmitting and receiving antenna 130 .

[0326] The transmitting and receiving unit 120 (receiving processing unit 1212) can also apply receiving processing such as analog-to-digital conversion, fast Fourier transform (FFT) processing, inverse discrete Fourier transform (IDFT) processing (as needed), filter processing, demapping, demodulation, decoding (which may also include error correction decoding), MAC layer processing, RLC layer processing, and PDCP layer processing to the obtained baseband signal to obtain user data, etc.

[0327] The transmitting and receiving unit 120 (measuring unit 123) may also perform measurements related to the received signal. For example, the measuring unit 123 may also perform radio resource management (RRM) measurements, channel state information (CSI) measurements, etc. based on the received signal. The measuring unit 123 may also measure received power (e.g., Reference Signal Received Power (RSRP)), received quality (e.g., Reference Signal Received Quality (RSRQ)), signal to interference plus noise ratio (SINR), signal to noise ratio (SNR)), signal strength (e.g., received signal strength indicator (RSSI)), propagation path information (e.g., CSI), etc. The measurement results may also be output to the control unit 110.

[0328] The transmission path interface 140 can also send and receive signals (return signaling) between the devices included in the core network 30, other base stations 10, etc., and can also obtain and transmit user data (user plane data) and control plane data for the user terminal 20.

[0329] In addition, the transmitting unit and the receiving unit of the base station 10 in the present disclosure may also be composed of at least one of the transmitting and receiving unit 120 , the transmitting and receiving antenna 130 , and the transmission path interface 140 .

[0330] The transmission and reception unit 120 may also transmit the initial transmission of the multicast downlink (DL) data. The control unit 110 may also control the retransmission of the multicast DL data based on the decoding result of the DL data (second embodiment).

[0331] The transmitting and receiving unit 120 may also transmit an initial transmission of downlink (DL) data that is scheduled and multicast based on the first downlink control information (DCI). The control unit 110 may also control retransmission of the DL data that is scheduled and unicast based on the second DCI based on the decoding result of the initial transmission (third embodiment).

[0332] The transmitting and receiving unit 120 may also transmit downlink (DL) data that is scheduled by a single downlink control information (DCI) and multicasted in multiple opportunities. The control unit 110 may also control the reception of Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK) information for the DL data based on the DCI (fifth embodiment).

[0333] (User Terminal)

[0334] Figure 17 This figure shows an example of the configuration of a user terminal according to one embodiment. The user terminal 20 includes a control unit 210, a transmitting / receiving unit 220, and a transmitting / receiving antenna 230. Furthermore, the control unit 210, the transmitting / receiving unit 220, and the transmitting / receiving antenna 230 may each be provided in one or more units.

[0335] In addition, in this example, the functional blocks of the characteristic parts of this embodiment are mainly shown, and it is also assumed that the user terminal 20 also has other functional blocks required for wireless communication. Part of the processing of each unit described below may also be omitted.

[0336] The control unit 210 controls the entire user terminal 20. The control unit 210 can be composed of a controller, a control circuit, and the like that are described based on common knowledge in the technical field to which this disclosure relates.

[0337] The control unit 210 may also control signal generation, mapping, etc. The control unit 210 may also control transmission, reception, measurement, etc. using the transmission and reception unit 220 and the transmission and reception antenna 230. The control unit 210 may also generate data, control information, sequences, etc. to be transmitted as signals and forward them to the transmission and reception unit 220.

[0338] The transceiver unit 220 may also include a baseband unit 221, an RF unit 222, and a measurement unit 223. The baseband unit 221 may also include a transmission processing unit 2211 and a reception processing unit 2212. The transceiver unit 220 may include a transmitter / receiver, an RF circuit, a baseband circuit, a filter, a phase shifter, a measurement circuit, a transceiver circuit, and the like, which are described based on common knowledge in the technical fields involved in this disclosure.

[0339] The transmitting and receiving unit 220 may be configured as an integrated transmitting and receiving unit or may be composed of a transmitting unit and a receiving unit. The transmitting unit may also be composed of a transmitting processing unit 2211 and an RF unit 222. The receiving unit may also be composed of a receiving processing unit 2212, an RF unit 222, and a measuring unit 223.

[0340] The transmitting and receiving antenna 230 can be formed of an antenna described based on common knowledge in the technical field involved in the present disclosure, such as an array antenna.

[0341] The transmitting and receiving unit 220 may also receive the aforementioned downlink channel, synchronization signal, downlink reference signal, etc. The transmitting and receiving unit 220 may also transmit the aforementioned uplink channel, uplink reference signal, etc.

[0342] The transmitting and receiving unit 220 may also use digital beamforming (eg, precoding), analog beamforming (eg, phase rotation), etc. to form at least one of a transmitting beam and a receiving beam.

[0343] The sending and receiving unit 220 (sending processing unit 2211) can also perform PDCP layer processing, RLC layer processing (for example, RLC retransmission control), MAC layer processing (for example, HARQ retransmission control), etc. on the data, control information, etc. obtained from the control unit 210 to generate a bit string to be sent.

[0344] The transmitting and receiving unit 220 (transmitting processing unit 2211) can also perform channel coding (which may also include error correction coding), modulation, mapping, filter processing, DFT processing (as needed), IFFT processing, precoding, digital-to-analog conversion and other transmission processing on the bit string to be sent, and output a baseband signal.

[0345] In addition, whether or not to apply DFT processing may also be based on the transform precoding setting. For a certain channel (e.g., PUSCH), if transform precoding is valid (enabled), the transmitting / receiving unit 220 (transmitting processing unit 2211) may perform DFT processing as the aforementioned transmission processing in order to transmit the channel using a DFT-s-OFDM waveform. Otherwise, the transmitting / receiving unit 220 (transmitting processing unit 2211) may perform DFT processing as the aforementioned transmission processing without performing DFT processing.

[0346] The transmitting and receiving unit 220 (RF unit 222 ) may also perform modulation, filter processing, amplification, etc. on the baseband signal to a radio frequency band, and transmit the signal in the radio frequency band via the transmitting and receiving antenna 230 .

[0347] On the other hand, the transmitting and receiving unit 220 (RF unit 222 ) may also perform amplification, filter processing, and demodulation into a baseband signal on the radio frequency band signal received by the transmitting and receiving antenna 230 .

[0348] The transmitting and receiving unit 220 (receiving processing unit 2212) can also apply receiving processing such as analog-to-digital conversion, FFT processing, IDFT processing (as needed), filter processing, demapping, demodulation, decoding (which may also include error correction decoding), MAC layer processing, RLC layer processing, and PDCP layer processing to the obtained baseband signal to obtain user data, etc.

[0349] The transmitting and receiving unit 220 (measuring unit 223) may also perform measurements related to received signals. For example, the measuring unit 223 may also perform RRM measurements, CSI measurements, etc. based on the received signals. The measuring unit 223 may also measure received power (e.g., RSRP), received quality (e.g., RSRQ, SINR, SNR), signal strength (e.g., RSSI), propagation path information (e.g., CSI), etc. The measurement results may also be output to the control unit 210.

[0350] In addition, the transmitting unit and the receiving unit of the user terminal 20 in the present disclosure may also be composed of at least one of the transmitting and receiving unit 220 and the transmitting and receiving antenna 230 .

[0351] The transmission and reception unit 220 may also transmit the initial transmission of the multicast downlink (DL) data. The control unit 210 may also receive the retransmission of the multicast DL data based on the decoding result of the DL data (second embodiment).

[0352] When the decoding of the DL data is successful, the control unit 210 may control not to transmit Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK) information for the initial transmission (second embodiment).

[0353] When the decoding of the DL data is successful, the control unit 210 may control the transmission of Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK) information indicating a positive response to the initial transmission (second embodiment).

[0354] The transmitting and receiving unit 220 may also receive downlink control information including information related to resources carrying the initially transmitted downlink shared channel (PDSCH) and information related to resources carrying the retransmitted PDSCH (second embodiment).

[0355] The transmitting and receiving unit 220 may also receive an initial transmission of downlink (DL) data that is scheduled and multicast based on first downlink control information (DCI). The control unit 210 may also control the reception of a retransmission of the DL data that is scheduled and unicast based on a second DCI based on the decoding result of the initial transmission (third embodiment).

[0356] The transmitting and receiving unit 220 may receive the second DCI after a specific time from the reception timing of the initial transmission (fourth embodiment).

[0357] The control unit 210 may also control blind detection of the second DCI based on the reception timing of the second DCI (fourth embodiment).

[0358] The transmitting and receiving unit 220 may also receive downlink (DL) data that is scheduled by a single downlink control information (DCI) and multicast in multiple opportunities. The control unit 210 may also control the transmission of Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK) information for the DL data based on the DCI (fifth embodiment).

[0359] The control unit 210 may also perform control so as not to transmit the HARQ-ACK information (fifth embodiment).

[0360] In the case where the reception processing of the DL data is successful in at least one of the multiple opportunities, the control unit 210 may also transmit HARQ-ACK information indicating a positive response to the DL data (fifth embodiment).

[0361] When the reception processing of the DL data in at least one of the multiple opportunities is successful, the control unit 210 may also control to use the HARQ-ACK resources corresponding to the initial opportunity among the at least one opportunity to send HARQ-ACK information for the DL data (fifth embodiment).

[0362] (Hardware Structure)

[0363] In addition, the block diagrams used in the description of the above embodiments show blocks of functional units. These functional blocks (structural units) are implemented by any combination of at least one of hardware and software. In addition, the implementation method of each functional block is not particularly limited. That is, each functional block can be implemented by a device that is physically or logically combined, or two or more physically or logically separated devices can be directly or indirectly (for example, by wired, wireless, etc.) connected and implemented by these multiple devices. The functional block can also be implemented by combining the above-mentioned one device or the above-mentioned multiple devices with software.

[0364] Here, the functions include judging, deciding, determining, calculating, calculating, processing, deriving, investigating, searching, confirming, receiving, sending, outputting, accessing, resolving, selecting, selecting, establishing, comparing, assuming, expecting, regarding, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, assigning, etc., but are not limited to these. For example, a functional block (structural unit) that implements a sending function may also be referred to as a transmitting unit, a transmitter, etc. Any of them are as described above, and the implementation method is not particularly limited.

[0365] For example, a base station, a user terminal, etc. in one embodiment of the present disclosure may also function as a computer that performs processing of the wireless communication method of the present disclosure. Figure 18 This figure shows an example of the hardware configuration of a base station and a user terminal according to one embodiment. The base station 10 and user terminal 20 described above can also be physically configured as a computer device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, and the like.

[0366] In addition, in this disclosure, the terms such as device, circuit, equipment, section, and unit are interchangeable. The hardware structure of the base station 10 and the user terminal 20 may include one or more of the devices shown in the figure, or may not include some of the devices.

[0367] For example, although only one processor 1001 is shown, multiple processors may be provided. Furthermore, processing may be performed by a single processor, or by two or more processors simultaneously, sequentially, or using other methods. Furthermore, processor 1001 may be implemented using more than one chip.

[0368] Regarding the various functions in the base station 10 and the user terminal 20, for example, they are achieved by reading specific software (program) into hardware such as the processor 1001 and the memory 1002, so that the processor 1001 performs calculations and controls communication via the communication device 1004, or controls at least one of the reading and writing of data in the memory 1002 and the storage 1003.

[0369] The processor 1001 controls the entire computer by, for example, operating an operating system. The processor 1001 may also be composed of a central processing unit (CPU) including an interface with peripheral devices, a control device, a computing device, registers, etc. For example, at least a portion of the control unit 110 (210) and the transmitting and receiving unit 120 (220) described above may also be implemented by the processor 1001.

[0370] In addition, the processor 1001 reads a program (program code), a software module, data, etc. from at least one of the storage 1003 and the communication device 1004 into the memory 1002 and performs various processes based on them. As a program, a program that causes a computer to perform at least a portion of the operations described in the above embodiments can be used. For example, the control unit 110 (210) can also be implemented by a control program stored in the memory 1002 and operated by the processor 1001, and the other functional blocks can also be implemented similarly.

[0371] The memory 1002 may also be a computer-readable recording medium, for example, comprised of at least one of a read-only memory (ROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a random access memory (RAM), or other suitable storage medium. The memory 1002 may also be referred to as a register, a cache, a main memory (main storage device), etc. The memory 1002 may store executable programs (program code), software modules, etc., for implementing the wireless communication method according to an embodiment of the present disclosure.

[0372] The storage 1003 may also be a computer-readable recording medium, such as a flexible disk, a floppy disk, an optical disk (such as a compact disk (Compact Disc ROM (CD-ROM)), etc.), a digital versatile disk, a Blu-ray disk), a removable disk, a hard disk drive, a smart card, a flash memory device (such as a card, a stick, or a key drive), a magnetic stripe, a database, a server, or other suitable storage media. The storage 1003 may also be referred to as an auxiliary storage device.

[0373] The communication device 1004 is hardware (a transmitting and receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as a network device, a network controller, a network card, a communication module, or the like. To implement at least one of frequency division duplex (FDD) and time division duplex (TDD), the communication device 1004 may also include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, and the like. For example, the aforementioned transmitting and receiving unit 120 (220), transmitting and receiving antenna 130 (230), and the like may also be implemented by the communication device 1004. The transmitting and receiving unit 120 (220) may also be implemented by physically or logically separating the transmitting unit 120a (220a) and the receiving unit 120b (220b).

[0374] The input device 1005 is an input device that receives input from the outside (e.g., a keyboard, mouse, microphone, switch, button, sensor, etc.). The output device 1006 is an output device that outputs to the outside (e.g., a display, speaker, light emitting diode (LED) lamp, etc.). Alternatively, the input device 1005 and the output device 1006 may be integrated (e.g., a touch panel).

[0375] Furthermore, the processor 1001, memory 1002, and other devices are connected via a bus 1007 for communicating information. The bus 1007 may be configured as a single bus or may be configured as different buses between the devices.

[0376] Furthermore, the base station 10 and the user terminal 20 may also be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and may use such hardware to implement part or all of each functional block. For example, the processor 1001 may also be implemented using at least one of these hardware components.

[0377] (Variation)

[0378] In addition, the terms described in this disclosure and the terms required for understanding this disclosure may also be replaced with terms having the same or similar meanings. For example, channel, symbol, and signal (signal or signaling) may be replaced with each other. In addition, a signal may also be a message. A reference signal may also be referred to as RS, or may be referred to as a pilot, pilot signal, etc. depending on the applied standard. In addition, a component carrier (CC) may also be referred to as a cell, frequency carrier, carrier frequency, etc.

[0379] A radio frame can also be composed of one or more periods (frames) in the time domain. Each period (frame) of the one or more periods (frames) that constitute a radio frame can also be called a subframe. Furthermore, a subframe can also be composed of one or more time slots in the time domain. A subframe can also be a fixed time length (e.g., 1 ms) that is independent of the parameter set (numerology).

[0380] Here, a parameter set may also refer to communication parameters applied to at least one of the transmission and reception of a signal or channel. For example, a parameter set may also represent at least one of subcarrier spacing (SCS), bandwidth, symbol length, cyclic prefix length, transmission time interval (TTI), the number of symbols per TTI, radio frame structure, specific filtering processing performed by the transmitter and receiver in the frequency domain, specific windowing processing performed by the transmitter and receiver in the time domain, and the like.

[0381] A time slot may also be composed of one or more symbols (Orthogonal Frequency Division Multiplexing (OFDM) symbols, Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols, etc.) in the time domain. In addition, a time slot may also be a time unit based on a parameter set.

[0382] A time slot may also contain multiple mini-slots. Each mini-slot may also be composed of one or more symbols in the time domain. Furthermore, a mini-slot may also be referred to as a sub-slot. A mini-slot may also be composed of fewer symbols than a time slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a mini-slot may also be referred to as PDSCH (PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a mini-slot may also be referred to as PDSCH (PUSCH) mapping type B.

[0383] Radio frames, subframes, time slots, mini-time slots, and symbols all represent time units used for signal transmission. Radio frames, subframes, time slots, mini-time slots, and symbols may also be referred to by their respective equivalents. Furthermore, the terms frame, subframe, time slot, mini-time slot, and symbol may be used interchangeably in this disclosure.

[0384] For example, a subframe can be called a TTI, multiple consecutive subframes can be called a TTI, and a slot or a mini-slot can be called a TTI. That is, at least one of a subframe and a TTI can be a subframe (1ms) in existing LTE, a period shorter than 1ms (e.g., 1-13 symbols), or a period longer than 1ms. Furthermore, the unit representing a TTI can be called a slot, a mini-slot, or the like, rather than a subframe.

[0385] Here, TTI refers to, for example, the minimum time unit for scheduling in wireless communications. For example, in the LTE system, a base station schedules each user terminal by allocating radio resources (such as the frequency bandwidth and transmit power available to each user terminal) in TTI units. The definition of TTI is not limited to this.

[0386] The TTI may also be a unit of time for transmitting channel-coded data packets (transport blocks), code blocks, code words, etc., and may also be a unit of processing for scheduling, link adaptation, etc. Furthermore, when a TTI is given, the time interval (e.g., the number of symbols) to which the transport blocks, code blocks, code words, etc. are actually mapped may be shorter than the TTI.

[0387] In addition, when a time slot or a mini-time slot is called a TTI, one or more TTIs (i.e., one or more time slots or one or more mini-time slots) can also be the minimum time unit of scheduling. In addition, the number of time slots (mini-time slots) that constitute the minimum time unit of scheduling can also be controlled.

[0388] A TTI having a time length of 1 ms may also be referred to as a normal TTI (TTI in 3GPP Rel. 8-12), a standard TTI, a long TTI, a normal subframe, a standard subframe, a long subframe, a time slot, etc. A TTI shorter than a normal TTI may also be referred to as a shortened TTI, a short TTI, a partial TTI (partial or fractional TTI), a shortened subframe, a short subframe, a mini-slot, a subslot, a time slot, etc.

[0389] In addition, long TTI (for example, normal TTI, subframe, etc.) can also be replaced by TTI with a time length exceeding 1ms, and short TTI (for example, shortened TTI, etc.) can also be replaced by TTI with a TTI length smaller than long TTI and greater than 1ms.

[0390] A resource block (RB) is a unit of resource allocation in the time and frequency domains. In the frequency domain, it may also include one or more consecutive subcarriers (subcarriers). The number of subcarriers included in an RB may be the same regardless of the parameter set, for example, it may be 12. The number of subcarriers included in an RB may also be determined based on the parameter set.

[0391] In addition, an RB may also include one or more symbols in the time domain, and may also be the length of a slot, a mini-slot, a subframe, or a TTI. A TTI, a subframe, etc. may also be composed of one or more resource blocks.

[0392] In addition, one or more RBs may also be referred to as a physical resource block (Physical RB (PRB)), a sub-carrier group (Sub-Carrier Group (SCG)), a resource element group (Resource Element Group (REG)), a PRB pair, an RB pair, etc.

[0393] Furthermore, a resource block may be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.

[0394] A Bandwidth Part (BWP) (also referred to as a fractional bandwidth) can also represent a subset of contiguous common resource blocks (RBs) used for a particular parameter set within a particular carrier. Common RBs can also be identified by their index relative to the common reference point of the carrier. PRBs can also be defined within a BWP and numbered within that BWP.

[0395] The BWP may include a UL BWP (BWP for UL) and a DL BWP (BWP for DL). For a UE, one or more BWPs may be configured within one carrier.

[0396] At least one of the configured BWPs may be activated, and the UE may not assume that it will transmit or receive specific signals / channels outside of the activated BWP. In addition, the terms "cell," "carrier," and the like in this disclosure may be replaced with "BWP."

[0397] The above-mentioned structures of radio frames, subframes, slots, mini-slots, and symbols are merely examples. For example, various modifications may be made to the number of subframes in a radio frame, the number of slots per subframe or radio frame, the number of mini-slots within a slot, the number of symbols and RBs within a slot or mini-slot, the number of subcarriers within an RB, the number of symbols within a TTI, the symbol length, and the cyclic prefix (CP) length.

[0398] Furthermore, the information and parameters described in this disclosure may be expressed as absolute values, relative values ​​relative to a specific value, or other corresponding information. For example, wireless resources may be indicated by specific indexes.

[0399] The names used for parameters, etc. in this disclosure are not intended to be limiting in any respect. Furthermore, the mathematical formulas for these parameters may differ from those explicitly disclosed in this disclosure. Various channels (PUCCH, PDCCH, etc.) and information elements can be identified by any suitable names, and therefore, the various names assigned to these various channels and information elements are not intended to be limiting in any respect.

[0400] Information, signals, and the like described in this disclosure may also be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, and the like that may be referred to throughout the foregoing description may also be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, light fields or photons, or any combination thereof.

[0401] Furthermore, information, signals, etc. can be output in at least one of the following directions: from a higher layer (upper layer) to a lower layer (lower layer), and from a lower layer to a higher layer. Information, signals, etc. can also be input and output via multiple network nodes.

[0402] Input and output information, signals, etc. may be stored in a specific location (e.g., memory) or managed using a management table. Input and output information, signals, etc. may be overwritten, updated, or appended. Output information, signals, etc. may also be deleted. Input information, signals, etc. may also be sent to other devices.

[0403] The notification of information is not limited to the methods / implementations described in the present disclosure, and may also be performed by other methods. For example, the notification of information in the present disclosure may also be implemented through physical layer signaling (e.g., downlink control information (Downlink Control Information (DCI))), uplink control information (Uplink Control Information (UCI))), high-layer signaling (e.g., Radio Resource Control (RRC)) signaling, broadcast information (Master Information Block (MIB)), System Information Block (SIB), etc.), Medium Access Control (MAC) signaling), other signals, or a combination thereof.

[0404] In addition, physical layer signaling may also be referred to as Layer 1 / Layer 2 (L1 / L2) control information (L1 / L2 control signal), L1 control information (L1 control signal), etc. In addition, RRC signaling may also be referred to as RRC message, for example, RRC Connection Setup message, RRC Connection Reconfiguration message, etc. In addition, MAC signaling may also be notified using MAC Control Element (CE), for example.

[0405] Furthermore, notification of specific information (eg, notification of “it is X”) is not limited to explicit notification, but may be performed implicitly (eg, by not notifying the specific information or by notifying other information).

[0406] The determination can be made by a value represented by a bit (0 or 1), a true or false value (Boolean value) represented by true (true) or false (false), or by comparing numerical values ​​(for example, comparing with a specific value).

[0407] The term “software” or “firmware” shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, sub-programs, software modules, applications, software applications, software packages, routines, sub-routines, objects, executable files, execution threads, procedures, functions, or the like.

[0408] Furthermore, software, instructions, information, and the like may also be transmitted and received via a transmission medium. For example, if the software is transmitted from a website, server, or other remote source using at least one of a wired technology (coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), etc.) and a wireless technology (infrared, microwave, etc.), at least one of these wired and wireless technologies is included within the definition of a transmission medium.

[0409] The terms "system" and "network" used in this disclosure can be used interchangeably. "Network" may also refer to devices included in the network (eg, base stations).

[0410] In the present disclosure, terms such as "precoding", "precoder", "weight (precoding weight)", "Quasi-Co-Location (QCL)" "Transmission Configuration Indication state (TCI state)", "spatial relation", "spatial domain filter", "transmission power", "phase rotation", "antenna port", "antenna port group", "layer", "number of layers", "rank", "resource", "resource set", "resource group", "beam", "beam width", "beam angle", "antenna", "antenna element", and "panel" can be used interchangeably.

[0411] In this disclosure, terms such as "base station (BS)", "wireless base station", "fixed station", "NodeB", "eNB (eNodeB)", "gNB (gNodeB)", "access point", "transmission point (TP)", "reception point (RP)", "transmission / reception point (TRP))", "panel", "cell", "sector", "cell group", "carrier", and "component carrier" are used interchangeably. In some cases, a base station may be referred to as a macro cell, small cell, femto cell, or pico cell.

[0412] A base station can accommodate one or more (for example, three) cells. When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be divided into multiple smaller areas, each of which can also provide communication services through a base station subsystem (for example, a small base station for indoor use (Remote Radio Head (RRH))). Terms such as "cell" or "sector" refer to a part or the entire coverage area of ​​at least one of a base station and a base station subsystem that provides communication services within that coverage area.

[0413] In the present disclosure, terms such as “mobile station (MS)”, “user terminal”, “user device (UE)”, and “terminal” can be used interchangeably.

[0414] The mobile station may also be referred to as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, hand set, user agent, mobile client, client, or several other appropriate terms.

[0415] At least one of the base station and the mobile station may also be referred to as a transmitting device, a receiving device, a wireless communication device, etc. Furthermore, at least one of the base station and the mobile station may also be a device mounted on a mobile object, a mobile object itself, etc. The mobile object may be a means of transportation (e.g., a vehicle, an airplane, etc.), a mobile object that moves unmanned (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). Furthermore, at least one of the base station and the mobile station also includes a device that does not necessarily move when performing communication operations. For example, at least one of the base station and the mobile station may also be an Internet of Things (IoT) device such as a sensor.

[0416] In addition, the base station in the present disclosure may also be replaced by a user terminal. For example, the various methods / implementations of the present disclosure may also be applied to a structure in which the communication between a base station and a user terminal is replaced by communication between multiple user terminals (for example, which may also be referred to as device-to-device (D2D)), vehicle-to-everything (V2X), etc.). In this case, it may also be configured such that the user terminal 20 has the functions of the above-mentioned base station 10. In addition, terms such as "uplink" and "downlink" may also be replaced by terms corresponding to inter-terminal communication (for example, "side"). For example, uplink channels, downlink channels, etc. may also be replaced by side channels.

[0417] Likewise, the user terminal in the present disclosure may be replaced by a base station. In this case, the base station 10 may have the functions of the user terminal 20 described above.

[0418] In the present disclosure, actions are assumed to be performed by a base station, and sometimes, depending on the circumstances, by its upper node. Obviously, in a network including one or more network nodes including a base station, various operations performed for communication with a terminal may be performed by the base station, one or more network nodes other than the base station (for example, a Mobility Management Entity (MME)), a Serving-Gateway (S-GW), etc., but not limited to these), or a combination thereof.

[0419] The various methods / implementations described in this disclosure may be used individually or in combination, and may be switched between them during execution. Furthermore, the processing procedures, sequences, flow charts, and the like of the various methods / implementations described in this disclosure may be reversed as long as they do not conflict. For example, the elements of various steps described in this disclosure are presented in an illustrative order, but are not limited to the specific order presented.

[0420] The various modes and embodiments described in the present disclosure may also be applied to Long Term Evolution (LTE), LTE-Advanced (LTE-A), LTE-Beyond (LTE-B), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (xG (x is, for example, an integer or a decimal)), Future Radio Access (FRA), New Radio Access Technology (RAT), New Radio (NR), New Radio Access (NX), Future Generation Radio Access (FX), Global System for Mobile Communications (GSM (registered trademark)), CDMA2000, Ultra Mobile Broadband (UMB), IEEE IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-WideBand (UWB)), Bluetooth (registered trademark), systems using other appropriate wireless communication methods, and next-generation systems based on these. In addition, multiple systems can also be combined for application (for example, LTE or LTE-A, combined with 5G, etc.).

[0421] The phrase “based on” used in this disclosure does not mean “based only on” unless otherwise specified. In other words, the phrase “based on” means both “based only on” and “based at least on.”

[0422] Any reference to an element using the designations "first," "second," etc., as used in this disclosure, does not necessarily define the quantity or order of these elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Therefore, reference to a first and a second element does not imply that only two elements may be used or that the first element must in some way take precedence over the second element.

[0423] The term "determining" as used in this disclosure may encompass a variety of actions. For example, "determining" may also include judging, calculating, computing, processing, deriving, investigating, looking up (e.g., searching in a table, database, or other data structure), ascertaining, etc. as performing a "determination."

[0424] In addition, "judgment (decision)" can also be a situation where receiving (for example, receiving information), transmitting (for example, sending information), input (input), output (output), accessing (for example, accessing data in a memory), etc. are regarded as making a "judgment (decision)".

[0425] Furthermore, "judgment (decision)" can also refer to situations where resolving, selecting, choosing, establishing, comparing, etc. can be considered as "judgment (decision)". In other words, "judgment (decision)" can also refer to situations where certain actions can be considered as "judgment (decision)".

[0426] In addition, “judgment (decision)” can also be replaced by “assuming (assuming)”, “expecting (expecting)”, “considering (considering)” and so on.

[0427] As used in this disclosure, the terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between the two elements being "connected" or "coupled." The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be replaced by "access."

[0428] In the present disclosure, when two elements are connected, it is possible to consider using one or more wires, cables, printed electrical connections, etc., as well as using electromagnetic energy with wavelengths in the wireless frequency domain, microwave region, light (both visible and invisible) region, etc. as several non-limiting and non-inclusive examples to be "connected" or "combined" with each other.

[0429] In the present disclosure, the term "A is different from B" may also mean "A and B are different from each other." Alternatively, the term may also mean "A and B are each different from C." Terms such as "separate" and "bound" may also be interpreted in the same way as "different."

[0430] When used in this disclosure, "include," "including," and variations thereof have the same inclusive meaning as the term "comprising." Furthermore, the term "or" used in this disclosure does not mean an exclusive or.

[0431] In the present disclosure, when an article is added by translation, such as a, an, and the in English, the present disclosure may also include a case where the noun following the article is in a plural form.

[0432] While the inventions disclosed herein have been described in detail above, it will be apparent to those skilled in the art that the inventions disclosed herein are not limited to the embodiments described herein. The inventions disclosed herein can be implemented in modified and altered forms without departing from the spirit and scope of the invention as defined by the claims. Therefore, the descriptions in this disclosure are for illustrative purposes only and are not intended to limit the inventions disclosed herein in any way.

Claims

1. A terminal comprising: a receiving unit for receiving an initial transmission of a physical downlink shared channel (PDSCH) scheduled using first downlink control information (DCI); and a control unit that controls reception of the second DCI based on a decoding result of the initial transmission of the PDSCH and a timing at which the second DCI scheduling the retransmission of the PDSCH is detected, The control unit receives the second DCI when decoding of the initial transmission of the PDSCH fails and the timing at which the second DCI is detected is after a specific timing, The control unit receives a retransmission of the PDSCH when receiving the second DCI, The initial transmission of the PDSCH is multicast, and the retransmission of the PDSCH is unicast.

2. The terminal according to claim 1, wherein: Respective DCI formats applied to the first DCI and the second DCI are different DCI formats.

3. The terminal according to claim 1, wherein: The control unit controls not to transmit Hybrid Automatic Repeat reQuest Acknowledgement (HARQ-ACK) information indicating a positive response to the initial transmission of the PDSCH when decoding of the PDSCH is successful. The terminal according to claim 1 , wherein: The control unit controls to transmit Hybrid Automatic Repeat reQuest Acknowledgement (HARQ-ACK) information indicating a positive response to the initial transmission of the PDSCH when decoding of the PDSCH is successful. The terminal according to claim 1 , wherein: Radio Network Temporary Identifiers (RNTIs) used in the first DCI and the second DCI are different RNTIs.

6. A wireless communication method, which is a wireless communication method of a terminal, receiving an initial transmission of a physical downlink shared channel (PDSCH) scheduled using first downlink control information (DCI); a step of controlling reception of the second DCI based on a decoding result of the initial transmission of the PDSCH and a timing at which the second DCI scheduling retransmission of the PDSCH is detected; The terminal receives the second DCI when decoding of the initial transmission of the PDSCH fails and the timing at which the second DCI is detected is after a specific timing; and In the case of receiving the second DCI, a step of receiving a retransmission of the PDSCH, The initial transmission of the PDSCH is multicast, and the retransmission of the PDSCH is unicast.

7. A system comprising a terminal and a base station, The terminal has: a receiving unit for receiving an initial transmission of a physical downlink shared channel (PDSCH) scheduled using first downlink control information (DCI); and a control unit that controls reception of the second DCI based on a decoding result of the initial transmission of the PDSCH and a timing at which the second DCI scheduling the retransmission of the PDSCH is detected, The control unit receives the second DCI when decoding of the initial transmission of the PDSCH fails and the timing at which the second DCI is detected is after a specific timing, The control unit receives a retransmission of the PDSCH when receiving the second DCI, The base station has: a transmitting unit, configured to transmit the initial transmission of the PDSCH; and a control unit that controls the retransmission of the PDSCH based on a decoding result of the initial transmission of the PDSCH, The initial transmission of the PDSCH is multicast, and the retransmission of the PDSCH is unicast.

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