Terminal and radio communication method

A terminal according to one aspect of the present disclosure includes a receiving section that receives a Physical Downlink Control Channel (PDCCH) configuration with a maximum number of control resource sets (CORESETs) exceeding 3, and a control section that assumes that a transmission configuration indication state (TCI state) for a PDCCH with respect to the CORESETs is designated on the basis of a Medium Access Control Control Element (MAC CE). According to one aspect of the present disclosure, it is possible to perform DL communication preferably even when multiple panels/TRPs are used.

CROSS-REFERENCE TO RELATED APPLICATION

This is a U.S. National Stage application of International Application No. PCT/JP2019/032070 filed Aug. 15, 2019. The contents of this application are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to a terminal and a radio communication method in next-generation mobile communication systems.

BACKGROUND ART

Successor systems of LTE (e.g., referred to as “5th generation mobile communication system (5G),” “5G+ (plus),” “New Radio (NR),” “3GPP Rel. 15 (or later versions),” and so on) are also under study.

CITATION LIST

SUMMARY OF INVENTION

Technical Problem

For NR, a user terminal (User Equipment (UE)) receives a downlink control channel (Physical Downlink Control Channel (PDCCH)) on the basis of a transmission configuration indication state (TCI state).

For NR, one or a plurality of transmission/reception points (TRPs) (multiple TRPs) that perform DL transmission (e.g., PDCCH transmission) to the UE by using one or a plurality of panels (multiple panels) is under study. For multi-PDCCH-based multi-TRP transmission, a maximum number of control resource sets (CORESETs) for each PDCCH configuration being greater than 3 is also under study.

However, in NR specifications thus far, multiple panels/TRPs are not considered, and thus there is a case where a TCI state for each PDCCH cannot be appropriately designated in a case where multiple PDCCHs are used. Accordingly, following existing NR specifications cannot preferably achieve spatial diversity gain, high rank transmission, and the like in a case where the multiple panels/TRPs are used, and thus an increase in communication throughput may be suppressed.

Thus, an object of the present disclosure is to provide a terminal and a radio communication method that can perform DL communication preferably even when multiple panels/TRPs are used.

Solution to Problem

A terminal according to one aspect of the present disclosure includes a receiving section that receives a Physical Downlink Control Channel (PDCCH) configuration with a maximum number of control resource sets (CORESETs) exceeding 3, and a control section that assumes that a transmission configuration indication state (TCI state) for a PDCCH with respect to the CORESETs is designated on the basis of a Medium Access Control Control Element (MAC CE).

Advantageous Effects of Invention

According to one aspect of the present disclosure, it is possible to perform DL communication preferably even when multiple panels/TRPs are used.

DESCRIPTION OF EMBODIMENTS

For NR, a UE that controls 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) of at least one of a signal and a channel (which may be expressed as a signal/channel; in the present disclosure, “A/B” may be similarly interpreted as “at least one of A and B”) and the like on the basis of a transmission configuration indication state (TCI state) is under study.

The TCI state may be a state applied to a downlink signal/channel. A state that corresponds to the TCI state applied to an uplink signal/channel may be expressed as spatial relation.

The TCI state is information related to quasi-co-location (QCL) of the signal/channel, and may be referred to as a spatial reception parameter, spatial relation information (SRI), or the like. The TCI state may be configured for the UE for each channel or for each signal.

QCL is an indicator indicating statistical properties of the signal/channel. For example, when a certain signal/channel and another signal/channel are in a relationship of QCL, it may be indicated that it is assumable that at least one of Doppler shift, a Doppler spread, an average delay, a delay spread, and a spatial parameter (for example, a spatial reception parameter (spatial Rx parameter)) is the same (the relationship of QCL is satisfied in at least one of these) between such a plurality of different signals/channels.

Note that the spatial reception parameter may correspond to a receive beam of the UE (for example, a receive analog beam), and the beam may be identified based on spatial QCL. The QCL (or at least one element in the relationship of QCL) in the present disclosure may be interpreted as sQCL (spatial QCL).

For the QCL, a plurality of types (QCL types) may be defined. For example, four QCL types A to D may be provided, which have different parameter(s) (or parameter set(s)) that can be assumed to be the same, and such parameter(s) (which may be referred to as QCL parameter(s)) are described below:QCL type A: Doppler shift, Doppler spread, average delay, and delay spread,QCL type B: Doppler shift and Doppler spread,QCL type C: Doppler shift and Average delay, andQCL type D: Spatial reception parameter.

Types A to C may correspond to QCL information related to synchronization processing of at least one of time and frequency, and type D may correspond to QCL information related to beam control.

A case that the UE assumes that a certain control resource set (CORESET), channel, or reference signal is in a relationship of specific QCL (for example, QCL type D) with another CORESET, channel, or reference signal may be referred to as QCL assumption.

The UE may determine at least one of a transmit beam (Tx beam) and a receive beam (Rx beam) of the signal/channel on the basis of the TCI state or the QCL assumption for the signal/channel.

The TCI state may be, for example, information related to QCL between a channel as a target (or a reference signal (RS) for the channel) and another signal (for example, another downlink reference signal (DL-RS)). The TCI state may be configured (indicated) by higher layer signaling or physical layer signaling, or a combination of these.

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, and the like, or a combination of these.

The MAC signaling may use, for example, a MAC control element (MAC CE), a MAC Protocol Data Unit y(PDU), or the like. The broadcast information may be, for example, a master information block (MIB), a system information block (SIB), minimum system information (Remaining Minimum System Information (RMSI)), other system information (OSI), or the like.

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

A channel for which the TCI state is configured (indicated) 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)).

The RS (DL-RS) to have a QCL relationship with the channel may be, for example, at least one of a synchronization signal block (SSB), a channel state information reference signal (CSI-RS), and a reference signal for measurement (Sounding Reference Signal (SRS)). Alternatively, the DL-RS may be a CSI-RS used for tracking (also referred to as a Tracking Reference Signal (TRS)), or a reference signal used for QCL detection (also referred to as a QRS).

The SSB is a signal block including 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 be referred to as an SS/PBCH block.

<TCI State for PDCCH>

Information related to QCL between the PDCCH (or a DMRS antenna port related to the PDCCH) and a certain DL-RS may be referred to as a TCI state for the PDCCH or the like.

The UE may determine the TCI state for a UE-specific PDCCH (CORESET), based on higher layer signaling.

For example, one or a plurality of (K) TCI states may be configured for the UE for each CORESET by using RRC signaling (ControlResourceSet information element). The UE may activate each of the one or the plurality of TCI states for each CORESET by using the MAC CE. The MAC CE may be referred to as a TCI state indication for UE-specific PDCCH MAC CE. The UE may perform monitoring of the CORESET, based on an active TCI state corresponding to the CORESET.

FIG.1is a diagram to show a structure of the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR.FIG.1shows bit sequences constituting the MAC CE, and the bit sequences are expressed by 2 octets (8 bits×2=16 bits) in total of shown octets (Octs) 1 to 2.

The MAC CE includes a serving cell Identifier (ID) field (“Serving Cell ID” field), a CORESET ID field (“CORESET ID” field), and a TCI state ID field (“TCI State ID” field).

The serving cell ID field is a 5-bit field indicating an ID for a serving cell to which the MAC CE is applied (in other words, in which a TCI state is designated/activated).

The CORESET ID field is a 4-bit field for identification of a CORESET ID (higher layer parameter “ControlResourceSetID”) being a TCI state indication target. The case that a value of the CORESET ID field is 0 indicates a shared CORESET (which may be referred to as CORESET #0, a CORESET zero, a CORESET for reception of SIB 1, and so on), and the value being 1 or more indicates a CORESET other than that.

CORESET #0 may be configured for the UE by configuration information for CORESET #0 (an RRC information element “controlResourceSetZero”), and another CORESET may be configured for the UE by CORESET configuration information (an RRC information element “controlResourceSet”).

The TCI state ID field is a 7-bit field for identification of a TCI state ID capable of being applied to a CORESET identified by the CORESET ID field.

When the CORESET ID field is configured to 0, the TCI state ID field may indicate a TCI state ID corresponding to any one of the first 64 pieces of TCI states out of TCI states configured with respect to PDSCH configuration information (an RRC information element “PDSCH-Config”) in an active Bandwidth Part (BWP) (TCI states configured by RRC parameters “tci-States-ToAddModList” and “tci-States-ToReleaseList”).

When the CORESET ID field is configured to a value other than 0, the TCI state ID field may indicate a TCI state ID corresponding to any one of TCI states configured with respect to CORESET configuration corresponding to an indicated CORESET ID (TCI states configured by RRC parameters “tci-StatesPDCCH-ToAddList” and “tci-StatesPDCCH-ToReleaseList”).

For NR, a scheme in which one or a plurality of transmission/reception points (TRPs) (multiple TRPs) perform DL transmission to a UE by using one or a plurality of panels (multiple panels) has been under study. A scheme in which the UE performs UL transmission to one or a plurality of TRPs has been under study.

Note that the plurality of TRPs may correspond to the same cell identifier (ID), or may correspond to different cell IDs. The cell ID may be a physical cell ID, or may be a virtual cell ID.

FIGS.2A to2Dare diagrams to show examples of a multi-TRP scenario. In these examples, it is assumed that each TRP can transmit four different beams, but this is not restrictive.

FIG.2Ashows an example of a case where only one TRP (in the present example, TRP1) out of the multiple TRPs performs transmission to the UE (which may be referred to as a single mode, a single TRP, or the like). In this case, TRP1transmits both a control signal (PDCCH) and a data signal (PDSCH) to the UE.

FIG.2Bshows an example of a case where only one TRP (in the present example, TRP1) out of the multiple TRPs transmits a control signal to the UE and the multiple TRPs transmit data signals (which may be referred to as a single master mode). The UE receives each PDSCH transmitted from the multiple TRPs, based on one piece of downlink control information (DCI).

FIG.2Cshows an example of a case where each of the multiple TRPs transmits part of a control signal to the UE and the multiple TRPs transmit data signals (which may be referred to as a master slave mode). In TRP1, part1of the control signal (DCI) may be transmitted, and in TRP2, part2of the control signal (DCI) may be transmitted. Part2of the control signal may depend on part1. The UE receives each PDSCH transmitted from the multiple TRPs, based on these parts of DCI.

FIG.2Dshows an example of a case where each of the multiple TRPs transmits a separate control signal to the UE and the multiple TRPs transmit data signals (which may be referred to as a multi-master mode). In TRP1, a first control signal (DCI) may be transmitted, and in TRP2, a second control signal (DCI) may be transmitted. The UE receives each PDSCH transmitted from the multiple TRPs, based on these pieces of DCI.

When a plurality of PDSCHs (which may be referred to as multiple PDSCHs) from the multiple TRPs as shown inFIG.2Bare scheduled with use of one piece of DCI, the DCI may be referred to as single DCI (single PDCCH). When a plurality of PDSCHs from the multiple TRPs as shown inFIG.2Dare each scheduled with use of a plurality of pieces of DCI, these plurality of pieces of the DCI may be referred to as multiple pieces of DCI (multiple PDCCHs).

From each TRP of the multiple TRPs, a different code word (CW) and a different layer may be transmitted. As one form of the multi-TRP transmission, non-coherent joint transmission (NCJT) has been under study.

In NCJT, for example, TRP1performs modulation mapping of the first code word and performs layer mapping so as to transmit the first PDSCH by using first precoding for a first number of layers (for example, two layers). TRP2performs modulation mapping of the second code word and performs layer mapping so as to transmit the second PDSCH by using second precoding for a second number of layers (for example, two layers).

Note that it may be defined that the plurality of PDSCHs (multiple PDSCHs) subjected to NCJT partially or entirely overlap regarding at least one of the time and frequency domains. In other words, at least one of time and frequency resources of the first PDSCH from the first TRP and the second PDSCH from the second TRP may overlap.

It may be assumed that these first PDSCH and second PDSCH are not in a relationship of quasi-co-location (QCL) (not quasi-co-located). Reception of the multiple PDSCHs may be interpreted as simultaneous reception of PDSCHs other than a certain QCL type (e.g., QCL type D).

According to the multi-TRP scenario as described above, more flexible transmission control using channels with satisfactory quality can be performed.

However, in NR specifications thus far, multiple panels/TRPs are not considered, and thus an QCL assumption in a case where the multiple panels/TRPs are used cannot be appropriately controlled.

Incidentally, existing Rel. 15 NR specifications have limited a maximum number of CORESETs for each PDCCH configuration (PDCCH-Config) to 3. In other words, a network may configure at most three CORESETs with respect to 1 BWP for 1 cell.

A CORESET ID (an RRC parameter “controlResourceSetID”) that a CORESET configuration (an RRC information element “ControlResourceSet”) has does not include a value ‘0.’ In other words, in the Rel. 15 NR specifications, the PDCCH configuration can include at most three CORESETs configurations, but the at most three configured CORESETs will not include CORESET #0.

At most 4 BWPs are configurable for 1 cell, and thus a maximum number of CORESETs for 1 serving cell (a maximum number of CORESETs configured with use of the CORESET configuration) is 12.

For multi-DCI-based multi-TRP transmission, a maximum number of CORESETs for each PDCCH configuration (and a maximum number of CORESETs per BWP may be interchangeably interpreted) being greater than 3 is under study. On the other hand, the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR shown inFIG.1includes a 4-bit CORESET ID field, and thus values capable of being expressed are from 0 to 15.

Thus, unless the number of CORESETs configured for the UE is limited or a CORESET ID being greater than 15 can be designated for the UE, a TCI state for each PDCCH cannot be appropriately designated in a case where multiple PDCCHs are used. However, such studies have not been performed thus far. Accordingly, following existing NR specifications cannot preferably achieve spatial diversity gain, high rank transmission, and the like in a case where the multiple panels/TRPs are used, and thus an increase in communication throughput may be suppressed.

Thus, the inventors of the present invention came up with the idea of a method for designating an assumption for CORESETs and a TCI state for PDCCHs capable of supporting the case where the multiple panels/TRPs are used.

Embodiments according to the present disclosure will be described in detail with reference to the drawings as follows. The radio communication methods according to respective embodiments may each be employed individually, or may be employed in combination.

Note that in the present disclosure, a panel, an Uplink (UL) transmission entity, a TRP, a spatial relation, a control resource set (COntrol REsource SET (CORESET)), a PDSCH, a codeword, a base station, a certain antenna port (e.g., a demodulation reference signal (DMRS) port), a certain antenna port group (e.g., a DMRS port group), a certain group (e.g., a code division multiplexing (CDM) group, a certain reference signal group, or a CORESET group), and the like may be interchangeably interpreted. A panel identifier (ID) and a panel may be interchangeably interpreted. A TRP ID and a TRP may be interchangeably interpreted.

First Embodiment

A maximum number of CORESETs for 1 serving cell may be judged on the basis of a maximum number of configured BWPs (embodiment 1-1).

In embodiment 1-1, the maximum number of the CORESETs for 1 serving cell may be obtained by (the maximum number=) a maximum number of CORESETs per BWP×the maximum number of the configured BWPs. For example, when a maximum number of CORESETs per BWP=5 and a maximum number of BWPs configured for multiple TRPs=4, a maximum number of CORESETs for 1 serving cell for the multi-TRPs may be (the maximum number=) 5×4=20.

In embodiment 1-1, it may be assumed that a maximum number of CORESETs for each CORESET group is not greater than a certain number (e.g., 11, 12, or the like) (is less than the certain number).

A maximum number of CORESETs for 1 serving cell may be assumed to be at most 16 (embodiment 1-2).

In embodiment 1-2, a UE may derive a maximum number of configured BWPs from the maximum number of the CORESETs for 1 serving cell and maximum number of CORESETs per BWP.

For example, when the maximum number of CORESETs per BWP is 5, the maximum number of the configured BWPs may be obtained by floor(the maximum number of the CORESETs for 1 serving cell/the maximum number of CORESETs per BWP)=floor(16/5)=3. Note that floor (x) is the floor function indicating a maximum integer less than or equal to x for a real number x.

When the maximum number of CORESETs per BWP is 4, the maximum number of the configured BWPs may be obtained by floor(the maximum number of the CORESETs for 1 serving cell/the maximum number of CORESETs per BWP)=floor(16/4)=4.

In other words, the UE may assume that the maximum number of CORESETs per BWP×the maximum number of the configured BWPs does not exceed a certain number (e.g., 15, 16, or the like).

According to the above-described first embodiment, even when a maximum number of CORESETs for each PDCCH configuration is high as compared to that of Rel. 15 NR, it is possible to appropriately acknowledge a maximum number of CORESETs per serving cell, and, for example, it is possible to appropriately activate a TCI state for each PDCCH by recognizing a size of a CORESET ID field for a MAC CE shown in a second embodiment described later.

Second Embodiment

When a maximum number of CORESETs per serving cell is less than or equal to 16, a UE may assume that a TCI state for a PDCCH for a CORESET in the serving cell is designated with use of a TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR (embodiment 2-1).

The UE may assume that a TCI state for a PDCCH for a CORESET in the serving cell is designated with use of a new TCI state indication for UE-specific PDCCH MAC CE (also simply referred to hereinafter as a “new MAC CE”) different from the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR (embodiment 2-2).

Note that “different from the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR” may mean that a MAC CE size is different, may mean that the MAC CE size is the same, but a size of a part of a field is different, or may mean that a new field is included.

A range of a value corresponding to a CORESET ID field for the new MAC CE may be a certain value greater than or equal to 0 (which may be referred to as, for example, a maximum number of CORESETs per CORESET group (“maxNrofControlResourceSetsPerGroup”) and so on). The certain value for each CORESET group may be the same, or may be different from each other.

The new MAC CE of embodiment 2-2 may include a field for identification of a CORESET group to which the MAC CE is applied (which may be referred to as a CORESET group ID field). The CORESET group ID field may be a separate (explicit) field, or may be a field included in a part of another field.

For example, the CORESET group ID field may be a part of a TCI state ID field. The CORESET group ID field may be indicated with 1 bit of the most significant bit (MSB) or 1 bit of the least significant bit (LSB) of the TCI state ID field. In this case, the remaining 6 bits of the TCI state ID field may indicate a TCI state for a CORESET group corresponding to the CORESET group ID field.

Note that the CORESET group ID field may be always included in the above-described new MAC CE. The CORESET group ID field may be assumed to exist only when at least one of CORESET group IDs are configured or use of CORESET groups is configured to “enabled” by higher layer signaling.

FIG.3is a diagram to show an example of the MAC CE according to embodiment 2-2. The MAC CE of the present example has the same size as that of the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR, but has a slightly different meaning of the TCI state ID field.

In the MAC CE ofFIG.3, when the CORESET ID field is configured to 0, the TCI state ID field may be interpreted as that of the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR.

In the MAC CE ofFIG.3, when the CORESET ID field is configured to anything other than 0, it may be interpreted that the 1-bit MSB of the TCI state ID field indicates a CORESET group ID field and the 6-bit LSB indicates a TCI state ID for a corresponding CORESET group.

For example, the UE may assume that the 6-bit LSB indicates a TCI state ID for a first CORESET group when the 1-bit MSB=‘0’ and the 6-bit LSB indicates a TCI state ID for a second CORESET group when the 1-bit MSB=‘1.’

FIG.4is a diagram to show an example of the MAC CE according to embodiment 2-2. The MAC CE of the present example is similar to that ofFIG.3, and differs in that the 1-bit LSB of the TCI state ID field indicates a CORESET group ID field and the 6-bit MSB indicates a TCI state ID for a corresponding CORESET group.

FIG.5is a diagram to show an example of the MAC CE according to embodiment 2-2. The MAC CE of the present example has a larger size (24 bits) than the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR.

The MAC CE ofFIG.5includes a 1-bit CORESET group ID field. The MAC CE may also include a 4-bit CORESET ID field. Note that a size of the CORESET ID field is not limited to this. The size of the CORESET ID field may be recognized by the UE on the basis of a maximum number of CORESETs per serving cell (the same may also be applied to another MAC CE).

The TCI state ID field in the MAC CE may be 7 bits, and may be interpreted as that of the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR.

FIG.6is a diagram to show an example of the MAC CE according to embodiment 2-2. The MAC CE of the present example has a larger size (24 bits) than the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR.

The MAC CE ofFIG.6does not include a CORESET group ID field. The UE may judge, from a CORESET ID value, a CORESET group ID to which the MAC CE is applied.

For example, the UE may assume that a TCI state ID field for the MAC CE indicates a TCI state for a first CORESET group (e.g., CORESET group 1) when a CORESET ID field for the MAC CE is 0 or more and X or less (e.g., X is an integer less than or equal to 11). A value of this X may be configured for the UE with use of higher layer signaling.

For example, the UE may assume that a TCI state ID field for the MAC CE indicates a TCI state for a second CORESET group (e.g., CORESET group 2) when a CORESET ID field for the MAC CE is X+1 or more and a maximum number of CORESETs per serving cell (which may be referred to as “maxNrofControlResourceSets” and so on)−1 or less.

Note that an association between the CORESET group ID and CORESET ID is not limited to this. The association may be predetermined by specifications, or may be configured for the UE by higher layer signaling or the like. The association may be determined on the basis of a BWP index, a CORESET index per TRP, or the like.

FIG.7is a diagram to show an example of the MAC CE according to embodiment 2-2. The MAC CE of the present example has a larger size (24 bits) than the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR.

In the MAC CE ofFIG.7, the TCI state ID field is not used as a TCI state ID in a case where a CORESET ID field is configured to 0. This is interpretation different from that of a TCI state ID field for an existing MAC CE. The TCI state ID field ofFIG.7may be 6 bits, or may be 7 bits.

On the other hand, the MAC CE ofFIG.7includes a TCI state ID field for CORESET #0 (“TCI State ID for CORESET #0” field). The TCI state ID field for CORESET #0 may be included only when the CORESET ID field is configured to 0, otherwise may not be included. The TCI state ID field for CORESET0ofFIG.7may be 6 bits, or may be 7 bits.

Note that when the MAC CE ofFIG.7includes both of the TCI state ID field and the TCI state ID field for CORESET #0, for example, the UE may judge a TCI state for a CORESET corresponding to a CORESET ID (value not being 0) on the basis of the TCI state ID field, and may judge a TCI state for a CORESET corresponding to CORESET #0 on the basis of the TCI state ID field for CORESET #0.

FIG.8is a diagram to show an example of the MAC CE according to embodiment 2-2. The MAC CE of the present example may have the same size as the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR.

The MAC CE ofFIG.8may be used for a CORESET other than CORESET #0. The UE may assume that a TCI state for CORESET #0 is designated by the existing MAC CE and a TCI state for a CORESET other than that is designated by the MAC CE ofFIG.8.

A CORESET ID field for the MAC CE ofFIG.8may be 4 bits, or may be 5 bits, for example. The CORESET ID field may be 4 bits when a maximum number of CORESETs per BWP=4 (in this case, 5 pieces of CORESETs including CORESET #0 may be available for each BWP), or may be 5 bits when a maximum number of CORESETs per BWP=5 (in this case, 5 pieces of CORESETs except CORESET #0 may be available for each BWP).

In the MAC CE ofFIG.8, the TCI state ID field is not used as a TCI state ID in a case where a CORESET ID field is configured to 0. The TCI state ID field ofFIG.8may be 6 bits, or may be 7 bits.

The UE may assume that the new MAC CE of embodiment 2-2 is applied when a certain higher layer parameter (e.g., an arbitrary CORESET group ID, multiple PDCCHs, multiple TRPs, and the like) is configured, otherwise may assume that the existing MAC CE is applied.

The UE may identify the above-described new MAC CE on the basis of a logical channel ID (Logical Channel Identifier (LCID)) included in a MAC sub-header for a MAC PDU. For example, the existing MAC CE is identified with the LCID=53, but the above-described new MAC CE may be identified with a value (e.g., any one of values from 33 to 46) different from that.

According to the above-described second embodiment, by using the new MAC CE that has a larger size of a CORESET ID field than that of the TCI state indication for UE-specific PDCCH MAC CE of Rel. 15 NR and that can designate a CORESET group ID, it is possible to appropriately designate a TCI state for each PDCCH even in a case where, for example, multiple PDCCHs are applied.

Other Embodiment

The present disclosure describes that the above-mentioned respective embodiments may be used in a case where multi-DCI (multi-PDCCH)-based multi-TRP transmission is performed, but is not limited to this. The above-mentioned respective embodiments may be used in a case where single-DCI (single-PDCCH)-based multi-TRP transmission is performed, or may be used in a case where single-TRP transmission is performed.

How to give CORESET ID indices (indexing) may be common (global) to all panels (or TRPs or CORESET groups), or may be independent for each panel (or TRP or CORESET group).

The radio communication system1may support dual connectivity between a plurality of base stations in the same RAT (for example, dual connectivity (NR-NR Dual Connectivity (NN-DC)) where both of an MN and an SN are base stations (gNB) of NR).

The radio communication system1may include a base station11that forms a macro cell C1of a relatively wide coverage, and base stations12(12ato12c) that form small cells C2, which are placed within the macro cell C1and which are narrower than the macro cell C1. The user terminal20may be located in at least one cell. The arrangement, the number, and the like of each cell and user terminal20are by no means limited to the aspect shown in the diagram. Hereinafter, the base stations11and12will be collectively referred to as “base stations10,” unless specified otherwise.

The user terminal20may be connected to at least one of the plurality of base stations10. The user terminal20may use at least one of carrier aggregation (CA) and dual connectivity (DC) using a plurality of component carriers (CCs).

Each CC may be included in at least one of a first frequency band (Frequency Range 1 (FR1)) and a second frequency band (Frequency Range 2 (FR2)). The macro cell C1may be included in FR1, and the small cells C2may be included in FR2. For example, FR1 may be a frequency band of 6 GHz or less (sub-6 GHz), and FR2 may be a frequency band which is higher than 24 GHz (above-24 GHz). Note that frequency bands, definitions and so on of FR1 and FR2 are by no means limited to these, and for example, FR1 may correspond to a frequency band which is higher than FR2.

The user terminal20may communicate using at least one of time division duplex (TDD) and frequency division duplex (FDD) in each CC.

The plurality of base stations10may be connected by a wired connection (for example, optical fiber in compliance with the Common Public Radio Interface (CPRI), the X2 interface and so on) or a wireless connection (for example, an NR communication). For example, if an NR communication is used as a backhaul between the base stations11and12, the base station11corresponding to a higher station may be referred to as an “Integrated Access Backhaul (IAB) donor,” and the base station12corresponding to a relay station (relay) may be referred to as an “IAB node.”

The base station10may be connected to a core network30through another base station10or directly. For example, the core network30may include at least one of Evolved Packet Core (EPC), 5G Core Network (5GCN), Next Generation Core (NGC), and so on.

The user terminal20may be a terminal supporting at least one of communication schemes such as LTE, LTE-A, 5G, and so on.

In the radio communication system1, a downlink shared channel (Physical Downlink Shared Channel (PDSCH)), which is used by each user terminal20on a shared basis, a broadcast channel (Physical Broadcast Channel (PBCH)), a downlink control channel (Physical Downlink Control Channel (PDCCH)) and so on, may be used as downlink channels.

In the radio communication system1, an uplink shared channel (Physical Uplink Shared Channel (PUSCH)), which is used by each user terminal20on a shared basis, an uplink control channel (Physical Uplink Control Channel (PUCCH)), a random access channel (Physical Random Access Channel (PRACH)) and so on may be used as uplink channels.

User data, higher layer control information, System Information Blocks (SIBs) and so on are communicated on the PDSCH. User data, higher layer control information and so on may be communicated on the PUSCH. The Master Information Blocks (MIBs) may be communicated on the PBCH.

Lower layer control information may be communicated on the PDCCH. For example, the lower layer control information may include downlink control information (DCI) including scheduling information of at least one of the PDSCH and the PUSCH.

Uplink control information (UCI) including at least one of channel state information (CSI), transmission confirmation information (for example, which may be also referred to as Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK), ACK/NACK, and so on), and scheduling request (SR) may be communicated by means of the PUCCH. By means of the PRACH, random access preambles for establishing connections with cells may be communicated.

In the radio communication system1, a synchronization signal (SS), a downlink reference signal (DL-RS), and so on may be communicated. In the radio communication system1, a cell-specific reference signal (CRS), a channel state information-reference signal (CSI-RS), a demodulation reference signal (DMRS), a positioning reference signal (PRS), a phase tracking reference signal (PTRS), and so on may be communicated as the DL-RS.

In the radio communication system1, a sounding reference signal (SRS), a demodulation reference signal (DMRS), and so on may be communicated as an uplink reference signal (UL-RS). Note that DMRS may be referred to as a “user terminal specific reference signal (UE-specific Reference Signal).”

FIG.10is a diagram to show an example of a structure of the base station according to one embodiment. The base station10includes a control section110, a transmitting/receiving section120, transmitting/receiving antennas130and a communication path interface (transmission line interface)140. Note that the base station10may include one or more control sections110, one or more transmitting/receiving sections120, one or more transmitting/receiving antennas130, and one or more communication path interfaces140.

Note that, the present example primarily shows functional blocks that pertain to characteristic parts of the present embodiment, and it is assumed that the base station10may include other functional blocks that are necessary for radio communication as well. Part of the processes of each section described below may be omitted.

The control section110controls the whole of the base station10. The control section110can be constituted with a controller, a control circuit, or the like described based on general understanding of the technical field to which the present disclosure pertains.

The control section110may control generation of signals, scheduling (for example, resource allocation, mapping), and so on. The control section110may control transmission and reception, measurement and so on using the transmitting/receiving section120, the transmitting/receiving antennas130, and the communication path interface140. The control section110may generate data, control information, a sequence and so on to transmit as a signal, and forward the generated items to the transmitting/receiving section120. The control section110may perform call processing (setting up, releasing) for communication channels, manage the state of the base station10, and manage the radio resources.

The transmitting/receiving section120may include a baseband section121, a Radio Frequency (RF) section122, and a measurement section123. The baseband section121may include a transmission processing section1211and a reception processing section1212. The transmitting/receiving section120can be constituted with a transmitter/receiver, an RF circuit, a baseband circuit, a filter, a phase shifter, a measurement circuit, a transmitting/receiving circuit, or the like described based on general understanding of the technical field to which the present disclosure pertains.

The transmitting/receiving section120may be structured as a transmitting/receiving section in one entity, or may be constituted with a transmitting section and a receiving section. The transmitting section may be constituted with the transmission processing section1211, and the RF section122. The receiving section may be constituted with the reception processing section1212, the RF section122, and the measurement section123.

The transmitting/receiving antennas130can be constituted with antennas, for example, an array antenna, or the like described based on general understanding of the technical field to which the present disclosure pertains.

The transmitting/receiving section120may transmit the above-described downlink channel, synchronization signal, downlink reference signal, and so on. The transmitting/receiving section120may receive the above-described uplink channel, uplink reference signal, and so on.

The transmitting/receiving section120may form at least one of a transmit beam and a receive beam by using digital beam forming (for example, precoding), analog beam forming (for example, phase rotation), and so on.

The transmitting/receiving section120(transmission processing section1211) may perform the processing of the Packet Data Convergence Protocol (PDCP) layer, the processing of the Radio Link Control (RLC) layer (for example, RLC retransmission control), the processing of the Medium Access Control (MAC) layer (for example, HARQ retransmission control), and so on, for example, on data and control information and so on acquired from the control section110, and may generate bit string to transmit.

The transmitting/receiving section120(transmission processing section1211) may perform transmission processing such as channel coding (which may include error correction coding), modulation, mapping, filtering, discrete Fourier transform (DFT) processing (as necessary), inverse fast Fourier transform (IFFT) processing, precoding, digital-to-analog conversion, and so on, on the bit string to transmit, and output a baseband signal.

The transmitting/receiving section120(RF section122) may perform modulation to a radio frequency band, filtering, amplification, and so on, on the baseband signal, and transmit the signal of the radio frequency band through the transmitting/receiving antennas130.

On the other hand, the transmitting/receiving section120(RF section122) may perform amplification, filtering, demodulation to a baseband signal, and so on, on the signal of the radio frequency band received by the transmitting/receiving antennas130.

The transmitting/receiving section120(reception processing section1212) may apply reception processing such as analog-digital conversion, fast Fourier transform (FFT) processing, inverse discrete Fourier transform (IDFT) processing (as necessary), filtering, de-mapping, demodulation, decoding (which may include error correction decoding), MAC layer processing, the processing of the RLC layer and the processing of the PDCP layer, and so on, on the acquired baseband signal, and acquire user data, and so on.

The transmitting/receiving section120(measurement section123) may perform the measurement related to the received signal. For example, the measurement section123may perform Radio Resource Management (RRM) measurement, Channel State Information (CSI) measurement, and so on, based on the received signal. The measurement section123may measure a received power (for example, Reference Signal Received Power (RSRP)), a received quality (for example, Reference Signal Received Quality (RSRQ), a Signal to Interference plus Noise Ratio (SINR), a Signal to Noise Ratio (SNR)), a signal strength (for example, Received Signal Strength Indicator (RSSI)), channel information (for example, CSI), and so on. The measurement results may be output to the control section110.

The communication path interface140may perform transmission/reception (backhaul signaling) of a signal with an apparatus included in the core network30or other base stations10, and so on, and acquire or transmit user data (user plane data), control plane data, and so on for the user terminal20.

Note that the transmitting section and the receiving section of the base station10in the present disclosure may be constituted with at least one of the transmitting/receiving section120, the transmitting/receiving antennas130, and the communication path interface140.

Note that the transmitting/receiving section120may transmit either or both of a plurality of downlink shared channels (Physical Downlink Shared Channels (PDSCHs)) (multiple PDSCHs) scheduled on the basis of a plurality of pieces of downlink control information (multiple PDSCHs).

The transmitting/receiving section120may transmit a Physical Downlink Control Channel (PDCCH) configuration with a maximum number of control resource sets (CORESETs) exceeding 3 to the user terminal20.

FIG.11is a diagram to show an example of a structure of the user terminal according to one embodiment. The user terminal20includes a control section210, a transmitting/receiving section220, and transmitting/receiving antennas230. Note that the user terminal20may include one or more control sections210, one or more transmitting/receiving sections220, and one or more transmitting/receiving antennas230.

Note that, the present example primarily shows functional blocks that pertain to characteristic parts of the present embodiment, and it is assumed that the user terminal20may include other functional blocks that are necessary for radio communication as well. Part of the processes of each section described below may be omitted.

The control section210controls the whole of the user terminal20. The control section210can be constituted with a controller, a control circuit, or the like described based on general understanding of the technical field to which the present disclosure pertains.

The control section210may control generation of signals, mapping, and so on. The control section210may control transmission/reception, measurement and so on using the transmitting/receiving section220, and the transmitting/receiving antennas230. The control section210generates data, control information, a sequence and so on to transmit as a signal, and may forward the generated items to the transmitting/receiving section220.

The transmitting/receiving section220may include a baseband section221, an RF section222, and a measurement section223. The baseband section221may include a transmission processing section2211and a reception processing section2212. The transmitting/receiving section220can be constituted with a transmitter/receiver, an RF circuit, a baseband circuit, a filter, a phase shifter, a measurement circuit, a transmitting/receiving circuit, or the like described based on general understanding of the technical field to which the present disclosure pertains.

The transmitting/receiving section220may be structured as a transmitting/receiving section in one entity, or may be constituted with a transmitting section and a receiving section. The transmitting section may be constituted with the transmission processing section2211and the RF section222. The receiving section may be constituted with the reception processing section2212, the RF section222, and the measurement section223.

The transmitting/receiving antennas230can be constituted with antennas, for example, an array antenna, or the like described based on general understanding of the technical field to which the present disclosure pertains.

The transmitting/receiving section220may receive the above-described downlink channel, synchronization signal, downlink reference signal, and so on. The transmitting/receiving section220may transmit the above-described uplink channel, uplink reference signal, and so on.

The transmitting/receiving section220may form at least one of a transmit beam and a receive beam by using digital beam forming (for example, precoding), analog beam forming (for example, phase rotation), and so on.

The transmitting/receiving section220(transmission processing section2211) may perform the processing of the PDCP layer, the processing of the RLC layer (for example, RLC retransmission control), the processing of the MAC layer (for example, HARQ retransmission control), and so on, for example, on data and control information and so on acquired from the control section210, and may generate bit string to transmit.

The transmitting/receiving section220(transmission processing section2211) may perform transmission processing such as channel coding (which may include error correction coding), modulation, mapping, filtering, DFT processing (as necessary), IFFT processing, precoding, digital-to-analog conversion, and so on, on the bit string to transmit, and output a baseband signal.

The transmitting/receiving section220(RF section222) may perform modulation to a radio frequency band, filtering, amplification, and so on, on the baseband signal, and transmit the signal of the radio frequency band through the transmitting/receiving antennas230.

On the other hand, the transmitting/receiving section220(RF section222) may perform amplification, filtering, demodulation to a baseband signal, and so on, on the signal of the radio frequency band received by the transmitting/receiving antennas230.

The transmitting/receiving section220(measurement section223) may perform the measurement related to the received signal. For example, the measurement section223may perform RRM measurement, CSI measurement, and so on, based on the received signal. The measurement section223may measure a received power (for example, RSRP), a received quality (for example, RSRQ, SINR, SNR), a signal strength (for example, RSSI), channel information (for example, CSI), and so on. The measurement results may be output to the control section210.

Note that the transmitting section and the receiving section of the user terminal20in the present disclosure may be constituted with at least one of the transmitting/receiving section220and the transmitting/receiving antennas230.

Note that the transmitting/receiving section220may receive a plurality of downlink shared channels (Physical Downlink Shared Channels (PDSCHs)) (multiple PDSCHs) on the basis of a plurality of pieces of downlink control information (multiple PDSCHs).

The transmitting/receiving section220may receive a Physical Downlink Control Channel (PDCCH) configuration with a maximum number of control resource sets (CORESETs) exceeding 3. The PDCCH configuration may include, for example, 5 pieces of CORESET configurations.

The control section210may assume that a transmission configuration indication state (TCI state) for a PDCCH with respect to the CORESETs is designated on the basis of a Medium Access Control Control Element (MAC CE). The MAC CE may be at least one of TCI state indication for UE-specific PDCCH MAC CEs, such as mentioned in the above-mentioned second embodiment.

The control section210may assume that a maximum number of the CORESETs per CORESET group does not exceed a certain number.

The control section210may assume that a value obtained by multiplying a maximum number of CORESETs per Bandwidth Part (BWP) by a maximum number of configured BWPs does not exceed a certain number.

The control section210may identify, on the basis of the MAC CE, a CORESET ID corresponding to a certain CORESET group Identifier (ID), and may judge a TCI state for a PDCCH with respect to a CORESET indicated by the CORESET ID.

The MAC CE may include, besides a TCI state field for a CORESET other than CORESET #0, a TCI state field for CORESET #0 only when a CORESET ID field is a specific value (e.g., 0).

Note that in the present disclosure, the words such as an apparatus, a circuit, a device, a section, a unit, and so on can be interchangeably interpreted. The hardware structure of the base station10and the user terminal20may be configured to include one or more of apparatuses shown in the drawings, or may be configured not to include part of apparatuses.

For example, although only one processor1001is shown, a plurality of processors may be provided. Furthermore, processes may be implemented with one processor or may be implemented at the same time, in sequence, or in different manners with two or more processors. Note that the processor1001may be implemented with one or more chips.

The processor1001controls the whole computer by, for example, running an operating system. The processor1001may be configured with a central processing unit (CPU), which includes interfaces with peripheral apparatus, control apparatus, computing apparatus, a register, and so on. For example, at least part of the above-described control section110(210), the transmitting/receiving section120(220), and so on may be implemented by the processor1001.

Furthermore, the processor1001reads programs (program codes), software modules, data, and so on from at least one of the storage1003and the communication apparatus1004, into the memory1002, and executes various processes according to these. As for the programs, programs to allow computers to execute at least part of the operations of the above-described embodiments are used. For example, the control section110(210) may be implemented by control programs that are stored in the memory1002and that operate on the processor1001, and other functional blocks may be implemented likewise.

The storage1003is a computer-readable recording medium, and may be constituted with, for example, at least one of a flexible disk, a floppy (registered trademark) disk, a magneto-optical disk (for example, a compact disc (Compact Disc ROM (CD-ROM) and so on), a digital versatile disc, a Blu-ray (registered trademark) disk), a removable disk, a hard disk drive, a smart card, a flash memory device (for example, a card, a stick, and a key drive), a magnetic stripe, a database, a server, and other appropriate storage media. The storage1003may be referred to as “secondary storage apparatus.”

The communication apparatus1004is hardware (transmitting/receiving device) for allowing inter-computer communication via at least one of wired and wireless networks, and may be referred to as, for example, a “network device,” a “network controller,” a “network card,” a “communication module,” and so on. The communication apparatus1004may be configured to include a high frequency switch, a duplexer, a filter, a frequency synthesizer, and so on in order to realize, for example, at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the above-described transmitting/receiving section120(220), the transmitting/receiving antennas130(230), and so on may be implemented by the communication apparatus1004. In the transmitting/receiving section120(220), the transmitting section120a(220a) and the receiving section120b(220b) can be implemented while being separated physically or logically.

Also, the base station10and the user terminals20may be structured to include hardware such as a microprocessor, a digital signal processor (DSP), an Application Specific Integrated Circuit (ASIC), a Programmable Logic Device (PLD), a Field Programmable Gate Array (FPGA), and so on, and part or all of the functional blocks may be implemented by the hardware. For example, the processor1001may be implemented with at least one of these pieces of hardware.

Here, numerology may be a communication parameter applied to at least one of transmission and reception of a certain signal or channel. For example, numerology may indicate at least one of a subcarrier spacing (SCS), a bandwidth, a symbol length, a cyclic prefix length, a transmission time interval (TTI), the number of symbols per TTI, a radio frame structure, a particular filter processing performed by a transceiver in the frequency domain, a particular windowing processing performed by a transceiver in the time domain, and so on.

A bandwidth part (BWP) (which may be referred to as a “fractional bandwidth,” and so on) may represent a subset of contiguous common resource blocks (common RBs) for certain numerology in a certain carrier. Here, a common RB may be specified by an index of the RB based on the common reference point of the carrier. A PRB may be defined by a certain BWP and may be numbered in the BWP.

Also, the information, parameters, and so on described in the present disclosure may be represented in absolute values or in relative values with respect to certain values, or may be represented in another corresponding information. For example, radio resources may be specified by certain indices.

Also, reporting of certain information (for example, reporting of “X holds”) does not necessarily have to be reported explicitly, and can be reported implicitly (by, for example, not reporting this certain information or reporting another piece of information).

At least one of a base station and a mobile station may be referred to as a “transmitting apparatus,” a “receiving apparatus,” a “radio communication apparatus,” and so on. Note that at least one of a base station and a mobile station may be device mounted on a mobile body or a mobile body itself, and so on. The mobile body may be a vehicle (for example, a car, an airplane, and the like), may be a mobile body which moves unmanned (for example, a drone, an automatic operation car, and the like), or may be a robot (a manned type or unmanned type). Note that at least one of a base station and a mobile station also includes an apparatus which does not necessarily move during communication operation. For example, at least one of a base station and a mobile station may be an Internet of Things (IoT) device such as a sensor, and the like.

Likewise, the user terminal in the present disclosure may be interpreted as base station. In this case, the base station10may have the functions of the user terminal20described above.

Actions which have been described in the present disclosure to be performed by a base station may, in some cases, be performed by upper nodes. In a network including one or a plurality of network nodes with base stations, it is clear that various operations that are performed to communicate with terminals can be performed by base stations, one or more network nodes (for example, Mobility Management Entities (MMEs), Serving-Gateways (S-GWs), and so on may be possible, but these are not limiting) other than base stations, or combinations of these.