Terminal, wireless communication method, base station and system

Abstract

A terminal according to an embodiment of this disclosure comprises: a transmission unit that transmits a plurality of repetitions of a physical random access channel, using a plurality of different beams; and a control unit that controls the reception of responses to the physical random access channels in one or more windows. The embodiment of the present disclosure makes it possible to improve coverage for a random access procedure.

Description

[Technical Field]

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

[0002] In Universal Mobile Telecommunications System (UMTS) networks, Long Term Evolution (LTE) was specified with the aim of achieving higher data rates and lower latency (Non-Patent Document 1). Also, LTE-Advanced (3GPP Rel. 10-14) was specified with the aim of achieving higher capacity and more advanced features than LTE (Third Generation Partnership Project (3GPP) Release (Rel.) 8, 9).

[0003] Successor systems to LTE (e.g., 5th generation mobile communication system (5G), 5G+ (plus), 6th generation mobile communication system (6G), New Radio (NR), 3GPP Rel. 15 or later) are also being considered. [Prior art documents] [Non-patent literature]

[0004] [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 [Problem to be solved by the invention]

[0005] In future wireless communication systems (e.g., NR), improvements in coverage are being considered.

[0006] However, the random access procedure for improving coverage is not clear, and if such a random access procedure is not clear, there is a risk that communication throughput will decrease.

[0007] Therefore, the present disclosure provides a terminal and a wireless communication method that improve the coverage of a random access procedure. 、 base station and systems One of the aims is to provide [Means for solving the problem]

[0008] A terminal according to one aspect of the present disclosure includes a transmitter that transmits multiple repetitions of a physical random access channel using multiple different beams, and a controller that controls reception of responses to the physical random access channel within one or more windows. The control unit determines a reference resource from a plurality of resources used in each of the plurality of repetitions, and starts the one or more windows after the reference resource. do. [Effects of the Invention]

[0009] According to one aspect of the present disclosure, the coverage of the random access procedure can be improved. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 shows an example of a RACH configuration information element. [Figure 2] 2A and 2B show an example of PRACH occasion and beam association. [Figure 3] FIG. 3 shows an example of a PRACH configuration. [Figure 4] FIG. 4 shows an example of PRACH mask index values. [Figure 5]FIG. 5 shows an example of RA configuration for BFR. [Figure 6] 6A to 6D show an example of a RAR window according to embodiment #4. [Figure 7] 7A and 7B show an example of an RAR window for PRACH repetition within a short period according to embodiment #4. [Figure 8] 8A and 8B show another example of an RAR window for PRACH repetition within a short period according to embodiment #4. [Figure 9] 9A and 9B show an example of Option A of Embodiment #10. [Figure 10] 10A and 10B show an example of Option B of embodiment #10. [Figure 11] 11A and 11B show an example of Option A of embodiment #11. [Figure 12] 12A and 12B show an example of Option B of embodiment #11. [Figure 13] 13A and 13B show an example of a unit resource 1 / 2. [Figure 14] 14A and 14B show an example of a unit resource 3. FIG. [Figure 15] 15A and 15B show an example of unit resource 4 / 5. [Figure 16] 16A and 16B show another example of the unit resource 5. FIG. [Figure 17] FIG. 17 shows yet another example of the unit resource 5. [Figure 18] 18A and 18B show an example of a unit resource 2 according to variation A. [Figure 19] 19A and 19B show an example of a unit resource 5 according to variation A. [Figure 20] 20A and 20B show an example of variation A1. [Figure 21] FIG. 21 shows an example of the transmission operation 1. [Figure 22] FIG. 22 shows an example of the transmission operation 2. [Figure 23] FIG. 23 shows an example of the transmission operation 3. [Figure 24] FIG. 24 shows an example of monitoring operation 2. [Figure 25] FIG. 25 shows an example of window operation 1 / 2. [Figure 26] FIG. 26 shows an example of window operations 3a / 3b / 3c. [Figure 27] 27A and 27B show an example of embodiment #A9. [Figure 28] 28A and 28B show an example of a novel instruction. [Figure 29] 29A and 29B are diagrams showing an example of an RO for PRACH repetition according to embodiment #B1. [Figure 30] 30A and 30B are diagrams showing another example of RO for PRACH repetition according to embodiment #B1. [Figure 31] 31A and 31B are diagrams showing an example of an RO for PRACH repetition according to embodiment #B2. [Figure 32] 32A and 32B are diagrams showing an example of an RO for PRACH repetition according to embodiment #B3. [Figure 33] 33A and 33B are diagrams showing another example of RO for PRACH repetition according to embodiment #B3. [Figure 34] FIG. 34 is a diagram illustrating an example of a schematic configuration of a wireless communication system according to an embodiment. [Figure 35] FIG. 35 is a diagram illustrating an example of the configuration of a base station according to an embodiment. [Figure 36] FIG. 36 is a diagram illustrating an example of the configuration of a user terminal according to an embodiment. [Figure 37] FIG. 37 is a diagram illustrating an example of the hardware configuration of a base station and a user terminal according to an embodiment. [Figure 38] FIG. 38 is a diagram illustrating an example of a vehicle according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (TCI, spatial relations, QCL) In NR, it is being considered to control the 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 encoding) in the UE of at least one of a signal and a channel (referred to as signal / channel) based on the transmission configuration indication state (TCI state).

[0012] The TCI state may represent that which is applied to a downlink signal / channel, and the equivalent of the TCI state which is applied to an uplink signal / channel may be expressed as a spatial relation.

[0013] The TCI state is information about the quasi-co-location (QCL) of signals / channels, and may also be called spatial reception parameters, spatial relation information, etc. The TCI state may be configured in the UE for each channel or signal.

[0014] A QCL is an index that indicates the statistical properties of a signal / channel. For example, if a signal / channel has a QCL relationship with another signal / channel, it may mean that it can be assumed that at least one of the Doppler shift, Doppler spread, average delay, delay spread, and spatial parameter (e.g., spatial Rx parameter) is the same between these different signals / channels (i.e., they are QCLs with respect to at least one of these).

[0015] The spatial reception parameters may correspond to a reception beam (e.g., a reception analog beam) of the UE, and the beam may be determined based on a spatial QCL. A QCL (or at least one element of a QCL) in the present disclosure may be replaced with an sQCL (spatial QCL).

[0016] A plurality of types (QCL types) of QCLs may be defined. For example, four QCL types A and B may be provided, each having different parameters (or parameter sets) that can be assumed to be the same. The parameters (which may be referred to as QCL parameters) are listed below: QCL Type A (QCL-A): Doppler shift, Doppler spread, mean delay and delay spread, QCL Type B (QCL-B): Doppler shift and Doppler spread, QCL Type C (QCL-C): Doppler shift and mean delay, · QCL Type D (QCL-D): Spatial reception parameters.

[0017] The assumption by a UE that a Control Resource Set (CORESET), channel, or reference signal has a specific QCL (e.g., QCL type D) relationship with another CORESET, channel, or reference signal may be referred to as a QCL assumption.

[0018] The UE may determine at least one of a transmit beam (Tx beam) and a receive beam (Rx beam) for a signal / channel based on the TCI condition or QCL assumption of the signal / channel.

[0019] The TCI state may be, for example, information about the QCL between the target channel (in other words, the Reference Signal (RS) for the channel) and another signal (e.g., another RS). The TCI state may be set (indicated) by higher layer signaling, physical layer signaling, or a combination thereof.

[0020] The physical layer signaling may be, for example, Downlink Control Information (DCI).

[0021] 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)).

[0022] Furthermore, the RS that has 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), a Sounding Reference Signal (SRS), a CSI-RS for tracking (also called a Tracking Reference Signal (TRS)), and a QCL detection reference signal (also called a QRS).

[0023] An SSB is a signal block that includes at least one of a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and a Physical Broadcast Channel (PBCH). An SSB may also be referred to as an SS / PBCH block.

[0024] An RS of QCL type X in a TCI state may refer to an RS that has a relationship of QCL type X with (the DMRS of) a certain channel / signal, and this RS may be called a QCL source of QCL type X in the TCI state.

[0025] (Initial Access Procedures) In the initial access procedure, the UE (RRC_IDLE mode) receives the SS / PBCH block (SSB), transmits Msg.1 (PRACH / random access preamble / preamble), receives Msg.2 (PDCCH, PDSCH including random access response (RAR)), transmits Msg.3 (PUSCH scheduled by RAR UL grant), and receives Msg.4 (PDCCH, PDSCH including UE contention resolution identity). After that, when the base station (network) transmits an ACK for Msg.4 from the UE, an RRC connection is established (RRC_CONNECTED mode).

[0026] SSB reception includes PSS detection, SSS detection, PBCH-DMRS detection, and PBCH reception. PSS detection detects part of the physical cell ID (PCI), detects (synchronizes) OFDM symbol timing, and performs (coarse) frequency synchronization. SSS detection includes detecting the physical cell ID. PBCH-DMRS detection includes detecting (part of) the SSB index within a half radio frame (5 ms). PBCH reception includes detecting the system frame number (SFN) and radio frame timing (SSB index), receiving configuration information for receiving remaining minimum system information (RMSI, SIB1), and recognizing whether the UE can camp on that cell (carrier).

[0027] SSB has a bandwidth of 20 RB and a time of 4 symbols. The transmission period of SSB can be set to {5, 10, 20, 40, 80, 160} ms. In the half frame, multiple symbol positions of SSB are specified based on the frequency range (FR1, FR2).

[0028] The PBCH has a payload of 56 bits. N repetitions of the PBCH are transmitted within a period of 80 ms, where N depends on the SSB transmission period.

[0029] The system information consists of the MIB, RMSI (SIB1), and other system information (OSI) carried by the PBCH. SIB1 contains information for RACH configuration and RACH procedures. The time / frequency resource relationship between the SSB and the PDCCH monitoring resource for SIB1 is configured by the PBCH.

[0030] A base station using beam correspondence transmits multiple SSBs using multiple beams in each SSB transmission period. The multiple SSBs have multiple SSB indices. When a UE detects an SSB, it transmits a PRACH in the RACH occasion associated with that SSB index and receives an RAR in the RAR window.

[0031] (Beam and Coverage) In high-frequency bands, if beamforming is not applied to synchronization signals / reference signals, coverage will be narrow, making it difficult for UEs to find base stations. On the other hand, if beamforming is applied to synchronization signals / reference signals to ensure coverage, a strong signal will reach a specific direction, but the signal will be even less likely to reach other directions. If the base station does not know the direction of the UE before it connects, it is impossible to transmit synchronization signals / reference signals using beams pointing only in the appropriate direction. One possible method is for the base station to transmit multiple synchronization signals / reference signals, each with a beam pointing in a different direction, and for the UE to recognize which beam it has found. Using thin (narrow) beams for coverage requires transmitting many synchronization signals / reference signals, which increases overhead and may reduce frequency utilization efficiency.

[0032] In order to reduce the number of beams (synchronization signals / reference signals) and reduce overhead, using a thick (wide) beam results in a narrower coverage area.

[0033] In future wireless communication systems (e.g., 6G), it is expected that the use of frequency bands such as millimeter waves and terahertz waves will become more widespread. It is conceivable that communication services will be provided by constructing cell areas / coverage using multiple narrow beams.

[0034] It is possible to expand the coverage area by using the existing FR2, or to use a higher frequency band than the existing FR2. To achieve this, it is desirable to improve beam management in addition to multi-TRP, reconfigurable intelligent surface (RIS), etc.

[0035] Coverage extensions are being considered, including PRACH extensions for frequency range (FR) 2. For example, PRACH repetition using the same beam or different beams is being considered. This PRACH extension may also be applied to FR1.

[0036] The PRACH extension may be applied to the short PRACH format or to other formats.

[0037] As shown in the example of Figure 1, the common RACH configuration (RACH-ConfigCommon) may include a general RACH configuration (rach-ConfigGeneric), a total number of RA preambles (totalNumberOfRA-Preambles), and an SSB per RACH occasion and a contention-based (CB) preamble per SSB (ssb-perRACH-OccasionAndCB-PreamblesPerSSB). rach-ConfigGeneric may include a PRACH configuration index (prach-ConfigurationIndex) and a message 1 FDM (msg1-FDM, the number of PRACH occasions FDMed in one time instance). ssb-perRACH-OccasionAndCB-PreamblesPerSSB may include the number of CB preambles per SSB for one Eighth SSBs per RACH occasion (one Eighth, one SSB associated with eight RACH occasions).

[0038] For a Type 1 random access procedure (four-step random access procedure, messages 1 / 2 / 3 / 4), the UE may apply the number N of SS / PBCH blocks associated with one PRACH occasion and the number R of CB preambles per SS / PBCH block per enabled PRACH occasion via ssb-perRACH-OccasionAndCB-PreamblesPerSSB.

[0039] For a Type 1 random access procedure, or for a Type 2 random access procedure with PRACH occasion configuration independent of the Type 1 random access procedure (two-step random access procedure, messages A / B), if N<1, one SS / PBCH block is mapped to 1 / N consecutive valid RACH occasions, and for each valid PRACH occasion, R CB preambles with consecutive indices associated with the SS / PBCH block index are provided, starting with preamble index 0. If N>=1, R CB preambles with consecutive indices associated with the SS / PBCH block index n (0<=n<-N-1) are provided, starting with preamble index n·N_preamble^total / N, where N_preamble^total is given by totalNumberOfRA-Preambles for a Type 1 random access procedure, and by msgA-TotalNumberOfRA-Preambles for a Type 2 random access procedure with PRACH occasion configuration independent of the Type 1 random access procedure. N_preamble^total is a multiple of N.

[0040] Starting from frame 0, the association period for mapping SS / PBCH blocks to PRACH occasions is the smallest value in the set determined by the PRACH configuration period according to the relationship (defined in the specification) between the PRACH configuration period and the association period (number of PRACH configuration periods) such that N_Tx^SSB SS / PBCH block indices are mapped to a PRACH occasion at least once within the association period. Here, the UE derives N_Tx^SSB from the value of SSB positions in burst (ssb-PositionsInBurst) in SIB1 or in the common serving cell configuration (ServingCellConfigCommon). If, after an integer number of mapping cycles from SS / PBCH block indices to PRACH occasions within the association period, there is a set of PRACH occasions or PRACH preambles that are not mapped to N_Tx^SSB SS / PBCH block indices, then no SS / PBCH block index is mapped to that set of PRACH occasions or PRACH preambles. The association pattern period includes one or more association periods and is determined such that the pattern between PRACH occasions and SS / PBCH block indices repeats at most every 160 ms. If, after an integer number of association periods, there is a PRACH occasion that is not associated with an SS / PBCH block index, that PRACH occasion is not used for PRACH.

[0041] For PRACH configuration periods of 10, 20, 40, 80, and 160 msec, the association periods are {1,2,4,8,16}, {1,2,4,8}, {1,2,4}, {1,2}, and {1}, respectively.

[0042] FIG. 2A shows an example (mapping 1) of association of PRACH occasions (RACH occasions (ROs)) and beams (SSB / CSI-RS). When ssb-perRACH-OccasionAndCB-PreamblesPerSSB indicates oneHalf,n16 (N=½, R=16) and msg1-FDM is 4, four ROs are FDM-multiplexed in one time instance, and one SSB is mapped to two ROs. Preamble indexes 0 to 15 are associated with two ROs, and preamble indexes 0 to 15 are associated with SS0B. In this way, when N<1, one SSB is mapped to multiple ROs. This increases the capacity of ROs per beam.

[0043] FIG. 2B shows another example (mapping 2) of RO-to-beam association. When ssb-perRACH-OccasionAndCB-PreamblesPerSSB indicates n4,n16 (N=4, R=16), msg1-FDM is 4, and N_preamble^total is 64, four ROs are FDM-multiplexed in one time instance, and four SSBs are mapped to one RO. Each RO is associated with SSBs 0 to 3. Preamble indices 0 to 15 are associated with SSB 0, preamble indices 15 to 31 are associated with SSB 1, preamble indices 32 to 47 are associated with SSB 2, and preamble indices 48 to 63 are associated with SSB 3. In this way, the same RO is associated with different SS / PBCH block indices, and different preambles use different SS / PBCH block indices. The base station can distinguish the associated SS / PBCH block indices based on the received PRACH.

[0044] The random access preamble can only be transmitted in the time resources specified in the random access configuration of the specification, and depends on whether FR1 or FR2 and the spectrum type (paired spectrum / supplementary uplink (SUL) / unpaired spectrum). The PRACH configuration index is given by the higher layer parameter prach-ConfigurationIndex or, if configured, by msgA-PRACH-ConfigurationIndex. In the specification, each value of the PRACH configuration index is associated with at least one of the following: preamble format, x and y in n_f (frame number) mod x = y, subframe number, starting symbol, number of PRACH slots in a subframe, number of time-domain PRACH occasions in a PRACH slot N_t^RA,slot, and PRACH duration N_dur^RA (Figure 3).

[0045] Whether PRACH repetition is applicable to a scenario, the type of RACH procedure triggered by different purposes is different. The type of RACH procedure may be at least one of the following: Contention-free random access (CFRA), PDCCH ordered RA (RA initiated by a PDCCH order), CFRA for beam failure recovery (BFR), CFRA for system information (SI) request, CFRA for reconfiguration with sync, etc. Contention-based random access (CBRA), RA triggered by the MAC entity, RA triggered by RRC with events, CBRA for BFR, etc. 4-step RACH. · 2-step RACH.

[0046] However, the settings / procedures for PRACH repetition are unclear. For example, it is unclear how PRACH resources for repetition (e.g., repetition pattern, repetition number) are set, the UE operation of preamble repetition transmission, the impact on counters / timers related to RACH, etc. If such settings / procedures are unclear, there is a risk of degradation in communication quality / communication throughput.

[0047] (RA response window) RA Response Window (ra-ResponseWindow) is the time window for monitoring RA Responses (RAR) (SpCell only). RA Contention Resolution Timer (ra-ContentionResolutionTimer) is the timer for RA contention resolution (SpCell only). Msg.B Response Window is the time window for monitoring RA Responses (RAR) for 2-step RA types (SpCell only).

[0048] Once the RA preamble is transmitted, the MAC entity performs the following actions 1 to 3, regardless of whether a measurement gap may occur.

[0049] [Operation 1] If a contention-free RA preamble for a BFR request is transmitted by the MAC entity, the MAC entity performs the following operations 1-1 and 1-2. [[Operation 1-1]] The MAC entity starts the ra-ResponseWindow set in the BFR configuration (BeamFailureRecoveryConfig) on ​​the first PDCCH occasion after the end of the RA preamble transmission. [[Operation 1-2]] While the ra-ResponseWindow is running, the MAC entity monitors PDCCH transmissions in the search space indicated by the BFR search space ID (recoverySearchSpaceId) of the SpCell identified by the C-radio network temporary identifier (RNTI).

[0050] [Operation 2] If not, the MAC entity performs the following operations 2-1 and 2-2. [[Operation 2-1]] The MAC entity starts the ra-ResponseWindow configured in the common RACH configuration (RACH-ConfigCommon) on the first PDCCH occasion after the end of the RA preamble transmission. [[Operation 2-2]] The MAC entity monitors the PDCCH transmission of the SpCell for the RAR identified by the RA-RNTI while the ra-ResponseWindow is running.

[0051] [Operation 3] If the ra-ResponseWindow configured in BeamFailureRecoveryConfig expires and a PDCCH transmission on the search space indicated by recoverySearchSpaceId addressed to the C-RNTI is received on the serving cell on which the preamble was transmitted, or if the ra-ResponseWindow configured in RACH-ConfigCommon expires and an RAR is received containing RA preamble identifiers matching the transmitted preamble index (PREAMBLE_INDEX), the MAC entity shall consider the RAR reception as a failure and increment the preamble transmission counter (PREAMBLE_TRANSMISSION_COUNTER) by 1.

[0052] The MAC entity may stop the ra-ResponseWindow (stop monitoring for RARs) after successful reception of an RAR containing RA preamble identifiers matching the transmitted PREAMBLE_INDEX.

[0053] For PDCCH monitoring within the RA response window, there are two cases: PDCCH for the base station's response to BFR and PDCCH for RAR. The following content may apply to both cases.

[0054] When the MSGA (Msg. A) preamble is transmitted, the MAC entity performs the following actions 4 to 6, regardless of whether a measurement gap may occur.

[0055] [Operation 4] The MAC entity starts the Msg.B response window (msgB-ResponseWindow) in the PDCCH monitoring window defined in the specification.

[0056] The msgB-ResponseWindow may start at the first symbol of the earliest CORESET for which the UE is configured to receive a PDCCH for a Type 1-PDCCH CSS set, which is at least one symbol after the last symbol of the PRACH occasion corresponding to the PRACH transmission. The length of the msgB-ResponseWindow may correspond to the SCS for the Type 1-PDCCH CSS set.

[0057] [Operation 5] The MAC entity monitors the PDCCH transmission of the SpCell for RAR identified by MSGB-RNTI while the msgB-ResponseWindow is running.

[0058] [Operation 6] If a C-RNTI MAC CE is included in its MSGA, the MAC entity monitors the PDCCH transmission of the SpCell for the RAR identified by the C-RNTI while the msgB-ResponseWindow is running.

[0059] The RA-RNTI associated with the PRACH occasion on which the RA preamble is transmitted is calculated as follows: RA-RNTI = 1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id

[0060] where s_id is the index of the first OFDM symbol of the PRACH occasion (0<=s_id<14). t_id is the index of the first slot of the PRACH occasion in the system frame (0<=t_id<80). The subcarrier spacing (SCS) for determining t_id is based on the value of μ. f_id is the index of the PRACH occasion in the frequency domain (0<=f_id<8). ul_carrier_id is the UL carrier used for RA preamble transmission (0 for normal uplink (NUL) carrier, 1 for supplementary uplink (SUL) carrier). RA-RNTI is calculated according to the specification. RA-RNTI is the RNTI for 4-step RACH.

[0061] The MSGB-RNTI associated with the PRACH occasion on which the RA preamble is transmitted is calculated as follows: MSGB-RNTI = 1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id+14×80×8×2

[0062] Here, s_id is the index of the first OFDM symbol of the PRACH occasion (0 <= s_id < 14). t_id is the index of the first slot of the PRACH occasion within the system frame (0 <= t_id < 80). The subcarrier spacing (SCS) for the determination of t_id is based on the value of μ. f_id is the index of the PRACH occasion in the frequency domain (0 <= f_id < 8). ul_carrier_id is the UL carrier used for RA preamble transmission (0 for normal uplink (NUL) carrier and 1 for supplementary uplink (SUL) carrier). MSGB-RNTI is the RNTI for two-step RACH.

[0063] (PDCCH order) <DCI format for PDCCH order> [[ID=⑧]]DCI format 1_0 includes an identifier field of the DCI format, a bit field always set to 1, and a frequency domain resource assignment field. The cyclic redundancy check (CRC) of DCI format 1_0 is scrambled by C-RNTI. When the frequency domain resource assignment field is all 1, that DCI format 1_0 is for the random access procedure started by the PDCCH order, and the remaining fields are the random access preamble, UL / supplementary Uplink (SUL) indicator, SS / PBCH index (SSB index), PRACH mask index, reserved bits (12 bits).

[0064] <PRACH occasion> It should be noted that in the original text, "⑧" in [[ID=⑧]] seems to be a mislabeling. It should probably be . This has been maintained in the translation for consistency with the original text.For a PRACH transmission triggered by a PDCCH order, the PRACH mask index field indicates the PRACH occasion of the PRACH transmission associated with the SS / PBCH block i index indicated by the SS / PBCH block index field of the PDCCH order if the value of the random access preamble index field is not zero.

[0065] For PRACH transmissions triggered by higher layers (PRACH transmissions not triggered by a PDCCH order), if ssb-ResourceList is provided, the PRACH mask index is indicated by ra-ssb-OccasionMaskIndex, which indicates the PRACH occasion for the PRACH transmission associated with the selected SS / PBCH block index.

[0066] The PRACH occasions are mapped consecutively for each corresponding SS / PBCH block index. The indexing of the PRACH occasions indicated by the mask index value is reset for each SS / PBCH block index and for each successive PRACH occasion mapping cycle. In the first available mapping cycle, the UE selects for PRACH transmission the PRACH occasion indicated by the PRACH mask index value for the indicated SS / PBCH block index.

[0067] For the indicated preamble index, the order of the PRACH occasions is as follows: First, in increasing order of frequency resource index for frequency multiplexed PRACH occasions. Second, in increasing order of time resource index for time multiplexed PRACH occasions within a PRACH slot. ·Third, in ascending order of PRACH slot index.

[0068] For a PRACH transmission triggered in response to a request from the upper layer, if a csirs-ResourceList is provided, the value of ra-OccasionList indicates a list of PRACH occasions for the PRACH transmission, and the PRACH occasion is associated with the selected CSI-RS index indicated by the csi-RS. The indexing of the PRACH occasions indicated by ra-OccasionList is reset for each association pattern period.

[0069] Figure 4 is a diagram showing an example of a PRACH mask index value. The PRACH mask index value / msgA-SSB-SharedRO-MaskIndex value is associated with the allowed PRACH occasions (values of the PRACH occasion index) of the SSB.

[0070] <Random Access Procedure in the MAC Entity> The random access procedure is started by a PDCCH order, the MAC entity itself, or the RRC for events compliant with the specification. Within the MAC entity, only one random access procedure can be in progress at any given time. The random access procedure for a SCell is started only by a PDCCH order with a ra-PreambleIndex different from 0b000000.

[0071] When a random access procedure is started on the serving cell, the MAC entity performs the following. · If the random access procedure is started by a PDCCH order and the ra-PreambleIndex explicitly provided by the PDCCH is not 0b000000, or if the random access procedure is started for reconfiguration with synchronization and a contention-free random access resource of the 4-step RA type is explicitly provided by rach-ConfigDedicated for the BWP selected for the random access procedure. Set RA_TYPE to 4-stepRA.

[0072] When the selected RA_TYPE is set to 4-stepRA, the MAC entity performs the following. · If ra-PreambleIndex is explicitly provided from the PDCCH and ra-PreambleIndex is not 0b000000, set PREAMBLE_INDEX to the notified ra-PreambleIndex and select the SSB notified by the PDCCH. · When the SSB is selected as above, determine the next available PRACH occasion from the PRACH occasions permitted by the restrictions given by ra-ssb-OccasionMaskIndex and corresponding to the selected SSB (the MAC entity randomly selects a PRACH occasion with equal probability from among consecutive PRACH occasions corresponding to the selected SSB according to the specification. The MAC entity may consider the possibility of the occurrence of a measurement gap when determining the next available PRACH occasion corresponding to the selected SSB).

[0073] <Time between PDCCH order reception and PRACH transmission> If the random access procedure is initiated by a PDCCH order, the UE shall transmit the PRACH within the selected PRACH occasion when the time between the last symbol of the PDCCH order reception and the first symbol of the PRACH transmission is greater than or equal to N_(T,2)+Δ_BWPSwitching+Δ_Delay+T_switch [msec] (time condition) as described in the specification, if required by the upper layer. Here, N_(T,2) is the duration of N_2 symbols corresponding to the PUSCH preparation time of UE processing capability 1. Assume that μ corresponds to the minimum SCS setting between the subcarrier spacing (SCS) setting of the PDCCH order and the SCS setting of the corresponding PRACH transmission. If the active UL BWP does not change, Δ_BWPSwitching = 0; otherwise, Δ_BWPSwitching is defined in the specification. In FR1, Δ_delay = 0.5 msec, and in FR2, Δ_delay = 0.25 msec. T_switch is the switching gap duration defined in the specification.

[0074] <Valid / Invalid Conditions of PRACH Occasion (Valid Conditions)> In paired spectrum (FDD) or SUL band, all PRACH occasions are valid. In unpaired spectrum (TDD), the PRACH occasion may follow the following Provisions 1 and 2. [Provision 1] If the UE is not configured with tdd-UL-DL-ConfigurationCommon, a PRACH occasion in a PRACH slot is valid if it does not precede an SS / PBCH block in the PRACH slot and starts at least N_gap symbols after the last SS / PBCH block received symbol, where N_gap is specified in the specification. If channelAccessMode=semistatic is configured, it does not overlap with the set of consecutive symbols before the start of the next channel occupation period in which the UE does not transmit. The candidate SS / PBCH block index of an SS / PBCH block corresponds to the SS / PBCH block index provided by ssb-PositionsInBurst in SIB1 or in ServingCellConfigCommon. [Regulation 2] If the UE is provided with tdd-UL-DL-ConfigurationCommon, a PRACH occasion in a PRACH slot is valid if: The PRACH occasion is within a UL symbol, or The PRACH occasion does not precede an SS / PBCH block in the PRACH slot and starts at least N_gap symbols after the last DL symbol and at least N_gap symbols after the last SS / PBCH block symbol, where N_gap is specified in the specification. If channelAccessMode=semistatic is provided, the PRACH occasion does not overlap with the set of consecutive symbols before the start of the next channel occupation period during which there must be no transmission, as specified in the specification. The candidate SS / PBCH block indices for the SS / PBCH blocks correspond to the SS / PBCH block indices provided by ssb-PositionsInBurst in SIB1 or in ServingCellConfigCommon, as specified in the specification.

[0075] (RAR reception and QCL assumed) In response to a PRACH transmission, the UE attempts to detect DCI format 1_0 with CRC scrambled by the corresponding RA-RNTI within the window controlled by the above-mentioned higher layers. The window starts at the first symbol of the earliest CORESET for which the UE is configured to receive a PDCCH for the Type 1-PDCCH CSS set, i.e., at least one symbol after the last symbol of the PRACH occasion corresponding to the PRACH transmission. The symbol period corresponds to the SCS for the Type 1-PDCCH CSS set. The length of the window is based on the SCS for the Type 1-PDCCH CSS set and is given by ra-responseWindow as the number of slots.

[0076] If the UE detects DCI format 1_0 with a CRC scrambled by the corresponding RA-RNTI and with least significant bits (LSBs) of the system frame number (SFN) field in that DCI format that are the same as the LSBs of the SFN with which the UE transmitted the PRACH, and the UE receives a transport block in the corresponding PDSCH, the UE may assume the same DMRS antenna port QCL properties for the SS / PBCH block or CSI-RS resource with which the UE associates the PRACH, regardless of whether the UE is provided with a TCI-State for the CORESET with which it receives the PDCCH with that DCI format 1_0.

[0077] If the UE attempts to detect DCI format 1_0 with a CRC scrambled by the corresponding RA-RNTI in response to a PRACH transmission initiated by a PDCCH order that triggers a CFRA procedure for an SpCell, the UE may assume that the PDCCH containing that DCI format 1_0 and that PDCCH order have the same DMRS antenna port QCL properties. If the UE attempts to detect DCI format 1_0 with a CRC scrambled by the corresponding RA-RNTI in response to a PRACH transmission initiated by a PDCCH order that triggers a CFRA procedure for a secondary cell, the UE may assume the DMRS antenna port QCL properties of the CORESET associated with the Type 1-PDCCH CSS set for reception of the PDCCH containing that DCI format 1_0.

[0078] If the preamble is repeated with different beams (on different SSBs or different ROs associated with different CSI-RSs), the UE may assume different QCLs (e.g., beams) for receiving Msg2 (e.g., base station response to RAR, BFR). For a UE with limited coverage, the purpose of PRACH repetition with different beams is to improve the decoding performance of the base station (assuming beam correspondence at the UE and the same DL / UL beams at the UE). It does not mean that the UE can decode DL reception with different beams. That is, the following observation 1 is obtained.

[0079] [View 1] For Msg2 reception after PRACH repetitions with different beams, it is preferable for the UE to monitor Msg2 with one beam (at least in FR2).

[0080] Based on View 1, it is necessary for the base station and the UE to have a common understanding of the QCL assumption for Msg2 reception. It is not clear how to achieve a common understanding of the QCL assumption for PRACH repetitions with different multiple beams. That is, the following View 2 is obtained.

[0081] [View 2] If the UE assumes one QCL assumption for reception (at least in FR2), the base station and the UE should have a common understanding of the QCL assumption for Msg2 reception. CFRA can more easily create a common understanding.

[0082] CBRA is mainly initiated by MAC / RRC. CFRA can be initiated by PDCCH order or MAC / RRC (e.g., BFR, listen before transmission (LBT) failure, system information (SI) request, etc.). For different cases, the solutions to the following problems are not clear: · Whether PRACH repetitions with different multiple beams are applied or not. Determining the different multiple beams available and the number of repetitions available with the different multiple beams. ·Determine QCL assumptions for Msg2 reception.

[0083] Here, we assume the same beam for DL ​​and UL at the UE and one QCL assumption for the reference beam for RAR reception. However, due to maximum permitted exposure (MPE) / maximum power reduction (MPR), different best beams may be possible for DL ​​and UL. In addition to PRACH coverage extension, PRACH with different beams can be used to improve the UL beam. Here, the following assumptions 1 and 2 are considered.

[0084] [DL / UL beam assumption 1] The existing PRACH is performed to identify the best DL beam, in which case additional PRACH repetitions with different beams (CFRA or CBRA) may be triggered for UL beam management.

[0085] [DL / UL beam assumption 2] The following embodiment #1 / #2 is used for PRACH repetitions with different beams. In this case, a reference resource / reference beam is indicated, and the QCL assumption of Msg2 is assumed to be the same as the reference beam. Therefore, the best DL beam is identified as the same as the reference beam. In this case, an extension to further realize UL beam management is considered.

[0086] In this way, the operation regarding the PRACH repetition with different beams is not clear, and if such operation is not clear, there is a risk of degradation in communication quality / communication throughput.

[0087] Therefore, the present inventors have conceived an operation for PRACH repetition involving multiple different beams, which can improve the reception performance of the PRACH at the base station and improve the coverage of the PRACH.

[0088] Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the drawings. Wireless communication methods according to the embodiments may be applied independently or in combination.

[0089] In the present disclosure, "A / B" and "at least one of A and B" may be interpreted interchangeably. Also, in the present disclosure, "A / B / C" may mean "at least one of A, B, and C."

[0090] In the present disclosure, terms such as activate, deactivate, indicate (or indicate), select, configure, update, and determine may be read interchangeably. In the present disclosure, terms such as support, control, controllable, operate, and operate may be read interchangeably.

[0091] In the present disclosure, Radio Resource Control (RRC), RRC parameters, RRC messages, higher layer parameters, information elements (IEs), configurations, etc. may be interchangeable. In the present disclosure, Medium Access Control (MAC) control elements (CEs), update commands, activation / deactivation commands, etc. may be interchangeable.

[0092] In the present disclosure, 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 thereof.

[0093] In the present disclosure, MAC signaling may use, for example, a MAC Control Element (MAC CE), a MAC Protocol Data Unit (PDU), etc. Broadcast information may be, for example, a Master Information Block (MIB), a System Information Block (SIB), Remaining Minimum System Information (RMSI), Other System Information (OSI), etc.

[0094] In the present disclosure, physical layer signaling may be, for example, Downlink Control Information (DCI), Uplink Control Information (UCI), and the like.

[0095] In this disclosure, the terms index, identifier (ID), indicator, resource ID, etc. may be interchangeable. In this disclosure, the terms sequence, list, set, group, cluster, subset, etc. may be interchangeable.

[0096] In this disclosure, the terms panel, UE panel, panel group, beam, beam group, precoder, Uplink (UL) transmitting entity, Transmission / Reception Point (TRP), base station, Spatial Relation Information (SRI), spatial relation, SRS Resource Indicator (SRI), Control Resource Set (CORESET), Physical Downlink Shared Channel (PDSCH), Codeword (CW), Transport Block (TB), Reference Signal (RS), antenna port (e.g., Demodulation Reference Signal (DMRS) port), antenna port group (e.g., DMRS port group), group (e.g., spatial relation group, Code Division Multiplexing (CDM) group, reference signal group, CORESET group, Physical Uplink Control Channel (PUCCH) group, PUCCH resource group), resource (e.g., reference signal resource, SRS resource), resource set (e.g., reference signal resource set), CORESET pool, downlink Transmission Configuration Indication state (TCI state) (DL TCI state), uplink TCI state (UL TCI state), unified TCI state, common TCI state, Quasi-Co-Location (QCL), QCL assumption, etc. may be read as interchangeable.

[0097] In the present disclosure, the SSB / CSI-RS index / indicator, beam index, and TCI state may be read interchangeably.

[0098] (Wireless communication method) In each embodiment, the terms period, cycle, frame, subframe, slot, symbol, occasion, and RO may be interchangeable.

[0099] In each embodiment, the terms "repetition period," "repetition configuration period," "repetition periodicity," and "repetition cycle" may be interchangeable.

[0100] In each embodiment, occasion, RACH occasion (RO), PRACH occasion, repetition resource, repetition configured resource, RO / repetition configured resource, time instance and frequency instance, time resource and frequency resource, RO / preamble resource may be read as interchangeable.

[0101] In each embodiment, the remaining RO, the RO after the next available RO, and the RO that satisfies the time condition may be read interchangeably.

[0102] In each embodiment, the terms RO indexing and repeating resource pattern may be interchangeable.

[0103] In each embodiment, the PDCCH order, PDCCH order DCI, DCI format 1_0, and message (Msg.) 0 may be interchangeable. In each embodiment, the PRACH, preamble, PRACH preamble, sequence, preamble format, and Msg. 1 may be interchangeable. In each embodiment, the response to the PRACH, RAR, Msg. 2, Msg. B, Msg. 4, base station response to BFR, and DCI scheduling the response may be interchangeable. In each embodiment, transmission other than the PRACH in the random access procedure, Msg. 3, PUSCH scheduled by RAR, HARQ-ACK / PUCCH for Msg. 4, and Msg. A PUSCH may be interchangeable.

[0104] In each embodiment, the terms beam, SSB, and SSB index may be interchangeable.

[0105] In each embodiment, repetition, repetition with the same beam, repetition RO with the same beam, and repetition associated with the same SSB index may be read interchangeably.

[0106] In each embodiment, the terms random access (RA) procedure, CFRA / CBRA, 4-step RACH / 2-step RACH, a specific type of random access procedure, a random access procedure using a specific PRACH format, a random access procedure initiated by a PDCCH order, a random access procedure not initiated by a PDCCH order, and a random access procedure initiated by a higher layer may be interchangeable.

[0107] In each embodiment, the terms reference resource, reference beam, resource corresponding to the reference beam, designated resource, designated beam, selected resource, and selected beam may be interchangeable.

[0108] The UE may receive configuration for multiple repetitions of the PRACH and may control transmission of the multiple repetitions with different beams.

[0109] The UE may transmit multiple repetitions of the PRACH using different beams, and may control reception of responses to the PRACH within one or more windows.

[0110] The UE may transmit multiple repetitions of the PRACH using different beams, and may determine a subsequent UL beam based on receiving a response to the PRACH.

[0111] The UE may transmit multiple repetitions of the PRACH using different beams, determine a reference beam corresponding to one of the different beams, and determine a subsequent UL beam based on receiving a response to the PRACH using the reference beam.

[0112] <Embodiment 0> In the following embodiments #A0 to #A10, the applicability of PRACH repetition with the same beam or different beams is described for the following cases: · 2-step RACH / 4-step RACH. ·CFRA / CBRA. · Different PRACH formats. ·UE of RRC IDLE / RRC INACTIVE / RRC CONNECTED.

[0113] The applicability of PRACH repetition with the same beam or different beams may be defined for the following cases, for which new restrictions may be defined in the specification, new UE capabilities may be defined, or RRC configuration signaling may be defined: FR1 / FR2 / FR2-1 / FR2-2 / FRx. RA procedures (CBRA / CFRA) triggered by different purposes (PDCCH order PRACH, BFR, LBT failure, SI request, UL unsync, UL data transmission in the absence of SR).

[0114] PRACH repetitions with different multiple beams may be applied only to specific RA schemes (e.g., only at least one of CFRA, PDCCH order RA, RA for BFR, RA for LBT failure, RA for SI request, RA for UL synchronization loss, RA for UL data transmission in the absence of SR).

[0115] According to this embodiment, for a particular RA, the UE can appropriately determine the PRACH repetitions with the same beam or different beams.

[0116] <Embodiment 1> If PRACH repetitions with different beams are configured / enabled for a certain purpose in the SIB / RRC IE from among the resources of the RO / preamble associated with the SSB / CSI-RS, and if at least one resource of the RO / preamble is selected by the UE in a repetition, the at least one resource may be indicated as the reference resource, and the associated beam (SSB / CSI-RS) may become the reference beam for the repetition. For a repetition, the reference beam may be assumed by the UE as the QCL for receiving Msg2, such as RAR and BFR, after the PRACH repetitions with different beams.

[0117] The reference resource of the RO / preamble for each SSB / CSI-RS may be explicitly configured by RRC or may be specified based on a rule. The index of the RO / preamble corresponding to each beam may be considered as the reference resource for each beam. The rule may, for example, select the resource corresponding to the minimum or maximum index of the beam / RO / preamble / resource as the reference resource.

[0118] When the UE determines X repetitions with different beams for each repetition for the selected beam and selected RO / preamble resource for PRACH transmission, only the reference resource of one beam may be selected for PRACH transmission so that there is only one QCL assumption for Msg2 reception. If the reference resource of more than one beam is allowed to be selected for transmission of one repetition, a rule for determining the QCL assumption for Msg2 reception may be defined. The rule may, for example, select the resource corresponding to the minimum or maximum index of the beam / RO / preamble as the reference resource.

[0119] It may be assumed that the UE uses the same preamble for multiple repetitions with different beams. If different preambles are used by the UE for multiple repetitions, it may be difficult for the base station to know that the preambles for the multiple repetitions are from the same UE, and the base station may not be able to perform decoding combination for the different preambles. If the preamble for multiple repetitions is the same, these problems may be mitigated.

[0120] FIG. 5 shows an example of RA configuration for BFR. One or more RO / preamble indices are associated with each beam (SSB index). Of the one or more indices, one index of the reference resource for the RO / preamble is configured by an RRC IE. In this example, resources #0a, #0b, #0c, and #0d are associated with SSB #0, and reference resource #0a is configured. In this example, resources #1a, #1b, #1c, and #1d are associated with SSB #1, and reference resource #1a is configured. In this example, resources #2a, #2b, #2c, and #2d are associated with SSB #2, and reference resource #2b is configured. In this example, resources #3a, #3b, #3c, and #3d are associated with SSB #3, and reference resource #3c is configured. For this configuration, the following examples 1 to 3 are considered.

[0121] [Example 1] The UE selects SSB#0 and #1 for preamble repetition and transmits PRACH on resources #0a (reference resource) and #1c (non-reference resource). The UE assumes the same QCL as SSB#0 for Msg2 reception.

[0122] [Example 2] The UE selects SSBs #0 and #1 for preamble repetitions and transmits PRACH on resources #0a (reference resources) and #1a (reference resources). The UE does not select resources #0a and #1a (reference resources of two beams) in one repetition.

[0123] [Example 3] The UE selects SSBs #0, #1, #2, and #3 for preamble repetition and transmits PRACH on resources #0b, #1c, #2b (reference resource), and #3d. The UE assumes the same QCL as SSB #2 for Msg2 reception.

[0124] According to this embodiment, the UE can properly determine the resources / beams for PRACH repetitions with different multiple beams.

[0125] <Embodiment 2> The above embodiment #1 is applicable to PDCCH-ordered PRACH and other CFRA / CBRA triggered by MAC / RRC. However, several other options are possible for PDCCH-ordered PRACH.

[0126] In the PDCCH order PRACH, the following solution may be used for the selected beam and the reference beam for the QCL assumption for Msg2.

[0127] 《Solution 1》 For beams selected for PRACH repetitions with different beams, PDCCH order DCI format 1_0 may indicate one or more additional fields of beam index (SSB index, 'SS / PBCH index') to indicate more than one beam for PRACH repetitions with different beams. The number of additional beam index indications may be configured by RRC or defined in the specifications. The number of additional beam index indications may be one, two, or more than two. The additional one or more fields may reuse at least a part of the 12 or 10 reserved bits. The additional one or more fields may follow either of fields 1 and 2 below. [Field 1] For one field of 'SS / PBCH index', the field size may be the existing 6 bits. [Field 2] For one field, 'SS / PBCH index', the field size may be set by RRC or determined according to the SSB configuration (e.g., SSB-PositionInBurst). If the number of SSBs transmitted is smaller, the field size may be smaller than 6 bits.

[0128] 《Solution 2》 For QCL assumption for Msg2 reception, if there are multiple SSB index fields in the PDCCH order DCI format 1_0, the UE may assume the SSB index of the first or last field among the multiple fields as the reference beam. When receiving the Msg2 PDCCH, the UE may assume the same QCL as the reference beam. In this case, it is not necessary to configure reference resources for each SSB.

[0129] The QCL assumption of PDCCH order DCI format 1_0 may be assumed by the UE as the reference beam for QCL assumption for Msg2 reception.

[0130] According to this embodiment, the UE can properly determine the beam for PRACH repetition / Msg2 with different multiple beams initiated by the PDCCH order.

[0131] <Embodiment 3> A new repetition resource configuration may be defined for the configuration of repetition patterns or repetition resources for PRACH repetitions with different multiple beams. The PRACH association period, PRACH configuration period, or PRACH occasion mapping cycle in the existing SIB / RRC may be considered as the PRACH repetition period. The UE may select multiple beams for RA preamble repetition from the PRACH repetition period.

[0132] The repetition number X may be the number of different beams selected by the UE for repetition with different beams.

[0133] The number of repetitions may be configured by an RRC IE / MAC CE, may be explicitly indicated in the PDCCH order DCI format 1_0, may be implicitly indicated by the number of SSB index fields in the PDCCH order DCI format 1_0 (similar to embodiment #B2 described later), or may be determined by the UE based on RSRP measurement results. As in embodiment #A2 / #A3 described later, the UE may determine X based on RSRP. There may be an association between the number of repetitions 1, 2, ..., X and the RO / preamble resources.

[0134] The rule for selecting multiple beams (SSB / CSI-RS) for one PRACH repetition by the UE may be either of the following selection rules 1 and 2.

[0135] [Selection Rule 1] The UE uses an existing method for selecting the N beams. For example, the existing method may be to select the N beams corresponding to measurements (e.g., RSRP) above a threshold. The existing method / threshold may be used with an existing threshold (e.g., rsrp-ThresholdSSB / rsrp-ThresholdCSI-RS) or new parameters for PRACH repetitions or new parameters for PRACH repetitions involving the same beam or different beams.

[0136] [Selection Rule 2] The UE uses an existing method for selecting a reference beam, and then the UE may follow either of the following selection rules 2-1 and 2-2. [[Selection Rule 2-1]] The UE selects N-1 iterative beams based on the new absolute RSRP threshold parameter. [[Selection Rule 2-2]] The UE selects N-1 repeat beams based on a new relative RSRP threshold parameter (e.g., rsrp-offset-ThresholdSSB / rsrp-offset-ThresholdCSI-RS) that is based on the offset relative to the reference beam. For example, a beam may be selected for repeat if the offset is less than or equal to 6 dB.

[0137] Considering that UEs within the coverage of SSB#A cannot detect SSB#M, there may be restrictions on the beams to be selected. In addition to selection rules 1 / 2, either of the following restriction methods 1 and 2 may be applied to further restrict the beams to be selected.

[0138] [Restriction method 1] The RRC configures multiple groups of beams, and in one iteration, the UE may select a beam in one group.

[0139] An example in which RRC configures multiple groups of SSBs / CSI-RS will be described below. Assuming SSBs #0-#15, group #1 includes SSBs #0, #1, #2, and #3, group #2 includes SSBs #4, #5, #6, and #7, group #3 includes SSBs #8, #9, #10, and #11, and group #4 includes SSBs #12, #13, #14, and #15.

[0140] [Restriction method 2] For each beam (particularly for selection rule 2), the RRC configures a list of beams associated with that beam. In one iteration, the UE may select a beam in one group. If one beam is selected by the UE as a reference beam, the UE may select the other N-1 beams from the list of beams configured by the RRC and associated with that reference beam.

[0141] An example will be described in which RRC sets a list of SSBs / CSI-RSs associated with each SSB. Assuming SSBs #0-#15, SSBs #14, #15, #1, and #2 are associated with SSB #0, SSBs #15, #0, #2, and #3 are associated with SSB #1, and so on. The SSB indices for the associations are incremented sequentially, and SSB #15 is associated with SSBs #13, #14, #0, and #1.

[0142] According to this embodiment, the UE can be appropriately configured with PRACH repetitions involving different beams.

[0143] <Embodiment 4> In the following embodiments #A0 to #A10, the start / restart of the RAR window for PRACH repetitions with the same beam is described. For example, the RAR window may start from the end of the first repetition, each repetition, or the last repetition. At least one of the methods in embodiments #A0 to #A10 may be applied to PRACH repetitions with different beams.

[0144] Meanwhile, taking into consideration the QCL assumption for Msg2 reception in embodiment #1 / #2, a new method for starting / restarting the RAR window for PRACH repetitions with different multiple beams may be defined.

[0145] The RAR window (ra-ResponseWindow) may start / restart at the first PDCCH occasion from the end of the RA preamble repetition of the reference resource or reference beam within one repetition. The RAR window (ra-ResponseWindow) may start / restart at the first PDCCH occasion from the end of one or more RA preamble repetitions after the RA preamble repetition of the reference resource or reference beam within one repetition (each RA preamble repetition after the RA preamble repetition of the reference resource or reference beam within one repetition).

[0146] Before the reference resource or reference beam is transmitted, the network does not know the QCL assumption for the RAR, so the network cannot send Msg2 to the UE, and the UE may not need to monitor the RAR.

[0147] A new RAR window for PRACH repetitions (e.g., ra-ResponseWindow-r18) may be introduced. Different new parameters may be introduced for PRACH repetitions with the same beam or different beams.

[0148] 6A to 6D, resource #0b of RO / preamble using beam of SSB#0, resource #1c of RO / preamble using beam of SSB#1, resource #2b of RO / preamble using beam of SSB#2, and resource #3d of RO / preamble using beam of SSB#3 are used for PRACH repetition transmission. Resource #2b may be the reference resource, and SSB#2 may be the reference beam.

[0149] 6A shows RAR window example 1. In this example, window operation 1 of embodiment #A8 described below is applied. The RAR window starts after the end of transmission of the last resource #3d.

[0150] Figure 6B shows RAR window example 2. In this example, case A of window operation 2 in embodiment #A8 described below is applied. The RAR window starts after the end of transmission for resources #0b, #1c, #2b, and #3d.

[0151] Figure 6C shows an example 3 of the RAR window. In this example, embodiment #4 is applied. The RAR window starts after the end of transmission on resources #2b and #3d, which correspond to the reference beam. The QCL assumption for RAR reception may be the same as that of SSB #2.

[0152] Figure 6D shows an example 4 of the RAR window. In this example, embodiment #4 is applied. The RAR window starts after the end of transmission of resource #2b corresponding to the reference beam. The QCL assumption for RAR reception may be the same as SSB #2.

[0153] Based on the repetition resource configuration for PRACH repetition with different beams in embodiment #4, the RO for each SSB is expected to be within a short duration without using a large gap as shown in the examples of Figures 6A to 6D.

[0154] 7A shows an example of SSB and RO association. ROs #0a, #0b, #0c, and #0d associated with SSB #0 and ROs #1a, #1b, #1c, and #1d associated with SSB #1 are arranged in a certain time resource. ROs #2a, #2b, #2c, and #2d associated with SSB #2 and ROs #3a, #3b, #3c, and #3d associated with SSB #3 are arranged in the following time resource. In the examples of FIGS. 7B, 8A, and 8B, among these ROs, ROs #0b, #1c, #2b, and #3d are used for PRACH repetition transmission.

[0155] 7B shows RAR window example 1. In this example, window operation 1 of embodiment #A8 described later is applied. The RAR window starts after the end of transmission of the last resources #2b and #3d.

[0156] 8A shows RAR window example 2. In this example, case A of window operation 2 in embodiment #A8 described later is applied. The RAR window starts after the end of transmission of resources #0b and #1c, and resources #2b and #3d.

[0157] Figure 8B shows an example 3 of the RAR window. In this example, embodiment #4 is applied. The RAR window starts after the end of transmission of resource #2b corresponding to the reference beam. The QCL assumption for RAR reception may be the same as SSB #2.

[0158] According to this embodiment, the UE can properly receive the RAR for PRACH repetitions with different beams.

[0159] <Embodiment 5> This embodiment relates to a combination of PRACH repetitions with the same beam and PRACH repetitions with different beams. A UE may support a combination of two or more repetitions with the same beam and one or more repetitions with one or more different beams.

[0160] It may be specified that the UE does not assume that PRACH repetitions with the same beam and PRACH repetitions with different beams are configured at the same time.

[0161] Separate UE capabilities may be defined / reported for support of PRACH repetition with the same beam and support of PRACH repetition with different beams. The UE may apply the supported PRACH repetition scheme without conditions / restrictions (at the UE's discretion). The UE may apply the supported PRACH repetition scheme subject to conditions / restrictions. The conditions / restrictions may be that RSRP / RSRQ is lower than a threshold or that the first PRACH transmission failed, i.e., Msg2 was not received.

[0162] The base station may be instructed / configured by the SIB / RRC configuration whether PRACH repetitions with the same beam or PRACH repetitions with different beams are used. This instruction / configuration may apply only to some scenarios, which may include at least one of handover and UL synchronization.

[0163] If this indication / configuration is not present, the UE may apply a default behavior, which may be one of the following: ·PRACH transmission for Rel.15 / 16 (no repetition). PRACH repetition with the same beam. · PRACH repetitions with different multiple beams.

[0164] According to this embodiment, the UE may suitably perform at least one of PRACH repetitions with the same beam and PRACH repetitions with different beams.

[0165] <Embodiment 10> This embodiment relates to DL / UL beam assumption 1 described above.

[0166] Option A After the PRACH repetitions of each beam, the UE may start an RAR window (ra-ResponseWindow) at the first PDCCH occasion from the end of each repetition of the RA preamble. The UE may assume that at most one Msg2 (e.g., RAR, base station response to BFR, etc.) is received within every RAR window. The UE may assume that the beam associated with the received Msg2 (PRACH repetition transmission beam) is the selected UL beam. The selected UL beam may be used as the default UL beam / QCL source for subsequent UL transmissions.

[0167] The QCL assumption of DL Msg2 may be the same as the selected DL beam identified in the previous existing 4-step RACH or in a previous operation, e.g., the beam of the PDCCH-ordered DCI that triggers the PDCCH-ordered PRACH repetition with different beams.

[0168] The selection of the UL beam may mean that the base station measures the PRACH preamble reception conditions, selects one preamble with good UL quality, and sends Msg2 within the RAR window for the selected good UL beam. If the base station sends Msg2 before the last PRACH repetition, the UL beam may not be the best beam, but it is a good enough UL beam.

[0169] If the RAR windows for each beam do not overlap, the timing of decoding Msg2 may be used to identify the UL beam corresponding to that Msg2.

[0170] 9A and 9B, the four UL beams used for the four repetitions of the PRACH correspond to SSBs #0, #1, #2, and #3, respectively, with SSB #1 being the best DL beam identified.

[0171] In the example of Figure 9A, four repetitions of the PRACH are transmitted in different time resource ROs. In this example, the UE starts an RAR window after each repetition. The four RAR windows are non-overlapping. Within each RAR window, the QCL assumption for DL ​​reception is SSB#1, which is the best DL beam. In this example, the UE decodes the RAR within the RAR window for SSB#2. This means that the selected good UL beam / UL QCL assumption is SSB#2.

[0172] If the RAR windows for each beam overlap, Msg2 for each beam may be identified by the RA-RNTI. For example, the parameters (s_id / t_id / f_id) used to calculate the RA-RNTI may be different for each iteration. This identification method may mean that the UE needs to attempt to receive multiple RA-RNTIs (CRCs scrambled with the RA-RNTIs, and DCIs with the CRCs) within the overlapping time period.

[0173] In the example of FIG. 9B, RO #0b associated with SSB #0 and RO #1c associated with SSB #1 are in the same time resource, followed by RO #2b associated with SSB #2 and RO #3d associated with SSB #3. In this example, the UE starts RAR window #0 after RO #0b, RAR window #1 after RO #1c, RAR window #2 after RO #2b, and RAR window #1 after RO #3d. RAR windows #0, #1, #2, and #3 overlap. When Msg2 for SSB #0 is transmitted within RAR window #0, RA-RNTI #0 is used. When Msg2 for SSB #1 is transmitted within RAR window #1, RA-RNTI #1 is used. When Msg2 for SSB #2 is transmitted within RAR window #2, RA-RNTI #2 is used. When Msg2 for SSB#3 is transmitted within RAR window#3, RA-RNTI#3 is used. Within each RAR window, the QCL assumption for DL ​​reception is SSB#1, which is the best DL beam. In this example, the UE uses a different RA-RNTI to decode Msg2 for each SSB. In this example, the UE decodes the RAR using RA-RNTI#3 for SSB#3. This means that the selected good UL beam / UL QCL assumption is SSB#3.

[0174] Option B After PRACH repetitions on different beams, the UE may start the RAR window (ra-ResponseWindow) at the first PDCCH occasion from the end of the last repetition transmission of the RA preamble. The UE may assume that at most one Msg2 (e.g., RAR, base station response to BFR, etc.) will be received within the RAR window. The UE may assume that the beam associated with the received Msg2 (PRACH repetition transmission beam) is the selected (best) UL beam. The selected UL beam may be used as the default UL beam / QCL source for subsequent UL transmissions.

[0175] The QCL assumption of DL Msg2 may be the same as the selected DL beam identified in the previous existing 4-step RACH or in a previous operation, e.g., the beam of the PDCCH-ordered DCI that triggers the PDCCH-ordered PRACH repetition with different beams.

[0176] The selection of the UL beam may mean that the base station measures the PRACH preamble reception conditions, selects one preamble with good UL quality, and sends Msg2 within the RAR window for the selected good UL beam.

[0177] The UE may need to attempt to receive all RA-RNTIs (CRCs scrambled by the RA-RNTIs, and DCIs each accompanied by the CRCs) for the preambles transmitted within the RAR window. The beam associated with the decoded Msg2 may be identified by the RA-RNTI (corresponding to the decoded Msg2). For example, the parameters (s_id / t_id / f_id) used to calculate the RA-RNTI may be different for each iteration.

[0178] 10A and 10B, the four UL beams used for the four repetitions of the PRACH correspond to SSBs #0, #1, #2, and #3, respectively, with SSB #1 being the best DL beam identified.

[0179] In the example of Figure 10A, four repetitions of the PRACH are transmitted in ROs of different time resources. In this example, the UE starts the RAR window after the last repetition. Within that RAR window, the QCL assumption for DL ​​reception is SSB#1, which is the best DL beam. The UE attempts to receive the RAR scheduling DCI using different RA-RNTIs within that RAR window. In this example, the UE decodes the RAR (RAR scheduling DCI) using the RA-RNTI of the RO for SSB#2. This means that the selected best UL beam / UL QCL assumption is SSB#2.

[0180] In the example of FIG. 10B, RO#0b associated with SSB#0 and RO#1c associated with SSB#1 are in the same time resource, followed by RO#2b associated with SSB#2 and RO#3d associated with SSB#3. In this example, the UE starts the RAR window after the last RO#2b and RO#3d in the time domain. Within that RAR window, the QCL assumption for DL ​​reception is SSB#1, which is the best DL beam. The UE attempts to receive the RAR scheduling DCI using different RA-RNTIs within that RAR window. In this example, the UE decodes the RAR (RAR scheduling DCI) using the RA-RNTI for SSB#3. This means that the selected best UL beam / UL QCL assumption is SSB#3.

[0181] According to this embodiment, the UE may suitably perform at least one of PRACH repetitions with the same beam and PRACH repetitions with different beams.

[0182] <Embodiment 11> This embodiment relates to DL / UL beam assumption 2 described above.

[0183] Option A In addition to embodiments #1 / #2 involving the indication / determination of a reference beam / reference resource, after each PRACH repetition of a beam, the UE may start an RAR window (ra-ResponseWindow) at the first PDCCH occasion from the end of each repeated transmission of the RA preamble. For Msg2 reception within each RAR window, the UE may assume the reference beam as the QCL assumption for Msg2 reception. However, the UE may assume that at most one Msg2 (e.g., RAR, base station response to BFR, etc.) is received within every RAR window. The UE may assume that the beam associated with the received Msg2 (PRACH repetition transmission beam) is the selected UL beam. The selected UL beam may be used as the default UL beam / QCL source for subsequent UL transmissions.

[0184] The QCL assumption for DL ​​Msg2 may be the reference beam in embodiment #1 / #2.

[0185] The selection of the UL beam may mean that the base station measures the PRACH preamble reception conditions, selects one preamble with good UL quality, and sends Msg2 within the RAR window for the selected good UL beam.

[0186] If the RAR windows for each beam do not overlap, the timing of decoding Msg2 may be used to identify the UL beam corresponding to that Msg2.

[0187] 11A and 11B, the four UL beams used for the four repetitions of the PRACH correspond to SSB#0, #1, #2, and #3, respectively. The reference beam is SSB#2. The reference resource is resource #2b of the RO / preamble.

[0188] In the example of Figure 11A, four repetitions of the PRACH are transmitted using different time resources, RO / preamble resources #0b, #1c, #2b, and #3d, respectively. In this example, the UE starts an RAR window after each repetition. The four RAR windows are non-overlapping. Within each RAR window, the QCL assumption for DL ​​reception is SSB#2, which is the reference beam. In this example, the UE decodes the RAR within the RAR window for SSB#1. This means that the selected good UL beam / UL QCL assumption is SSB#1.

[0189] If the RAR windows for each beam overlap, Msg2 for each beam may be identified by the RA-RNTI. For example, the parameters (s_id / t_id / f_id) used to calculate the RA-RNTI may be different for each iteration. This identification method may mean that the UE needs to attempt to receive multiple RA-RNTIs (CRCs scrambled with the RA-RNTIs, and DCIs with the CRCs) within the overlapping time period.

[0190] In the example of FIG. 11B, RO#0b associated with SSB#0 and RO#1c associated with SSB#1 are in the same time resource, followed by RO#2b associated with SSB#2 and RO#3d associated with SSB#3. In this example, the UE starts RAR window#0 after RO#0b, starts RAR window#1 after RO#1c, starts RAR window#2 after RO#2b, and starts RAR window#1 after RO#3d. RAR windows#0, #1, #2, and #3 overlap. When Msg2 for SSB#0 is transmitted within RAR window#0, RA-RNTI#0 is used. When Msg2 for SSB#1 is transmitted within RAR window#1, RA-RNTI#1 is used. When Msg2 for SSB#2 is transmitted within RAR window#2, RA-RNTI#2 is used. When Msg2 for SSB#3 is transmitted within RAR window#3, RA-RNTI#3 is used. Within each RAR window, the QCL assumption for DL ​​reception is SSB#2, which is the reference beam. In this example, the UE uses a different RA-RNTI to decode Msg2 for each SSB. In this example, the UE decodes the RAR using RA-RNTI#3 for SSB#3. This means that the selected good UL beam / UL QCL assumption is SSB#3.

[0191] In embodiment #10, PRACH repetition with different beams may be an additional scheme for UL beam management only, with functionality similar to SRS for beam management.

[0192] In embodiment #11, PRACH repetition with different beams may be a novel scheme that can be used to identify both DL beams and UL beams within one procedure.

[0193] Option B In addition to the embodiments #1 / #2 involving the indication / determination of a reference beam / reference resource, after PRACH repetitions of different beams, the UE may start an RAR window (ra-ResponseWindow) at the first PDCCH occasion from the end of the last repeated transmission of the RA preamble. For Msg2 reception within the RAR window, the UE may assume the reference beam as the QCL assumption for Msg2 reception. The UE may assume that at most one Msg2 (e.g., RAR, base station response to BFR, etc.) is received within the RAR window. The UE may assume that the beam associated with the received Msg2 (PRACH repetition transmission beam) is the selected best UL beam. The selected UL beam may be used as the default UL beam / QCL source for subsequent UL transmissions.

[0194] The QCL assumption for DL ​​Msg2 may be the reference beam in embodiment #1 / #2.

[0195] The selection of the UL beam may mean that the base station measures the PRACH preamble reception conditions, selects one preamble with good UL quality, and sends Msg2 within the RAR window for the selected good UL beam.

[0196] The UE may need to attempt to receive all RA-RNTIs (CRCs scrambled by the RA-RNTIs, and DCIs each accompanied by the CRCs) for the preambles transmitted within the RAR window. The beam associated with the decoded Msg2 may be identified by the RA-RNTI (corresponding to the decoded Msg2). For example, the parameters (s_id / t_id / f_id) used to calculate the RA-RNTI may be different for each iteration.

[0197] 12A and 12B, the four UL beams used for the four repetitions of the PRACH correspond to SSBs #0, #1, #2, and #3, respectively. The reference beam is SSB #2. The reference resource is resource #2b of the RO / preamble.

[0198] In the example of Figure 12A, four repetitions of the PRACH are transmitted in ROs of different time resources. In this example, the UE starts the RAR window after the last repetition. Within that RAR window, the QCL assumption for DL ​​reception is SSB#2, which is the reference beam. The UE attempts to receive the RAR scheduling DCI using different RA-RNTIs within that RAR window. In this example, the UE decodes the RAR (RAR scheduling DCI) using the RA-RNTI of the RO for SSB#1. This means that the selected best UL beam / UL QCL assumption is SSB#1.

[0199] In the example of FIG. 12B, RO#0b associated with SSB#0 and RO#1c associated with SSB#1 are in the same time resource, followed by RO#2b associated with SSB#2 and RO#3d associated with SSB#3. In this example, the UE starts the RAR window after the last RO#2b and RO#3d in the time domain. Within that RAR window, the QCL assumption for DL ​​reception is SSB#2, which is the reference beam. The UE attempts to receive the RAR scheduling DCI using different RA-RNTIs within that RAR window. In this example, the UE decodes the RAR (RAR scheduling DCI) using the RA-RNTI for SSB#1. This means that the selected best UL beam / UL QCL assumption is SSB#1.

[0200] According to this embodiment, the UE can appropriately determine the UL beam for PRACH repetitions with different beams based on the indicated reference resource / reference beam.

[0201] <Embodiment 1#A0> For coverage extension, PRACH repetition may be applied.

[0202] If the PRACH is repeated multiple times, the coverage (link budget) of the PRACH increases. For the PRACH repetition, only PRACH format B4 (the longest format (having the most symbols) in the short sequence) may be applied, or some other PRACH formats may be applied, or all PRACH formats may be applied. For short sequences, the PRACH format may be adjusted (scaled) based on the PRACH SCS.

[0203] Only a 4-step RACH may be applied to the PRACH repetition, which is most likely to be used in scenarios with limited coverage. A 2-step RACH may also be applied to the PRACH repetition.

[0204] According to this embodiment, the coverage of the PRACH can be improved.

[0205] <Embodiment #A1> This embodiment relates to PRACH repetition.

[0206] For CFRA / CBRA, PRACH repetition with the same beam may be applied to at least one RA of the following objects 1a-1 to 1a-6. [Subject 1a-1] CFRA only. [Subject 1a-2] CBRA only. [Subject 1a-3] Both the CFRA and the CBRA. [Subject 1a-4] Among the CFRA and CBRA, the RA reported by the UE capability. For at least one of the CFRA and CBRA, the UE capability regarding PRACH repetition with the same beam may be defined, and the UE capability may report that the UE supports PRACH repetition with the same beam for at least one of the CFRA and CBRA RA. [Subject 1a-5] CFRA and CBRA, which are configured by RRC signaling. For an RRC CONNECTED UE, RRC signaling may configure PRACH repetition enable / disable for at least one of CFRA and CBRA. [Subject 1a-6] RA for a specific RA purpose. Regarding PRACH repetition, at least one of availability and UE capability may be defined for a specific RA purpose, and the specific RA purpose may be indicated by at least one of the availability and the UE capability. The availability may be an information element (higher layer parameter) that enables PRACH repetition for an RA for the specific RA purpose. The UE capability may indicate that PRACH repetition is supported for an RA for the specific RA purpose. The specific RA purpose may be, for example, a PDCCH order RA, an RA for SI request, an RA for BFR, an RA triggered by the MAC layer, an RA triggered by the RRC layer, etc.

[0207] For 2-step RA / 4-step RA, PRACH repetition with the same beam may be applied to at least one RA of the following subjects 1b-1 to 1b-5. [Subject 1b-1] 2-step RA only. [Subject 1b-2] 4-step RA only. [Subject 1b-3] Both 2-step RA and 4-step RA. [Subject 1b-4] Among the two-step RA and the four-step RA, the UE capability is reported. For at least one of the two-step RA and the four-step RA, the UE capability for PRACH repetition with the same beam is defined, and the UE capability may report that the UE supports PRACH repetition with the same beam for at least one of the two-step RA and the four-step RA. [Subject 1b-5] 2-step RA and 4-step RA configured by RRC signaling. For an RRC_CONNECTED UE, RRC signaling may configure PRACH repetition enable / disable for at least one of 2-step RA and 4-step RA.

[0208] Considering different PRACH formats, PRACH repetition may be applied to some or all PRACH formats, and UE capability regarding PRACH repetition may be defined for one, some, or all PRACH formats.

[0209] The PRACH repetition with the same beam may be applied to some or all of the RRC IDLE UEs, RRC INACTIVE UEs, and RRC CONNECTED UEs. A new PRACH configuration for applying the PRACH repetition with the same beam to IDLE / INACTIVE UEs may be provided in the SIB. A new PRACH configuration / indication for applying the PRACH repetition with the same beam to CONNECTED UEs may be provided by RRC signaling / MAC CE / DCI.

[0210] At least one of the conditions / objectives for which PRACH repetitions with the same beam can be used in this embodiment may be the conditions / objectives for which PRACH repetitions with different beams can be used.

[0211] This embodiment clarifies the conditions / objects under which PRACH repetitions with the same beam or different beams are applied.

[0212] <Embodiment 2#A2> This embodiment relates to the configuration of the repetition pattern / resource / number of repetitions of the PRACH.

[0213] The PRACH repetition pattern / resource may be repeated for at least one unit resource among the following unit resources 1 to 6. The at least one unit resource among the unit resources 1 to 6 may be configured by the SIC / RRC IE or may be specified in a specification. [Unit Resource 1] Association Period. The association period may be X SSB mapping periods / cycles, or may be a period that includes ROs mapped to all SSBs and unused ROs that can be mapped to beams for repetition. [Unit resource 2] PRACH setting period / cycle. [Unit Resource 3] X time units. For example, the time unit may be a slot / subframe / time domain PRACH occasion (RO). [Unit resource 4] X frequency units. For example, the frequency units may be PRACH occasions in the frequency domain. [Unit Resource 5] X PRACH Occasions (RO). [Unit Resource 6] X SSBs (PRACH Occasions (ROs) mapped to X SSBs).

[0214] From unit resource 1 to unit resource 6, two PRACH repetitions corresponding to the same SSB are closer to each other.

[0215] For unit resource 1, the second and subsequent repeating resources may occur after all SSBs have been mapped to PRACH occasions at least once. In the example of FIG. 13A, the length of the PRACH configuration period is 10 ms. In this example, the repeating resource (association period) is two PRACH configuration periods. In each repeating resource, there are ROs for SSBs 0 to 40 in the first PRACH configuration period, and ROs for SSBs 41 to 63 and unused ROs in the second PRACH configuration period. PRACH is repeated in the ROs for the same SSBs in each repeating resource. In this example, unused ROs are not used for repetition.

[0216] For unit resources 2 to 6, the second repeating resource may occur before all SSBs have been mapped to a PRACH occasion at least once. In the example of Figure 13B for unit resource 2, the repeating resource is one PRACH configuration period. In this example, the number of repetitions is 2. Within each of the first and second repeating resources (PRACH configuration periods), there are ROs for SSBs 0 to 40. Within the next first and second repeating resources (PRACH configuration periods), there are ROs for SSBs 41 to 63 and an unused RO. PRACH is repeated in the ROs for the same SSB within each repeating resource.

[0217] In the example of Figure 14A for unit resource 3, the repetition resource is 2 ms. In this example, the number of repetitions is 2. In each of the first and second repetition resources, there is an RO for SSBs 0 to 9. In each of the next first and second repetition resources, there is an RO for SSBs 10 to 19. The PRACH is repeated in the RO for the same SSB in each repetition resource.

[0218] 14B for unit resource 3, the repeating resource is two time-domain ROs according to the above-mentioned mapping 1. In the first repeating resource, SSBs 0, 0, 1, and 1 are mapped to four ROs in the first time-domain RO, and SSBs 2, 2, 3, and 3 are mapped to four ROs in the second time-domain RO. The same SSBs as in the first repeating resource are also mapped in the second repeating resource. PRACH is repeated in the ROs for the same SSBs in each repeating resource.

[0219] In the example of Figure 15A for unit resource 4, the repeating resource is two frequency domain ROs according to the above-mentioned mapping 2. SSBs 0 to 3 and SSBs 4 to 7 are mapped to two frequency domain ROs in the first time domain RO in the first repeating resource, respectively. The same SSBs as in the first repeating resource are also mapped to the second repeating resource. The PRACH is repeated in the ROs for the same SSBs in each repeating resource.

[0220] In the example of Figure 15B for unit resource 5, the repeating resource is four ROs according to the above-mentioned mapping 2. SSBs 0 to 3, SSBs 4 to 7, SSBs 8 to 11, and SSBs 12 to 15 are mapped to the four ROs in the first repeating resource (first time-domain RO), respectively. The same SSBs as in the first repeating resource are also mapped to the second repeating resource (second time-domain RO). PRACH is repeated in the ROs for the same SSBs in each repeating resource.

[0221] In the example of Figure 16A for unit resource 5, according to the above-mentioned mapping 2, the repeated resource is one RO. SSBs 0 to 3 are mapped to one RO in the first repeated resource (first frequency domain RO). The same SSBs as in the first repeated resource are also mapped to the second repeated resource (second frequency domain RO). The PRACH is repeated in the RO for the same SSB in each repeated resource.

[0222] In the example of Figure 16B for unit resource 5, according to the above-mentioned mapping 1, the repeating resource is one SSB (RO mapped to one SSB). One SSB is mapped to two frequency domain ROs. SSB0 is mapped to the first and second ROs (first and second frequency domain ROs) in the first repeating resource. The same SSB as in the first repeating resource is also mapped to the second repeating resource (third and fourth ROs, third and fourth frequency domain ROs). PRACH is repeated in the ROs for the same SSB in each repeating resource.

[0223] The number of repetitions may be explicitly or implicitly set / indicated by the SIB / RRC IE, or may be specified in the specifications.

[0224] In the explicit indication, the repetition number Y may be set to 1, 2, 3, 4, etc. Y=1 may indicate no repetition. Along with the repetition number, the repetition period / cycle may be configured for the UE or calculated / determined by the UE. For example, in the above-mentioned unit resource 1, if the repetition number is 2, the UE may determine / calculate the repetition period as 20*2=40 ms. That is, Y repetitions may occur within 40 ms.

[0225] The explicit instruction may only indicate whether repetition is invalid (none) or repetition is valid. In this case, a default repetition count may be specified in the specification. When the explicit instruction indicates that repetition is valid, the repetition count may be the default repetition count.

[0226] The cell-specific PRACH repetition count may be broadcast by the SIB. The UE-specific PRACH repetition count may be set by the RRC. The UE-specific PRACH repetition count may be applied to the PRACH of the RRC INACTIVE / CONNECTED UE. The UE may determine the actual PRACH repetition count according to a determination rule or UE implementation. For example, if the measured values of the SSB's RSRP / RSRQ / SINR / quality / power are lower than a threshold and the UE is set with PRACH repetition, the UE may transmit the PRACH multiple times (transmit the PRACH repetition). The threshold may be specified in the specification or set by the RRC IE. A plurality of thresholds / ranges associated with the PRACH repetition count may be set. For example, the UE may determine the PRACH repetition count corresponding to the maximum threshold below which its measured value falls among the plurality of thresholds, or may determine the PRACH repetition count corresponding to the range including its measured value among the plurality of ranges. For example, if the measured value is RSRP, the repetition count when the measured value < M_1 [dBm] may be 4, the repetition count when M_1 < measured value <= M_2 [dBm] may be 2, and the repetition count when M_2 < measured value [dBm] may be 1

[0227] The operation of the UE to determine the repetition count may be applied only to the UE that supports PRACH repetition.

[0228] In the implicit instruction, the UE may determine / calculate the repetition number based on a decision rule or a restriction. For example, the UE may calculate the repetition number based on the instruction / specified repetition period. For example, in the above-mentioned unit resource 1, if the repetition period is specified / set to 160 ms, the UE may determine / calculate the repetition period as 160 ms / 20=8 ms.

[0229] The repetition period may mean that all indicated SSB index to RO mappings are repeated Y times within that period.

[0230] In the example of Figure 17 for unit resource 5, according to the above-mentioned mapping 2, the number of repetitions is 3, and the repetition resource is one RO. SSBs 0 to 3 are mapped to one RO in the first repetition resource (first frequency domain RO). The same SSB as in the first repetition resource is also mapped to each of the second and third repetition resources (second and third frequency domain ROs). PRACH is repeated in the RO for the same SSB in each repetition resource.

[0231] The first PRACH transmission may always be a single PRACH transmission. If there is no Msg.2 (RAR) reception, the UE may transmit a PRACH with repetition. The PRACH with repetition may be accompanied by power ramping.

[0232] Variation A Different PRACH resources (including preambles / ROs) may be configured with different repetition numbers. In this case, for cases where coverage is limited, the UE can select an RO / preamble with repetition settings. A UE with good coverage can select an RO / preamble without repetition settings. For example, the UE may have a repetition number of 1 for SSBs 0 to 15, a repetition number of 2 for SSBs 16 to 31, a repetition number of 3 for SSBs 32 to 47, and a repetition number of 4 for SSBs 48 to 63. For example, the repetition number for preambles 0 to 31 may be 1, and the repetition number for preambles 32 to 63 may be 4.

[0233] In the example of Figure 18A for unit resource 2, the repetition resource is one PRACH configuration period (10 ms). The number of repetitions of ROs for SSBs 0 to 40 is 2, and the number of repetitions of ROs for SSBs 41 to 63 is 1. Within each of the first and second repetition resources (PRACH configuration periods), there are ROs for SSBs 0 to 40. PRACH is repeated in the ROs for the same SSBs within each repetition resource. Within the next PRACH configuration period, there are ROs for SSBs 41 to 63 and an unused RO. PRACH within this PRACH configuration period is not repeated.

[0234] 18B for unit resource 2, the repetition resource is one PRACH configuration period (10 ms). In this example, the repetition number for preambles 0 to 15 is 2, and the repetition number for preambles 16 to 31 is 1.

[0235] If any of preambles 0 to 15 is used, the number of repetitions is 2. Within each of the first and second repetition resources (PRACH configuration periods), there is an RO for SSBs 0 to 40. Within each of the next first and second repetition resources (PRACH configuration periods), there is an RO for SSBs 41 to 63 and an unused RO. PRACH is repeated in the RO for the same SSB within each repetition resource. If the base station decodes / receives preamble 1 associated with SSB #x within the first repetition resource, it is assumed that the base station will decode / receive the same preamble associated with the same SSB within the second repetition resource. The base station may perform joint decoding / reception to improve PRACH decoding / reception performance.

[0236] If any of preambles 16 to 31 is used, there is no repetition. If the base station decodes / receives preamble 17 associated with SSB#y in the first repetition resource, the base station assumes that there is no repetition associated with the same SSB in the second repetition resource. However, the base station may decode / receive a preamble associated with SSB#y in the second repetition resource. In this case, the base station may recognize the preamble as a preamble from another UE for access. The base station does not need to jointly decode / receive the two preambles.

[0237] In the example of Figure 19A for unit resource 5, according to the above mapping 2, the repeating resource is four ROs. The number of repeats for ROs for SSBs 0 to 40 is two, and the number of repeats for ROs for SSBs 41 to 63 is one. SSBs 0 to 3, SSBs 4 to 7, SSBs 8 to 11, and SSBs 12 to 15 are mapped to the four ROs in the first repeating resource (first time-domain RO), respectively. The same SSBs as those in the first repeating resource are also mapped to the second repeating resource (second time-domain RO). PRACH is repeated in the ROs for the same SSBs in each repeating resource. SSBs 32 to 35, SSBs 36 to 39, SSBs 40 to 43, and SSBs 44 to 47 are mapped to the four ROs in the fifth time-domain RO, respectively. There is no PRACH repetition for these ROs.

[0238] In the example of Figure 19B for unit resource 5, according to mapping 2 above, the repeated resource is four ROs. The repetition number for preamble indexes 0 to 7 for SSB0 is 1, and the repetition number for preamble indexes 8 to 15 for SSB0 is 2. The repetition number for preamble indexes 16 to 23 for SSB1 is 1, and the repetition number for preamble indexes 24 to 31 for SSB1 is 2. The repetition number for preamble indexes 32 to 39 for SSB2 is 1, and the repetition number for preamble indexes 40 to 47 for SSB2 is 2. The repetition number for preamble indexes 48 to 55 for SSB3 is 1, and the repetition number for preamble indexes 56 to 63 for SSB3 is 2.

[0239] SSBs 0 to 3, SSBs 4 to 7, SSBs 8 to 11, and SSBs 12 to 15 are mapped to the four ROs in the first time domain RO, respectively. If preamble index 8 to 15 is used for SSB0, preamble index SSBs 24 to 31 are used for SSB1, preamble index 40 to 47 are used for SSB2, and preamble index 56 to 63 are used for SSB3, the number of repetitions for the first time domain RO is 2. The same SSBs as those in the first repetition resource are also mapped to the second repetition resource (second time domain RO). PRACH is repeated in the ROs for the same SSBs in each repetition resource.

[0240] Variation A1 If the number of SSBs per RO (ssb-perRACH-Occasion) is less than 1, no (additional) repetition resource configuration is required. If repetition is enabled, several ROs mapped to one SSB may be considered as repetition resources. The number of repetitions may be configured.

[0241] In the example of Figure 20A, according to the above-mentioned mapping 1, if OccasionAndCB-PreamblesPerSSB indicates oneHalf,n16 (N=1 / 2, R=16) and msg1-FDM is 4, four ROs are FDMed in one time instance and one SSB is mapped to two ROs (the above-mentioned mapping 1).

[0242] In this example, if repetition is configured, the UE may consider the second RO mapped to each SSB as the second repetition RO for that SSB. In this example, some SSBs / ROs may be configured with a certain repetition number and some SSBs / ROs may not be configured with repetition. In this example, different preambles may be associated with different repetition numbers, including repetition number = 1 (no repetition).

[0243] In the example of Figure 20B, if ssb-perRACH-OccasionAndCB-PreamblesPerSSB indicates oneFourth,n16 (N=1 / 4, R=16) and msg1-FDM is 4, four ROs are FDM'd in one time instance and the four ROs are mapped to one SSB (mapping 2 described above).

[0244] In this example, if repetition is configured and the repetition count is 2, the UE may consider two of the four ROs mapped to each SSB as the second repetition ROs for that SSB. In this example, if repetition is configured and the repetition count is 4, the UE may consider the second, third, and fourth of the four ROs mapped to each SSB as the second, third, and fourth repetition ROs for that SSB, respectively. In this example, different SSBs / ROs may be associated with different repetition counts, including repetition count = 1 (no repetition). In this example, different preambles may be associated with different repetition counts, including repetition count = 1 (no repetition).

[0245] According to this embodiment, the repetition pattern / resource / number of repetitions of the PRACH can be determined appropriately.

[0246] <Embodiment #A3> In Rel. 15 / 16, the specifications usually map PRACH occasions and SSB indices. There is no definition of PRACH beams in the specifications. However, since beam correspondence is mandatory in Rel. 15, the most likely UE implementation is to use the SSB beam associated with the PRACH occasion. In this case, the base station can use the SSB to receive the PRACH associated with the PRACH occasion. The beam may be a CSI-RS beam.

[0247] This embodiment relates to UE behavior regarding PRACH repeated transmissions.

[0248] For any of the settings of unit resources 1 to 6 described above, the UE may recognize the association between multiple PRACH resources repeated for the same beam. The UE may also recognize which RO is the x-th repeated transmission.

[0249] <<Send operation 1>> For a selected beam (beam determination timing), if the next available RO associated with that beam is not the first repeated transmission RO within the repetition period, the UE may follow one of the following transmission start ROs 1 to 2.

[0250] [Transmission Start RO1] The UE may transmit the same PRACH preamble on ROs associated with the same PRACH preamble repetitions up to the last RO in the repetition period (from the xth repetition to the last repetition). The actual number of repetitions may be less than the maximum number of repetitions (configured / reported) in one repetition period. This behavior may mean that if the base station receives a PRACH preamble in the xth repetition RO associated with an SSB, the base station assumes that it will receive the same preamble in the (x+1)th repetition RO, the (x+2)th repetition RO, etc. This behavior may not mean that the base station must receive the same preamble in the (x+1)th repetition RO, the (x+2)th repetition RO, etc.

[0251] In the example of Figure 21, the number of repetitions is 4. There are four repetitions in one repetition period. If the UE selects SSB0 for PRACH after the second repetition, the UE may transmit the PRACH preamble from the third repetition to the last (fourth) repetition associated with the same PRACH preamble / SSB0.

[0252] [Transmission Begins RO2] The UE may wait until the next repetition period and start transmitting the PRACH preamble on the associated RO from the first repetition RO.

[0253] <<Sending operation 2>> For the selected beam, the UE may determine the PRACH resource (RO / preamble) based on the RSRP value, in which case the UE may assume that different PRACH resources are configured with different repetition numbers.

[0254] For example, if threshold 1<=measured RSRP and the channel condition is good, the UE may select a PRACH resource with repetition number=1. Here, if, for the selected SSB#0, preambles 0 to 15 correspond to repetition number=1, preambles 16 to 31 correspond to repetition number=2, and preambles 32 to 47 correspond to repetition number=4, the UE may select one preamble from preambles 0 to 15. In this case, as in the example of Figure 22 (Good RSRP), the UE may select preamble 5.

[0255] For example, if threshold 3<=measured RSRP<threshold 2 and the channel condition is medium, the UE may select a PRACH resource with repetition count=2. Here, the UE may select one preamble from preambles 16 to 31. Threshold 2 may be equal to threshold 1. In this case, as in the example of Figure 22 (Medium RSRP), the UE may select preamble 20.

[0256] For example, if threshold 5<=measured RSRP<threshold 4 and the channel condition is poor, the UE may select a PRACH resource with repetition number=4, where the UE may select one preamble from preambles 32 to 47. Threshold 4 may be equal to threshold 3.

[0257] In this transmission operation, the UE may take into account (or may regard as) a configured number of repetitions for each PRACH resource.

[0258] In this transmission operation, the UE may consider (or consider as) the remaining actual number of repetitions for each PRACH resource.

[0259] <<Sending operation 3>> When the UE selects a beam for PRACH transmission (from multiple beams), the UE may select the beam according to at least one of the following selection methods 1 to 3 (taking into account at least one parameter of selection methods 1 to 3):

[0260] [Selection method 1] The UE takes into account the RSRP value of each beam, as in existing specifications.

[0261] [Selection method 2] The UE considers the repetition number configured for the PRACH resource associated with each beam in addition to the RSRP value of each beam. For example, for beams with the same repetition number for the PRACH resource, the UE may need to compare the RSRP value of each beam. For example, for beams with different repetition numbers for the PRACH resource and similar RSRP values, the UE may select a beam with an appropriate repetition number based on the RSRP range (similar to transmission operation 2 described above). For example, for beams with different repetition numbers for the PRACH resource and similar RSRP values, the UE may select the beam with the largest repetition number. For example, for beams with different RSRP measurement results and different repetition numbers for the PRACH resource, the UE may select a beam by prioritizing either the RSRP measurement result or the repetition number.

[0262] All SSBs may be configured with the same maximum number of repetitions (so that all beams have the same coverage capability). However, for PRACH resources (ROs / preambles) associated with one SSB, some PRACH resources may be configured with a large number of repetitions and some PRACH resources may be configured with a smaller number of repetitions or no repetitions. UEs accessing any SSB may select PRACH resources corresponding to different numbers of repetitions.

[0263] In the example of Figure 23, the repetition number is 4, and there are four repetition ROs in one repetition period. SSBs 0, 1, 30, and 31 are mapped into each repetition RO. The UE may select an SSB for PRACH by considering SSB 0 and SSB 30, which have the highest RSRP values. Considering that the next RO for SSB 30 is the second repetition RO and the next RO for SSB 0 is the third repetition RO, the UE may select SSB 30, which has the larger number of actual repetitions.

[0264] [Selection method 3] In addition to the RSRP value of each beam, the UE also considers the next available RO repetition order associated with that beam (or the remaining actual number of repetitions associated with each beam). This is similar to selection method 2, except that the actual number of repetitions associated with each beam is considered instead of the configured number of repetitions for each beam. In this case, all SSBs may be associated with the same maximum number of repetitions. At the time the UE selects a beam for access, the remaining actual number of repetitions associated with each beam may be different.

[0265] For example, for some beams above the RSRP threshold, the UE may give the beam with the first repetition RO (second repetition RO, third repetition RO, etc.) as the next available repetition RO associated with a beam having a higher priority than the beam with the second repetition RO (third repetition RO, fourth repetition RO, etc.) as the next available repetition RO associated with the beam. This may mean that the UE selects the beam and its RO with the higher actual repetition number from all beams that meet the RSRP threshold.

[0266] According to this embodiment, the UE can determine the PRACH resource / beam appropriately.

[0267] <Embodiment #A4> This embodiment relates to a counter for the preamble.

[0268] When the second or subsequent repetitions (2nd, 3rd, ...) of the preamble are transmitted, at least one of the following parameters 1 to 3 may be unaffected (not incremented). This may mean that repeated preamble transmissions do not affect the maximum number of transmissions / count / power ramping. [Parameter 1] Preamble transmission counter (PREAMBLE_TRANSMISSION_COUNTER). [Parameter 2] Preamble power ramping (PREAMBLE_POWER_RAMPING_COUNTER). [Parameter 3] Preamble received target power (PREAMBLE_RECEIVED_TARGET_POWER).

[0269] According to this embodiment, the UE can transmit the PRACH repetitions appropriately.

[0270] <Embodiment #A5> This embodiment relates to the number of repetitions in the RACH procedure.

[0271] The influence of the number of PRACH repetitions on the number of repetitions for the remaining RACH procedures may be either of the following influences 1 and 2.

[0272] [Impact 1] The PRACH repetition number influences the repetition numbers for the remaining RACH procedures. At least one of the following repetition numbers 1 to 4 may be derived from the PRACH repetition number: [Repetition number 1] Repetition number of Msg.2. [Repetition number 2] Repetition number of Msg.3. [Repetition number 3] Repetition number of Msg.4. [Number of repetitions: 4] Msg.4 Number of repetitions of HARQ-ACK transmission (PUCCH).

[0273] The mapping between the PRACH repetition and at least one of the repetition numbers 1 to 4 may be configured by higher layer signaling or may be specified in a specification.

[0274] [Impact 2] The number of PRACH repetitions does not affect the number of repetitions for the remaining RACH procedures. At least one of the repetition numbers 1 to 4 may be determined independently of the PRACH repetitions or may be specified.

[0275] According to this embodiment, the UE can appropriately determine the number of repetitions in the RACH procedure.

[0276] <Embodiment 6> This embodiment relates to Msg.2 / Msg.B.

[0277] For repetition, Msg.2 may follow either of Msg.2 actions 1 and 2 below. [Msg.2 Operation 1] Whether Msg.2 supports repetition may be configured by SIB / RRC or may be configured together with RACH configuration. UE capability regarding Msg.2 repetition may be defined. [Msg.2 Operation 2] Repeated Msg.2 is not supported.

[0278] For repetition, Msg. B may follow either of Msg. B actions 1 and 2 below. [Msg.B operation 1] Whether Msg.B supports repetition may be configured by SIB / RRC or may be configured together with RACH configuration. UE capability regarding Msg.B repetition may be defined. [Msg.B operation 2] Repeated Msg. B is not supported.

[0279] According to this embodiment, the UE can properly receive Msg.2 / Msg.B.

[0280] <Embodiment #A7> This embodiment relates to monitoring at least one of Msg.2 and DCI for Msg.2.

[0281] The UE may follow one of the following monitoring actions 1, 2, or 2a to monitor at least one of the DCI with cyclic redundancy check (CRC) scrambled by the RA-RNTI and Msg.2 before sending all PRACH repetitions.

[0282] [Monitoring operation 1] The UE does not monitor at least one of the DCI with CRC scrambled by the RA-RNTI and Msg.2 before sending all PRACH repetitions, which can reduce the power consumption of DCI measurements.

[0283] [Monitoring operation 2] The UE monitors at least one of the DCI with CRC scrambled by the RA-RNTI and Msg.2 before sending all of the PRACH repetitions, which results in faster initial access. After receiving at least one of the DCI with CRC scrambled by the RA-RNTI and Msg.2, the UE may not transmit or may not be required to transmit the remaining PRACH.

[0284] In the example of Figure 24, the number of repetitions of the PRACH is 4. After the second repetition RO, the UE may monitor at least one of the DCI with CRC scrambled by the RA-RNTI and Msg.2.

[0285] [Monitoring behavior 2a] The UE may monitor at least one of Msg.2 and DCI with CRC scrambled by RA-RNTI (if it can / wants to do so) before sending all PRACH repetitions. Even if the base station can detect the first PRACH and sends Msg.2, the base station does not know whether the UE can monitor Msg.2 or not. Therefore, until the base station can receive Msg.3, the base station may send Msg.2, assuming that the UE can monitor at least one of Msg.2 and DCI with CRC scrambled by RA-RNTI after sending all PRACH repetitions.

[0286] According to this embodiment, the UE can properly receive Msg.2.

[0287] <Embodiment 8> In this embodiment, it is assumed that there is no Msg.2 / Msg.B repetition.

[0288] If Msg.1 repetition is configured, the UE / MAC entity may follow at least one of the following window actions 1 to 3 with respect to the ra-ResponseWindow:

[0289] 《Window Operation 1》 The UE / MAC entity starts the ra-ResponseWindow on the first PDCCH occasion from the end of the last actual repeated transmission of the RA preamble, which may be the last repeated RO for the associated SSB within the repetition period. This action may mean that the UE starts monitoring the RAR (which may include monitoring the base station's response to the BFR) after transmitting all repeated preambles.

[0290] 《Window Operation 2》 The UE / MAC entity starts / restarts the ra-ResponseWindow on the first PDCCH occasion from the end of each actual repeated transmission of the RA preamble. This action may mean that the UE monitors the RAR (which may include monitoring the base station's response to the BFR) before completing the transmission of all repeated preambles. Subsequent preamble repetitions may be dropped.

[0291] [Case A] If the ra-ResponseWindow length is smaller than the gap distance between two PRACH preamble repetitions, the ra-ResponseWindow may be considered as three separate windows for RAR monitoring after each PRACH. If an RAR is successfully received within the ra-ResponseWindow, the UE may stop / drop subsequent PRACH / Msg.1 repetitions. If an RAR is successfully received within the ra-ResponseWindow, the UE may stop / drop subsequent PRACH / Msg.1 repetitions after Msg.3 transmission. If an RAR is successfully received within the ra-ResponseWindow, the UE may stop / drop subsequent PRACH / Msg.1 repetitions after Msg.4 reception.

[0292] [Case B] If the ra-ResponseWindow length is greater than the gap distance between two PRACH preamble repetitions, the ra-ResponseWindow may be considered as one window for RAR monitoring after the first actual PRACH transmission with the window restarting after each repeat transmission. If an RAR is successfully received after a PRACH repetition, the UE may stop / drop subsequent preamble repetitions (which may or may not be after Msg.3 / Msg.4). In this case, the UE may also stop the window.

[0293] Using the aforementioned repeat setting of unit resources 2 to 6, the gap distance is very small, and case B may be possible.

[0294] In the example of Figure 25, similar to Figure 23 above, the UE selects SSB30 and starts repeat transmission from the second repeat RO. In the example of window operation 1, the UE starts the ra-ResponseWindow after every repeat (fourth repeat RO). In the example of case A of window operation 2, the UE starts the ra-ResponseWindow after each repeat (second, third, and fourth repeat RO). The length of each ra-ResponseWindow is shorter than the time interval between two repeats. In the example of case B of window operation 2, the UE starts the ra-ResponseWindow after each repeat (second, third, and fourth repeat RO). The length of each ra-ResponseWindow is longer than the time interval between two repeats.

[0295] 《Window Operation 3》 The UE / MAC entity starts the ra-ResponseWindow on the first PDCCH occasion from the end of the first actual repetition of the RA preamble. The window may expire before the UE receives the RAR and before the completion of the PRACH repetition. If the base station sends an RAR after the second PRACH repetition, the UE may not be able to monitor the RAR.

[0296] After the UE starts the ra-ResponseWindow after the first actual iteration, the UE may follow one of the following window actions 3a, 3b, 3c.

[0297] [Window Action 3a] The UE may not assume that the ra-ResponseWindow expires before the end of the last preamble repetition or before a time X (a particular time) after the end of the last preamble repetition.

[0298] [Window Action 3b] If the window expires and the window expiration timing is before the last repeat RO of the SSB associated with the same preamble or before time X after the last repeat RO of the SSB associated with the same preamble, and the UE does not successfully receive the RAR, the UE may restart the window (considering that the ra-ResponseWindow length is not long enough for the last repeat, i.e., the ra-ResponseWindow expires before the end of the last preamble repetition or before time X (a specific time) after the end of the last preamble repetition).

[0299] [Window Action 3c] In the case where, based on window operation 3b, the expiration timing of the window is before the last repeat RO of the SSB associated with the same preamble or before time X after the last repeat RO of the SSB associated with the same preamble, the UE may restart the window after the last repeat in addition to restarting the window after expiration.

[0300] In each of window operations 3a to 3c, if RAR is successfully received after a PRACH repetition, the UE may stop / drop subsequent preamble repetitions (which may or may not be after Msg.3 / Msg.4). In this case, the UE may also stop the window.

[0301] In the example of Figure 26, similar to Figure 23 above, the UE selects SSB30 and starts repeat transmission from the second repeat RO. In the example of windowed operation 3a, the ra-ResponseWindow starts after the first repeat (first repeat RO) and expires a time X after the end of the last repeat (fourth repeat RO). In the example of windowed operation 3b, the ra-ResponseWindow starts after the first repeat (first repeat RO), expires before the end of the last repeat (fourth repeat RO), is restarted, and expires after the last repeat (fourth repeat RO). In another example of windowed operation 3b, the ra-ResponseWindow starts after each repeat and is restarted if it expires before the next repeat. In the last repeat (fourth repeat RO), the ra-ResponseWindow expires a time X after the end of that repeat. In the example of windowed operation 3c, the ra-ResponseWindow starts after the first repeat (first repeat RO), expires before the last repeat (fourth repeat RO), and is restarted. Furthermore, the ra-ResponseWindow is restarted after the end of the last iteration (the fourth iteration RO).

[0302] UE capabilities regarding window operations 1 / 2 / 3 / 3a / 3b / 3c may be defined. UE capabilities regarding whether or not to support restarting a window when it expires or is repeated may be defined.

[0303] Windowing operations 1 / 2 / 3 / 3a / 3b / 3c may be applied to the msgB-ResponseWindow for two-step RACH, where at least one additional symbol of the value of the last symbol of the PRACH occasion corresponding to the PRACH transmission may be taken into account for the start of the window after each PRACH preamble in each windowing operation.

[0304] According to this embodiment, the UE can properly receive Msg.2 / Msg.B.

[0305] <Embodiment Item #A9> This embodiment relates to the RNTI.

[0306] The RA-RNTI calculation may follow at least one of the following calculation methods 1 to 4.

[0307] 《Calculation method 1》 The RA-RNTI calculation uses the parameters of the first actual PRACH transmission in all repeated ROs. For example, the parameters may include s_id / t_id / f_id. This calculation method can be applied to all window operations in the above embodiment #A8.

[0308] In the example of Figure 27A, the number of repetitions is 4, and at least one of DCI with CRC scrambled by RA-RNTI and Msg.2 is associated with the first repetition RO, and RA-RNTI is calculated using parameters of the first actual PRACH transmission.

[0309] 《Calculation method 2》 The RA-RNTI calculation uses the parameters of the last PRACH transmission. For example, the parameters may include s_id / t_id / f_id. This calculation method can be applied to window operation 1 in embodiment #A8 above.

[0310] 《Calculation method 3》 The RA-RNTI calculation uses the parameters of the PRACH transmission of each repetition (latest repetition) before the end of the next repetition RO. For example, the parameters may include s_id / t_id / f_id. This calculation method can be applied to window operation 2 / 3 in the above-mentioned embodiment #A8.

[0311] In the example of Figure 27B, the number of repetitions is 4, and at least one of DCI with a CRC scrambled by the RA-RNTI and Msg.2 is associated with each repetition RO. The RA-RNTI for the DCI after the last repetition is calculated using the parameters of the last PRACH transmission.

[0312] 《Calculation method 4》 The RA-RNTI calculation takes into account different parameters after the restart of the ra-ResponseWindow. For example, the parameters may include s_id / t_id / f_id. For example, if the window is restarted after a certain iteration, the RA-RNTI calculation may use the parameters of the latest iteration for the RA-RNTI in the subsequent window time. For example, if the window is restarted after the window expires, the RA-RNTI calculation may use the parameters of the latest iteration for the RA-RNTI in the subsequent window time, or the parameters for the RA-RNTI may not be updated in this condition.

[0313] UE capabilities regarding whether to change the RA-RNTI for the window for repetition of PRACH preamble transmission may be defined.

[0314] Different calculation methods among calculation methods 1 to 4 may be applied to multiple window operations in the above-mentioned embodiment #A8, or to different windows in a window operation in embodiment #A8, or to different durations / lengths of each window in embodiment #A8.

[0315] Calculation methods 1 to 4 may be applied to the MSGB-RNTI of the two-step RACH.

[0316] According to this embodiment, the UE can properly receive Msg.2 / Msg.B.

[0317] <Embodiment 10> This embodiment relates to UE capabilities.

[0318] The way in which the UE reports its UE capability regarding support for PRACH repetition may follow either of the following reporting methods 1 and 2.

[0319] 《Reporting method 1》 Different preambles / occasions of the PRACH may be defined for UEs that support PRACH repetition and UEs that do not support PRACH repetition. UEs that do not support PRACH repetition may include Rel. 15 / 16 UEs.

[0320] For UEs that support different numbers (maximum numbers) of PRACH repetitions, different preambles / occasions for the PRACH may be defined.

[0321] By using different preambles / occasions for the PRACH, the base station can recognize whether the UE supports PRACH repetition. The UE may further send additional information about its UE capability of supporting PRACH repetition in Msg.3 or a subsequent RRC IE / MAC CE. For example, the additional information may indicate the maximum number of PRACH repetitions supported by the UE, or whether the UE supports at least one of PRACH repetition in two-step RACH and PRACH repetition in four-step RACH.

[0322] 《Reporting method 2》 The same preamble / occasion of the PRACH may be defined for UEs that support PRACH repetition and UEs that do not support PRACH repetition. UEs that do not support PRACH repetition may include Rel. 15 / 16 UEs.

[0323] The base station cannot determine whether the UE supports PRACH repetition through PRACH measurement. The UE may send additional information about its capability to support PRACH repetition in Msg.3 or a subsequent RRC IE / MAC CE. For example, the additional information may indicate whether the UE supports PRACH repetition, the maximum number of PRACH repetitions supported by the UE, or whether the UE supports at least one of PRACH repetition in two-step RACH and PRACH repetition in four-step RACH.

[0324] According to this embodiment, the UE can transmit the PRACH repetitions appropriately.

[0325] <Embodiment #B1> This embodiment relates to a random access procedure initiated by a PDCCH order.

[0326] In a random access procedure initiated by a PDCCH order, at least one indication of whether the PRACH is a repeated transmission (using the same beam) and the number of repetitions of the PRACH (using the same beam) may be in accordance with either of the following indication methods 1 and 2.

[0327] 《Instruction method 1》 An explicit new indication for indicating at least one of whether or not to repeat (repeated or not) and the number of repetitions may use reserved bits in the DCI (DCI format 1_0, PDCCH order). The RRC configuration of the repetition pattern / repetition resource / repetition number may be in accordance with at least one of the above-mentioned embodiments #A0 to #A10. The DCI for the PDCCH order may include a new field for the new indication. The new field may utilize one or more bits of the existing reserved bits.

[0328] Figure 28A shows Example 1 of a new indication. A value (code point) of 0 in the new indication corresponds to no repetition, and a value of 1 corresponds to repetition. This association may be reversed. If the value 1 indicates that repetition is enabled, the number of repetitions may follow the maximum number of repetitions for each RO set by the RRC, or may follow the actual remaining number of repetitions within the repetition period.

[0329] Figure 28B shows Example 2 of a new instruction. The maximum number of repetitions corresponding to each RO set by the RRC is assumed to be 4. Values ​​(code points) of the new instruction 0, 1, 2, and 3 correspond to the number of repetitions of 1 (non-repetition), 2, 3, and 4, respectively. The maximum number of repetitions, the number of values, and the number of repetitions corresponding to each RO are not limited to this example. The maximum number of repetitions may be more than 4, the number of values ​​may be more than 4, or the number of repetitions may be more than 4.

[0330] 《Instruction method 2》 There may be no need for an explicit new indication to indicate at least one of whether or not to perform repetition (repetition or non-repetition) and the number of repetitions. At least one of whether or not to perform repetition (repetition or non-repetition) and the number of repetitions may be implicitly indicated by at least one of a PRACH mask index and an RO of SSB in the PDCCH order. The repetition pattern / repetition resource / repetition number for each RO may be configured by RRC.

[0331] The instructions / settings may comply with at least one of the following relationships 1 to 4:

[0332] [Relationship 1] For different ROs, the RRC configured repetition number may be the same.

[0333] [Relationship 2] For different ROs, the RRC may configure different repetition numbers. For example, for PRACH occasion (RO) indexes 1 / 2 / ... / 7 / 8, different repetition numbers may be configured in the same manner as the repetition number configuration in at least one of the above-described embodiments #A0 to #A10. For example, for PRACH occasions (ROs) with even indexes and PRACH occasions (ROs) with odd indexes, different repetition numbers may be configured in the same manner as the repetition number configuration in at least one of the above-described embodiments #A0 to #A10.

[0334] [Relationship 3] The number of repetitions may not be the maximum set value (the set maximum value). The number of repetitions may be assumed by the UE as a number obtained by referring to a rule. For example, the number of repetitions may be assumed to be the remaining number of repetitions associated with only the indicated / configured ROs / SSBs within the repetition period or only the valid ROs / SSBs within the repetition period.

[0335] [Relationship 4] For UEs that support PDCCH-ordered PRACH repetitions, a new table (association / correspondence) for PRACH mask index values ​​may be defined, where each index may indicate an RO and a repetition number.

[0336] Interpretation of repeat numbers For the number of repetitions indicated in indication method 1 or 2, either of the following counting methods A and B may be applied. [Counting Method A] The RO repetition resource configured for the indicated SSB may be counted against the repetition number, regardless of whether the RO is enabled or disabled. [Counting method B] The valid RO repetition resources set for the indicated SSB (valid RO repetition resources among the RO repetition resources set for the indicated SSB) may be counted against the repetition number.

[0337] Counting methods A / B may be applied to PDCCH-ordered PRACH as well as PRACH transmissions with a number of repetitions initiated and indicated by the MAC entity / higher layers / RRC.

[0338] Counting method A may be applied only to non-first repetitions with a repetition count > 1. This may mean that the first actual PRACH transmission is always on a valid RO. The determination of whether a PRACH occasion is valid may follow the validity conditions in "Conditions for valid / invalid PRACH occasions" above.

[0339] In the example of Figure 29A, RRC configures repetition resources for each repetition period using a maximum number of repetitions = 4. Four repetitions (first to fourth repetition configuration resources) of RO#2 for SSB#0 are configured within the repetition period.

[0340] FIG. 29B shows an example in which counting method A is applied to the configuration of FIG. 29A. In this example, the UE receives a PDCCH order DCI between the first repetition setting resource and the second repetition setting resource. The time between the reception of the PDCCH order DCI and the first actual transmission resource satisfies the time condition of "time between PDCCH order reception and PRACH transmission" described above. The DCI indicates SSB#0 and RO#2. The indicated repetition number is 2. The third repetition setting resource is invalid. In this example, the invalid RO is also counted in the repetition number. The only repetition setting resource actually transmitted by the UE is the second repetition setting resource.

[0341] FIG. 30A shows an example in which counting method B is applied to the configuration of FIG. 29A. In this example, the UE receives a PDCCH order DCI between the first and second repetition setting resources. The time between the reception of the PDCCH order DCI and the first actual transmission resource satisfies the time condition of "time between PDCCH order reception and PRACH transmission" described above. The DCI indicates SSB#0 and RO#2. The indicated repetition number is 2. The third repetition setting resource is invalid. In this example, the invalid RO is not counted in the repetition number. The repetition setting resources actually transmitted by the UE are the second and fourth repetition setting resources.

[0342] To satisfy the specified number of repetitions, the same PRACH preamble may be repeated over multiple repetition periods. Whether or not such a case is permitted will be described in embodiment #B2 below.

[0343] FIG. 30B shows an example in which counting method B is applied to the configuration of FIG. 29A. In this example, the UE receives a PDCCH order DCI between the first and second repetition setting resources in the first repetition period. The time between the reception of the PDCCH order DCI and the first actual transmission resource satisfies the time condition of "time between PDCCH order reception and PRACH transmission" described above. The DCI indicates SSB#0 and RO#2. The indicated repetition number is 4. The third repetition setting resource is invalid. In this example, the invalid RO is not counted in the repetition number. The repetition setting resources actually transmitted by the UE are the second and fourth repetition setting resources in the first repetition period and the first and second repetition setting resources in the second repetition period.

[0344] According to this embodiment, the UE can appropriately transmit the PRACH repetition based on the PDCCH order.

[0345] <Embodiment #B2> This embodiment relates to limiting the number of repetitions of the PDCCH-ordered PRACH.

[0346] Regarding the number of repetitions, at least one of the following periods 1 and 2 may be envisaged. [Period 1] Repetitions of the same PRACH preamble may occur over multiple repetition periods. [Period 2] Repetitions of the same PRACH preamble should be within one repetition period.

[0347] In the case of a combination of either of the above-mentioned periods 1 and 2 and either of the above-mentioned counting methods A and B, at least one of the following restrictions 1 to 4 may be applied. [Restriction 1] There is no limit to the number of repetitions indicated. [Restriction 2] The UE shall not assume that the indicated number of repetitions is greater than an RRC-configured value, which may be, for example, an RRC-configured maximum number of repetitions per repetition period. [Restriction 3] The UE shall not assume that the indicated number of repetitions is greater than the number of remaining configured ROs within the repetition period. [Restriction 4] The UE shall not assume that the indicated number of repetitions is greater than the number of remaining valid ROs within the repetition period.

[0348] For the case of Period 1 and Counting Method A, at least one of Restrictions 1 and 2 may apply.

[0349] For the case of Period 2 and Counting Method A, at least one of Restrictions 1 to 4 may apply.

[0350] For the case of Period 1 and Counting Method B, at least one of Restrictions 1 and 2 may apply.

[0351] For the case of Period 2 and Counting Method B, at least one of Restrictions 1 to 4 may apply.

[0352] In the example of Figures 31A and 31B, the setup of Figure 29A described above is performed.

[0353] FIG. 31A shows an example of Restriction 3 for the case of Period 2 and Counting Method A. In this example, the UE receives a PDCCH order DCI between the first and second repetition setting resources. The time between the reception of the PDCCH order DCI and the resource of the first actual transmission satisfies the time condition of "time between PDCCH order reception and PRACH transmission" described above. The DCI indicates SSB#0 and RO#2. The indicated repetition number is 3. The third repetition setting resource is invalid. In this example, the repetition setting resources actually transmitted by the UE are the second and fourth repetition setting resources. In this example, the UE does not expect to be instructed using the repetition number=4.

[0354] Figure 31B shows an example of Restriction 4 for the case of Period 2 and Counting Method B. In this example, the UE receives a PDCCH order DCI between the first and second repetition setting resources. The time between the reception of the PDCCH order DCI and the resource of the first actual transmission satisfies the time condition of "time between PDCCH order reception and PRACH transmission" described above. The DCI indicates SSB#0 and RO#2. The indicated repetition number is 2. The third repetition setting resource is invalid. In this example, the repetition setting resources actually transmitted by the UE are the second and fourth repetition setting resources. In this example, the UE does not expect to be instructed using the repetition number = 3 or 4.

[0355] In the case of Period 2 and Counting Method A, or in the case of Period 2 and Counting Method B, if the indicated repetition number is greater than the number of remaining configured ROs in the repetition period, or if the indicated repetition number is greater than the number of remaining valid ROs in the repetition period, the UE may follow one of the following default repetition number assumptions 1 to 3 (default repetition number assumptions). [Default iteration count assumed to be 1] The UE assumes no repetitions (repetition count=1). [Default iteration count assumed 2] The UE assumes the indicated number of repetitions as the number of all actual remaining configured ROs within the repetition period. [Default iteration count assumed to be 3] The UE assumes the indicated number of repetitions as the number of all actual remaining valid ROs within the repetition period.

[0356] Different assumptions among the default repetition number assumptions 1 to 3 may be applied to the case of period 2 and counting method A and the case of period 2 and counting method B.

[0357] For any combination of either Period 1 or 2 and either Counting Method A or B, if no repetition number is specified, any of Default Repetition Number Assumptions 1 to 3 may be applied. For different combinations of either Period 1 or 2 and either Counting Method A or B, different assumptions among Default Repetition Number Assumptions 1 to 3 may be applied.

[0358] The calculation of the actual remaining number of configured / valid ROs takes into account the ROs that meet the time condition of "time between PDCCH order reception and PRACH transmission" mentioned above in the repetition period.

[0359] The selection of the indicated RO will be described in detail in embodiment #B3 below. In embodiment #B2, embodiment #B3 may be used to determine the actual transmission RO from the RO selected by the UE.

[0360] According to this embodiment, the number of repetitions of the PRACH based on the PDCCH order can be appropriately determined / configured / indicated.

[0361] <Embodiment #B3> This embodiment relates to the selection of an RO.

[0362] If a repeat transmission is indicated for the PDCCH order PRACH, the UE may select an RO (for actual transmission) from the next available one or more indicated ROs from all repeat RO resources corresponding to the indicated SSB and the indicated number of repetitions.

[0363] The UE may follow at least one of the following selection methods 1 and 2.

[0364] <<Selection Method 1>> The indexing of the RO (repetition resource pattern) may be per SSB / per repetition / per mapping cycle. At least one of the above embodiments #A0 to #A10 may be applied to the indexing of the RO. If the next available RO#x is the first repetition setting resource, the UE may select RO#x of the ith, (i+1)th, (i+2)th, ... repetition setting resource for transmission (as the RO for actual transmission) until the specified repetition number (number of ROs for transmission) is reached.

[0365] In the examples of Figures 32A and 32B and Figures 33A and 33B, if ssb-perRACH-OccasionAndCB-PreamblesPerSSB indicates oneEighth,n16 (N=1 / 8, R=16) and msg1-FDM is 2, then two ROs are FDM'd in one time instance and eight ROs are mapped to one SSB.

[0366] Figure 32A shows an example of existing SSB-RO mapping (repetition count = 1). Between the first and second time instances, a PDCCH order DCI is received. The DCI indicates SSB#0 and RO#5. The UE selects the next available RO for the indicated SSB.

[0367] The above-described embodiment #B2 may be used in conjunction with embodiment #B3 to select an RO for actual transmission based on a different interpretation of the indicated number of repetitions.

[0368] Figure 32B shows an example of a repetition resource pattern for each SSB. Each repetition resource corresponds to eight ROs mapped to one SSB. Between the third and fourth time instances, a PDCCH order DCI is received. The DCI indicates SSB#0 and RO#5. The UE selects the next available RO for the indicated SSB (SSB#0 and RO#5) for transmission, up to the indicated number of repetitions.

[0369] Figure 33A shows an example of a repetition resource pattern per SSB and per RO. Each repetition setting resource corresponds to one SSB and one RO. Between the third and fourth time instances, a PDCCH order DCI is received. The DCI indicates SSB#0 and RO#5. The UE selects the next available RO for the indicated SSB for transmission (SSB#0 and RO#5) up to the indicated number of repetitions.

[0370] <<Selection Method 2>> The indexing of ROs (repeated resource pattern) may be per SSB, per mapping cycle for all repetitions. Assuming that the repetition resource pattern is configured per SSB, the i-th repetition for the indicated RO#x (e.g., x=1, 2, ..., 8) may be regarded as RO#(x+i*M) (i=0, 1, 2, ...), where M is the maximum number of ROs per SSB. Within the repetition period, the UE may select for transmission (as the actual transmission RO) from the next available one or more indicated RO#(x+i*M) until the indicated number of repetitions is reached.

[0371] For example, for an indicated preamble index, the order of the PRACH occasions may be as follows: First, in increasing order of frequency resource index for frequency multiplexed PRACH occasions. Second, in increasing order of time resource index for time multiplexed PRACH occasions within a PRACH slot. ·Third, in ascending order of PRACH slot index. ·Fourth, ascending order of repetition number (repeat number).

[0372] For example, the order of PRACH occasions corresponding to the same repetition number may be in ascending order of PRACH slot index. For example, the order of PRACH occasions corresponding to the same PRACH slot may be in ascending order of time resource index. For example, the order of (frequency multiplexed) PRACH occasions corresponding to the same time resource index may be in ascending order of frequency resource index.

[0373] Figure 33B shows an example of a repetition resource pattern for each SSB. Each repetition resource corresponds to eight ROs mapped to one SSB. A PDCCH order DCI is received between the third and fourth time instances. The DCI indicates SSB#0 and RO#5. If M=8 and RO#5 is indicated, the indication also implies indication of RO#13, RO#21, and RO#29. The UE may select an RO for actual transmission from among the ROs based on the indicated repetition number. The UE selects RO#(x+i*M) for transmission from the next available RO for the indicated SSB up to the indicated repetition number.

[0374] The indexing of ROs in selection methods 1 and 2 may be applied to other PRACH resource configurations as well as PDCCH-ordered PRACH.

[0375] According to this embodiment, the UE can properly determine the RO for the actual transmission of the PRACH repetition based on the PDCCH order.

[0376] <Other embodiments> 《UE capability information / upper layer parameters》 Higher layer parameters (RRC IEs) / UE capabilities corresponding to the functions (features) in each of the above embodiments may be defined. The higher layer parameters may indicate whether the functions are enabled. The UE capabilities may indicate whether the UE supports the functions.

[0377] A UE for which higher layer parameters corresponding to the function are configured may perform the function. It may also be specified that "a UE for which higher layer parameters corresponding to the function are not configured shall not perform the function (for example, in accordance with Rel. 15 / 16)."

[0378] A UE that reports / transmits a UE capability indicating that it supports the function may perform the function. It may also be specified that "a UE that does not report a UE capability indicating that it supports the function shall not perform the function (e.g., in accordance with Rel. 15 / 16)."

[0379] If the UE reports / transmits a UE capability indicating that it supports the function and the corresponding upper layer parameter is configured, the UE may perform the function. It may also be specified that "if the UE does not report / transmit a UE capability indicating that it supports the function or if the corresponding upper layer parameter is not configured, the UE shall not perform the function (e.g., in accordance with Rel. 15 / 16)."

[0380] Which embodiment / option / choice / function of the above multiple embodiments is used may be configured by higher layer parameters, may be reported by the UE as a UE capability, may be specified in a specification, or may be determined by the reported UE capability and the configuration of higher layer parameters.

[0381] The UE capabilities may indicate whether the UE supports at least one of the following functions: Dynamic / explicit indication of the number of repetitions within the PDCCH order DCI. · Counting the set RO for the indicated number of repetitions. · Counting valid ROs for the indicated number of repetitions. Repetition of the same PRACH preamble occurs over multiple repetition periods. · Repetition of the same PRACH preamble is limited to one repetition period. The indicated number of repetitions is limited. For example, the indicated number of repetitions does not exceed the RRC configured value (maximum value). For example, the indicated number of repetitions does not exceed the number of remaining configured ROs in one repetition period. For example, the indicated number of repetitions does not exceed the number of valid ROs in one repetition period. -Introduce default iteration count assumptions for different cases (combinations). PRACH repetition or PRACH repetition resource configuration. At least one of PRACH repetition in CFRA and PRACH repetition in CBRA. At least one of PRACH repetition in 2-step RACH and PRACH repetition in 4-step RACH. · PRACH repetition in special purpose RA. One or more unit resources from unit resources 1 to 6. -Repeat Msg.2. -Repeat Msg.B. Window operation 1 / 2 / 3 / 3a / 3b / 3c. · Restarting the window if it expires or is repeated. · Changing the RA-RNTI for the window for repetition of PRACH preamble transmission. PRACH repetitions with different beams (e.g., first embodiment). At least one of a reference beam and a reference resource of an RO / preamble. Support at least one of a reference beam and a reference resource of an RO / preamble in each of different cases. The QCL assumption in Msg2 (base station response to RAR, BFR, etc.) is the reference beam. In each of the different cases, the QCL assumption in Msg2 is the reference beam. · Limits on beams selected for repetition. The RAR window starts after the reference resource / reference beam. · Separate RAR window for each PRACH repetition (with same beam / different multiple beams). · RAR window after the last PRACH iteration (with same beam / different multiple beams). Separate RA-RNTI for Msg2 monitoring in each RAR window for each PRACH repetition (with same beam / different multiple beams). Association between Msg2 and UL beam / QCL assumption, i.e., Msg2 reception implies that the associated beam is a good / best selected UL beam or QCL assumption for subsequent UL transmission.

[0382] The UE capability may indicate at least one of the following values: · Maximum number of repetitions for PDCCH order PRACH. · Number of PRACH repetitions (maximum). -Recurrence period setting. · Maximum number of repetitions (different multiple beams) in PRACH repetitions with different multiple beams.

[0383] The above UE capabilities / upper layer parameters allow the UE to achieve the above functions while maintaining compatibility with existing specifications.

[0384] (wireless communication system) The configuration of a wireless communication system according to an embodiment of the present disclosure will be described below. In this wireless communication system, communication is performed using any one of the wireless communication methods according to the above embodiments of the present disclosure or a combination thereof.

[0385] 34 is a diagram illustrating an example of a schematic configuration of a wireless communication system according to an embodiment. The wireless communication system 1 may be a system that realizes communication using Long Term Evolution (LTE) or 5th generation mobile communication system New Radio (5G NR) specified by the Third Generation Partnership Project (3GPP).

[0386] The wireless communication system 1 may also support dual connectivity between multiple Radio Access Technologies (RATs) (Multi-RAT Dual Connectivity (MR-DC)). MR-DC may 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 (NE-DC)), etc.

[0387] 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.

[0388] The wireless communication system 1 may support dual connectivity between multiple base stations within the same RAT (for example, dual connectivity in which both the MN and the SN are NR base stations (gNBs) (NR-NR Dual Connectivity (NN-DC))).

[0389] The wireless communication system 1 may include a base station 11 that forms a macrocell C1 with a relatively wide coverage, and base stations 12 (12a-12c) that are located within the macrocell C1 and form small cells C2 that are smaller than the macrocell C1. A user terminal 20 may be located within at least one of the cells. The locations and numbers of the cells and user terminals 20 are not limited to the embodiment shown in the figure. Hereinafter, when there is no need to distinguish between the base stations 11 and 12, they will be collectively referred to as base station 10.

[0390] 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 (CC) and dual connectivity (DC).

[0391] 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 C1 may be included in FR1, and the small cell C2 may 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 above 24 GHz (above-24 GHz). Note that the frequency bands and definitions of FR1 and FR2 are not limited to these, and for example, FR1 may be a frequency band higher than FR2.

[0392] 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.

[0393] The multiple base stations 10 may be connected by wire (for example, optical fiber conforming to the Common Public Radio Interface (CPRI), an X2 interface, or the like) or wirelessly (for example, NR communication). For example, when NR communication is used as a backhaul between the base stations 11 and 12, the base station 11 corresponding to the upper station may be called an Integrated Access Backhaul (IAB) donor, and the base station 12 corresponding to the relay station (relay) may be called an IAB node.

[0394] The base station 10 may be connected to the core network 30 directly or via another base station 10. The core network 30 may include, for example, at least one of an Evolved Packet Core (EPC), a 5G Core Network (5GCN), a Next Generation Core (NGC), and the like.

[0395] The user terminal 20 may be a terminal compatible with at least one of communication methods such as LTE, LTE-A, and 5G.

[0396] An Orthogonal Frequency Division Multiplexing (OFDM)-based radio access scheme may be used in the radio communication system 1. For example, Cyclic Prefix OFDM (CP-OFDM), Discrete Fourier Transform Spread OFDM (DFT-s-OFDM), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), or the like may be used in at least one of the downlink (DL) and uplink (UL).

[0397] The radio access scheme may also be called a waveform. Note that 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.

[0398] In the wireless communication system 1, a downlink shared channel (Physical Downlink Shared Channel (PDSCH)) shared by each user terminal 20, a broadcast channel (Physical Broadcast Channel (PBCH)), a downlink control channel (Physical Downlink Control Channel (PDCCH)), etc. may be used as the downlink channel.

[0399] Furthermore, in the wireless communication system 1, 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. may be used as an uplink channel.

[0400] The PDSCH transmits user data, higher layer control information, System Information Block (SIB), etc. The PUSCH may transmit user data, higher layer control information, etc. Furthermore, the PBCH may transmit Master Information Block (MIB).

[0401] Lower layer control information may be transmitted by the PDCCH. The lower layer control information may include, for example, Downlink Control Information (DCI) including scheduling information for at least one of the PDSCH and the PUSCH.

[0402] Note that the DCI for scheduling the PDSCH may be referred to as a DL assignment, a DL DCI, etc., and the DCI for scheduling the PUSCH may be referred to as an UL grant, a UL DCI, etc. Note that the PDSCH may be interpreted as DL data, and the PUSCH may be interpreted as UL data.

[0403] A control resource set (CORESET) and a search space may be used to detect the PDCCH. The CORESET corresponds to resources to search for DCI. The search space corresponds to a search region and a search method for PDCCH candidates. One CORESET may be associated with one or more search spaces. The UE may monitor a CORESET associated with a certain search space based on the search space configuration.

[0404] One search space may correspond to PDCCH candidates corresponding to one or more aggregation levels. One or more search spaces may be called a search space set. Note that the terms "search space," "search space set," "search space setting," "search space set setting," "CORESET," "CORESET setting," etc. in the present disclosure may be read interchangeably.

[0405] The PUCCH may transmit uplink control information (UCI) including at least one of channel state information (CSI), acknowledgement information (which may be called, for example, Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK), ACK / NACK, etc.), and scheduling request (SR). The PRACH may transmit a random access preamble for establishing a connection with a cell.

[0406] In the present disclosure, downlink, uplink, etc. may be expressed without adding "link." Also, various channels may be expressed without adding "Physical" to the beginning.

[0407] In the wireless communication system 1, a synchronization signal (SS), a downlink reference signal (DL-RS), etc. may be transmitted. In the wireless communication system 1, 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), etc. may be transmitted as DL-RS.

[0408] The synchronization signal may be, for example, at least one of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS). A signal block including the SS (PSS, SSS) and the PBCH (and DMRS for the PBCH) may be referred to as an SS / PBCH block, an SS Block (SSB), or the like. Note that the SS, SSB, and the like may also be referred to as reference signals.

[0409] Furthermore, in the wireless communication system 1, a sounding reference signal (SRS), a demodulation reference signal (DMRS), etc. may be transmitted as an uplink reference signal (UL-RS). Note that the DMRS may also be called a user equipment-specific reference signal (UE-specific reference signal).

[0410] (base station) 35 is a diagram showing an example of the configuration of a base station according to an embodiment. The base station 10 includes a control unit 110, a transceiver unit 120, a transceiver antenna 130, and a transmission line interface 140. Note that the base station may include one or more of each of the control unit 110, the transceiver unit 120, the transceiver antenna 130, and the transmission line interface 140.

[0411] In this example, the functional blocks of the characteristic parts of the present embodiment are mainly shown, and it may be assumed that the base station 10 also has other functional blocks necessary for wireless communication. Some of the processing of each unit described below may be omitted.

[0412] The control unit 110 performs overall control of the base station 10. The control unit 110 can be configured from a controller, a control circuit, and the like that are explained based on common understanding in the technical field to which the present disclosure relates.

[0413] The control unit 110 may control signal generation, scheduling (e.g., resource allocation, mapping), etc. The control unit 110 may control transmission and reception using the transceiver unit 120, the transceiver antenna 130, and the transmission path interface 140, measurement, etc. The control unit 110 may generate data to be transmitted as signals, control information, sequences, etc., and transfer them to the transceiver unit 120. The control unit 110 may perform call processing (setting up, releasing, etc.) of communication channels, status management of the base station 10, management of radio resources, etc.

[0414] The transceiver unit 120 may include a baseband unit 121, a radio frequency (RF) unit 122, and a measurement unit 123. The baseband unit 121 may include a transmission processing unit 1211 and a reception processing unit 1212. The transceiver unit 120 may be configured with a transmitter / receiver, an RF circuit, a baseband circuit, a filter, a phase shifter, a measurement circuit, a transceiver circuit, etc., which are described based on common understanding in the technical field related to the present disclosure.

[0415] The transmitting / receiving unit 120 may be configured as an integrated transmitting / receiving unit, or may be composed of a transmitting unit and a receiving unit. The transmitting unit may be composed of a transmission processing unit 1211 and an RF unit 122. The receiving unit may be composed of a reception processing unit 1212, an RF unit 122, and a measurement unit 123.

[0416] The transmitting and receiving antenna 130 can be configured from an antenna described based on common understanding in the technical field to which the present disclosure pertains, such as an array antenna.

[0417] The transceiver 120 may transmit the above-mentioned downlink channel, synchronization signal, downlink reference signal, etc. The transceiver 120 may receive the above-mentioned uplink channel, uplink reference signal, etc.

[0418] The transceiver 120 may form at least one of a transmission beam and a reception beam using digital beamforming (for example, precoding), analog beamforming (for example, phase rotation), or the like.

[0419] The transceiver 120 (transmission processing unit 1211) may perform Packet Data Convergence Protocol (PDCP) layer processing, Radio Link Control (RLC) layer processing (e.g., RLC retransmission control), Medium Access Control (MAC) layer processing (e.g., HARQ retransmission control), etc. on data, control information, etc. obtained from the control unit 110, and generate a bit string to be transmitted.

[0420] The transceiver 120 (transmission processor 1211) may perform transmission processing such as channel coding (which may include error correction coding), modulation, mapping, filtering, Discrete Fourier Transform (DFT) processing (if necessary), Inverse Fast Fourier Transform (IFFT) processing, precoding, and digital-to-analog conversion on the bit string to be transmitted, and output a baseband signal.

[0421] The transmitting / receiving unit 120 (RF unit 122) may perform modulation to a radio frequency band, filtering, amplification, etc. on the baseband signal, and transmit the radio frequency band signal via the transmitting / receiving antenna .

[0422] On the other hand, the transmitting / receiving unit 120 (RF unit 122) may perform amplification, filtering, demodulation to a baseband signal, etc. on the radio frequency band signal received by the transmitting / receiving antenna .

[0423] The transceiver 120 (reception processing unit 1212) may apply reception processing such as analog-to-digital conversion, Fast Fourier Transform (FFT) processing, Inverse Discrete Fourier Transform (IDFT) processing (if necessary), filtering, demapping, demodulation, decoding (which may include error correction decoding), MAC layer processing, RLC layer processing, and PDCP layer processing to the acquired baseband signal, thereby acquiring user data, etc.

[0424] The transceiver 120 (measurement unit 123) may perform measurements on the received signal. For example, the measurement unit 123 may perform Radio Resource Management (RRM) measurements, Channel State Information (CSI) measurements, etc. based on the received signal. The measurement unit 123 may 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 be output to the control unit 110.

[0425] The transmission path interface 140 may transmit and receive signals (backhaul signaling) between devices included in the core network 30, other base stations 10, etc., and may acquire and transmit user data (user plane data), control plane data, etc. for the user terminal 20.

[0426] The transmitting section and receiving section of the base station 10 in the present disclosure may be configured by at least one of the transmitting / receiving section 120, the transmitting / receiving antenna 130, and the transmission path interface 140.

[0427] The transceiver 120 may transmit a configuration for multiple repetitions of the physical random access channel. The controller 110 may control reception of the multiple repetitions with different beams.

[0428] The transceiver 120 may receive multiple repetitions of the PRACH transmitted using different beams, and the controller 110 may control transmission of responses to the PRACH within one or more windows.

[0429] The transceiver 120 may receive multiple repetitions of the PRACH using different beams, and the controller 110 may control transmission of the response based on an uplink beam following the response to the PRACH.

[0430] The transceiver 120 may receive multiple repetitions of the physical random access channel using multiple different beams. The controller 110 may indicate a reference beam corresponding to one of the multiple different beams for receiving a response to the physical random access channel, and may control transmission of the response based on the uplink beam after the response.

[0431] (user terminal) 36 is a diagram showing an example of the configuration of a user terminal according to one embodiment. The user terminal 20 includes a control unit 210, a transceiver unit 220, and a transceiver antenna 230. Note that the user terminal 20 may include one or more of each of the control unit 210, the transceiver unit 220, and the transceiver antenna 230.

[0432] Note that this example mainly shows functional blocks of the characteristic parts of the present embodiment, and it may be assumed that the user terminal 20 also has other functional blocks necessary for wireless communication. Some of the processing of each unit described below may be omitted.

[0433] The control unit 210 performs overall control of the user terminal 20. The control unit 210 can be configured from a controller, a control circuit, and the like that are explained based on common understanding in the technical field to which the present disclosure relates.

[0434] The control unit 210 may control signal generation, mapping, etc. The control unit 210 may also control transmission and reception, measurement, etc. using the transceiver unit 220 and the transceiver antenna 230. The control unit 210 may generate data, control information, sequences, etc. to be transmitted as signals, and transfer them to the transceiver unit 220.

[0435] The transceiver unit 220 may include a baseband unit 221, an RF unit 222, and a measurement unit 223. The baseband unit 221 may include a transmission processing unit 2211 and a reception processing unit 2212. The transceiver unit 220 may be configured from a transmitter / receiver, an RF circuit, a baseband circuit, a filter, a phase shifter, a measurement circuit, a transceiver circuit, etc., which are described based on common understanding in the technical field related to the present disclosure.

[0436] The transmitting / receiving unit 220 may be configured as an integrated transmitting / receiving unit, or may be composed of a transmitting unit and a receiving unit. The transmitting unit may be composed of a transmission processing unit 2211 and an RF unit 222. The receiving unit may be composed of a reception processing unit 2212, an RF unit 222, and a measurement unit 223.

[0437] The transmitting / receiving antenna 230 can be configured as an antenna described based on common understanding in the technical field to which the present disclosure pertains, such as an array antenna.

[0438] The transceiver 220 may receive the above-mentioned downlink channel, synchronization signal, downlink reference signal, etc. The transceiver 220 may transmit the above-mentioned uplink channel, uplink reference signal, etc.

[0439] The transceiver 220 may form at least one of a transmission beam and a reception beam using digital beamforming (for example, precoding), analog beamforming (for example, phase rotation), or the like.

[0440] The transceiver 220 (transmission processing unit 2211) may perform PDCP layer processing, RLC layer processing (e.g., RLC retransmission control), MAC layer processing (e.g., HARQ retransmission control), etc. on data, control information, etc. obtained from the control unit 210, and generate a bit string to be transmitted.

[0441] The transceiver 220 (transmission processor 2211) may perform transmission processing such as channel coding (which may include error correction coding), modulation, mapping, filtering, DFT processing (if necessary), IFFT processing, precoding, and digital-to-analog conversion on the bit string to be transmitted, and output a baseband signal.

[0442] Whether or not to apply DFT processing may be based on the setting of transform precoding. When transform precoding is enabled for a certain channel (e.g., PUSCH), the transceiver unit 220 (transmission processing unit 2211) may perform DFT processing as the transmission processing to transmit the channel using a DFT-s-OFDM waveform, and when transform precoding is not enabled, the transceiver unit 220 may not perform DFT processing as the transmission processing.

[0443] The transmitting / receiving unit 220 (RF unit 222) may perform modulation to a radio frequency band, filtering, amplification, etc. on the baseband signal, and transmit the radio frequency band signal via the transmitting / receiving antenna 230.

[0444] On the other hand, the transmitting / receiving unit 220 (RF unit 222) may perform amplification, filtering, demodulation to a baseband signal, etc. on the radio frequency band signal received by the transmitting / receiving antenna 230.

[0445] The transceiver 220 (reception processing unit 2212) may apply reception processing such as analog-to-digital conversion, FFT processing, IDFT processing (if necessary), filtering, demapping, demodulation, decoding (which may include error correction decoding), MAC layer processing, RLC layer processing, and PDCP layer processing to the acquired baseband signal to acquire user data, etc.

[0446] The transceiver 220 (measurement unit 223) may perform measurements on the received signal. For example, the measurement unit 223 may perform RRM measurement, CSI measurement, etc. based on the received signal. The measurement unit 223 may 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 be output to the control unit 210.

[0447] The transmitting section and receiving section of the user terminal 20 in the present disclosure may be configured by at least one of the transmitting / receiving section 220 and the transmitting / receiving antenna 230.

[0448] The transceiver 220 may receive configuration for multiple repetitions of the physical random access channel, and the controller 210 may control transmission of the multiple repetitions with different beams.

[0449] The control unit 210 may use a reference resource among a plurality of resources used in each of a plurality of repetitions for quasi co-location (QCL) estimation of reception of a response to the physical random access channel.

[0450] The reference resource may be indicated by downlink control information.

[0451] The control unit 210 may select the different beams based on the measurement results.

[0452] The transceiver 220 may transmit multiple repetitions of the physical random access channel using different beams, and the controller 210 may control reception of responses to the physical random access channel within one or more windows.

[0453] The control unit 210 may start a window after the last iteration of the plurality of iterations.

[0454] The control unit 210 may start one window after each of the multiple iterations.

[0455] The control unit 210 may determine a reference resource from a plurality of resources used in each of the plurality of iterations, and start one or more windows after the reference resource.

[0456] The transceiver 220 may transmit multiple repetitions of the PRACH using different beams, and the controller 210 may determine a subsequent uplink beam based on receiving a response to the PRACH.

[0457] The control unit 210 may determine the uplink beam based on at least one of the timing of receiving the response and a radio network temporary identifier (RNTI) used to receive the response.

[0458] The control unit 210 may control monitoring the response within a window after each of the multiple iterations.

[0459] The control unit 210 may control monitoring the response within a window after a last iteration of the plurality of iterations.

[0460] The transceiver 220 may transmit multiple repetitions of the physical random access channel using multiple different beams. The controller 210 may determine a reference beam corresponding to one of the multiple different beams and determine a subsequent uplink beam based on receiving a response to the physical random access channel using the reference beam.

[0461] The control unit 210 may determine the uplink beam based on at least one of the timing of receiving the response and a radio network temporary identifier (RNTI) used to receive the response.

[0462] The control unit 210 may control monitoring the response within a window after each of the multiple iterations.

[0463] The control unit 210 may control monitoring the response within a window after a last iteration of the plurality of iterations.

[0464] (Hardware configuration) The block diagrams used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wires, wirelessly, etc.) and these multiple devices. The functional block may also be realized by combining the single device or multiple devices with software.

[0465] Here, the functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, election, establishment, comparison, assumption, expectation, deeming, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission may be called a transmitting unit, transmitter, etc. As mentioned above, the implementation method of each is not particularly limited.

[0466] For example, a base station, a user terminal, etc. according to an embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Fig. 37 is a diagram illustrating an example of the hardware configuration of a base station and a user terminal according to an embodiment. The above-described base station 10 and user terminal 20 may 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, etc.

[0467] In this disclosure, terms such as apparatus, circuit, device, section, unit, etc. may be read interchangeably. The hardware configurations of the base station 10 and the user terminal 20 may be configured to include one or more of the devices shown in the drawings, or may be configured to exclude some of the devices.

[0468] For example, although only one processor 1001 is shown, there may be multiple processors. Furthermore, processing may be performed by one processor, or processing may be performed by two or more processors simultaneously, serially, or in other ways. Furthermore, processor 1001 may be implemented by one or more chips.

[0469] Each function in the base station 10 and the user terminal 20 is realized, for example, by loading predetermined software (programs) onto hardware such as a processor 1001 and a memory 1002, causing the processor 1001 to perform calculations, control communication via the communication device 1004, and control at least one of reading and writing data in the memory 1002 and the storage 1003.

[0470] The processor 1001, for example, runs an operating system to control the entire computer. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, at least a part of the above-mentioned control unit 110 (210), transmission / reception unit 120 (220), etc. may be realized by the processor 1001.

[0471] The processor 1001 also reads programs (program codes), software modules, data, etc. from at least one of the storage 1003 and the communication device 1004 into the memory 1002, and executes various processes in accordance with these. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. For example, the control unit 110 (210) may be realized by a control program stored in the memory 1002 and running on the processor 1001, and the other functional blocks may be realized in a similar manner.

[0472] The memory 1002 is a computer-readable recording medium and may be configured by at least one of, for example, 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, or the like. The memory 1002 may store executable programs (program codes), software modules, and the like for implementing a wireless communication method according to an embodiment of the present disclosure.

[0473] Storage 1003 is a computer-readable recording medium and may be constituted by at least one of, for example, a flexible disk, a floppy disk, a magneto-optical disk (e.g., a compact disc (e.g., a Compact Disc ROM (CD-ROM)), a digital versatile disc, a Blu-ray disc), a removable disk, a hard disk drive, a smart card, a flash memory device (e.g., a card, stick, key drive), a magnetic stripe, a database, a server, or other suitable storage medium. Storage 1003 may also be referred to as a secondary storage device.

[0474] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, or a communication module. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the above-mentioned transmission / reception unit 120 (220), transmission / reception antenna 130 (230), etc. may be realized by the communication device 1004. The transmission / reception unit 120 (220) may be implemented as a transmission unit 120a (220a) and a reception unit 120b (220b) that are physically or logically separated.

[0475] The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (for example, a display, a speaker, a light emitting diode (LED) lamp, etc.) that outputs to the outside. The input device 1005 and the output device 1006 may be integrated into one device (for example, a touch panel).

[0476] Furthermore, each device, such as the processor 1001 and the memory 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0477] Furthermore, the base station 10 and the user terminal 20 may 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 some or all of the functional blocks may be realized using such hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

[0478] (Variation) Note that terms explained in the present disclosure and terms necessary for understanding the present disclosure may be replaced with terms having the same or similar meanings. For example, a channel, a symbol, and a signal (signal or signaling) may be interchangeable. A signal may also be a message. A reference signal may be abbreviated as RS, and may also be called a pilot, pilot signal, etc. depending on the applicable standard. A component carrier (CC) may also be called a cell, frequency carrier, carrier frequency, etc.

[0479] A radio frame may be composed of one or more periods (frames) in the time domain. Each of the one or more periods (frames) constituting a radio frame may be called a subframe. Furthermore, a subframe may be composed of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0480] Here, the numerology may be a communication parameter applied to at least one of transmission and reception of a signal or channel, and may indicate at least one of, for example, 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 specific filtering process performed by a transceiver in the frequency domain, and a specific windowing process performed by a transceiver in the time domain.

[0481] A slot may be composed of one or more symbols in the time domain (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol or a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol), and may be a time unit based on numerology.

[0482] A slot may include multiple minislots. Each minislot may consist of one or multiple symbols in the time domain. A minislot may also be called a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (PUSCH) mapping type B.

[0483] A radio frame, a subframe, a slot, a minislot, and a symbol all represent time units for transmitting signals. The radio frame, the subframe, the slot, the minislot, and the symbol may be referred to by other names corresponding to the radio frame, the subframe, the slot, the minislot, and the symbol. Note that the time units such as a frame, a subframe, a slot, a minislot, and a symbol in the present disclosure may be interchangeable.

[0484] For example, one subframe may be referred to as a TTI, or multiple consecutive subframes may be referred to as a TTI, or one slot or one minislot may be referred to as a TTI. That is, at least one of a subframe and a TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (for example, 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0485] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station performs scheduling to allocate radio resources (such as frequency bandwidth and transmission power that can be used by each user terminal) to each user terminal in TTI units. However, the definition of TTI is not limited to this.

[0486] The TTI may be a transmission time unit for a channel-encoded data packet (transport block), a code block, a code word, etc., or may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the time interval (e.g., the number of symbols) to which a transport block, a code block, a code word, etc. is actually mapped may be shorter than the TTI.

[0487] When one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit for scheduling. Also, the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0488] A TTI having a time length of 1 ms may be called a regular TTI (TTI in 3GPP Rel. 8-12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, minislot, subslot, slot, etc.

[0489] In addition, a long TTI (e.g., a normal TTI, a subframe, etc.) may be interpreted as a TTI having a time length of more than 1 ms, and a short TTI (e.g., a shortened TTI, etc.) may be interpreted as a TTI having a TTI length shorter than the TTI length of a long TTI and equal to or greater than 1 ms.

[0490] A resource block (RB) is a resource allocation unit in the time domain and the frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of numerology, for example, 12. The number of subcarriers included in an RB may also be determined based on numerology.

[0491] In addition, an RB may include one or more symbols in the time domain and may have a length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc. may each be composed of one or more resource blocks.

[0492] Note that one or more RBs may also be called a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, etc.

[0493] 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.

[0494] A Bandwidth Part (BWP), which may also be referred to as a fractional bandwidth, may represent a subset of contiguous common resource blocks (RBs) for a given numerology on a given carrier, where the common RBs may be identified by their index relative to a common reference point of the carrier. PRBs may be defined in a given BWP and numbered within that BWP.

[0495] The BWP may include an UL BWP (a BWP for UL) and a DL BWP (a BWP for DL). One or more BWPs may be configured for a UE within one carrier.

[0496] At least one of the configured BWPs may be active, and the UE may not expect to transmit or receive a given signal / channel outside the active BWP. Note that the terms "cell," "carrier," etc. in this disclosure may be read as "BWP."

[0497] The above-described structures of radio frames, subframes, slots, minislots, symbols, etc. are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, the number of symbols in a TTI, the symbol length, the cyclic prefix (CP) length, etc. may be changed in various ways.

[0498] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, may be expressed using relative values ​​from a predetermined value, or may be expressed using other corresponding information. For example, a radio resource may be indicated by a predetermined index.

[0499] The names used for parameters and the like in this disclosure are not intended to be limiting in any way. Furthermore, the mathematical expressions and the like using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (PUCCH, PDCCH, etc.) and information elements may 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 way.

[0500] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0501] Furthermore, information, signals, etc. may be output from a higher layer to a lower layer and / or from a lower layer to a higher layer. Information, signals, etc. may be input / output via multiple network nodes.

[0502] Input and output information, signals, etc. may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information, signals, etc. may be overwritten, updated, or added. Output information, signals, etc. may be deleted. Input information, signals, etc. may be transmitted to another device.

[0503] Notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, notification of information in the present disclosure may be performed by physical layer signaling (e.g., Downlink Control Information (DCI) and Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, broadcast information (Master Information Block (MIB) and System Information Block (SIB)), Medium Access Control (MAC) signaling), other signals, or a combination thereof.

[0504] Note that the physical layer signaling may be called Layer 1 / Layer 2 (L1 / L2) control information (L1 / L2 control signal), L1 control information (L1 control signal), etc. Furthermore, the RRC signaling may be called an RRC message, such as an RRC connection setup message or an RRC connection reconfiguration message. Furthermore, the MAC signaling may be notified using, for example, a MAC Control Element (CE).

[0505] Furthermore, notification of specified information (e.g., notification that "it is X") is not limited to explicit notification, but may be made implicitly (e.g., by not notifying the specified information or by notifying other information).

[0506] The determination may be made by a value represented by one bit (0 or 1), by a Boolean value represented by true or false, or by a comparison of numerical values ​​(e.g., comparison with a predetermined value).

[0507] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0508] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0509] As used in this disclosure, the terms "system" and "network" may be used interchangeably. A "network" may refer to devices included in the network (e.g., base stations).

[0510] 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," "transmit 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," "panel," etc. may be used interchangeably.

[0511] In this disclosure, terms such as "base station (BS)," "radio 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," "component carrier," etc. may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, picocell, etc.

[0512] A base station can accommodate one or more (e.g., three) cells. When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be divided into multiple smaller areas, and each smaller area can be provided with communication service by a base station subsystem (e.g., a small indoor base station (Remote Radio Head (RRH))). The term "cell" or "sector" refers to a part or the entire coverage area of ​​a base station and / or base station subsystem that provides communication service within this coverage.

[0513] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0514] A 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, handset, user agent, mobile client, client, or some other suitable terminology.

[0515] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a wireless communication device, etc. Note that at least one of the base station and the mobile station may be a device mounted on a moving object, the moving object itself, etc.

[0516] The mobile body is a movable object that can move at any speed and naturally includes cases where the mobile body is stationary. Examples of the mobile body include, but are not limited to, vehicles, transport vehicles, automobiles, motorcycles, bicycles, connected cars, excavators, bulldozers, wheel loaders, dump trucks, forklifts, trains, buses, handcars, rickshaws, ships and other watercraft, airplanes, rockets, satellites, drones, multicopters, quadcopters, balloons, and objects mounted thereon. The mobile body may also be a mobile body that moves autonomously based on an operation command.

[0517] The mobile object may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). Note that at least one of the base station and the mobile station may also include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an Internet of Things (IoT) device such as a sensor.

[0518] 38 is a diagram showing an example of a vehicle according to an embodiment. Vehicle 40 includes a drive unit 41, a steering unit 42, an accelerator pedal 43, a brake pedal 44, a shift lever 45, left and right front wheels 46, left and right rear wheels 47, axles 48, an electronic control unit 49, various sensors (including a current sensor 50, an RPM sensor 51, an air pressure sensor 52, a vehicle speed sensor 53, an acceleration sensor 54, an accelerator pedal sensor 55, a brake pedal sensor 56, a shift lever sensor 57, and an object detection sensor 58), an information service unit 59, and a communication module 60.

[0519] The drive unit 41 is configured with at least one of an engine, a motor, and a hybrid of an engine and a motor, for example. The steering unit 42 includes at least a steering wheel (also called a handle) and is configured to steer at least one of the front wheels 46 and the rear wheels 47 based on the operation of the steering wheel operated by the user.

[0520] The electronic control unit 49 is composed of a microprocessor 61, memory (ROM, RAM) 62, and a communication port (e.g., an input / output (IO) port) 63. Signals are input to the electronic control unit 49 from various sensors 50-58 provided in the vehicle. The electronic control unit 49 may also be called an Electronic Control Unit (ECU).

[0521] The signals from the various sensors 50-58 include a current signal from a current sensor 50 that senses the current of the motor, a rotation speed signal of the front wheels 46 / rear wheels 47 obtained by a rotation speed sensor 51, an air pressure signal of the front wheels 46 / rear wheels 47 obtained by an air pressure sensor 52, a vehicle speed signal obtained by a vehicle speed sensor 53, an acceleration signal obtained by an acceleration sensor 54, a depression amount signal of the accelerator pedal 43 obtained by an accelerator pedal sensor 55, a depression amount signal of the brake pedal 44 obtained by a brake pedal sensor 56, an operation signal of the shift lever 45 obtained by a shift lever sensor 57, and a detection signal for detecting obstacles, vehicles, pedestrians, etc. obtained by an object detection sensor 58.

[0522] The information service unit 59 is composed of various devices, such as a car navigation system, an audio system, speakers, a display, a television, and a radio, for providing (outputting) various information such as driving information, traffic information, and entertainment information, and one or more ECUs for controlling these devices. The information service unit 59 uses information acquired from external devices via the communication module 60 or the like to provide various information / services (for example, multimedia information / multimedia services) to the occupants of the vehicle 40.

[0523] The information service unit 59 may include input devices (e.g., keyboards, mice, microphones, switches, buttons, sensors, touch panels, etc.) that accept input from the outside, and may also include output devices (e.g., displays, speakers, LED lamps, touch panels, etc.) that output to the outside.

[0524] The driving assistance system unit 64 is configured with various devices that provide functions for preventing accidents and reducing the driver's driving burden, such as millimeter-wave radar, Light Detection and Ranging (LiDAR), cameras, positioning locators (e.g., Global Navigation Satellite System (GNSS)), map information (e.g., High Definition (HD) maps, Autonomous Vehicle (AV) maps), gyro systems (e.g., Inertial Measurement Units (IMUs), Inertial Navigation Systems (INSs)), Artificial Intelligence (AI) chips, and AI processors, as well as one or more ECUs that control these devices. The driving assistance system unit 64 also transmits and receives various information via the communication module 60 to realize driving assistance functions or autonomous driving functions.

[0525] The communication module 60 can communicate with the microprocessor 61 and components of the vehicle 40 via the communication port 63. For example, the communication module 60 transmits and receives data (information) via the communication port 63 to and from the drive unit 41, steering unit 42, accelerator pedal 43, brake pedal 44, shift lever 45, left and right front wheels 46, left and right rear wheels 47, axles 48, the microprocessor 61 and memory (ROM, RAM) 62 in the electronic control unit 49, and the various sensors 50-58, which are provided in the vehicle 40.

[0526] The communication module 60 is a communication device that can be controlled by the microprocessor 61 of the electronic control unit 49 and can communicate with an external device. For example, it transmits and receives various information to and from the external device via wireless communication. The communication module 60 may be located either inside or outside the electronic control unit 49. The external device may be, for example, the above-mentioned base station 10 or user terminal 20. Furthermore, the communication module 60 may be, for example, at least one of the above-mentioned base station 10 and user terminal 20 (or may function as at least one of the base station 10 and user terminal 20).

[0527] The communication module 60 may transmit at least one of signals from the above-mentioned various sensors 50-58 input to the electronic control unit 49, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 59 to an external device via wireless communication. The electronic control unit 49, the various sensors 50-58, the information service unit 59, etc. may be referred to as input units that accept input. For example, the PUSCH transmitted by the communication module 60 may include information based on the above-mentioned input.

[0528] The communication module 60 receives various information (traffic information, traffic signal information, vehicle distance information, etc.) transmitted from external devices and displays it on an information service unit 59 provided in the vehicle. The information service unit 59 may also be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker based on the PDSCH received by the communication module 60 (or data / information decoded from the PDSCH)).

[0529] Furthermore, the communication module 60 stores various information received from external devices in a memory 62 that can be used by the microprocessor 61. Based on the information stored in the memory 62, the microprocessor 61 may control the drive unit 41, steering unit 42, accelerator pedal 43, brake pedal 44, shift lever 45, left and right front wheels 46, left and right rear wheels 47, axles 48, various sensors 50-58, and the like provided in the vehicle 40.

[0530] Furthermore, a base station in the present disclosure may be read as a user terminal. For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple user terminals (which may be called, for example, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). In this case, the user terminal 20 may be configured to have the functions of the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "sidelink"). For example, terms such as uplink channel and downlink channel may be read as sidelink channel.

[0531] Similarly, the user terminal in the present disclosure may be read as a base station, in which case the base station 10 may be configured to have the functions of the user terminal 20 described above.

[0532] In the present disclosure, an operation described as being performed by a base station may be performed by its upper node in some cases. It is apparent that in a network including one or more network nodes having 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 (such as, but not limited to, a Mobility Management Entity (MME) and a Serving-Gateway (S-GW)), or a combination thereof.

[0533] Each aspect / embodiment described in this disclosure may be used alone, in combination, or switched depending on the implementation. Furthermore, the order of the processing procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be changed unless inconsistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the specific order presented.

[0534] Each aspect / embodiment described in the present disclosure may be a technology other than 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 (x is, for example, an integer or decimal number)), 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 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE The present invention may be applied to systems that use 802.20, Ultra-WideBand (UWB), Bluetooth (registered trademark), or other appropriate wireless communication methods, or to next-generation systems that are expanded, modified, created, or defined based on these. It may also be applied to a combination of multiple systems (e.g., a combination of LTE or LTE-A and 5G).

[0535] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0536] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must in some way precede the second element.

[0537] The term "determining," as used in this disclosure, may encompass a wide variety of actions. For example, "determining" may be considered to be judging, calculating, computing, processing, deriving, investigating, looking up, search, inquiry (e.g., looking up in a table, database, or another data structure), ascertaining, etc.

[0538] Additionally, "determining" may be considered to be "determining" receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), etc.

[0539] Also, "decision" may be considered to be "deciding" resolving, selecting, choosing, establishing, comparing, etc. In other words, "decision" may be considered to be "deciding" on some action.

[0540] Furthermore, "judgment (decision)" may be interpreted as "assuming," "expecting," "considering," or the like.

[0541] The "maximum transmit power" in this disclosure may mean the maximum value of transmit power, the nominal UE maximum transmit power, or the rated UE maximum transmit power.

[0542] 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 two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access."

[0543] In this disclosure, when two elements are connected, they may be considered to be "connected" or "coupled" to one another using one or more wires, cables, printed electrical connections, etc., as well as using electromagnetic energy having wavelengths in the radio frequency range, microwave range, light (both visible and invisible) range, etc., as some non-limiting and non-exhaustive examples.

[0544] In the present disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "coupled" may also be interpreted in the same way as "different."

[0545] When used in this disclosure, the terms "include," "including," and variations thereof are intended to be inclusive, similar to the term "comprising." Furthermore, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0546] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0547] Although the invention according to the present disclosure has been described in detail above, it is clear to those skilled in the art that the invention according to the present disclosure is not limited to the embodiments described in the present disclosure. The invention according to the present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the invention as defined by the description of the claims. Therefore, the description of the present disclosure is intended to be illustrative and explanatory and does not impose any limiting meaning on the invention according to the present disclosure.

Claims

1. a transmitter for transmitting multiple repetitions of a physical random access channel using multiple different beams; a control unit for controlling reception of responses to the physical random access channel within one or more windows; The control unit determines a reference resource from a plurality of resources used in each of the plurality of repetitions, and starts the one or more windows after the reference resource.

2. transmitting multiple repetitions of a physical random access channel using multiple different beams; and controlling reception of responses to the physical random access channel in one or more windows; A wireless communication method for a terminal, comprising determining a reference resource from a plurality of resources used in each of the plurality of repetitions, and starting the one or more windows after the reference resource.

3. a receiver for receiving multiple repetitions of a physical random access channel transmitted using multiple different beams; a control unit for controlling transmission of a response to the physical random access channel within one or more windows; The control unit determines a reference resource from a plurality of resources used in each of the plurality of repetitions, and starts transmitting the response in the one or more windows after the reference resource.

4. A system including a terminal and a base station, The terminal a transmitter for transmitting multiple repetitions of a physical random access channel using multiple different beams; a control unit for controlling reception of responses to the physical random access channel within one or more windows; the control unit determines a reference resource from a plurality of resources used in each of the plurality of repetitions, and starts the one or more windows after the reference resource; The base station A system having a receiver for receiving the plurality of repetitions.

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