Method and apparatus for transmission and reception of random access channel in wireless communication system

Abstract

According to one embodiment of the present specification, a method performed by a terminal comprises the steps of: transmitting a PRACH on the basis of at least one RO; and receiving the RAR. The at least one RO includes a plurality of ROs belonging to a group of ROs for a plurality of transmissions of the PRACH. The plurality of ROs includes i) a first RO and ii) at least one second RO. The at least one second RO is characterized by comprising an RO determined in an ascending order of the time resource index after the first RO based on the frequency resource index associated with the first RO.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for transmitting and receiving a random access channel in a wireless communication system. Background Art

[0002] Mobile communication systems have evolved to provide voice services while ensuring user activity. Mobile communication systems are expanding their services from voice only to data. The current surge in data traffic is exhausting resources, and user demand for higher data rate services brings the need for more advanced mobile communication systems.

[0003] The next generation of mobile communication systems needs to meet requirements such as handling the explosive growth of data traffic, significantly increasing the transmission rate for each user, working with a large number of connected devices, and supporting very low end-to-end latency and high energy efficiency. To this end, various research efforts are being conducted on various technologies, such as dual connectivity, massive multiple-input multiple-output (MIMO), in-band full-duplex, non-orthogonal multiple access (NOMA), ultra-wideband support, and device networking.

[0004] According to the current PRACH configuration, multiple PRACH opportunities (ROs) with the same beam index (e.g., SS / PBCH block index or SSB index) may exist in the form of frequency division multiplexing (FDM) at a specific time instance. When determining an RO group for multiple PRACH transmissions, the terminal needs to decide at which frequency position to select the RO to form the RO group. Summary of the invention

[0005] Technical issues

[0006] As described above, there may be multiple ROs for FDM at one time instance. Conventional solutions do not provide any definition for determining the RO group for multiple PRACH transmissions. Therefore, there is ambiguity in the determination of the RO group in the terminal / base station operation. As a specific example, it is unclear on the terminal side which RO should be used to configure the determination of the RO group. In this case, the base station may process multiple PRACH transmissions based on the RO group of one terminal as PRACH transmissions from multiple terminals. Conversely, the base station may process PRACH transmissions from multiple terminals as PRACH transmissions based on the RO group of one terminal.

[0007] The present disclosure provides methods for removing ambiguity in determining RO groups for multiple PRACH transmissions.

[0008] The technical objectives to be achieved by the present disclosure are not limited to those technical objectives described above only as examples, and other technical objectives not mentioned can be clearly understood by those skilled in the art to which the present disclosure belongs from the following description.

[0009] Technical Solution

[0010] According to an embodiment of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system includes: transmitting a physical random access channel (PRACH) based on at least one PRACH opportunity (RO); and receiving a random access response (RAR).

[0011] The at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of the PRACH.

[0012] Multiple ROs are associated with the same synchronization signal / physical broadcast channel block index (SS / PBCH block index).

[0013] The plurality of ROs include: i) a first RO and ii) one or more second ROs.

[0014] The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

[0015] The first RO may be a starting RO of an RO group, and the one or more second ROs may be the remaining ROs of the RO group.

[0016] The frequency resource index associated with the one or more second ROs may be the same as the frequency resource index associated with the first RO.

[0017] The frequency resource index associated with the first RO may be associated with a resource block (RB).

[0018] The RO group may be one of multiple RO groups associated with the same SS / PBCH block index.

[0019] A first RO of a first RO group among the plurality of RO groups may be associated with a lowest frequency resource index.

[0020] The first RO of each of the plurality of RO groups may be: i) determined in ascending order of frequency resource indexes with respect to the same time resource index, and ii) then determined in ascending order of time resource indexes with respect to the same frequency resource index.

[0021] A frequency resource index and / or a time resource index associated with a first RO of one of the plurality of RO groups may be different from a frequency resource index and / or a time resource index associated with a first RO of another RO group among the plurality of RO groups.

[0022] The first RO may be based on one of the ROs that is frequency division multiplexed (FDM) in one time instance.

[0023] The method may also include receiving configuration information related to the PRACH. The configuration information may include information for the number of multiple transmissions. The number of multiple ROs may be based on the number of multiple transmissions.

[0024] According to another embodiment of the present disclosure, a user equipment operating in a wireless communication system includes one or more transceivers, one or more processors, and one or more memories operably connected to the one or more processors, the one or more memories storing instructions for configuring the one or more processors to perform operations based on execution by the one or more processors.

[0025] The operations include transmitting a physical random access channel (PRACH) based on at least one PRACH opportunity (RO) and receiving a random access response (RAR).

[0026] The at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of the PRACH.

[0027] Multiple ROs are associated with the same synchronization signal / physical broadcast channel block index (SS / PBCH block index).

[0028] The plurality of ROs include: i) a first RO and ii) one or more second ROs.

[0029] The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

[0030] According to another embodiment of the present disclosure, a device includes one or more memories and one or more processors functionally connected to the one or more memories.

[0031] The one or more memories include instructions that, upon execution by the one or more processors, configure the one or more processors to perform operations.

[0032] The operations include transmitting a physical random access channel (PRACH) based on at least one PRACH opportunity (RO) and receiving a random access response (RAR).

[0033] The at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of the PRACH.

[0034] Multiple ROs are associated with the same synchronization signal / physical broadcast channel block index (SS / PBCH block index).

[0035] The plurality of ROs include: i) a first RO and ii) one or more second ROs.

[0036] The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

[0037] One or more non-transitory computer-readable media according to another embodiment of the present disclosure stores one or more instructions.

[0038] One or more instructions executable by one or more processors are configured to allow the one or more processors to perform operations.

[0039] The operations include transmitting a physical random access channel (PRACH) based on at least one PRACH opportunity (RO) and receiving a random access response (RAR).

[0040] The at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of the PRACH.

[0041] Multiple ROs are associated with the same synchronization signal / physical broadcast channel block index (SS / PBCH block index).

[0042] The plurality of ROs include: i) a first RO and ii) one or more second ROs.

[0043] The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

[0044] According to another embodiment of the present disclosure, a method performed by a base station in a wireless communication system includes: receiving a physical random access channel (PRACH) based on at least one PRACH opportunity (RO); and sending a random access response (RAR).

[0045] The at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of a PRACH of the UE.

[0046] Multiple ROs are associated with the same synchronization signal / physical broadcast channel block index (SS / PBCH block index).

[0047] The plurality of ROs include: i) a first RO and ii) one or more second ROs.

[0048] The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

[0049] According to another embodiment of the present disclosure, a base station operating in a wireless communication system includes one or more transceivers, one or more processors, and one or more memories operably connected to the one or more processors, the one or more memories storing instructions for configuring the one or more processors to perform operations based on execution by the one or more processors.

[0050] The operations include receiving a physical random access channel (PRACH) based on at least one PRACH opportunity (RO) and sending a random access response (RAR).

[0051] The operations include receiving a physical random access channel (PRACH) and sending a random access response (RAR) based on at least one physical random access channel (PRACH) opportunity (RO).

[0052] The at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of a PRACH of the UE.

[0053] Multiple ROs are associated with the same synchronization signal / physical broadcast channel block index (SS / PBCH block index).

[0054] The plurality of ROs include: i) a first RO and ii) one or more second ROs.

[0055] The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

[0056] Beneficial Effects

[0057] According to an embodiment of the present disclosure, for multiple transmissions of PRACH, ROs belonging to an RO group are defined in ascending order of time resource index based on a frequency resource index associated with a first RO. When there are multiple ROs associated with the same SS / PBCH block index, the problem of ambiguity about which ROs should be used to transmit PRACH multiple times can be solved.

[0058] The effects that can be achieved by the present disclosure are not limited to those described above by way of example only, and other effects and advantages of the present disclosure will be more clearly understood by those skilled in the art to which the present disclosure belongs from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 Physical channels and general signal transmission used in the 3GPP system are illustrated.

[0060] Figure 2 The SSB architecture is illustrated.

[0061] Figure 3 SSB transmission is illustrated.

[0062] Figure 4 RACH opportunities for each preamble format are illustrated.

[0063] Figure 5 The random access procedure is illustrated.

[0064] Figure 6 Determination of an RO group according to an embodiment of the present disclosure is illustrated.

[0065] Figure 7 is a flowchart for describing a method performed by a user equipment (UE) according to an embodiment of the present disclosure.

[0066] Figure 8 is a flowchart for describing a method performed by a base station (BS) according to another embodiment of the present disclosure.

[0067] Fig. 9 is a diagram illustrating the configuration of a first device and a second device according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0068] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following detailed description in conjunction with the accompanying drawings is intended to describe example embodiments of the present disclosure, but does not represent the only embodiment of the present disclosure. The following detailed description includes specific details to convey a thorough understanding of the present disclosure. However, it will be readily understood by those skilled in the art that embodiments of the present disclosure can be practiced even without these details.

[0069] In some cases, to avoid conceptual ambiguity, well-known structures or devices may be omitted or shown in block diagrams, while focusing on the core features of each structure and device.

[0070] In the following, downlink (DL) means communication from a base station to a terminal, and uplink (UL) means communication from a terminal to a base station. In the downlink, the sender may be part of a base station, and the receiver may be part of a terminal. In the uplink, the sender may be part of a terminal, and the receiver may be part of a base station. The base station may be represented as a first communication device, and the terminal may be represented as a second communication device. The base station (BS) may be replaced with terms including a fixed station, a node B, an evolved node B (eNB), a next generation node B (gNB), a base transceiver system (BTS), an access point (AP), a network (5G network), an AI system, a roadside unit (RSU), a vehicle, a robot, an unmanned aerial vehicle (UAV), an augmented reality (AR) device, a virtual reality (VR) device, and the like. In addition, the terminal may be fixed or mobile, and may be replaced by terms including user equipment (UE), mobile station (MS), user terminal (UT), mobile subscriber station (MSS), subscriber station (SS), advanced mobile station (AMS), wireless terminal (WT), machine type communication (MTC) device, machine to machine (M2M) device and device to device (D2D) device, vehicle, robot, AI module, unmanned aerial vehicle (UAV), augmented reality (AR) device, virtual reality (VR) device, etc.

[0071] Physical channels and general signaling

[0072] Figure 1 The physical channels and general signal transmission used in the 3GPP system are shown. In the wireless communication system, the UE receives information from the eNB through the downlink (DL), and the UE sends information to the eNB through the uplink (UL). The information sent and received by the eNB and the UE includes data and various control information, and there are various physical channels according to the type / purpose of the information sent and received by the eNB and the UE.

[0073] When the UE is powered on or newly enters a cell, the UE performs an initial cell search operation, such as synchronization with the eNB (S101). To this end, the UE may receive a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the eNB, and synchronize with the eNB and obtain information such as a cell ID. Thereafter, the UE may receive a physical broadcast channel (PBCH) from the eNB and obtain intra-cell broadcast information. In addition, the UE receives a downlink reference signal (DL RS) in the initial cell search step to check the downlink channel status.

[0074] The UE that has completed the initial cell search receives a physical downlink control channel (PDCCH) and receives a physical downlink shared channel (PDSCH) according to information loaded on the PDCCH to acquire more specific system information (S102).

[0075] In addition, when there is no radio resource to first access the eNB or for signal transmission, the UE may perform a random access procedure (RACH) to the eNB (S103 to S106). To this end, the UE may send a specific sequence as a preamble through a physical random access channel (PRACH) (S103 and S105), and receive a response message (random access response (RAR) message) to the preamble through a PDCCH and a corresponding PDSCH. In the case of a contention-based RACH, a contention resolution procedure (S106) may be additionally performed.

[0076] The UE performing the above process may then perform PDCCH / PDSCH reception (S107) and physical uplink shared channel (PUSCH) / physical uplink control channel (PUCCH) transmission (S108) as a general uplink / downlink signal transmission process. Specifically, the UE may receive downlink control information (DCI) via the PDCCH. Here, the DCI may include control information such as resource allocation information for the UE, and the format may be applied differently depending on the purpose of use.

[0077] In addition, the control information sent by the UE to the eNB through the uplink or received by the UE from the eNB may include a downlink / uplink ACK / NACK signal, a channel quality indicator (CQI), a precoding matrix index (PMI), a rank indicator (RI), etc. The UE may send control information such as CQI / PMI / RI through the PUSCH and / or the PUCCH.

[0078] Synchronization Signal Block (SSB) transmission and related operations

[0079] Figure 2 The SSB architecture is illustrated.

[0080] The UE can perform cell search, system information acquisition, beam alignment for initial access, DL measurement, etc. based on SSB. SSB is used in combination with SS / synchronization signal / physical broadcast channel (PBCH) blocks.

[0081] Reference Figure 2, SSB consists of PSS, SSS and PBCH. SSB consists of four consecutive OFDM symbols, and PSS, PBCH, SSS / PBCH and PBCH are transmitted for each OFDM symbol. Each of PSS and SSS can be composed of one OFDM symbol and 127 subcarriers, and PBCH consists of 3 OFDM symbols and 576 subcarriers. Polarization coding and quadrature phase shift keying (QPSK) are applied to PBCH. PBCH consists of data RE and demodulation reference signal (DMRS) RE for each OFDM symbol. There are three DMRS REs for each RB, and there are three data REs between DMRS REs.

[0082] Figure 3 SSB transmission is illustrated.

[0083] Reference Figure 3 , SSB is transmitted periodically according to the SSB period. The SSB basic period assumed by the UE in the initial cell search is defined as 20ms. After the cell is connected, the SSB period can be configured by the network (e.g., base station (BS)) to be one of {5ms, 10ms, 20ms, 40ms, 80ms, 160ms}. At the beginning of the SSB period, an SSB burst set is constructed. The SSB burst set can be constructed by a 5ms time window (i.e., half a frame), and the SSB can be transmitted up to L times within the SS burst set. L, which is the maximum number of transmissions of the SSB, can be given as follows according to the frequency band of the carrier. A time slot includes a maximum of two SSBs.

[0084] - For the frequency range up to 3 GHz, L = 4

[0085] - For the frequency range from 3 GHz to 6 GHz, L = 8

[0086] - For the frequency range from 6 GHz to 52.6 GHz, L = 64

[0087] The temporal position of the SSB candidates in the SS burst set may be defined according to the SCS as follows: The temporal position of the SSB candidates is indexed from 0 to L-1 in temporal order within the SSB burst set (ie, half-frame).

[0088] - Case A - 15kHz SCS: The index of the starting symbol of the candidate SSB is given as {2,8}+14*n. When the carrier frequency is 3 GHz or lower, n=0,1. When the carrier frequency is 3 to 6 GHz, n=0,1,2,3.

[0089] - Case B - 30kHz SCS: The index of the starting symbol of the candidate SSB is given as {4,8,16,20}+28*n. When the carrier frequency is 3 GHz or lower, n=0. When the carrier frequency is 3 to 6 GHz, n=0,1.

[0090] - Case C - 30kHz SCS: The index of the starting symbol of the candidate SSB is given as {2,8}+14*n. When the carrier frequency is 3GHz or lower, n=0,1. When the carrier frequency is 3 to 6GHz, n=0,1,2,3.

[0091] - Case D - 120kHz SCS: The index of the starting symbol of the candidate SSB is given as {4,8,16,20}+28*n. When the carrier frequency is greater than 6GHz, n=0,1,2,3,5,6,7,8,10,11,12,13,15,16,17,18.

[0092] - Case E - 240kHz SCS: The index of the starting symbol of the candidate SSB is given as {8, 12, 16, 20, 32, 36, 40, 44} + 56*n. When the carrier frequency is greater than 6GHz, n = 0, 1, 2, 3, 5, 6, 7, 8.

[0093] The RACH time slot is described below.

[0094] A RACH slot includes one or more RACH opportunities.

[0095] For subcarrier spacing of {1.25kHz, 5kHz}, the time slot duration is 1ms; for subcarrier spacing of {15kHz, 30kHz, 60kHz, 120kHz}, the time slot has a scalable duration (i.e.: 1ms, 0.5ms, 0.25ms, 0.125ms).

[0096] For the short preamble format, the starting OFDM symbol index in the RACH slot has a value of {0, 2, x}.

[0097] Figure 4 RACH opportunities for each preamble format are illustrated.

[0098] Reference Figure 4 , a RACH slot may include one or more RACH opportunities (RO) for each preamble format (eg, A1, A2, . . . , C2). Figure 4 (a) in FIG. 1 illustrates the case where the starting OFDM symbol is "0", and Figure 4 (b) in FIG. 1 illustrates the case where the starting OFDM symbol is "2".

[0099] Figure 5The random access procedure is illustrated.

[0100] Figure 5 (a) in FIG. 1 illustrates a contention-based RACH process, and Figure 5 (b) in FIG. 1 illustrates a contention-free RACH process.

[0101] The following describes MSG1 transmission.

[0102] The subcarrier spacing for MSG1 is configured in the RACH configuration and provided in the handover command regarding the contention-free RA procedure for handover.

[0103] Preamble indexes used for contention-based random access (CBRA) and contention-free random access (CFRA) are continuously mapped to one SSB in one RACH transmission opportunity.

[0104] CBRA: The association between SS blocks (SSBs) within an SS burst set and a subset of RACH resources and / or preamble indices is configured by a parameter set in the RMSI.

[0105] CFRA: The UE may be configured to send multiple MSG1s through dedicated multiple RACH transmission opportunities in the time domain before the monitored RAR window ends.

[0106] Furthermore, the association between the CFRA preamble and the SSB is reconfigured via UE-specific RRC.

[0107] The random access procedure may be a Type-1 random access procedure (4-step RA) or a Type-2 random access procedure (2-step RA).

[0108] The type 1 random access procedure may include sending a random access preamble (Msg1) in a physical random access channel (PRACH), receiving a random access response (RAR) (Msg2), sending a PUSCH (Msg3) scheduled by a UL grant of the RAR, and a PDSCH (Msg4) for contention resolution. If the random access procedure is a contention-free random access (CFRA), Msg3 transmission and Msg4 reception are omitted.

[0109] The type 2 random access procedure may include sending a random access preamble and PUSCH (MsgA) and receiving a RAR (MsgB).

[0110] Table 1 below shows configuration / operation related to the random access preamble.

[0111] [Table 1]

[0112]

[0113]

[0114]

[0115] The configuration / definition / operation according to the above Table 1 may be referenced to facilitate clarification of the definition / operation of the embodiments to be described below. As an example, the FDM RO to be described below may refer to the frequency-reused PRACH opportunity mentioned in Table 1. As an example, in the embodiments to be described below, the beam index may refer to the SS / PBCH block index mentioned in Table 1. As an example, in the embodiments to be described below, the RO may refer to the valid PRACH opportunity mentioned in Table 1. As an example, in the embodiments to be described below, multiple ROs with the same beam index may refer to 1 / N (where N<1) consecutive valid PRACH opportunities to which one SS / PBCH index is mapped.

[0116] Tables 2 to 4 below illustrate PRACH configuration tables to which the embodiments to be described below may be applied.

[0117] [Table 2]

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127]

[0128] [Table 3]

[0129]

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136]

[0137]

[0138]

[0139] [Table 4]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154] For example, in the embodiments described below, the RO may be an RO based on one of Tables 2 to 4 described above.

[0155] The above content may be applied in combination with the method of the present disclosure described below, or may be supplemented to clarify the technical features of the method described in the present disclosure.

[0156] In addition, the method related to the configuration of the PRACH transmission opportunity described below is related to uplink transmission and can be equally applied to the uplink signal transmission method in the above-mentioned NR system (licensed band) or U band system (unlicensed band). The technical ideas described in the present disclosure can be modified or replaced to adapt to the terms, expressions, structures, etc. defined in each system so that they can be implemented in the corresponding system.

[0157] For example, uplink transmission performed by the method related to the configuration of PRACH transmission timing described below can be performed in an L cell (a cell operating in a licensed band (L band)) and / or a U cell (a cell operating in an unlicensed band (U band)) defined in an NR system or a U band system.

[0158] NR supports multiple parameter sets (or subcarrier spacing (SCS)) to support a variety of 5G services. For example, if the SCS is 15kHz, NR supports wide areas in traditional cellular bands; if the SCS is 30kHz / 60kHz, NR supports dense urban areas, lower latency and wider carrier bandwidth; if the SCS is 60kHz or higher, NR supports bandwidths greater than 24.25GHz to overcome phase noise.

[0159] The NR frequency band is defined as two types of frequency ranges FR1 and FR2. FR1 and FR2 can be configured as shown in the following Table 5. FR2 can refer to millimeter wave (mmW).

[0160] [Table 5]

[0161] Frequency range specification Corresponding frequency range Subcarrier spacing FR1 410MHz-7125MHz 15,30,60kHz FR2 24250MHz-52600MHz 60,120,240kHz

[0162] Considering that the PRACH preamble is repeatedly transmitted for uplink coverage enhancement of the existing NR system. At this time, it is necessary to define how beam operation and / or power control operate when the UE repeatedly transmits the PRACH preamble. Therefore, the present disclosure aims to propose a method for selecting a specific RO from multiple FDM ROs when repeatedly transmitting the PRACH preamble, and operations of the UE and the BS.

[0163] In the present disclosure, "RO" may refer to a RACH opportunity or a PRACH opportunity. In the embodiments described below, the RO may be based on Tables 1 to 4. As an example, the configuration related to the RO in the embodiments to be described below may be based on at least one of Tables 1 to 4. As an example, the number of PRACH opportunities in a PRACH time slot in the embodiments to be described below may be based on Tables 2 to 4.

[0164] How to select a specific RO among FDM ROs

[0165] The BS may configure / indicate the number of repetitions for PRACH repetition transmission (eg, multiple transmissions of PRACH) in the UE.

[0166] Thereafter, the UE may select / determine the RO of the beam index mapped to the best SSB based on the mapping of SSB to RO (see Table 1). It may be determined from which RO among the ROs to start repeated transmission. In other words, the starting RO may be determined among the ROs. The scheme for determining the starting RO is described in detail below.

[0167] As an example, the starting RO may be determined by the UE. In other words, the terminal may autonomously determine which RO among the selected ROs to start repeated transmission. As an example, the starting RO may be determined by the configuration / indication of the BS. The UE may perform repeated transmission from the starting RO configured / indicated by the BS. As an example, the starting RO may be predefined. The UE may use the predefined RO as the starting RO to perform repeated transmission.

[0168] At this time, when selecting / determining the RO for performing repeated transmission, it can be assumed that multiple ROs mapped to the beam index (e.g., SS / PBCH block index) of the SSB (best SSB) selected by the UE are frequency division multiplexed (FDM) and configured. Operation / definition / configuration is required as to which RO the UE should select from the frequency division multiplexed ROs.

[0169] According to an embodiment, based on a value configured / indicated by the BS in the UE through higher layer signaling (eg, SIB, etc.), the corresponding UE may select a specific RO.

[0170] As an example, the BS may indicate a frequency resource index (frequency domain index) of a specific RO among a plurality of ROs in the UE through higher layer signaling.

[0171] As an example, it can be assumed that the BS configures the number of FDM ROs (which may have the same beam index) to be at most N through an SSB to RO mapping setting value (e.g., ssb-perRACH-OccasionAndCB-PreamblesPerSSB) and a total FDM RO setting value (e.g., msg1-FDM). The BS can configure / indicate one of the N FDM ROs in the UE through higher layer signaling (e.g., SIB, etc.). The UE can perform repeated transmission by selecting a specific RO at a position configured / indicated by the BS among multiple FDM ROs (having the same beam index).

[0172] According to an embodiment, which RO should be selected may be pre-defined between the UE and the BS.

[0173] As an example, when multiple FDM ROs (with the same beam index) can be allocated, the RO for repeated transmission of PRACH can be defined as follows. The UE can perform repeated transmission by selecting the RO that is continuously located at the lowest (or highest) frequency among multiple FDM ROs with the same beam index. At this time, according to the preamble index, cell ID, SFN index, etc. initially selected by the UE, the position of the corresponding specific RO in the frequency domain can be defined / configured differently.

[0174] As an example, for the first time, the UE may select / determine one RO among multiple FDM ROs with the same beam index. At this time, the one RO may be the starting RO of the RO group. The UE may select and configure an RO at the same frequency position as the above-selected RO (starting RO). The frequency position may be based on a frequency resource index, a frequency domain index, or a resource block index (RB index). For example, the frequency domain based on the frequency position may refer to a resource block (RB). In other words, the UE may determine / select one or more ROs having the same starting RB as the starting RO in ascending order of the time resource index after the starting RO.

[0175] As an example, when the UE initially selects a RO located at the highest (or lowest) frequency among multiple FDM ROs with the same beam index, the UE may be configured to select a RO similarly located at the highest (or lowest) frequency thereafter. When the reference RO used to determine the RA-RNTI value is one of the FDM ROs, the corresponding method may be preferred.

[0176] The configuration / determination of the RO group related to the above-described embodiment refers to Figure 6 Give a description.

[0177] Figure 6 Determination of an RO group according to one embodiment of the present disclosure is illustrated.

[0178] Reference Figure 6 , a starting RO (e.g., a first starting RO) of an RO group (e.g., a first RO group) may be based on one of the ROs frequency-multiplexed in the time domain. The remaining ROs in the RO group may have the same frequency position (e.g., a position based on a frequency resource index, a position of a starting RB based on an RB index) as the starting RO. The starting RO and the remaining ROs in the RO group may be associated with the same SSB index (e.g., SSB#0). More specifically, based on the frequency position associated with the starting RO (e.g., a frequency resource index, an RB index, or a starting RB), the remaining ROs belonging to the RO group may be determined in ascending order of (a time resource index (e.g., at least one of a time domain resource index, a symbol index, a time slot index, or a subframe index)) after the starting RO.

[0179] Table 6 below shows the conventions associated with multiple PRACH transmissions.

[0180] [Table 6]

[0181]

[0182]

[0183]

[0184]

[0185] The contents in Table 6 above may be referenced to clarify the definition / operation of the above embodiments. For example, a frequency resource index (or frequency domain position) associated with a starting RO in an RO group may be associated with a starting RB.

[0186] RO jump method between FDM ROs

[0187] When the UE uses only the RO located in a specific frequency domain when performing repeated transmission of PRACH, it may be advantageous to use the frequency domain equally for each RO. In other words, it may be preferred that different UEs use ROs located in different frequency domains. However, in reality, there is a possibility that the RO located in a specific frequency domain is used by different UEs. Therefore, in order to solve these problems, a RO hopping method between FDM ROs may be considered.

[0188] As an example, the BS may configure / indicate an RO hopping pattern in the UE through high-level signaling (e.g., SIB, etc.). As a result, the corresponding UE may perform repeated transmission while hopping an RO (e.g., a starting RO in an RO group). In other words, the UE may perform repeated transmission while changing the frequency position of the RO based on the configured / indicated RO hopping pattern. According to the above embodiment, when the RO group includes ROs selected in ascending order of time resource index based on a frequency resource index associated with the starting RO, the hopping of the RO according to the embodiment may refer to hopping in the RO group (starting). For example, the frequency resource index associated with the starting RO of a first RO group (any one RO group) among multiple RO groups may be different from the frequency resource index associated with the starting RO of a second RO group (another RO group) among multiple RO groups.

[0189] The RO hopping pattern may have different initial values ​​according to the preamble index, cell ID, SFN index and / or frequency-domain RO index initially selected by the UE.

[0190] The BS may configure / indicate in the UE whether to enable the RO hopping operation through high-layer signaling (e.g., SIB, etc.). When the RO hopping operation is enabled, the UE may perform PRACH repetition transmission while hopping the RO. When the RO hopping operation is disabled, the UE may perform PRACH repetition transmission using the RO predefined in the above method instead of RO hopping.

[0191] The proposed method may be configured / applied to another UL signal / channel such as MSG3 PUSCH, MSGA preamble / PUSCH and / or PUSCH / PUCCH. Obviously, since the examples of the above-mentioned proposed scheme may also be included as one of the implementation methods of the present disclosure, these examples may be regarded as a proposed scheme. In addition, the above-mentioned proposed scheme may be implemented independently, but may also be implemented in the form of a combination (or merger) of some proposed schemes. A rule is defined so that the BS notifies the UE of whether to apply the proposed method (or information about the rules of the proposed method) through a predefined signal (e.g., a physical layer signal or a high-layer signal). The high layer may include, for example, one or more of the functional layers such as MAC, RLC, RRC, and SDAP.

[0192] The methods, embodiments, or descriptions for implementing the methods proposed in the present disclosure may be applied alone, or one or more methods (or embodiments or descriptions) may be applied in combination.

[0193] Although the above embodiments are described using terms such as RO, RO group, etc., this is for convenience of description. Regarding the repetition of PRACH transmission, the above embodiments can be expressed in different ways by using existing defined terms (e.g., effective PRACH opportunity). For example, the above embodiments can be replaced with operations / expressions based on the following Table 7 that can be applied.

[0194] [Table 7]

[0195]

[0196]

[0197] Referring to Table 7, the terms according to the above-mentioned embodiment may be replaced as follows.

[0198] As an example, "RO Group" can be replaced by " Preamble code repetition". "First RO group" can be replaced by "first Preamble Repeat".

[0199] As an example, "starting RO" can be replaced by "first The first valid PRACH opportunity of the preamble repetition.

[0200] As an example, “ROs for PRACH repetitive transmission (e.g., multiple transmissions of PRACH) (e.g., the starting RO and the remaining ROs)” may be replaced with “ROs for PRACH transmission”. Repeated PRACH opportunity (or valid PRACH opportunity)". In terms of implementation, the operation of the BS / UE according to the above embodiment (eg, the operation related to the RO for repeated transmission of PRACH) can be described below. Fig. 9 Devices in (e.g., Fig. 9 Processed by processors 110 and 210).

[0201] In addition, the operation of the BS / UE according to the above embodiment (eg, the operation related to the RO for repeated transmission of the PRACH) can also be stored in the form of instructions / programs (eg, instructions or executable codes) in a memory (eg, Fig. 9 140 and 204) for driving at least one processor (e.g., Fig. 9 110 and 210 in ).

[0202] In the following, reference will be made to Figure 7 and Figure 8 The above implementation is described in detail from the operation of UE and BS. The methods described below are only for the convenience of distinction. Needless to say, some components of any one method can be replaced by some components of another method, or can be combined and applied with each other.

[0203] Figure 7 is a flowchart for describing a method performed by a user equipment (UE) according to an embodiment of the present disclosure.

[0204] Reference Figure 7 According to an embodiment of the present disclosure, the method performed by the UE in the wireless communication system includes a PRACH transmission step S710 and a RAR reception step S720.

[0205] In S710, the UE sends a physical random access channel (PRACH) to the BS based on at least one PRACH opportunity (RO). The PRACH may be based on a type 1 random access procedure or a type 2 random access procedure. As an example, the PRACH may be sent based on Table 1 above.

[0206] According to an embodiment, the at least one RO may include a plurality of ROs belonging to an RO group for multiple transmissions of the PRACH. The multiple transmissions of the PRACH may refer to repeated transmissions of the PRACH.

[0207] According to an embodiment, multiple ROs may be associated with the same synchronization signal / physical broadcast channel block index (SS / PBCH block index).

[0208] According to an embodiment, the plurality of ROs may include i) a first RO and ii) one or more second ROs. As an example, the first RO may be a starting RO of a first RO group, and the one or more second ROs may be the remaining ROs of the RO group. As an example, the first RO may be based on one of the ROs of frequency division multiplexing (FDM) in a time instance. As a specific example, the RO group is the first RO group among the plurality of RO groups, and the first RO may be an RO associated with the lowest frequency resource index among the ROs of frequency division multiplexing.

[0209] According to an embodiment, the one or more second ROs may include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO. The frequency resource index associated with the first RO may be associated with a resource block (RB).

[0210] According to an embodiment, the frequency resource index associated with one or more second ROs may be the same as the frequency resource index associated with the first RO. As an example, the RO group may include ROs for TDM based on the same frequency resource index. For example, the frequency domain position (or starting RB) of the first RO may be the same as the frequency domain position (or starting RB) of one or more second ROs.

[0211] According to an embodiment, the RO group may be one of a plurality of RO groups associated with the same SS / PBCH block index. A first RO of a first RO group among the plurality of RO groups may be associated with the lowest frequency resource index. For example, referring to Figure 6 , a first RO (1st starting RO) of a first RO group (1st RO group) among the four RO groups may be associated with the lowest frequency resource index.

[0212] According to an embodiment, the plurality of RO groups may include RO groups arranged based on a predefined time domain / frequency domain pattern (eg, a frequency hopping pattern).

[0213] For example, multiple RO groups may be based on different frequency resource indexes and / or different time resource indexes. That is, the frequency resource index and / or time resource index associated with the corresponding starting RO among the multiple RO groups may be different. The frequency resource index and / or time resource index associated with the first RO of one RO group among the multiple RO groups may be different from the frequency resource index and / or time resource index associated with the first RO of another RO group among the multiple RO groups. Specifically, the frequency resource index and / or time resource index associated with the starting RO of the N-1th RO group among the multiple RO groups may be different from the frequency resource index and / or time resource index associated with the starting RO of the Nth RO group among the multiple RO groups.

[0214] As an example, a first RO group among the plurality of RO groups (or a first RO of the first RO group (starting RO)) may be associated with a lowest frequency resource index. The first RO of each RO group in the plurality of RO groups may be i) determined in ascending order of frequency resource indexes with respect to the same time resource index, and ii) then determined in ascending order of time resource indexes with respect to the same frequency resource index.

[0215] The above embodiment uses the terms "RO group" and "RO" for description, but this is for convenience of description and may be replaced with other terms (based on the terms in Table 7). The terms / features according to the above embodiment may be expressed variously as follows.

[0216] As an example, “a first RO and one or more second ROs belonging to an RO group” may be replaced with “valid PRACH opportunities (or N PRACH opportunities) for N repetitions (e.g., N repetitions, or N preamble repetitions, where N>1) of PRACH transmission. N may be based on the number of repetitions described above, and may also be referred to as the number of preamble repetitions.

[0217] As an example, "a first RO and one or more second ROs determined for repeated transmission" may be replaced with "a RO (or PRACH occasion) determined for N repetitions".

[0218] One or more second ROs associated with the same SS / PBCH block index belonging to the RO group are determined in ascending order of the time resource index based on the frequency resource index associated with the first RO (i.e., the same frequency resource index). Such a feature can be expressed as follows. As an example, the valid PRACH opportunities (or N PRACH opportunities) i) are continuous in the time domain, ii) use the same resources, and iii) are associated with the same SS / PBCH block index.

[0219] As an example, "RO group" may be replaced by "N repetitions" (or N preamble repetitions). As an example, "first RO group" may be replaced by "first N repetitions or first N preamble repetitions".

[0220] As an example, "the first RO (starting RO)" can be replaced with the first valid PRACH opportunity. For example, "the first RO of the first RO group" can be replaced with "the first valid PRACH opportunity of the first N repetitions".

[0221] As an example, the above-mentioned features related to the arrangement of RO groups (the first RO of each RO group) can be expressed as features related to the arrangement of the first valid PRACH opportunities of N repetitions of PRACH transmission.

[0222] Specifically, the first valid PRACH opportunity for the first N repetitions may be associated with the lowest frequency resource index. The first valid PRACH opportunity for the subsequent N repetitions may be determined as follows. The first valid PRACH opportunity for each N repetitions after the first N repetitions may be i) determined in ascending order of frequency resource indexes relative to the same time resource index, and ii) then determined in ascending order of time resource indexes relative to the same frequency resource index.

[0223] In other words, the frequency resource index and / or time resource index associated with the first valid PRACH opportunity repeated N times may be different from the frequency resource index and / or time resource index associated with the first valid PRACH opportunity repeated N times before. In S720, the UE receives a random access response (RAR) from the BS. The RAR may be based on Msg2 of a type 1 random access procedure or MsgB of a type 2 random access procedure.

[0224] The method may further include a configuration information receiving step. Specifically, the UE receives configuration information related to the PRACH from the BS. According to an implementation manner, the configuration information may include information about the number (or number of times) of multiple transmissions. The number of multiple transmissions may be based on the number of repetitions configured / indicated by high-level signaling in the above implementation manner. For example, the number of multiple transmissions may refer to the "number of multiple PRACH transmissions" in Table 6. The configuration information receiving step may be performed before S710.

[0225] The number of multiple ROs may be based on the number of multiple transmissions. As an example, the number of multiple ROs may be the same as the number of multiple transmissions. Specifically, when the number of multiple transmissions is 2, the number of multiple ROs may be 2.

[0226] The operations based on the above S710 and S720 and the configuration information receiving step can be performed by Fig. 9 For example, the UE 200 may control one or more transceivers 230 and / or one or more memories 240 to perform operations based on steps S710 and S720 and the configuration information receiving step.

[0227] Hereinafter, the following embodiments will be described in detail from the operation aspect of the BS.

[0228] S810 and S820 and the configuration information sending step described below correspond to Figure 7 S710 and S720 and the configuration information receiving step described in the above description. By considering the corresponding relationship, redundant description is omitted. That is, the specific description of the BS operation described below can be used Figure 7 Replace with a description / example that corresponds to the operation. For example, Figure 7The description / implementation of S710 and S720 in the embodiment may be additionally applied to the BS operations of S810 and S820 to be described below. As an example, Figure 7 The description / implementation of the UE operation in the configuration information receiving step in the embodiment may be additionally applied to the BS operation in the configuration information sending step to be described below.

[0229] Figure 8 is a flowchart for describing a method performed by a base station according to another embodiment of the present disclosure.

[0230] Reference Figure 8 , a method performed by a BS in a wireless communication system according to another embodiment of the present disclosure includes a PRACH receiving step S810 and a RAR sending step S720.

[0231] In S810 , the BS receives a physical random access channel (PRACH) from a UE based on at least one PRACH opportunity (RO).

[0232] In S820, the BS sends a random access response (RAR) to the UE.

[0233] The method may further include a configuration information sending step. Specifically, the BS sends the configuration information related to the PRACH to the UE.

[0234] The operations based on the above S810 and S820 and the configuration information sending step can be performed by Fig. 9 For example, the BS 100 may control one or more transceivers 130 and / or one or more memories 140 to perform operations based on S810 and S820 and the configuration information sending step.

[0235] Refer to the following Fig. 9 The following describes a device to which the embodiments of the present disclosure are applicable (a device that implements the method / operation according to the embodiments of the present disclosure).

[0236] Fig. 9 The configurations of the first device and the second device according to the embodiment of the present disclosure are illustrated.

[0237] The first device 100 may include a processor 110 , an antenna unit 120 , a transceiver 130 , and a memory 140 .

[0238] The processor 110 may perform signal processing related to the baseband, and includes a high-level processing unit 111 and a physical layer processing unit 115. The high-level processing unit 111 may process operations of a MAC layer, an RRC layer, or a higher layer. The physical layer processing unit 115 may process operations of a PHY layer. For example, if the first device 100 is a base station (BS) device in BS-UE communication, the physical layer processing unit 115 may perform uplink received signal processing, downlink transmitted signal processing, etc. For example, if the first device 100 is a first UE device in inter-UE communication, the physical layer processing unit 115 may perform downlink received signal processing, uplink transmitted signal processing, sidelink transmitted signal processing, etc. In addition to performing signal processing related to the baseband, the processor 110 may also control the overall operation of the first device 100.

[0239] The antenna unit 120 may include one or more physical antennas, and if the antenna unit 120 includes multiple antennas, MIMO transmission / reception is supported. The transceiver 130 may include a radio frequency (RF) transmitter and an RF receiver. The memory 140 may store information processed by the processor 110 and software, an operating system, and applications related to the operation of the first device 100. The memory 140 may also include components such as a buffer.

[0240] In the embodiments described in the present disclosure, the processor 110 of the first device 100 may be configured to implement operations of a BS in BS-UE communication (or operations of a first UE device in inter-UE communication).

[0241] The second device 200 may include a processor 210 , an antenna unit 220 , a transceiver 230 , and a memory 240 .

[0242] The processor 210 may perform signal processing related to the baseband, and includes a high-level processing unit 211 and a physical layer processing unit 215. The high-level processing unit 211 may process operations of a MAC layer, an RRC layer, or a higher layer. The physical layer processing unit 215 may process operations of a PHY layer. For example, if the second device 200 is a UE device in BS-UE communication, the physical layer processing unit 215 may perform downlink received signal processing, uplink transmitted signal processing, etc. For example, if the second device 200 is a second UE device in inter-UE communication, the physical layer processing unit 215 may perform downlink received signal processing, uplink transmitted signal processing, side link received signal processing, etc. In addition to performing signal processing related to the baseband, the processor 210 may also control the overall operation of the second device 200.

[0243] The antenna unit 220 may include one or more physical antennas, and if the antenna unit 220 includes multiple antennas, MIMO transmission / reception is supported. The transceiver 230 may include an RF transmitter and an RF receiver. The memory 240 may store information processed by the processor 210 and software, operating systems, and applications related to the operation of the second device 200. The memory 240 may also include components such as a buffer.

[0244] In the embodiments described in the present disclosure, the processor 210 of the second device 200 may be configured to implement operations of a UE in BS-UE communication (or operations of a second UE device in inter-UE communication).

[0245] The description of the BS and the UE in BS-UE communication (or the first UE device and the second UE device in inter-UE communication) in the examples of the present disclosure are equally applicable to the operations of the first device 100 and the second device 200, and redundant descriptions are omitted.

[0246] In addition to LTE, NR, and 6G, the wireless communication technology implemented in the apparatus 100 and the apparatus 200 according to the present disclosure may also include a narrowband Internet of Things (NB-IoT) for low-power communication. For example, the NB-IoT technology may be an example of a low-power wide area network (LPWAN) technology and may be implemented in standards such as LTE Cat NB1 and / or LTE Cat NB2. The NB-IoT technology is not limited to the above names.

[0247] Additionally or alternatively, the wireless communication technology implemented in the apparatus 100 and the apparatus 200 according to the present disclosure may perform communication based on the LTE-M technology. For example, the LTE-M technology may be an example of the LPWAN technology and may be referred to as various names, such as enhanced machine type communication (eMTC). For example, the LTE-M technology may be implemented with at least one of various standards, such as 1) LTE CAT0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-BL (non-bandwidth limited), 5) LTE-MTC, 6) LTE machine type communication and / or 7) LTE M. The LTE-M technology is not limited to the above names.

[0248] Additionally or alternatively, in consideration of low power communication, the wireless communication technology implemented in the apparatus 100 and the apparatus 200 according to the present disclosure may include at least one of ZigBee, Bluetooth, and a low power wide area network (LPWAN), and is not limited to the above names. For example, ZigBee technology may create a personal area network (PAN) related to small / low power digital communication based on various standards such as IEEE 802.15.4, and may be referred to by various names.

Claims

1. A method performed by a user equipment UE in a wireless communication system, the method comprising the following steps: Sending a PRACH based on at least one physical random access channel PRACH opportunity RO; as well as Receive a random access response RAR, wherein the at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of the PRACH, The multiple ROs are associated with the same synchronization signal / physical broadcast channel block index SS / PBCH block index, wherein the plurality of ROs include i) a first RO and ii) one or more second ROs, and The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

2. The method according to claim 1, wherein: The first RO is a starting RO in the RO group, and The one or more second ROs are the remaining ROs in the RO group.

3. The method according to claim 1, wherein: The frequency resource index associated with the one or more second ROs is the same as the frequency resource index associated with the first RO.

4. The method according to claim 1, wherein: The frequency resource index associated with the first RO is associated with a resource block RB.

5. The method according to claim 1, wherein: The RO group is one of a plurality of RO groups associated with the same SS / PBCH block index, and The first RO of the first RO group among the multiple RO groups is associated with the lowest frequency resource index.

6. The method according to claim 5, wherein: The first RO of each of the plurality of RO groups is i) determined in ascending order of frequency resource indexes with respect to the same time resource index, and ii) then determined in ascending order of time resource indexes with respect to the same frequency resource index.

7. The method according to claim 5, wherein: A frequency resource index and / or a time resource index associated with a first RO of one of the plurality of RO groups is different from a frequency resource index and / or a time resource index associated with a first RO of another RO group of the plurality of RO groups.

8. The method according to claim 1, wherein: The first RO is based on one of the ROs that is frequency division multiplexed FDM in one time instance.

9. The method according to claim 1, further comprising the steps of: receiving configuration information related to the PRACH, wherein the configuration information includes information about the number of transmissions, and The number of the plurality of ROs is based on the number of the plurality of transmissions.

10. A user equipment operating in a wireless communication system, the user equipment comprising: one or more transceivers; one or more processors; as well as one or more memories operatively connectable to the one or more processors and storing instructions that, upon execution by the one or more processors, configure the one or more processors to perform operations, The operations include: sending a PRACH based on at least one physical random access channel PRACH opportunity RO, and receiving a random access response RAR, and wherein the at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of the PRACH, The multiple ROs are associated with the same synchronization signal / physical broadcast channel block index SS / PBCH block index, wherein the plurality of ROs include i) a first RO and ii) one or more second ROs, and The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

11. A device, comprising: one or more memories and one or more processors functionally connected to the one or more memories, wherein the one or more memories include instructions that configure the one or more processors to perform operations based on execution by the one or more processors, and The operations include: sending a PRACH based on at least one physical random access channel PRACH opportunity RO, and receiving a random access response RAR, and wherein the at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of the PRACH, The multiple ROs are associated with the same synchronization signal / physical broadcast channel block index SS / PBCH block index, wherein the plurality of ROs include i) a first RO and ii) one or more second ROs, and The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

12. One or more non-transitory computer-readable media storing one or more instructions, wherein: The one or more instructions executable by one or more processors are configured to allow the one or more processors to perform operations, and wherein the operations include: Sending a PRACH based on at least one physical random access channel PRACH opportunity RO; and Receive a random access response RAR, wherein the at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of the PRACH, The multiple ROs are associated with the same synchronization signal / physical broadcast channel block index SS / PBCH block index, wherein the plurality of ROs include i) a first RO and ii) one or more second ROs, and The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

13. A method performed by a base station in a wireless communication system, the method comprising the following steps: receiving a PRACH based on at least one physical random access channel PRACH opportunity RO; as well as Send a random access response RAR, wherein the at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of the PRACH of the UE, The multiple ROs are associated with the same synchronization signal / physical broadcast channel block index SS / PBCH block index, wherein the plurality of ROs include i) a first RO and ii) one or more second ROs, and The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

14. A base station operating in a wireless communication system, the base station comprising: one or more transceivers; one or more processors; as well as one or more memories operatively connectable to the one or more processors and storing instructions that, upon execution by the one or more processors, configure the one or more processors to perform operations, The operations include: receiving a PRACH based on at least one physical random access channel PRACH opportunity RO; and Send a random access response RAR, and wherein the at least one RO includes a plurality of ROs belonging to an RO group for a plurality of transmissions of the PRACH of the UE, The multiple ROs are associated with the same synchronization signal / physical broadcast channel block index SS / PBCH block index, wherein the plurality of ROs include i) a first RO and ii) one or more second ROs, and The one or more second ROs include ROs determined in ascending order of time resource indexes after the first RO based on frequency resource indexes associated with the first RO.

Images