Method and apparatus for transmitting and receiving a random access channel in a wireless communication system

Abstract

A method performed by a terminal according to an embodiment of the present specification includes transmitting a PRACH based on at least one RO and receiving an RAR. The at least one RO includes a plurality of ROs belonging to an RO group for multiplexing the PRACH. The plurality of ROs includes i) a first RO and ii) one or more second ROs. The one or more second ROs include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO.

Description

[Technical Field]

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

[0002] Mobile communication systems were developed to provide voice services while ensuring user activity. However, the scope of mobile communication systems has expanded beyond voice to include data services, and currently, explosive traffic growth is causing resource shortages and users are demanding faster services, so more advanced mobile communication systems are required.

[0003] The requirements for next-generation mobile communication systems are significant: they must be able to accommodate explosive data traffic, dramatically increase the transmission rate per user, accommodate a significantly increased number of connected devices, achieve extremely low end-to-end latency, and be energy efficient. To achieve this, various technologies are being researched, including dual connectivity, massive multiple input multiple output (MIMO), in-band full duplex, non-orthogonal multiple access (NOMA), super wideband support, and device networking.

[0004] Currently, according to the PRACH configuration, multiple ROs (pRACH Occasions) having the same beam index (e.g., SS / PBCH block index or SSB index) can exist in a frequency division multiplexing (FDM) format at a specific time instance. When determining an RO group for multiple PRACH transmissions, the UE needs to determine which frequency position RO to select to configure the RO group. Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, there may be multiple ROs that are FDM-multiplexed in one time instance. The conventional scheme does not provide any definition for determining an RO group for multiple PRACH transmissions. Therefore, ambiguity occurs in the operation of a terminal / base station in relation to the determination of an RO group. For example, it is unclear from the terminal's perspective which RO should be used as a basis for determining an RO group. In such a case, the base station can process multiple PRACH transmissions based on one terminal's RO group as PRACH transmissions from multiple terminals. Conversely, the base station can process PRACH transmissions from multiple terminals as PRACH transmissions based on one terminal's RO group.

[0006] The purpose of this specification is to propose a method for removing ambiguity in determining an RO group for multiple PRACH transmissions.

[0007] The technical problems to be solved in this specification are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those having ordinary skill in the art to which the present invention pertains from the description below. [Means for solving the problem]

[0008] In one embodiment of the present specification, a method performed by a terminal in a wireless communication system includes transmitting a Physical Random Access Channel (PRACH) based on at least one PRACH occasion (RO) and receiving a Random Access Response (RAR).

[0009] The at least one RO includes a plurality of ROs that belong to an RO group for multiple transmissions of the PRACH.

[0010] The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block index (SS / PBCH Block index).

[0011] The plurality of ROs includes i) a first RO and ii) one or more second ROs.

[0012] The one or more second ROs may include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO.

[0013] The first RO may be a starting RO of the RO group, and the one or more second ROs may be remaining ROs of the RO group.

[0014] 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.

[0015] The frequency resource index associated with the first RO may be associated with a resource block (RB).

[0016] The RO group may be one of a plurality of RO groups associated with the same SS / PBCH Block index;

[0017] A first RO of a first RO group among the plurality of RO groups may be associated with the lowest frequency resource index.

[0018] The first RO of each of the plurality of RO groups may be determined i) in ascending order of frequency resource index for the same time resource index, and ii) thereafter in ascending order of time resource index for the same frequency resource index.

[0019] 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 of the plurality of RO groups.

[0020] The first RO may be based on one of the Frequency Division Multiplexing (FDM) ROs at one time instance.

[0021] The method may further include receiving configuration information associated with the PRACH, the configuration information may include information regarding the number of multiple transmissions, and the number of ROs may be based on the number of multiple transmissions.

[0022] A terminal operating in a wireless communication system according to another embodiment of the present specification comprises one or more transceivers, one or more processors, and one or more memories operably connected to the one or more processors and storing instructions that, when executed by the one or more processors, configure the one or more processors to perform operations.

[0023] The operations include transmitting a Physical Random Access Channel (PRACH) based on at least one PRACH occasion (PRACH) and receiving a Random Access Response (RAR).

[0024] The at least one RO includes a plurality of ROs that belong to an RO group for multiple transmissions of the PRACH.

[0025] The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block index (SS / PBCH Block index).

[0026] The plurality of ROs includes i) a first RO and ii) one or more second ROs.

[0027] The one or more second ROs may include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO.

[0028] According to yet another embodiment of the present disclosure, an apparatus includes one or more memories and one or more processors operatively coupled to the one or more memories.

[0029] The one or more memories contain instructions that, upon being executed by the one or more processors, configure the one or more processors to perform actions.

[0030] The operations include transmitting a Physical Random Access Channel (PRACH) based on at least one PRACH occasion (PRACH) and receiving a Random Access Response (RAR).

[0031] The at least one RO includes a plurality of ROs that belong to an RO group for multiple transmissions of the PRACH.

[0032] The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block index (SS / PBCH Block index).

[0033] The plurality of ROs includes i) a first RO and ii) one or more second ROs.

[0034] The one or more second ROs may include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO.

[0035] According to yet another embodiment of the present disclosure, one or more non-transitory computer-readable media store one or more instructions.

[0036] One or more instructions executable by one or more processors configure the one or more processors to perform an action.

[0037] The operations include transmitting a Physical Random Access Channel (PRACH) based on at least one PRACH occasion (PRACH) and receiving a Random Access Response (RAR).

[0038] The at least one RO includes a plurality of ROs that belong to an RO group for multiple transmissions of the PRACH.

[0039] The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block index (SS / PBCH Block index).

[0040] The plurality of ROs includes i) a first RO and ii) one or more second ROs.

[0041] The one or more second ROs may include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO.

[0042] According to yet another embodiment of the present specification, 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 occasion (RO) and transmitting a Random Access Response (RAR).

[0043] The at least one RO includes a plurality of ROs that belong to an RO group for multiple transmissions of the PRACH.

[0044] The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block index (SS / PBCH Block index).

[0045] The plurality of ROs includes i) a first RO and ii) one or more second ROs.

[0046] The one or more second ROs may include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO.

[0047] In accordance with yet another embodiment of the present specification, a base station operating in a wireless communication system comprises one or more transceivers, one or more processors, and one or more memories operably connected to the one or more processors and storing instructions that, when executed by the one or more processors, configure the one or more processors to perform operations.

[0048] The operations include receiving a Physical Random Access Channel (PRACH) opportunity (PRACH) based on at least one PRACH occasion (PRACH), and transmitting a Random Access Response (RAR).

[0049] The method includes receiving a Physical Random Access Channel (PRACH) opportunity (PRACH) based on at least one PRACH opportunity (RO) and transmitting a Random Access Response (RAR).

[0050] The at least one RO includes a plurality of ROs that belong to an RO group for multiple transmissions of the PRACH.

[0051] The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block index (SS / PBCH Block index).

[0052] The plurality of ROs includes i) a first RO and ii) one or more second ROs.

[0053] The one or more second ROs may include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO. [Effects of the Invention]

[0054] According to an embodiment of the present specification, for multiple transmissions of PRACH, ROs belonging to an RO group are defined in ascending order of time resource index based on the frequency resource index associated with the first RO. When there are multiple ROs associated with the same SS / PBCH block index, the problem of ambiguity regarding which RO should be used for multiple PRACH transmissions can be resolved.

[0055] The effects that can be obtained in this specification are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those having ordinary skill in the art to which the present invention pertains from the following description. [Brief explanation of the drawings]

[0056] [Figure 1] 1 illustrates the physical channels and general signaling used in 3GPP® systems. [Figure 2] The SSB structure is illustrated. [Figure 3] An example of SSB transmission is shown below. [Figure 4] Preamble format indicates different RACH occasions. [Figure 5] 1 illustrates a random access procedure. [Figure 6] 1 illustrates the determination of an RO group according to an embodiment of the present specification. [Figure 7] 10 is a flowchart illustrating a method performed by a terminal according to an embodiment of the present specification. [Figure 8] 10 is a flowchart illustrating a method performed by a base station according to another embodiment of the present disclosure. [Figure 9] FIG. 1 is a diagram illustrating the configurations of a first device and a second device according to an embodiment of the present specification. DETAILED DESCRIPTION OF THE INVENTION

[0057] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The detailed description disclosed below, together with the accompanying drawings, is intended to describe exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention can be practiced. The following detailed description includes specific details to provide a thorough understanding of the present invention. However, those skilled in the art will recognize that the present invention can be practiced without such specific details.

[0058] In some cases, well-known structures and devices may be omitted or shown in block diagram form, focusing on the core functions of each structure and device, in order to avoid obscuring the concepts of the present invention.

[0059] Hereinafter, downlink (DL) refers to communication from a base station to a terminal, and uplink (UL) refers to communication from a terminal to a base station. In the downlink, the transmitter may be part of the base station, and the receiver may be part of the terminal. In the uplink, the transmitter may be part of the terminal, and the receiver may be part of the base station. The base station may also be expressed as a first communication device, and the terminal may also be expressed as a second communication device. A base station (BS) may also be replaced with terms such as a fixed station, Node B, evolved-Node B (eNB), Next Generation Node B (gNB), base transceiver system (BTS), access point (AP), network (5G network), AI system, road side unit (RSU), vehicle, robot, unmanned aerial vehicle (UAV), augmented reality (AR) device, and virtual reality (VR) device. Furthermore, a terminal may be fixed or mobile, and may be replaced with terms such as UE (User Equipment), MS (Mobile Station), UT (user terminal), MSS (Mobile Subscriber Station), SS (Subscriber Station), AMS (Advance Mobile Station), WT (Wireless terminal), MTC (Machine-Type Communication) device, M2M (Machine-to-Machine) device, D2D (Device-to-Device) device, vehicle, robot, AI module, drone (Unmanned Aerial Vehicle, UAV), AR (Augmented Reality) device, VR (Virtual Reality) device, etc.

[0060] Physical Channels and General Signaling

[0061] 1 illustrates physical channels and general signal transmission used in a 3GPP system. In a wireless communication system, a terminal receives information from a base station via a downlink (DL), and transmits information to the base station via an uplink (UL). Information exchanged between the base station and the terminal includes data and various control information, and various physical channels exist depending on the type / use of the information exchanged.

[0062] When a terminal is powered on or newly enters a cell, it performs an initial cell search operation, such as synchronizing with a base station (S101). To this end, the terminal receives a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the base station to synchronize with the base station and acquire information such as a cell ID. Thereafter, the terminal receives a physical broadcast channel (PBCH) from the base station to acquire broadcast information within the cell. Meanwhile, the terminal can receive a downlink reference signal (DLRS) during the initial cell search step to check the downlink channel status.

[0063] After completing the initial cell search, the terminal can acquire more specific system information by receiving a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) based on the information carried on the PDCCH (S102).

[0064] Meanwhile, when a terminal first connects to a base station or when there are no radio resources for signal transmission, the terminal can perform a random access procedure (RACH) with the base station (S103 to S106). To this end, the terminal transmits a specific sequence as a preamble over a physical random access channel (PRACH) (S103 and S105) and can receive a response message (Random Access Response (RAR) message) to the preamble over a PDCCH and a corresponding PDSCH. In the case of a contention-based RACH, a contention resolution procedure can be additionally performed (S106).

[0065] After performing the above-described procedures, the UE 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 procedure. In particular, the UE may receive downlink control information (Downlink Control Information (DCI)) via the PDCCH. Here, the DCI includes control information such as resource allocation information for the UE, and different formats may be applied depending on the purpose of use.

[0066] Meanwhile, control information that a terminal transmits to a base station via an uplink or that the terminal receives from a base station may include a downlink / uplink ACK / NACK signal, a CQI (Channel Quality Indicator), a PMI (Precoding Matrix Index), an RI (Rank Indicator), etc. The terminal may transmit the above-mentioned control information such as the CQI / PMI / RI via a PUSCH and / or a PUCCH.

[0067] SSB (Synchronization Signal Block) transmission and related operations

[0068] FIG. 2 illustrates the SSB structure.

[0069] The terminal can perform cell search, system information acquisition, beam alignment for initial connection, DL measurement, etc. based on SSB. SSB is used together with the SS / PBCH (Synchronization Signal / Physical Broadcast Channel) block.

[0070] As shown in Figure 2, an SSB consists of a PSS, SSS, and PBCH. An SSB consists of four consecutive OFDM symbols, and a PSS, PBCH, SSS / PBCH, and PBCH are transmitted for each OFDM symbol. Each of the PSS and SSS consists of one OFDM symbol and 127 subcarriers, and the PBCH consists of three OFDM symbols and 576 subcarriers. Polar coding and Quadrature Phase Shift Keying (QPSK) are applied to the PBCH. The PBCH consists of a data RE and a Demodulation Reference Signal (DMRS) RE for each OFDM symbol. There are three DMRS REs for each RB, and three data REs exist between the DMRS REs.

[0071] FIG. 3 illustrates an SSB transmission.

[0072] As shown in Figure 3, SSBs are transmitted periodically according to the SSB periodicity. The SSB basic period assumed by the terminal during initial cell search is defined as 20 ms. After cell connection, the SSB period can be set by the network (e.g., base station) to one of {5 ms, 10 ms, 20 ms, 40 ms, 80 ms, 160 ms}. An SSB burst set is configured at the start of the SSB period. The SSB burst set consists of a 5 ms time window (i.e., half-frame), and an SSB can be transmitted a maximum of L times within the SSB burst set. The maximum number of SSB transmissions, L, can be given by the frequency band of the carrier as follows: One slot contains a maximum of two SSBs.

[0073] ·For frequency range up to 3GHz, L=4

[0074] ·For frequency range from 3GHz to 6GHz, L=8

[0075] ·For frequency range from 6GHz to 52.6GHz, L=64

[0076] The time position of an SSB candidate within an SS burst set can be defined by the SCS as follows: The time position of an SSB candidate is indexed (SSB index) from 0 to L-1 in time order within an SSB burst set (i.e., half-frame).

[0077] Case A - 15kHz SCS: The index of the starting symbol of the candidate SSB is given as {2, 8}+14*n. If the carrier frequency is 3GHz or less, n=0, 1. If the carrier frequency is 3GHz-6GHz, n=0, 1, 2, 3.

[0078] Case B - 30kHz SCS: The index of the starting symbol of the candidate SSB is given as {4, 8, 16, 20}+28*n. If the carrier frequency is 3GHz or less, n=0. If the carrier frequency is 3GHz-6GHz, n=0, 1.

[0079] Case C-30kHz SCS: The index of the starting symbol of the candidate SSB is given as {2, 8}+14*n. If the carrier frequency is 3GHz or less, n=0, 1. If the carrier frequency is 3GHz-6GHz, n=0, 1, 2, 3.

[0080] Case D-120kHz SCS: The index of the starting symbol of the candidate SSB is given as {4, 8, 16, 20}+28*n, where n=0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18 if the carrier frequency is greater than 6GHz.

[0081] 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, where n=0, 1, 2, 3, 5, 6, 7, 8 if the carrier frequency is greater than 6GHz.

[0082] Next, the RACH slot will be described.

[0083] A RACH slot contains one or more RACH occasion(s).

[0084] The slot duration is 1 ms for {1.25 kHz, 5 kHz} subcarrier spacing, and has scalable duration (i.e., 1 ms, 0.5 ms, 0.25 ms, 0.125 ms) for {15 kHz, 30 kHz, 60 kHz, 120 kHz} subcarrier spacing.

[0085] For the Short preamble format, etc., the starting OFDM symbol index in the RACH slot has values ​​{0, 2, x}.

[0086] FIG. 4 shows RACH occasions for different preamble formats.

[0087] As shown in Figure 4, a RACH slot can include one or more RACH occurrences (ROs) for each preamble format (e.g., A1, A2, ..., C2). Figure 4(a) shows the case where the starting OFDM symbol is "0", and Figure 4(b) shows the case where the starting OFDM symbol is "2".

[0088] FIG. 5 illustrates a random access procedure.

[0089] FIG. 5(a) shows a contention-based RACH procedure, and FIG. 5(b) shows a contention-free RACH procedure.

[0090] The following describes MSG1 transmission.

[0091] The subcarrier spacing for MSG1 is set in the RACH configuration and is provided in the handover command for a contention-free RA procedure for handover.

[0092] The preamble indexes for contention based random access (CBRA) and contention free random access (CFRA) are mapped consecutively to one SSB in one RACH transmission opportunity.

[0093] CBRA: Within an SS burst set, the association between an SS block (SSB) and a subset of RACH resources and / or preamble indexes is set by a parameter set in RMSI.

[0094] CFRA: The UE can be configured to transmit multiple MSG1s via dedicated multiple RACH transmission opportunities in the time domain before the end of the monitored RAR window.

[0095] The association between the CFRA preamble and the SSB is then re-established via UE-specific RRC.

[0096] 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).

[0097] The Type-1 random access procedure can include transmitting a random access preamble (Msg1) on a physical random access channel (PRACH), receiving a random access response (RAR) (Msg2), transmitting a PUSCH scheduled by a UL grant of the RAR (Msg3), and transmitting a PDSCH (Msg4) for contention resolution. If the random access procedure is contention-free random access (CFRA), the operations of transmitting Msg3 and receiving Msg4 are omitted.

[0098] The Type-2 random access procedure may include transmitting a random access preamble and a PUSCH (MsgA) and receiving an RAR (MsgB).

[0099] Table 1 below illustrates the settings / operations associated with the random access preamble.

[0100] [Table 1-1]

[0101] [Table 1-2]

[0102] [Table 1-3]

[0103] The settings / definitions / operations according to Table 1 may be referred to in order to clarify the definitions / operations of the embodiments described below. As an example, an FDMed RO described below may refer to the frequency multiplexed PRACH occasions mentioned in Table 1. As an example, a beam index may refer to the SS / PBCH block index mentioned in Table 1 in the embodiments described below. As an example, an RO may refer to the valid PRACH occasions mentioned in Table 1 in the embodiments described below. As an example, multiple ROs having the same beam index may refer to 1 / N (where N<1) consecutive valid PRACH occasions to which one SS / PBCH index is mapped.

[0104] Tables 2 to 4 below show examples of PRACH configuration tables that can be applied to the embodiments described later.

[0105] [Table 2-1]

[0106] [Table 2-2]

[0107] Table 2-3

[0108] Table 2-4

[0109] Table 2-5

[0110] Table 2-6

[0111] Table 2-7

[0112] Table 2-8

[0113] Table 2-9

[0114] Table 3-1

[0115] Table 3-2

[0116] Table 3-3

[0117] Table 3-4

[0118] Table 3-5

[0119] Table 3-6

[0120] Table 3-7

[0121] Table 3-8

[0122] Table 3-9

[0123] Table 4-1

[0124] JPEG0007812975000023.jpg209148

[0125] Table 4-2

[0126] Table 4-3

[0127] Table 4-4

[0128] [Table 4-5]

[0129] [Table 4-6]

[0130] [Table 4-7]

[0131] [Table 4-8]

[0132] [Table 4-9]

[0133] [Table 4-10]

[0134] [Table 4-11]

[0135] [Table 4-12]

[0136] For example, in the embodiments described below, the RO may be based on one of Tables 2 to 4.

[0137] The above contents may be applied in combination with the method proposed in this specification, which will be described later, or may be supplemented to clarify the technical features of the method proposed in this specification.

[0138] In addition, the method related to the PRACH transmission occasion configuration described below is related to uplink transmission and can be similarly applied to the uplink signal transmission method in the NR system (licensed band) or U-Band system (unlicensed band) described above, and it goes without saying that the technical ideas proposed in this specification can be realized in these systems as well, and can be modified or replaced to suit the terms, expressions, structures, etc. defined in each system.

[0139] For example, uplink transmission via the method associated with the PRACH transmission occasion configuration described below can be performed in an L-cell (a cell operating in the licensed band (L-band)) and / or a U-cell (a cell operating in the unlicensed band (U-band)) defined in an NR system or a U-band system.

[0140] NR supports multiple numerologies (or subcarrier spacing (SCS)) to support various 5G services. For example, a 15 kHz SCS supports wide areas in traditional cellular bands, a 30 kHz / 60 kHz SCS supports dense-urban areas, lower latency, and wider carrier bandwidths, and a 60 kHz or higher SCS supports bandwidths greater than 24.25 GHz to overcome phase noise.

[0141] The NR frequency band is defined as two types of frequency ranges (FR1 and FR2). FR1 and FR2 can be configured as shown in Table 5 below. FR2 can also refer to millimeter wave (mmW).

[0142] [Table 5]

[0143] Meanwhile, in order to enhance UL coverage in the existing NR system, repeated transmission of a PRACH preamble is being considered. In this case, it is necessary to define how beam operation and / or power control operates when a UE repeatedly transmits a PRACH preamble. Therefore, this specification proposes a method for selecting a specific RO from multiple FDMed ROs when repeatedly transmitting a PRACH preamble, and a corresponding UE base station operation.

[0144] In this specification, "RO" may refer to a RACH occasion or a PRACH occasion. In the embodiments described below, the RO may be based on Tables 1 to 4. As an example, settings related to the RO in the embodiments described below may be based on at least one of Tables 1 to 4. As an example, the number of ROs in a slot (number of PRACH occasions within a PRACH slot) in the embodiments described below may be based on Tables 2 to 4.

[0145] Specific RO selection method among FDMed ROs

[0146] The base station can set / instruct the terminal to set / indicate a repetition number for PRACH repeated transmission (eg, multiple transmissions of PRACH).

[0147] Then, the UE can select / determine an RO mapped to the beam index of the best SSB based on SSB-to-RO mapping (see Table 1). It can also determine from which RO among the ROs the repeated transmission starts. In other words, it can determine a starting RO among the ROs. Hereinafter, a method for determining the starting RO will be described in detail.

[0148] As an example, the starting RO may be determined by the terminal. That is, the terminal may determine by itself which RO to repeatedly transmit from among the selected ROs. As an example, the starting RO may be determined based on a setting / instruction of a base station. The terminal may perform repeated transmission from the starting RO set / instructed by the base station. As an example, the starting RO may be predefined. The terminal may perform repeated transmission using the predefined RO as the starting RO.

[0149] In this case, when selecting / determining an RO for repeated transmission, it may be assumed that multiple ROs mapped to a beam index (e.g., SS / PBCH block index) of an SSB (the best SSB) selected by the UE are configured using Frequency Division Multiplexing (FDM). Operation / definition / configuration is required for which RO the UE should select from the FDMed ROs.

[0150] According to one embodiment, a terminal can select a specific RO based on a value set / instructed to the terminal by the base station through higher layer signaling (e.g., SIB, etc.).

[0151] For example, the base station may indicate the frequency resource index (f-domain index) of a specific RO among a plurality of ROs to the terminal through higher layer signaling.

[0152] As an example, it may be assumed that the base station configures up to N ROs (which may have the same beam index) to be FDMed via an SSB-to-RO mapping configuration value (e.g., ssb-perRACH-OccasionAndCB-PreamblesPerSSB) and a total FDMed RO configuration value (e.g., msg1-FDM). The base station can configure / instruct one of the N FDMed ROs to the terminal via higher layer signaling (e.g., SIB, etc.). The terminal can select a specific RO at a location configured / instructed by the base station from multiple FDMed ROs (which have the same beam index) and perform repeated transmission.

[0153] According to one embodiment, which RO should be selected can be predefined between the terminal and the base station.

[0154] As an example, when multiple FDMed ROs (having the same beam index) can be allocated, the RO for repeated transmission of PRACH can be defined as follows: The UE can always select the RO located at the lowest (or highest) frequency among multiple FDMed ROs having the same beam index and perform repeated transmission. In this case, the location of the specific RO on the frequency domain can be defined / set differently depending on the preamble index, Cell-ID, SFN index, etc. initially selected by the UE.

[0155] For example, the UE may select / determine one RO from among multiple FDMed ROs having the same beam index at the first time. In this case, the one RO may be a starting RO of an RO group. The UE may select / set an RO at the same frequency location as the previously selected RO. The frequency location 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 location may refer to a resource block (RB). In other words, after the starting RO, the UE may determine / select one or more ROs having the same starting RB as the starting RO in ascending order of time resource index.

[0156] For example, if the UE initially selects an RO located at the highest (or lowest) frequency among a plurality of FDMed ROs having the same beam index, it may be configured to subsequently select an RO located at the highest (or lowest) frequency. This method is preferably used when the reference RO for determining the RA-RNTI value is one of the FDMed ROs.

[0157] The configuration / determination of an RO group related to the above-described embodiment will be described with reference to FIG.

[0158] FIG. 6 illustrates the determination of an RO group according to an embodiment of the present disclosure.

[0159] As shown in FIG. 6, the starting RO (e.g., 1st starting RO) of an RO group (e.g., 1st RO group) may be based on one of the ROs frequency-multiplexed in the time domain. The remaining ROs (e.g., 1st RO group) of the RO group may have the same frequency location (e.g., location based on frequency resource index, location of starting RB based on RB index) as the starting RO. The starting RO and the remaining ROs (e.g., 1st RO group) of the RO group may be associated with the same SSB index (e.g., SSB #0). More specifically, based on the frequency location (e.g., frequency resource index, RB index, or starting RB) associated with the starting RO, the remaining ROs belonging to the RO group may be determined in ascending order of time resource index (e.g., at least one of time domain resource index, symbol index, slot index, or subframe index) after the starting RO.

[0160] Table 6 below shows the agreements associated with multiple PRACH transmissions.

[0161] [Table 6-1]

[0162] [Table 6-2]

[0163] [Table 6-3]

[0164] [Table 6-4]

[0165] [Table 6-5]

[0166] The contents of Table 6 may be referred to in order to clarify the definitions / operations of the above-described embodiments. For example, the frequency resource index (or frequency domain position) associated with the starting RO of an RO group may be associated with the starting resource block (RB).

[0167] FDMed RO to RO hopping method

[0168] When a UE uses only ROs located in a specific frequency region when repeatedly transmitting a PRACH, it is preferable that the frequency region be used evenly for each RO. In other words, it is preferable that ROs located in different frequency regions are used by different UEs. However, in reality, ROs located in a specific frequency region may be used by different UEs. Therefore, to solve this problem, an RO hopping method may be considered between FDMed ROs.

[0169] For example, a base station may configure / instruct an RO hopping pattern to a terminal via higher layer signaling (e.g., SIB, etc.) in advance. The terminal may then perform repeated transmissions while hopping through an RO (e.g., a starting RO of an RO group). In other words, the terminal may perform repeated transmissions while changing the frequency position of the RO based on the configured / instructed RO hopping pattern. According to the above-described embodiment, if an RO group includes ROs selected in ascending order of time resource index based on a frequency resource index associated with a starting RO, RO hopping according to this embodiment may refer to hopping of the starting RO group. For example, a frequency resource index associated with a starting RO of a first RO group (any one of the RO groups) among multiple RO groups may be different from a frequency resource index associated with a starting RO of a second RO group (another RO group) among the multiple RO groups.

[0170] The RO hopping pattern can be set to have different initial values ​​depending on the preamble index, cell ID, SFN index, and / or f-domain RO index initially selected by the UE.

[0171] The base station can configure / instruct the terminal whether or not the RO hopping operation is enabled via higher layer signaling (e.g., SIB, etc.). If the RO hopping operation is enabled, the terminal can hop over the RO and perform PRACH repeat transmission. If the RO hopping operation is disabled, the terminal can perform PRACH repeat transmission using a predefined RO, such as in the above-described method, instead of RO hopping.

[0172] The proposed method may be configured / applied to other UL signals / channels such as MSG3 PUSCH, MSGA Preamble / PUSCH, and / or PUSCH / PUCCH. Furthermore, since the above-described example of the proposed method may be included as one of the implementation methods of the present specification, it is clear that it may be considered as a type of proposed method. Furthermore, the above-described proposed methods may be implemented independently, or may be implemented in a combined (or merged) form of some of the proposed methods. Rules may be defined so that the base station notifies the terminal of information on whether the proposed methods are applicable (or information on rules for the proposed methods) via a predefined signal (e.g., a physical layer signal or a higher layer signal). The higher layer may include one or more functional layers such as MAC, RLC, PDCP, RRC, and SDAP.

[0173] The methods, embodiments, or explanations for implementing the methods proposed in this specification may each be applied separately, or one or more methods (or embodiments or explanations) may be combined and applied.

[0174] The above-described embodiments have been described using terms such as RO and RO group, but this is for convenience of explanation. The above-described embodiments can be expressed differently in terms of PRACH transmission repetition using existing defined terms (e.g., valid PRACH occasions). For example, the above-described embodiments can be alternatively applied to operations / expressions based on Table 7.

[0175] [Table 7-1]

[0176] [Table 7-2]

[0177] Referring to Table 7, the terms and the like relating to the above-described embodiments and the like can be replaced as follows.

[0178] [Table 8]

[0179] In addition, the operations of the base station / terminal according to the above-mentioned embodiments (e.g., operations related to RO for repeated transmission of PRACH) may also be stored in a memory (e.g., 140, 240 in FIG. 9) in the form of commands / programs (e.g., instructions, executable code) for driving at least one processor (e.g., 110, 210 in FIG. 9).

[0180] Hereinafter, the above-mentioned embodiment will be described in detail in terms of the operation of a terminal and a base station with reference to Figures 7 and 8. The methods described below are merely categorized for the convenience of explanation, and it goes without saying that some components of one method may be replaced with some components of another method or may be combined with each other and applied.

[0181] FIG. 7 is a flowchart illustrating a method performed by a terminal according to an embodiment of the present specification.

[0182] As shown in FIG. 7, the method performed by a terminal in a wireless communication system according to an embodiment of the present specification includes a PRACH transmission step (S710) and an RAR reception step (S720).

[0183] At S710, the terminal transmits a Physical Random Access Channel (PRACH) occasion (RO) to the base station based on at least one PRACH occasion. The PRACH may be based on a Type-1 random access procedure or a Type-2 random access procedure. For example, the PRACH may be transmitted based on Table 1.

[0184] 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, where multiple transmissions of the PRACH may refer to repeated transmission of the PRACH.

[0185] According to one embodiment, the plurality of ROs may be associated with the same Synchronization Signal / Physical Broadcast Channel Block index (SS / PBCH Block index).

[0186] According to one embodiment, the plurality of ROs may include i) a first RO and ii) one or more second ROs. For example, the first RO may be a starting RO of the RO group, and the one or more second ROs may be remaining ROs of the RO group. For example, the first RO may be based on one of ROs frequency-division multiplexed (FDM) at one time instance. As a specific example, based on the RO group being the first RO group among a plurality of RO groups, the first RO may be an RO associated with the lowest frequency resource index among the FDMed ROs.

[0187] According to an embodiment, the one or more second ROs may include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO. The frequency resource index associated with the first RO may be associated with a resource block (RB).

[0188] According to one embodiment, a 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. For example, the RO group may include ROs that are time-division multiplexed based on the same frequency resource index. For example, a frequency domain location (or starting RB) of the first RO may be the same as a frequency domain location (or starting RB) of the one or more second ROs.

[0189] According to one embodiment, the RO group may be one of a plurality of RO groups associated with the same SS / PBCH block index. The first RO of the first RO group among the plurality of RO groups may be associated with the lowest frequency resource index. For example, as shown in FIG. 6, the first RO of the first RO group among four RO groups may be associated with the lowest frequency resource index.

[0190] According to one embodiment, the plurality of RO groups may include RO groups arranged based on a predefined time / frequency domain pattern (eg, a frequency hopping pattern).

[0191] For example, the RO groups may be based on different frequency resource indexes and / or different time resource indexes. That is, the frequency resource indexes and / or time resource indexes associated with the starting ROs of the RO groups may be different. The frequency resource index and / or time resource index associated with a first RO of one of the RO groups may be different from the frequency resource index and / or time resource index associated with a first RO of another of the RO groups. Specifically, the frequency resource index and / or time resource index associated with a starting RO of the (N-1)th RO group among the RO groups may be different from the frequency resource index and / or time resource index associated with a starting RO of the Nth RO group among the RO groups.

[0192] For example, the first RO group (or the first RO (starting RO) of the first RO group) among the plurality of RO groups may be associated with the lowest frequency resource index. The first ROs among the plurality of RO groups may be determined i) in ascending order of frequency resource indexes for the same time resource index, or ii) thereafter in ascending order of time resource indexes for the same frequency resource index.

[0193] Although the above-described embodiments have been described using the terms "RO group" and "RO," this is for convenience of explanation and may be replaced with other terms (terms based on Table 7). The terms / features according to the above-described embodiments may be expressed differently as follows:

[0194] As an example, "a first RO and one or more second ROs belonging to an RO group" can be replaced with "valid PRACH occasions (or N PRACH opportunities) for N repetitions of PRACH transmission (e.g., N repetitions or N preamble repetitions, where N>1)." N can be based on the repetition number described above and may also be referred to as the number of preamble repetitions.

[0195] As an example, "a first RO and one or more second ROs determined for repeated transmission" can be replaced with "ROs (or PRACH occasions) determined for N repetitions."

[0196] As described above, one or more second ROs belonging to an RO group associated with the same SS / PBCH block index are determined in ascending order of time resource index based on the frequency resource index (i.e., the same frequency resource index) associated with the first RO. This characteristic can be expressed as follows: For example, the valid PRACH occasions (or N PRACH opportunities) are i) consecutive in time, ii) use the same frequency resource, and iii) associated with the same SS / PBCH block index.

[0197] As an example, "RO group" can be replaced with "N repetitions" (or N preamble repetitions). For example, "first RO group" can be replaced with "first N repetitions (first N repetitions or first N preamble repetitions)."

[0198] As an example, "starting RO" can be replaced with "first valid PRACH occasion." For example, "first RO of first RO group" can be replaced with "first valid PRACH occasion of first N repetitions."

[0199] As an example, the characteristics related to the arrangement of the above-mentioned RO groups (the first RO of each RO group) can be expressed as characteristics related to the arrangement of the first valid PRACH occasion of N repetitions of PRACH transmission.

[0200] Specifically, the first valid PRACH occasion of the first N repetitions may be associated with the lowest frequency resource index. The first valid PRACH occasion of the subsequent N repetitions may be determined as follows: After the first N repetitions, the first valid PRACH occasion of each N repetitions may be determined i) in ascending order of frequency resource index for the same time resource index, and ii) thereafter in ascending order of time resource index for the same frequency resource index.

[0201] In other words, the frequency resource index and / or time resource index associated with the first valid PRACH occasion of N repetitions may be different from the frequency resource index and / or time resource index associated with the first valid PRACH occasion of the previous N repetitions. At S720, the terminal receives a Random Access Response (RAR) from the base station. The RAR may be based on Msg2 of the Type-1 random access procedure or MsgB of the Type-2 random access procedure.

[0202] The method may further include receiving configuration information. Specifically, the terminal receives configuration information associated with the PRACH from a base station. According to one embodiment, the configuration information may include information regarding the number of multiple transmissions. The number of multiple transmissions may be based on a repetition number set / instructed via a higher layer in the above-described embodiment. For example, the number of multiple transmissions may refer to "the number of multiple PRACH transmissions" in Table 6. The receiving configuration information may be performed before S710.

[0203] The number of the ROs may be based on the number of multiplexings. For example, the number of the ROs may be equal to the number of multiplexings. Specifically, if the number of multiplexings is 2, the number of the ROs may be 2.

[0204] The operations based on the above-described steps S710 to S720 and the setting information receiving step can be realized by the device of Fig. 9. For example, the terminal 200 can control one or more transceivers 230 and / or one or more memories 240 to perform the operations based on steps S710 to S720 and the setting information receiving step.

[0205] The above-described embodiment will now be described in detail from the perspective of base station operation.

[0206] S810 to S820 and a setting information transmission step described below correspond to S710 to S720 and a setting information reception step described in FIG. 7. In consideration of the correspondence, duplicated explanations will be omitted. That is, specific explanations of the base station operation described below can be replaced with the explanations / embodiments of FIG. 7 corresponding to the operations. As an example, the explanations / embodiments of S710 to S720 in FIG. 7 can be further applied to the base station operation of S810 to S820 described below. As an example, the explanations / embodiments of the terminal operation of the setting information reception step in FIG. 7 can be further applied to the base station operation of the setting information transmission step described below.

[0207] FIG. 8 is a flowchart illustrating a method performed by a base station according to another embodiment of the present specification.

[0208] As shown in FIG. 8, a method performed by a base station in a wireless communication system according to another embodiment of the present specification includes a PRACH receiving step (S810) and an RAR transmitting step (S820).

[0209] At S810, the base station receives a Physical Random Access Channel (PRACH) occasion (PRACH) from the terminal based on at least one PRACH occasion (RO).

[0210] At S820, the base station sends a random access response (RAR) to the terminal.

[0211] The method may further include transmitting configuration information, wherein the base station transmits configuration information associated with the PRACH to the terminal.

[0212] The operations based on the above-described steps S810 to S820 and the setting information transmission step can be realized by the device of Fig. 9. For example, the base station 100 can control one or more transceivers 130 and / or one or more memories 140 to perform the operations based on steps S810 to S820 and the setting information transmission step.

[0213] An apparatus to which the embodiments of the present specification can be applied (an apparatus that implements the methods / operations according to the embodiments of the present specification) will be described below with reference to FIG.

[0214] FIG. 9 is a diagram illustrating the configuration of a first device and a second device according to an embodiment of the present specification.

[0215] The first device 100 may include a processor 110 , an antenna unit 120 , a transceiver 130 , and a memory 140 .

[0216] The processor 110 performs baseband-related signal processing and may include an upper layer processor 111 and a physical layer processor 115. The upper layer processor 111 may process operations of the MAC layer, the RRC layer, or higher layers. The physical layer processor 115 may process operations of the PHY layer. For example, if the first device 100 is a base station device in base station-terminal communication, the physical layer processor 115 may perform uplink receive signal processing, downlink transmit signal processing, etc. For example, if the first device 100 is a first terminal device in terminal-terminal communication, the physical layer processor 115 may perform downlink receive signal processing, uplink transmit signal processing, sidelink transmit signal processing, etc. In addition to performing baseband-related signal processing, the processor 110 may also control the overall operation of the first device 100.

[0217] The antenna unit 120 may include one or more physical antennas, and when multiple antennas are included, it may support MIMO transmission and reception. The transceiver 130 may include an RF (Radio Frequency) transmitter and an RF receiver. The memory 140 may store information processed by the processor 110, as well as software, an operating system, applications, etc. related to the operation of the first device 100, and may also include components such as buffers.

[0218] The processor 110 of the first device 100 can be configured to implement the operation of a base station in base station-terminal communication (or the operation of a first terminal device in terminal-terminal communication) in the embodiments described in this disclosure.

[0219] The second device 200 may include a processor 210 , an antenna unit 220 , a transceiver 230 , and a memory 240 .

[0220] The processor 210 performs baseband-related signal processing and may include an upper layer processing unit 211 and a physical layer processing unit 215. The upper layer processing unit 211 may process operations of the MAC layer, the RRC layer, or higher layers. The physical layer processing unit 215 may process operations of the PHY layer. For example, if the second device 200 is a terminal device in base station-terminal communication, the physical layer processing unit 215 may perform downlink reception signal processing, uplink transmission signal processing, etc. For example, if the second device 200 is a second terminal device in terminal-terminal communication, the physical layer processing unit 215 may perform downlink reception signal processing, uplink transmission signal processing, sidelink reception signal processing, etc. In addition to performing baseband-related signal processing, the processor 210 may also control the overall operation of the second device 200.

[0221] The antenna unit 220 may include one or more physical antennas, and when multiple antennas are included, it may support MIMO transmission and reception. The transceiver 230 may include an RF transmitter and an RF receiver. The memory 240 may store information processed by the processor 210, as well as software, an operating system, applications, etc. related to the operation of the second device 200, and may also include components such as buffers.

[0222] The processor 210 of the second device 200 may be configured to implement the operation of a terminal in base station-terminal communication (or the operation of a second terminal device in terminal-terminal communication) in the embodiments described in this disclosure.

[0223] In the operation of the first device 100 and the second device 200, the matters described in the examples of the present disclosure regarding the base station and terminal in base station-terminal communication (or the first terminal and second terminal in terminal-terminal communication) can be equally applied, and duplicate explanations will be omitted.

[0224] Here, the wireless communication technology implemented by the devices 100 and 200 of the present disclosure may include not only LTE, NR, and 6G, but also Narrowband Internet of Things (NB-IoT) for low-power communication. For example, the NB-IoT technology is an example of a Low Power Wide Area Network (LPWAN) technology, and can be implemented by standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the aforementioned names.

[0225] Additionally or alternatively, the wireless communication technology implemented in the devices 100 and 200 of the present disclosure may perform communication based on LTE-M technology. For example, LTE-M technology is an example of LPWAN technology and is referred to by various names such as enhanced machine type communication (eMTC). For example, LTE-M technology may be implemented by at least one of various standards such as 1) LTE CAT 0, 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, and is not limited to the above names.

[0226] Additionally or alternatively, the wireless communication technology implemented in the devices 100 and 200 of the present disclosure may include at least one of ZigBee, Bluetooth, and a Low Power Wide Area Network (LPWAN), which consider low-power communication, but is not limited to the aforementioned names. For example, ZigBee technology can create personal area networks (PANs) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and may be called by various names.

[0227] [Claims of international applications] [Claim 1] 1. A method performed by a terminal in a wireless communication system, comprising: transmitting a Physical Random Access Channel (PRACH) based on at least one PRACH occasion (RO); receiving a Random Access Response (RAR); The at least one RO includes a plurality of ROs belonging to an RO group for multiple transmissions of the PRACH; The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block Index (SS / PBCH BI); the plurality of ROs includes i) a first RO and ii) one or more second ROs; The method, wherein the one or more second ROs include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO. [Claim 2] The first RO is a starting RO of the RO group; The method of claim 1 , wherein the one or more second ROs are remaining ROs of the RO group. [Claim 3] The method of 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. [Claim 4] The method of claim 1, wherein the frequency resource index associated with the first RO is associated with a resource block (RB). [Claim 5] the RO group is one of a plurality of RO groups associated with the same SS / PBCH BI; The method of claim 1, wherein a first RO of a first RO group among the plurality of RO groups is associated with a lowest frequency resource index. [Claim 6] A first RO of each of the plurality of RO groups: i) Determined in ascending order of frequency resource indexes for the same time resource index; ii) thereafter, the time resource indexes are determined in ascending order for the same frequency resource index. [Claim 7] 6. The method of 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 of the plurality of RO groups. [Claim 8] 2. The method of claim 1, wherein the first RO is based on one of Frequency Division Multiplexing (FDM) ROs at one time instance. [Claim 9] receiving configuration information associated with the PRACH; the setting information includes information regarding the number of multiple transmissions; The method of claim 1 , wherein the number of the plurality of ROs is based on the number of multiplexings. [Claim 10] 1. A terminal operating in a wireless communication system, comprising: one or more transmitters and receivers; one or more processors; one or more memories operably connected to the one or more processors and storing instructions that, when executed by the one or more processors, configure the one or more processors to perform operations; The operation is transmitting a Physical Random Access Channel (PRACH) based on at least one PRACH occasion (RO); receiving a Random Access Response (RAR); The at least one RO includes a plurality of ROs belonging to an RO group for multiple transmissions of the PRACH; The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block Index (SS / PBCH BI), the plurality of ROs includes i) a first RO and ii) one or more second ROs; The one or more second ROs include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO. [Claim 11] 1. An apparatus comprising: one or more memories; and one or more processors operatively coupled to the one or more memories, the one or more memories contain instructions that, when executed by the one or more processors, configure the one or more processors to perform actions; The operation is transmitting a Physical Random Access Channel (PRACH) based on at least one PRACH occasion (RO); receiving a Random Access Response (RAR); The at least one RO includes a plurality of ROs belonging to an RO group for multiple transmissions of the PRACH; The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block Index (SS / PBCH BI), the plurality of ROs includes i) a first RO and ii) one or more second ROs; The apparatus, wherein the one or more second ROs include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO. [Claim 12] one or more non-transitory computer-readable media storing one or more instruction words, one or more instructions executable by one or more processors to configure the one or more processors to perform an operation; The operation is transmitting a Physical Random Access Channel (PRACH) based on at least one PRACH occasion (RO); receiving a Random Access Response (RAR); The at least one RO includes a plurality of ROs belonging to an RO group for multiple transmissions of the PRACH; The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block index (SS / PBCH BI); the plurality of ROs includes i) a first RO and ii) one or more second ROs; The one or more second ROs include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO. [Claim 13] 1. A method performed by a base station in a wireless communication system, comprising: receiving a Physical Random Access Channel (PRACH) based on at least one PRACH occasion (RO); transmitting a Random Access Response (RAR); The at least one RO includes a plurality of ROs belonging to an RO group for multiple transmissions of the PRACH by a terminal; The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block index (SS / PBCH BI); the plurality of ROs includes i) a first RO and ii) one or more second ROs; The method, wherein the one or more second ROs include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO. [Claim 14] 1. A base station operating in a wireless communication system, comprising: one or more transmitters and receivers; one or more processors; one or more memories operably connected to the one or more processors and storing instructions that, when executed by the one or more processors, configure the one or more processors to perform operations; The operation is receiving a Physical Random Access Channel (PRACH) based on at least one PRACH occasion (RO); transmitting a Random Access Response (RAR); The at least one RO includes a plurality of ROs belonging to an RO group for multiple transmissions of the PRACH by a terminal; The ROs are associated with the same Synchronization Signal / Physical Broadcast Channel Block index (SS / PBCH Block index), the plurality of ROs includes i) a first RO and ii) one or more second ROs; The one or more second ROs include ROs determined in ascending order of time resource index after the first RO based on a frequency resource index associated with the first RO.

Claims

1. 1. A method comprising: transmitting a Physical Random Access Channel (PRACH) based on a set including valid PRACH opportunities for preamble repetitions; receiving a Random Access Response (RAR); the valid PRACH opportunities are consecutive in time, use the same frequency resources, and are associated with the same Synchronization Signal / Physical Broadcast Channel Block Index (SS / PBCH BI).

2. The set comprises: i) the first valid PRACH opportunity; and ii) includes one or more second valid PRACH opportunities; the first valid PRACH opportunity is a starting valid PRACH opportunity of the set; 2. The method of claim 1, wherein the one or more second available PRACH opportunities are one or more remaining available PRACH opportunities of the set.

3. The method of claim 2 , wherein a frequency resource index associated with the one or more second valid PRACH opportunities is the same as a frequency resource index associated with the first valid PRACH opportunity.

4. The method of claim 2, wherein the frequency resource index associated with the first valid PRACH opportunity is associated with a resource block (RB).

5. the set is one of a plurality of sets associated with the same SS / PBCH BI; 10. The method of claim 1, wherein a first valid PRACH opportunity of a first set of the plurality of sets is associated with a lowest frequency resource index of frequency resource indexes for frequency multiplexed PRACH opportunities.

6. After a first set of the plurality of sets, the first available PRACH opportunity of a subsequent set is: i) determined in ascending order of frequency resource index for the same time resource index; ii) thereafter, determining in ascending order of time resource indexes for time multiplexed PRACH opportunities for the same frequency resource index.

7. 6. The method of claim 5, wherein at least one of a frequency resource index and / or a time resource index associated with one first valid PRACH opportunity of the plurality of sets is different from other first valid PRACH opportunities of the plurality of sets.

8. 3. The method of claim 2, wherein the first valid PRACH opportunity is based on one of a frequency division multiplexed (FDMed) PRACH opportunity at one time instance.

9. receiving configuration information associated with the PRACH; The setting information includes information regarding a repetition number, The method of claim 1, wherein the number of valid PRACH opportunities is based on the number of repetitions.

10. A terminal, one or more transceivers; one or more processors; one or more memories operably connected to the one or more processors and storing instructions that, when executed by the one or more processors, configure the one or more processors to perform operations; The operation is transmitting a Physical Random Access Channel (PRACH) based on a set including valid PRACH opportunities for preamble repetitions; receiving a Random Access Response (RAR); The valid PRACH opportunities are consecutive in time, use the same frequency resources, and are associated with the same Synchronization Signal / Physical Broadcast Channel Block Index (SS / PBCH BI).

11. A base station, one or more transceivers; one or more processors; one or more memories operably connected to the one or more processors and storing instructions that, when executed by the one or more processors, configure the one or more processors to perform operations; The operation is receiving a Physical Random Access Channel (PRACH) based on a set containing valid PRACH opportunities for preamble repetitions; and transmitting a Random Access Response (RAR), The valid PRACH opportunities are consecutive in time, use the same frequency resources, and are associated with the same Synchronization Signal / Physical Broadcast Channel Block Index (SS / PBCH BI).

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