Method and apparatus for transmitting and receiving random access preambles in wireless communication systems

Abstract

A method performed by a terminal according to one embodiment of this specification includes the steps of transmitting a PRACH based on the number of preamble iterations and receiving a RAR. The PRACH is transmitted based on at least one set determined within a time period. Each set includes valid PRACH occasions based on the number of preamble iterations. The time period is defined such that the at least one set can be determined within the time period for all configured numbers related to the number of preamble iterations.

Description

Technical Field

[0001] This specification relates to a method and apparatus for transmitting and receiving a random access preamble in a wireless communication system.

Background Art

[0002] Mobile communication systems were developed to provide voice services while ensuring user mobility. However, mobile communication systems have expanded their scope to include not only voice but also data services, and currently, due to the explosive increase in traffic, a shortage of resources has occurred, 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, and they must support the accommodation of explosive data traffic, a revolutionary increase in transmission rate per user, the accommodation of a significantly increased number of connected devices, very low end-to-end latency, and high energy efficiency. For this purpose, various technologies such as dual connectivity, massive multiple input multiple output (Massive MIMO), in-band full duplex, non-orthogonal multiple access (NOMA), super wideband support, and device networking are being studied.

[0004] On the other hand, in Rel-18, PRACH repetition is supported. Specifically, PRACH is transmitted based on valid PRACH occasions (RO) based on the number of preamble repetitions.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The RO-based time associated with PRACH repetitive transmission can vary depending on the number of preamble repetitions. For example, the RO-based time when the number of preamble repetitions is 4 may be longer than the RO-based time when the number of preamble repetitions is 2. In such cases, it is necessary to specify whether the time period for determining the RO should be defined separately for each preamble repetition or as a common value.

[0006] This specification proposes a method for solving the aforementioned problems.

[0007] The technical problems that this specification seeks to solve are not limited to those mentioned above, and other technical problems not mentioned can be clearly understood by a person skilled in the art to which this invention pertains from the following description. [Means for solving the problem]

[0008] A method performed by a terminal in a wireless communication system according to one embodiment of this specification includes the steps of transmitting a Physical Random Access Channel (PRACH) based on a number of preamble repetitions, and receiving a Random Access Response (RAR).

[0009] The PRACH is transmitted based on at least one set determined within a time period. Each set includes valid PRACH occasions based on the number of preamble iterations.

[0010] The time period is defined such that, for all configured numbers related to the number of preamble iterations, at least one set can be determined within the time period.

[0011] The time period can be based on the smallest integer multiple of the association pattern periods, of which at least one set can be determined for all the set number of times.

[0012] The association period may be the smallest integer number in a set determined by the PRACH configuration period, which ensures that the Synchronization Signal / Physical Broadcast Channel (SS / PBCH, block index) is mapped to a PRACH opportunity at least once within the association period.

[0013] Each association pattern period may contain one or more association periods.

[0014] The at least one set that can be determined within the aforementioned time period is associated with each of the SS / PBCH block indices.

[0015] Each association pattern period can be 10, 20, 40, 80, or 160 (msec).

[0016] The aforementioned at least one set can be repeated for each time period.

[0017] The method may further include the step of receiving a random access setting. The random access setting may include information about multiple preamble sets. Each preamble set may include preambles related to feature combinations.

[0018] The number of preamble repetitions can be one of the number of preamble repetitions associated with the plurality of preamble sets.

[0019] The number of repetitions of the aforementioned preamble may be 2, 4, or 8.

[0020] The at least one set may include i) a first set and ii) one or more subsequent sets.

[0021] Each of the first valid PRACH occasions in the one or more subsequent sets may occur after the first valid PRACH occasion in the previous set.

[0022] A terminal operating in a wireless communication system according to yet another embodiment of this specification includes one or more transceivers, one or more processors, and one or more memories connected to the one or more processors for storing instructions.

[0023] The instruction is characterized in that, based on the fact that it is performed by one or more processors, the one or more processors are configured to perform all the steps of any one of the methods.

[0024] Apparatus according to other embodiments of this specification includes one or more memories and one or more processors functionally connected to the one or more memories.

[0025] The one or more memories are characterized by storing instructions that, based on being executed by the one or more processors, configure the one or more processors to execute all steps of the method of any one of the claims of the method.

[0026] One or more non-transitory computer-readable media according to other embodiments herein store instructions. The instructions executable by one or more processors are characterized by configuring the one or more processors to execute all steps of the method of any one of the claims of the method.

[0027] A method performed by a base station in a wireless communication system according to other embodiments herein includes receiving a Physical Random Access Channel (PRACH) based on a number of preamble repetitions and transmitting a Random Access Response (RAR).

[0028] The PRACH is received based on at least one set determined within a time period. Each set includes valid PRACH occasions based on the number of preamble repetitions.

[0029] The time period is defined such that for all configured numbers related to the number of preamble repetitions, the at least one set can be determined within the time period.

[0030] A base station operating in a wireless communication system according to yet another embodiment of this specification includes one or more transceivers, one or more processors, and one or more memories connected to the one or more processors for storing instructions.

[0031] The instructions are characterized in that, based on the fact that they are to be executed by one or more processors, the one or more processors are configured to perform all the steps of the method. [Effects of the Invention]

[0032] In the embodiments described herein, regardless of the value set for the number of preamble iterations, at least one set can be determined within the time period. This offers advantages in terms of implementation complexity and signaling overhead compared to defining / setting / instructing a time period for each preamble iteration.

[0033] Furthermore, since there is no limit to the number of repetitions that can be set for each specific time period, the flexibility related to setting the number of PRACH repetitions can be increased. In other words, regardless of what number of preamble repetitions is set on the terminal, a set of valid PRACH occasions based on the set number of preamble repetitions can be determined within the time period.

[0034] Furthermore, for all set number of repetitions, the time period is defined so that at least one set including the valid PRACH occasions can be determined, but the number of remaining PRACH occasions can be minimized when valid PRACH occasions for PRACH repetitions are selected.

[0035] The effects described herein are not limited to those mentioned above, and other effects not mentioned herein can be clearly understood by a person with ordinary skill in the art to which this specification pertains from the following description. [Brief explanation of the drawing]

[0036] [Figure 1] This shows the physical channel and general signal transmission in a 3GPP (registered trademark; hereafter the same) system. [Figure 2] This shows the RACHocasos for each preamble format. [Figure 3] The random access procedure is shown below. [Figure 4] RRC parameters related to RACHpartitioning are shown. [Figure 5] This is an example of a RO related to PRACH iteration according to the embodiments of this specification. [Figure 6] This is another example of a RO related to the PRACH iteration according to the embodiments of this specification. [Figure 7] This is another example of a RO related to the PRACH iteration according to the embodiments of this specification. [Figure 8] This is yet another example of a RO related to a PRACH iteration according to the embodiments of this specification. [Figure 9] Examples of RO for multiple iteration counts according to the embodiments of this specification. [Figure 10] This is another example of RO for multiple iteration counts according to the embodiments of this specification. [Figure 11] This is yet another example of RO for multiple iteration counts according to the embodiments of this specification. [Figure 12] This is a flowchart illustrating a method performed by a terminal according to one embodiment of this specification. [Figure 13] This is a flowchart illustrating a method performed by a base station according to other embodiments of this specification. [Figure 14] This figure shows the configurations of the first and second apparatus according to embodiments of this specification. [Modes for carrying out the invention]

[0037] Preferred embodiments of the present invention will be described in detail below 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 not to show only the embodiments in which the invention can be carried out. The following detailed description includes specific details in order to provide a complete understanding of the invention. However, those skilled in the art will see that the invention can be carried out without such specific details.

[0038] In some cases, known structures and devices may be omitted or shown in the form of block diagrams focusing on the core function of each structure and device, in order to avoid ambiguity of the concept of the present invention.

[0039] In the following, 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 downlink, the transmitter can be part of the base station, and the receiver can be part of the terminal. In uplink, the transmitter can be part of the terminal, and the receiver can be part of the base station. The base station can also be described as the first communication device, and the terminal as the second communication device. The term base station (BS) can be replaced with terms such as fixed station, Node B, eNB (evolved-Node B), gNB (Next Generation Node B), BTS (base transceiver system), access point (AP), network (5G network), AI system, RSU (roadside unit), vehicle, robot, drone (unmanned aerial vehicle, UAV), AR (Augmented Reality) device, and VR (Virtual Reality) device. Furthermore, a terminal can be fixed or mobile, and can be replaced with terms such as UE (User Equipment), MS (Mobile Station), UT (user terminal), MSS (Mobile Subscriber Station), SS (Subscriber Station), AMS (Advanced Mobile Station), WT (Wireless terminal), MTC (Machine-Type Communication) equipment, M2M (Machine-to-Machine) equipment, D2D (Device-to-Device) equipment, vehicle, robot, AI module, drone (Unmanned Aerial Vehicle, UAV), AR (Augmented Reality) equipment, and VR (Virtual Reality) equipment.

[0040] Physical channels and general signal transmission

[0041] Figure 1 illustrates the physical channels and typical signal transmissions used in 3GPP systems. In wireless communication systems, terminals receive information from base stations via the downlink (DL) and transmit information to base stations via the uplink (UL). The information transmitted and received between base stations and terminals includes data and various control information, and various physical channels exist depending on the type and purpose of the information being transmitted and received.

[0042] When a terminal is powered on or enters a new cell, it performs initial cell search operations, such as synchronizing with the base station (S101). To do this, 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 obtain information such as the cell ID. Subsequently, the terminal receives the Physical Broadcast Channel (PBCH) from the base station to obtain broadcast information within the cell. Meanwhile, the terminal receives a Downlink Reference Signal (DLRS) during the initial cell search step to check the downlink channel status.

[0043] After completing the initial cell search, the terminal can obtain more specific system information by receiving the Physical Downlink Control Channel (PDCCH) and the Physical Downlink Shared Channel (PDSCH) via the information carried on the PDCCH (S102).

[0044] On the other hand, if the terminal is initially connected to a base station or does not have radio resources for signal transmission, it can perform a Random Access Procedure (RACH) with respect to the base station (S103-S106). To do this, the terminal transmits a specific sequence in the preamble via a Physical Random Access Channel (PRACH) (S103 and S105), and can receive a Random Access Response (RAR) message for the preamble via the PDCCH and the corresponding PDSCH. In the case of a competitive RACH, an additional Contention Resolution Procedure can be performed (S106).

[0045] A terminal that has performed the procedures described above can then perform PDCCH / PDSCH reception (S107) and Physical Uplink Shared Channel (PUSCH) / Physical Uplink Control Channel (PUCCH) transmission (S108) as a general uplink signal transmission procedure. In particular, the terminal can receive Downlink Control Information (DCI) via PDCCH. Here, DCI includes control information such as resource allocation information for the terminal, and its format can be applied in different ways depending on its intended use.

[0046] On the other hand, control information that a terminal transmits to or receives from a base station via the uplink may include downlink / uplink ACK / NACK signals, CQI (Channel Quality Indicator), PMI (Precoding Matrix Index), RI (Rank Indicator), etc. The terminal can transmit the aforementioned control information such as CQI / PMI / RI via PUSCH and / or PUCCH.

[0047] Next, I will explain the RACH traction.

[0048] A RACH slot contains one or more RACH occasion(s).

[0049] The slot duration is 1 ms for {1.25 kHz, 5 kHz} subcarrier spacings, and has scalable durations (i.e., 1 ms, 0.5 ms, 0.25 ms, 0.125 ms) for {15 kHz, 30 kHz, 60 kHz, 120 kHz} subcarrier spacings.

[0050] For short preamble formats, the OFDM symbol index starting with the RACH slot has {0, 2, x} values.

[0051] Figure 2 shows RACH occasions by preamble format.

[0052] As shown in Figure 2, a RACH slot can contain one or more RACH occasions (ROs) for each preamble format (e.g., A1, A2, ...C2). Figure 2(a) shows the case where the starting OFDM symbol is "0", and Figure 2(b) shows the case where the starting OFDM symbol is "2".

[0053] Figure 3 illustrates a random access procedure.

[0054] Figure 3(a) shows a contention-based RACH procedure, and Figure 5(b) shows a contention-free RACH procedure.

[0055] The following explains how to send an MSG1.

[0056] The subcarrier spacing for MSG1 is set in the RACH configuration and provided in the handover instruction for non-competitive RA procedures for handover.

[0057] The preamble indices for CBRA (contention-based random access) and CFRA (contention-free random access) are sequentially mapped to one SSB per RACH transmission occasion.

[0058] Within a CBRA:SS burst set, the relationships between SS blocks (SSBs) and subsets such as RACH resources and / or preamble indices are defined by a parameter set in RMSI.

[0059] CFRA:UE can be configured to send multiple MSG1s via a dedicated multiple RACH transmission opportunity in the time domain before the end of the monitored RAR window.

[0060] The connection between the CFRA preamble and the SSB is then re-established via the UE-specific RRC.

[0061] The random access procedure may be either a Type-1 random access procedure (4-step RA) or a Type-2 random access procedure (2-step RA).

[0062] The aforementioned Type-1 random access procedure may include sending a random access preamble (Msg1) on a physical random access channel (PRACH), receiving a random access response (RAR) (Msg2), sending a PUSCH scheduled by the UL grant of the RAR (Msg3), and performing a PDSCH for contention resolution (Msg4). If the random access procedure is contention-free random access (CFRA), the Msg3 transmission and Msg4 reception operations are omitted.

[0063] The aforementioned Type-2 random access procedure may include sending a random access preamble and a PUSCH (MsgA) and receiving a RAR (MsgB).

[0064] Table 1 illustrates the settings and operations associated with random access preambles.

[0065] [Table 1]

[0066] JPEG2026509116000003.jpg175147

[0067] JPEG2026509116000004.jpg157147

[0068] JPEG2026509116000005.jpg163146

[0069] JPEG2026509116000006.jpg166147

[0070] JPEG2026509116000007.jpg122146

[0071] The settings / definitions / operations described in Table 1 above may be referenced to clarify the definitions / operations of the embodiments described later. For example, in the embodiments described later, RO may mean valid PRACH occasions mentioned in Table 1. For example, in the embodiments described later, multiple ROs having the same beam index may mean 1 / N (where N < 1) consecutive valid PRACH occasions mapped to one SS / PBCH index.

[0072] Tables 2-4 below illustrate PRACH configuration tables that can be applied to embodiments described later.

[0073] [Table 2]

[0074] JPEG2026509116000009.jpg211147

[0075] JPEG2026509116000010.jpg209148

[0076] JPEG2026509116000011.jpg218148

[0077] JPEG2026509116000012.jpg216148

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[0080] JPEG2026509116000015.jpg218149

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[0082] Table 3

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[0090] JPEG2026509116000025.jpg201148

[0091] Table 4

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[0098] JPEG2026509116000033.jpg205147

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[0100] JPEG2026509116000035.jpg207147

[0101] JPEG2026509116000036.jpg213149

[0102] JPEG2026509116000037.jpg210148

[0103] JPEG2026509116000038.jpg72147

[0104] For example, in the embodiments described later, RO may be an RO based on one of Tables 2 to 4.

[0105] The above-mentioned information can be applied in combination with the method proposed herein, as described later, or can be supplemented to clarify the technical features of the method proposed herein.

[0106] Furthermore, the methods related to the PRACH transmission occasion configuration described later are related to uplink transmission and can be similarly applied to the uplink signal transmission methods in the aforementioned NR system (licensed band) or U-Band system (unlicensed band). It goes without saying that the technical ideas proposed herein can be realized in such systems as well, and can be modified or substituted to suit the terminology, expressions, structures, etc., defined in each system.

[0107] For example, uplink transmission via methods associated with the PRACH transmission occasion configuration described later can be performed in L-cells (cells operating in the licensed band (L-band)) and / or U-cells (cells operating in the unlicensed band (U-band)) as defined in the NR system or U-Band system.

[0108] NR supports multiple numerologies (or subcarrier spacings (SCS)) to support various 5G services. For example, an SCS of 15kHz supports wide area in traditional cellular bands, an SCS of 30kHz / 60kHz supports dense-urban, lower latency, and wider carrier bandwidth, and an SCS of 60kHz or higher supports bandwidths greater than 24.25GHz to overcome phase noise.

[0109] The NR frequency band is defined as a frequency range of two types (FR1, FR2). FR1 and FR2 can be configured as shown in Table 5 below. Furthermore, FR2 can refer to millimeter waves (mmW).

[0110] [Table 5]

[0111] Various RAN1 work items are defined to allow for the differentiation of terminal / base station operations based on RACHresource (e.g., PRACH preamble index). For example, terminals related to redcap, small data transmission, Msg.3 PUSCHrepetition, etc., are defined to request the base station to use the relevant feature by selecting a specific preamble index in the PRACHpreamble transmission step. However, defining separate operations for each work item in this way can increase the complexity of terminal / base station implementation.

[0112] Therefore, the concept of "Feature Combination" was introduced in the RAN2 Rel-17 RACH partitioning work item to efficiently support terminal / base station operations that require partitioning using RACH resources (e.g., PRACH preamble index). That is, the base station sets a specific PRACH resource (e.g., preamble start index and total number indication) to set / instruct the terminal that a specific single feature or specific combination of features is supported. A terminal intending to use / request a specific feature and / or specific combination of features may, during the execution of the RACH procedure, select one of the PRACH preamble indices in the region allocated to the desired specific feature and / or specific feature combination and transmit a PRACH preamble. The RRC parameters for this operation may be "FeatureCombinationPreambles" and "FeatureCombination". Table 6 below illustrates the aforementioned "FeatureCombinationPreambles" and "FeatureCombination".

[0113] [Table 6] JPEG2026509116000041.jpg97139

[0114] Multiple FeatureCombinationPreambles parameters can be set within RACH-ConfigCommon. The preamble index intervals corresponding to each region (i.e., regions / partitions based on preamble(s) belonging to each of the multiple FeatureCombinationPreambles parameters) must be set so as not to overlap. In addition, the features and / or combinations of features set in each region must also be set so as not to overlap with each other. Based on the RACH resources (e.g., preamble(s)) selected by the terminal as described above, the parameters for the random access procedure may be initialized / determined.

[0115] In this specification, “RACHresource” (or “PRACHresource”) may be interpreted / substituted for “Random access resource.” For example, a Featurecombination associated with a RACHresource (e.g., a feature or a combination of features) may be interpreted / substituted for a Featurecombination associated with a set of Random access resources.

[0116] On the other hand, in addition to the RACH-ConfigCommon that was assigned to the existing BWP-UplinkCommon, base stations can assign additional RACHconfigurations via AdditionalRACH-Config-r17. BWP-UplinkCommon can be configured based on an SIB (e.g., SIB1). The RACHprocedure can be performed by a Rel-16 terminal / Rel-17 terminal as follows:

[0117] For Rel-16 terminals that cannot read AdditionalRACH-Config-r17, the terminal will execute the RACH procedure based on the RACH-ConfigCommon assigned to the existing BWP-UplinkCommon.

[0118] For terminals running Rel-17 or later that can read AdditionalRACH-Config-r17, the terminal will check the RACH-ConfigCommon assigned to the existing BWP-UplinkCommon and the RACH-ConfigCommon assigned to AdditionalRACH-Config-r17, and then execute the RACH procedure.

[0119] Furthermore, one or more of the aforementioned FeatureCombinationPreambles may be configured in the RACH-ConfigCommon assigned to the existing BWP-UplinkCommon. One or more of the aforementioned FeatureCombinationPreambles may also be configured in the RACH-ConfigCommon assigned to AdditionalRACH-Config-r17. This will be explained below with reference to Figure 4.

[0120] Figure 4 illustrates the RACH partitioning-related RRC parameters. Specifically, Figure 4 shows the connection relationships / hierarchies of the RACH partitioning-related RRC parameters.

[0121] Refer to Figure 4 for a detailed explanation of each parameter. For convenience of explanation, RRC parameters (e.g., BWP - UplinkCommon parameters) will be written as parameter names (e.g., BWP - UplinkCommon).

[0122] BWP-UplinkCommon includes i) RACH-ConfigCommon, ii) msgA-ConfigCommon, and iii) one or more AdditionalRACH-Configs (#1, #2…).

[0123] Each AdditionalRACH-Config includes i) RACH-ConfigCommon and ii) msgA-ConfigCommon.

[0124] Each RACH-ConfigCommon contains one or more FeatureCombinationPreambles.

[0125] Each FeatureCombinationPreamble contains a FeatureCombination.

[0126] Table 7 shows examples of the RRC parameters mentioned above.

[0127] [Table 7]

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[0129] JPEG2026509116000044.jpg214147

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[0135] On the other hand, the introduction of PRACH preamble repetition transmission is being considered to enhance the UL coverage of existing NR systems. Therefore, it is necessary to define how to configure PRACH resources to support PRACH repetition. Accordingly, this specification proposes a starting slot design method for PRACH repetition and related terminal / base station operations when PRACH repetition is introduced into an NR system and when a feature for PRACH repetition is introduced into PRACH partitioning.

[0136] The following sections will examine in detail the methods for designing a starting RACH slot and RACH occasion for PRACH repetition. In this specification, "RO" can mean Physical Random Access Channel (PRACH) occasion.

[0137] Method 1

[0138] The following describes how to configure a system so that there is one starting RO using the same UL beam within a specific interval (the interval between starting RACH slots).

[0139] Two methods are being discussed for resource allocation and / or resource partitioning for PRACH repetition. One method involves the base station configuring the RACHConfigCommon, which is included in the RACHConfigCommon assigned to BWP-UplinkCommon, by partitioning the RACH resources for single PRACH transmission and PRACH repetition transmission at the preamble level. The other method involves the base station further allocating a new RACH configuration (e.g., utilizing AdditionalRACH-Config-r17) to allocate an RO (RACH occasion) independent of the existing RO (i.e., RO for single PRACH transmission) for PRACH repetition transmission.

[0140] However, if the base station allocates / configures RACH resources for PRACH repetition transmission using the method described above without any additional information, the terminal will be able to select an RO located at any given time from all the ROs configured through that method and start PRACH repetition. If such behavior is permitted, problems may arise from the perspective of base station reception.

[0141] In other words, if RACH repetition can be initiated at any RO located at any given time, the base station must operate as follows: Specifically, the base station must i) store the RACH preambles repeatedly transmitted to multiple ROs in separate storage spaces to match the total number of cases that the terminal can transmit in accordance with the number of repetitions, and ii) perform separate non-coherent (or coherent) detection for each of the corresponding storage spaces.

[0142] As mentioned above, if RACH repetition can be initiated at an RO located at any given time, the decoding complexity of the base station but It will start to increase.

[0143] Therefore, to solve such problems, the base station needs to set / instruct, through higher layer signaling, a specific point in time (e.g., RACHSLOT, RO, and / or time period) at which a terminal can initiate PRACH repetitive transmission.

[0144] The first method involves pre-defining a specific point in time when a terminal can begin repeated PRACH transmission. This specific point in time can be set / defined as the time and interval at which a starting RACH slot (or starting RO) can occur. The starting RACH slot can be set / defined based on the SFN (system frame number), SF (subframe) index, slot index, association period, association pattern period, etc. The starting RO can be set / defined by the RO index within the relevant RACH slot and / or the starting OFDM symbol that initiates the RO.

[0145] For example, one starting RACHslot can be the (earliest) RACHSLOT of a particular SFN (e.g., SFN0), and the interval between starting RACHSLOTs can be set across K SFNs (e.g., K = 1, 2, etc., a positive integer).

[0146] For example, a starting RACHslot can be the (first-allocated) RACHslot for a particular SF index. For example, a starting RACHslot can be directly configured / defined based on a specific SFN, SF index, and slot index.

[0147] Furthermore, the starting RO may be a valid RO that uses the UL beam selected by the terminal that was assigned first within the starting RACHSLOT.

[0148] Characteristically, the interval between the starting RACH slots may be set / defined based on at least one of the following: i) PRACH configuration, ii) SSB-to-RO mapping, and / or iii) repetition number (N).

[0149] As an example, when considering PRACH configuration, SSB-to-RO mapping and / or repetition number, it can be assumed that a particular UE requires at least two RACHSLOTs to perform N repeated transmissions based on the same UL beam (same SS / PBCH block index). The interval between the starting RACHslots can be the number of SFNs of a size that contains the two RACHslots. In other words, if there is one RACHslot in one SFN... If included, the two SFNs can be the interval between starting RACHslots.

[0150] Furthermore, the interval between the relevant starting RACH slots may be set based on units other than SFN units. Specifically, the interval between starting RACH slots (i.e., the time period including RO for PRACH repetitive transmission) may be set / defined / determined based on RO level, slot level, subframe level, association period, or association pattern period, etc.

[0151] For example, a RACHslot located at an integer multiple of the distance between a specific SFN's (e.g., SFN0)RACHslot and a starting RACHslot determined from the same SFN by a predefined rule may be defined as a starting RACHslot for repetitive transmission.

[0152] The proposed method can be illustrated with a concrete example as shown in Figure 5.

[0153] Figure 5 shows an example of RO associated with PRACH iteration according to the embodiment of this specification. Specifically, Figure 5 illustrates the Starting RACHslot, starting RO, and interval between starting RACHslots when the same UL beam is mapped to each RO.

[0154] Referring to Figure 5, the following settings are assumed: SCS (Subcarrier Spacing) is 15 kHz. The PRACH format is PRACH format A1 (2 OFDM symbols per RO). Six ROs are defined for a given RACH slot. All ROs are associated with the same UL beam (same SSB).

[0155] At this time, if the base station sets / instructs the repetition number to 8, the terminal will need at least two RACH slots to perform 8 PRACH preamble repetition transmissions. Since one RACH slot is defined per SFN, the interval between starting RACH slots can be two SFNs. The location of the first starting RACH slot can be assumed to be SFN0, and the starting RO can be the first RO using the same UL beam of that starting RACH slot. After this, the remaining four ROs until the next starting RACH slot can be set / defined not to be used in the PRACH repetition. When configured in this way, the terminal can operate as follows:

[0156] The terminal is starting RACHslot Inside The terminal can select a starting RO corresponding to the selected UL beam as the starting RO for PRACH repetition, and can continuously select a total of eight ROs corresponding to the same UL beam, including this one, on a time axis. The terminal can then perform PRACH repetition based on the selected ROs.

[0157] Another specific example can be illustrated as shown in Figure 6.

[0158] Figure 6 is another example of ROs related to PRACH iteration according to the embodiments of this specification. Specifically, Figure 6 illustrates the Starting RACHslot, starting ROs, intervals between starting RACHslots, etc., when different UL beams are mapped to each RO.

[0159] Referring to Figure 6, the following settings are assumed: SCS (Subcarrier Spacing) is 15 kHz. The PRACH format is PRACH format A1 (occupying 2 OFDM symbols per RO). Six ROs are defined for a given RACH slot. Two different UL beams are mapped to each RO.

[0160] When the base station sets / instructs the repetition number to 4, the terminal will need at least two RACH slots to perform four PRACHpreamble repetition transmissions. Since one RACH slot is defined per SFN, the interval between starting RACH slots can be two SFNs. In this case, the location of the first starting RACH slot can be assumed to be SFN0, and the starting RO can be the first RO using the same UL beam of that starting RACH slot. Subsequently, the four ROs remaining before the next starting RACH slot can be set / defined not to be used in the PRACH repetition. When configured in this way, the terminal can operate as follows:

[0161] The terminal can select a starting RO corresponding to the UL beam selected by the terminal within the starting RACH slot as the starting RO for PRACH repetition, and may sequentially select a total of four ROs corresponding to the same UL beam, including this one, over time. The terminal can then perform PRACH repetition based on the selected ROs.

[0162] As a second approach, we carefully examine methods that can increase the flexibility of base station resource utilization. The following specifically describes how a base station can set / define a particular point in time when a terminal can initiate PRACH repeated transmission.

[0163] The base station sets / instructs the timing and interval at which it can become a starting RACH slot (or starting RO) via higher layer signaling (e.g., SIB). For example, a specific starting RACH slot may be set / instructed based on the SFN, SF index, slot index, association period, association pattern period, etc. If the base station does not set / instruct a specific starting RACH slot, the terminal can determine that it can become the (first assigned) starting RACHSLOT for a specific SFN (e.g., SFN0) and execute the RACH procedure. Characteristically, the starting RO can also be distinguished by the base station setting / instructing a RO index, OFDM symbol index, etc. in advance. If the base station does not set / instruct a starting RO, the terminal can understand the first assigned and validated RO within the starting RACH slot as the starting RO and execute the RACH procedure.

[0164] Furthermore, the startingRACH slot interval can be set / instructed based on RO level, slot level, subframe level, SFN level, association period, association pattern period, etc. If the applicable starting RACHSLOT interval is not set / instructed by the base station, the terminal will understand that it will use a pre-reserved (or defined) starting RACHSLOT interval and can perform the RACH procedure. As an example, the pre-promised starting RACH slot interval may be the same as or similar to the first method proposed earlier.

[0165] As a result, the RACHslot of a specific SFN set / instructed by the base station, and the RACHslot located at an integer multiple of the interval between starting RACHslots set / instructed by the base station from the said specific SFN, can each be defined as a starting RACHslot for repeated transmission.

[0166] From this point forward, the terminal can operate as follows, according to the set value.

[0167] The terminal selects i) a starting RACH slot that has been set since the terminal decided to perform the RACH procedure using PRACHpreamble repetitive transmission (e.g., the earliest one set), and ii) a starting RO set for the UL beam that the terminal intends to use within that starting RACH slot. The terminal also selects additional ROs (time consecutively) that use the same UL beam as the selected RO, for a number of repetitions (as allocated by the base station). The terminal can then perform PRACH repetitive transmission based on the selected ROs; that is, it can be defined to select ROs sequentially from the starting RO without leaving any vacant slots.

[0168] The base station determines when a terminal initiates a PRACH repetition transmission at a specific RACHSLOT and / or a specific RO. The base station can perform non-coherent (or coherent) detection by accumulating preambles received at the relevant RO only to the repetition number (configured by the base station), starting from the relevant RO. The base station can then transmit a RAR to the terminal based on the detection result. The terminal can then transmit Msg. 3 PUSCH based on the relevant RAR.

[0169] Furthermore, although the terminal further selects valid ROs (in time consecutive) that use the same UL beam present between the proposed starting RO and the next starting RO, there are cases where only a number of ROs less than the repetition number are selected (and in some cases many invalid ROs are generated).

[0170] In such cases, the terminal can behave as follows:

[0171] For example, a terminal can be defined so that it no longer interprets a given starting RO as a starting RO for PRACH repetition, and then any valid ROs that exist up to the next starting RO can be configured / defined so that they are no longer used for PRACH repetition. For instance, valid ROs that exist up to the next starting RO can be used for a single PRACH transmission. Subsequently, the terminal can be configured to perform PRACH repetition starting with the next available starting RO among the ROs used for PRACH repetition.

[0172] For example, a terminal can also determine a starting RO as the starting RO for a PRACH repetition. The terminal can then perform PRACH repetition transmissions based on the ROs validated from that starting RO. In other words, a terminal can be configured / defined to perform PRACH repetition transmissions even if the number of valid ROs is less than the repetition number, and to drop the remaining repetition transmissions.

[0173] Method 2

[0174] The following describes how to configure a system so that there are two or more starting ROs using the same UL beam within a specific interval (starting RACHSLOT interval).

[0175] According to Method 1, when an interval between starting RACHSLOTs is set / instructed, there is one starting RO using the same UL beam during the period corresponding to that interval. In this case, the base station can appropriately instruct (or appropriately define in advance) the interval between the starting RACHSlots so that the number of remaining ROs after the terminal selects the ROs necessary for PRACH preamble repetition can be minimized.

[0176] However, if the interval between starting RACH slots is not appropriate (e.g., set / defined to be excessively long compared to the SSB-to-RO mapping or repetition number), there may be an excessive number of ROs remaining after the terminal has selected the ROs needed for PRACH preamble repetition. This can cause delays when terminals supporting PRACH repetition perform their initial access. Therefore, the following methods can be considered to resolve this.

[0177] First, if the starting RACHslot, starting RO, and interval between starting RACHslots can be set / instructed similarly to the previously proposed method, the starting RO that the terminal can select for PRACH preamble repetition may be the first starting RO set / instructed as described above. The second starting RO may be a valid RO that includes the first starting RO and immediately follows a number of valid ROs equal to the repetition number. The third starting RO may be a valid RO that includes the second starting RO and immediately follows a number of valid ROs equal to the repetition number. As described above, among the subsequent ROs, if the number of valid ROs equal to the repetition number is guaranteed up to immediately before a new starting RACH slot, according to the interval between the previously set / defined starting RACHSLOTs, then there will be further starting ROs.

[0178] In other words, for an RO (e.g., RO#X) immediately following the selection of the previous N ROs to become the starting RO, a number of ROs equal to the repetition number must be secured when valid ROs, including the RO in question (e.g., RO#X), are selected consecutively. If fewer ROs than the repetition number are secured, the RO in question (e.g., RO#X) cannot become the starting RO, and the remaining ROs, including the RO in question (e.g., RO#X), up to the slot immediately before the new starting RACH slot, can no longer be used for repetition purposes (e.g., used for standalone PRACH transmission, etc.).

[0179] Alternatively, even if fewer ROs (Relay Orders) than the repetition number are available, the terminal will set / define / analyze the relevant RO (e.g., RO#X) as the starting RO and perform repeated PRACH transmission. The terminal can be configured / defined to discard (i.e., drop) any portion that is less than the repetition number without transmitting it. This can be illustrated in Figure 7.

[0180] Figure 7 shows yet another example of ROs related to PRACH iterations according to the embodiments of this specification. Specifically, Figure 7 illustrates the Starting RACHSLOT, starting RO, and intervals between starting RACHSLOTs when the same UL beam is mapped to each RO.

[0181] Referring to Figure 7, the following settings are assumed: SCS (Subcarrier Spacing) is 15 kHz. The PRACH format is PRACH format A1 (2 OFDM symbols per RO). Six ROs are defined for a given RACHSLOT. All ROs are associated with the same UL beam (same SSB).

[0182] At this point, if the base station sets / instructs the repetition number to 8 and sets the interval between starting RACH slots to three SFNs, a total of two starting ROs can be defined. That is, we can assume that the location of the first starting RACH slot is SFN0. The first starting RO may be the first RO to use the same UL beam in the starting RACHSLOT, and the second starting RO may be the RO that exists immediately after the eight ROs have been selected for the eight repeated transmissions. Subsequently, the two ROs remaining until the next starting RACHSLOT may be set / defined not to be used for PRACH repetition. When set in this way, UE1 can select the first starting RO corresponding to the UL beam selected by the terminal in the starting RACH slot as the starting RO for PRACH repetition, and then sequentially select the ROs corresponding to a total of eight identical UL beams, including this one, in the time axis to perform PRACH repetition. UE2 can select a second starting RO (RO#2 of SFN#1) as the starting RO for PRACH repetition, and then sequentially select ROs corresponding to a total of eight identical UL beams, including this one, in the time axis to perform PRACH repetition.

[0183] Method 3

[0184] The following describes how a base station can set / instruct the number of starting ROs (or RO groups) using the same UL beam within a specific interval (the interval between starting RACH slots) via higher layer signaling.

[0185] Method 3 is a method that addresses the technical challenges attempted to be solved through Methods 1 and 2 while allowing for flexible configuration in terms of base station allocation. This will be explained in detail below.

[0186] The base station can set / instruct the starting RACH slot (and / or starting RO) "S", the number of RO groups for repeated PRACH transmission within the given interval "K", the interval between starting RACH slots (or the period during which K RO groups are set) "P", etc., through higher layer signaling.

[0187] In this case, one RO group can be set / defined as consisting of only N ROs for PRACH repetition transmission. If there are K such RO groups, then N ROs will appear a total of K times, and so on. * This means that K ROs can be used for PRACH repetitive transmission applications.

[0188] When a terminal receives the above-mentioned settings / instructions, it may select a number of ROs corresponding to the specific starting RO for the UL beam selected by the terminal, up to the repetition number. The terminal can then perform PRACH repetitive transmission based on the selected ROs. The terminal can then interpret that the remaining ROs not included in the K RO group will not be used for repetitive transmission and can perform the RACH procedure.

[0189] For example, if the repetition number N=8, S can be set to SFN#0, K to 1, and P to two SFNs. Such a setting is the same as the example in Figure 5 of Method 1.

[0190] As another example, if the repetition number N=8, S can be set to SFN#0, K to 2, and P to 3 SFNs. Such a setting is the same as the example in Figure 7 of Method 2.

[0191] If the repetition number N=8, setting S to SFN#0, K to 1, and P to three SFNs allows us to represent it as shown in Figure 8.

[0192] Figure 8 is another example of ROs related to PRACH iterations according to the embodiments of this specification. Specifically, Figure 8 illustrates the Starting RACHSLOT, starting RO, and intervals between starting RACHSLOTs when the same UL beam is mapped to each RO.

[0193] In other words, referring to Figure 8, since only one RO group exists between the three SFNs, the remaining 10 ROs, excluding the 8 ROs used for PRACH repetition, can be configured not to be used for repeated transmission.

[0194] In the above specification, the statement that a terminal performs PRACH repetition using "ROs that use the same UL beam" can mean that a terminal performs PRACH repetition using "ROs associated / linked to the same SSB index".

[0195] Furthermore, performing a PRACH repetition using the "RO of the UL beam selected by the terminal" can be interpreted as performing a PRACH repetition using the "RO associated / linked to the SSB index selected by the terminal."

[0196] The embodiments described above primarily assume a situation where, when a terminal performs PRACH iterative transmission, it selects an RO associated / linked to the same SSB index and does not change the UL Tx beam. However, the scope of application of these embodiments is not limited to this situation. Specifically, even when repeatedly transmitting PRACH while changing the UL Tx beam by selecting an RO associated / linked to the same SSB index, the operation based on the embodiments described above can be configured / applied.

[0197] Furthermore, this specification describes the proposed method under the assumption that one repetition number is used for a specific RACH resource. When RACH resources (e.g., preamble index, etc.) are shared by repetition number, the actual base station cannot know whether a particular preamble index is transmitted to repetition number N1 or repetition number N2. This forces the base station to send a RAR grant at least twice (once at the end of N1 and once at the end of N2). Therefore, it is essentially assumed that one repetition number is used for a specific RACH resource.

[0198] On the other hand, this configuration presents the problem that the base station must predefine many UL resources for the RACH resource. Ultimately, it can be considered that multiple repetition numbers may be assigned / configured for a particular RACH resource. This has the advantage that the base station does not have to predefine too many resources for the RACH resource. Therefore, when multiple repetition numbers are used / configured for a particular RACH resource, the starting RACH slot, starting RACHocasion, or their interval, period, etc., can be similarly applied based on the proposed method. As an example, the multiple repetition numbers may include two or more of 2, 4, and / or 8.

[0199] Characteristically, even when multiple repetition numbers are assigned to a specific RACH resource, the proposed method for setting the starting RACHSLOT (or starting RACH occasion) can be commonly applied / defined. However, settings such as the interval between starting RACH slots (or the period during which a starting RACH slot is defined) can be applied / defined differently for each repetition number, or they can be set / applied commonly regardless of the repetition number.

[0200] In one embodiment, it may be assumed that the interval between starting RACHSLOTs (or the period during which starting RACHSLOTs are defined) is set to differ for each repetition number. Similar to the proposed method, the interval between starting RACHslots (or the period during which starting RACH slots are defined) may be calculated or instructed / set and used for each repetition number.

[0201] In one embodiment, it may be assumed that the interval between starting RACHSLOTs (or the period during which starting RACHSLOTs are defined) is set / defined to 1 regardless of the repetition number. For example, the value in question may be set / defined based on the largest repetition number value among the repetition numbers used for a particular RACH resource. In other words, the interval between starting RACHSLOTs (i.e., the time period for determining ROs based on the repetition number) may be set / defined such that for all setting counts associated with the repetition number, at least one set containing ROs based on the relevant repetition number is determined.

[0202] The base station can set / instruct different intervals between starting RACHSLOTs (or the period in which a starting RACHSLOT is defined) for each repetition number. After determining a repetition number according to a predefined rule, the terminal can perform a PRACH repetition transmission using the corresponding starting RACH slot (and / or starting RACHoccasion) location and interval between starting RACH slots (or the period in which a starting RACH slot is defined). Subsequently, the base station can know in advance which RO the actual transmission of a terminal performing a PRACH repetition transmission using a particular repetition number will end at. The base station can configure and transmit an appropriate RAR to the terminal based on the preamble transmitted up to the end point for each repetition number.

[0203] On the other hand, if the base station sets / instructs "N" as the repetition number value for PRACHrepetition based on the proposed method, the base station can first determine and operate based on the following two cases in which RO groups are created.

[0204] Case 1) RO group consisting of N valid ROs

[0205] -> Base station / terminal selectable for PRACHrepetition transmission / reception

[0206] Case 2) RO groups with fewer than N valid ROs.

[0207] -> Base station / terminal cannot be selected for PRACHrepetition transmission / reception.

[0208] Characteristically, in the case of Case 1 described above, from the base station's perspective, it is a valid RO group that can be selected for receiving PRACH repetition, but from the terminal's perspective, it can be subdivided and judged and acted upon in the following two cases.

[0209] Case 1-1) In the case where all N valid ROs (from a system perspective) are permitted to transmit from the terminal perspective.

[0210] -> Terminal can be selected for PRACH repetition transmission

[0211] Case 1-2) When some of the N valid ROs (from a system perspective) (e.g., M ROs) are ROs whose transmission is not permitted from the terminal's perspective (e.g., ROs whose transmission is not permitted from the terminal's perspective due to collisions with other signals / channels within DC (dual connectivity) and / or single carriers).

[0212] -> The terminal is unavailable for PRACH repetition transmission. (i.e., the terminal drops the ROs belonging to the RO group in question.) The terminal can then select an RO group consisting of N ROs from the existing RO groups that are permitted for transmission from the terminal's perspective and perform PRACH repetition.

[0213] -> Alternatively, the terminal may be selectable for PRACH repetition transmission, but configured to perform PRACH repetition using NM ROs and not send M PRACH preambles.

[0214] Alternatively, for PRACH repetition transmission, the terminal can select NM ROs from the relevant RO group, and then select the remaining M ROs from other RO groups that are configured later (after the terminal has made RO selections), and then perform PRACH repetition using a total of N ROs.

[0215] Furthermore, when allocating RACH resources for different repetition counts using a separate preamble on shared RO (i.e., a method using R17 feature combination), multiple RACH resources applicable to different repetition numbers can be separated and configured at the preamble level within a given RACH configuration. In this case, a starting RO and / or one starting RO period can be set / defined independently of the repetition number.

[0216] For example, a base station can set one starting RO and / or one starting RO period via higher layer signaling (e.g., SIB1) independently of the repetition number. For example, one starting RO and / or one starting RO period may be defined independently of the repetition number.

[0217] At this time, the starting RO and / or starting RO period must be set / determined / defined so that the maximum number of ROs associated with the same SSBindex are secured.

[0218] For example, starting RO offset values ​​may be set or predefined for different repetition numbers (e.g., for repetition numbers excluding the maximum repetition number). Specifically, the starting RO offset value may be set / instructed by the base station to the terminal via higher layer signaling (e.g., SIB1). This has the advantage that, compared to all repetitions of different numbers starting at a pre-set / instructed starting RO, applying a starting RO offset by repetition number distributes the ROs that start repetitions, reducing interference between preamble indices at base station reception. This can improve reception performance. Characteristically, the starting RO offset value may be set / instructed in the form of an exponential or multiple of 2 in RO units (or slot units or RACH slot units or subframe units or SFN units, etc.). Also, when a starting RO offset is set, a specific preamble index interval can be left unused for repetitions at a pre-set starting RO position. Since the base station can also know this area in advance, it can be used for configuring other UEs (for example, configuring CFRA for other UEs).

[0219] As an example, the RO group for the highest repetition number can be constructed starting from a pre-configured / instructed / defined starting RO. The RO group for a relatively lower repetition number can be constructed starting from the RO at which a further configured / instructed / defined starting RO offset value is applied to the pre-configured / instructed / defined starting RO. This can be represented graphically as shown in Figure 9.

[0220] Figure 9 shows examples of RO for multiple repetition counts according to the embodiments of this specification. Specifically, Figure 9 illustrates starting RO, starting RO period, starting RO offset, etc., for multiple repetition numbers when R=2 and R=4 are assigned in a separated preamble in shared RO system.

[0221] In other words, referring to Figure 9, when R=4, it follows the starting RO and starting RO period (set / instructed or predefined through higher layer signaling), and when R=2, it follows the starting RO period, etc., but the starting RO can be set at a point separated from the starting RO by the starting RO offset.

[0222] However, if the above method is applied, a problem arises where, if the repetition number is relatively low, repeated transmission opportunities are not obtained even though there are enough ROs that can be composed of an RO group. Therefore, as a way to solve this problem, it may be defined that only one RO group is set up / selected during one starting RO period for the PRACH repeat transmission with the highest repetition number. As an example, the base station can set / instruct, via higher layer signaling, how many RO groups can be set up within a specific period (e.g., starting RO period) on a per-repetition basis.

[0223] Furthermore, if the number of RO groups instructed by the base station is less than the total number of RO groups that may exist within the specified period, the terminal and the base station must know in advance where the relevant RO groups should be located. For example, in such a situation, the relevant RO groups can be set to start from the beginning of the specified period and to be defined in the number of RO groups instructed by the base station. As another example, the base station can also set / instruct the terminal to set the starting position of the relevant RO groups at the slot (or subframe, RO, etc.) level via higher layer signaling. In this case, the RO groups must be set so that they do not overlap with each other. This can be represented diagrammatically as shown in Figure 10.

[0224] Figure 10 is another example of RO for multiple iteration counts according to the embodiments of this specification. Specifically, Figure 10 illustrates the starting RO, starting RO period, number of RO group in single period, etc., for multiple repetition numbers when R=2 and R=4 are assigned in a separated preamble in a shared RO system.

[0225] In other words, referring to Figure 10, when R = 4, one RO group is set / selected within one starting RO period.

[0226] Alternatively, base stations can set different starting ROs and / or different starting RO periods for each different repetition number. This configuration allows for the effective configuration of RO groups without additional parameter settings or instructions, as it sets the appropriate starting RO period for each repetition number. This can be illustrated as shown in Figure 11.

[0227] Figure 11 is another example of RO for multiple repetition counts according to the embodiments of this specification. Specifically, Figure 11 illustrates the case where R=2 and R=4 are assigned in a separated preamble in sharedRO system, and the starting RO, starting RO period, starting RO offset, etc., are set independently for multiple repetition numbers.

[0228] The method described above primarily targets the separate preamble on shared RO system (i.e., the system using the R17 feature combination). However, the method can also be applied to the separated RO system (e.g., the system using the additional RACH configuration, or the system that separates TDMed RO).

[0229] The proposed method can be set / applied to other UL signals / Channels such as MSG3 PUSCH, MSGA Preamble / PUSCH, and / or PUSCH / PUCCH. Furthermore, examples of the proposed methods described above can be included as one of the implementation methods in this specification, and are therefore clearly considered as a type of proposed method. While the proposed methods described above can be implemented independently, they can also be implemented in combination (or merged) forms of some of the proposed methods. Information regarding the applicability of the proposed methods (or information regarding the rules for the proposed methods) can be communicated by rules to a base station via a predefined signal (e.g., a physical layer signal or a higher layer signal). The higher layer can include one or more functional layers such as MAC, RLC, PDCP, RRC, and SDAP.

[0230] The methods, embodiments, or descriptions for implementing the methods proposed herein may be applied separately, or one or more methods (or embodiments or descriptions) may be applied in combination.

[0231] In terms of implementation, the operation of the base station / terminal according to the above embodiment (for example, operation based on at least one of Methods 1 to 3) can be processed by the device shown in Figure 14 (for example, processors 110 and 210 in Figure 14), which will be described later.

[0232] Furthermore, the operation of the base station / terminal according to the above embodiment (for example, operation based on at least one of Methods 1 to 3) may also be stored in memory (for example, 140, 240 in Figure 14) in the form of instructions / programs (e.g., instruction, executable code) for driving at least one processor (e.g., 110, 210 in Figure 14).

[0233] The embodiments described above will now be specifically explained below with reference to Figures 12 and 13, focusing on the operation of the terminal and base station. It should be noted that, for the sake of clarity, some components of one method may be substituted for or combined with components of another method.

[0234] Figure 12 is a flowchart illustrating a method performed by a terminal according to one embodiment of this specification.

[0235] Referring to Figure 12, a method performed by a terminal according to one embodiment of this specification includes a PRACH transmission step S1210 and a RAR reception step S1220.

[0236] In S1210, the terminal transmits a Physical Random Access Channel (PRACH) to the base station based on the number of preamble repetitions.

[0237] The PRACH may be transmitted based on at least one set determined within a time period. For example, the PRACH may be transmitted based on Table 1. Each set may include valid PRACH occasions based on the number of preamble iterations. The at least one “set” may mean at least one “RO group” in the embodiments described above (embodiments based on at least one of Methods 1 to 3).

[0238] For example, the number of repetitions of the preamble may be 2, 4, or 8.

[0239] In one embodiment, the time period may be defined such that at least one set can be determined within the time period for all configured numbers (e.g., 2, 4, or 8) related to the number of preamble iterations. The time period may be based on the interval between time intervals / starting RO periods / starting RACHSLOTs defined based on at least one of Methods 1 to 3.

[0240] As an example, the time period may be defined based on the association pattern period. That is, the time period means the shortest time in which a valid PRACH opportunity can be selected / secured based on all setting counts (2, 4, or 8). More specifically, the time period may be based on the smallest integer multiple of the association pattern periods for which at least one set can be determined for all setting counts. As a concrete example, it may be assumed that the number of association pattern periods for which at least one set can be determined for all setting counts is 2, 3, 4... In this case, the time period may be only twice the association pattern period. That is, the time period may be defined as the smallest number of association pattern periods.

[0241] The association period may be the smallest integer number in a set determined by the PRACH configuration period, which ensures that the Synchronization Signal / Physical Broadcast Channel (SS / PBCH, block index) is mapped to the PRACH opportunity at least once within the association period (see, for example, Table 1).

[0242] Each association pattern period may contain one or more association periods. The minimum integer can mean the number of association pattern periods that correspond to the shortest length / shortest time for which the at least one set can be determined. Each association pattern period may be 10, 20, 40, 80, or 160 (msec). As an example, if the minimum integer is K, the time period may be defined as K times 10, 20, 40, 80, or 160 (msec).

[0243] The at least one set that can be determined within the aforementioned time period is the The SS / PBCH block indices can be associated with each of the following. That is, within the time period, at least one set of effective PRACH opportunities associated with each of the SS / PBCH block indices can be determined. According to one embodiment, at least one set can be repeated with each time period. For example, if the time period is 40 milliseconds, the at least one set can be repeated every 40 milliseconds.

[0244] In one embodiment, the at least one set is i) a first set, and ii) one or more subsequent sets (subsequent sets) This may include, that is, the at least one set may include subsequent sets of the first set (second set, third set, etc.). Specifically, the first valid PRACH occasion of each of the one or more subsequent sets may be after the valid PRACH occasion of the previous set. As a specific example, the first valid PRACH occasion of the second set may be greater than or equal to the valid PRACH occasion of the first set. Here, “first valid PRACH occasion” may mean “starting RO” in the embodiments described above (embodiments based on at least one of Methods 1 to 3).

[0245] In S1220, the terminal receives a Random Access Response (RAR) from the base station. The RAR may be based on MSG2 of a Type-1 random access procedure or MSGB of a Type-2 random access procedure.

[0246] The method may further include a step of receiving a random access setting. In the random access setting receiving step, the terminal receives a random access setting from the base station.

[0247] The aforementioned random access configuration includes information about multiple preamble sets. Each preamble set may contain preambles related to feature combinations.

[0248] As an example, referring to Figure 4, Table 6, and Table 7, the random access setting can be based on i) a RACH-ConfigCommon parameter set by the BWP-UplinkCommon parameter, or ii) a RACH-ConfigCommon parameter set based on one or more AdditionalRACH-Config parameters. The information regarding the multiple preamble sets can mean the information regarding the FeatureCombinationPreambles parameter within the RACH-ConfigCommon parameter (e.g., featureCombinationPreamblesList). The information regarding each preamble set can be based on the FeatureCombinationPreambles parameter.

[0249] As mentioned above, a preamble repetition count can be set for each preamble (each preamble set) associated with a feature combination. Therefore, the preamble repetition count can be one of the preamble repetition counts associated with the plurality of preamble sets. That is, each of the preamble repetition counts can mean a preamble repetition count set based on information about each preamble set (the FeatureCombinationPreambles parameter). As a specific example, the FeatureCombinationPreambles parameter can include information about the preamble repetition count (for example, the msg1-RepetitionNum-r18 parameter). The msg1-RepetitionNum-r18 parameter can be set to n2, n4, or n8.

[0250] The operations based on steps S1210 to S1220 and the random access setting reception step described above can be implemented by the device shown in Figure 14. For example, terminal 200 can control one or more transceivers 230 and / or one or more memories 240 to perform operations based on steps S1210 to S1220 and the random access setting reception step.

[0251] The above-mentioned embodiment will now be described in detail from the perspective of the base station's operation.

[0252] The S1310-S1320 and random access setting transmission steps described later correspond to the S1210-S1220 and random access setting reception steps described in Figure 12. Considering this correspondence, redundant explanations will be omitted. That is, the specific explanations of base station operations described later can be replaced by the explanations / examples in Figure 12 corresponding to those operations. For example, the explanations / examples of S1210-S1220 in Figure 12 can be further applied to the base station operations of S1310-S1320 described later. For example, the explanations / examples of terminal operations in the random access setting reception step can be further applied to the base station operations of the random access setting transmission step described later.

[0253] Figure 13 is a flowchart illustrating a method performed by a base station according to other embodiments of this specification.

[0254] Referring to Figure 13, a method performed by a base station according to other embodiments of this specification includes a PRACH reception step S1310 and a RAR transmission step S1320.

[0255] In S1310, the base station receives a Physical Random Access Channel (PRACH) from the terminal based on the number of preamble repetitions.

[0256] In S1320, the base station transmits a Random Access Response (RAND) to the terminal.

[0257] The method may further include a random access setting transmission step. In the random access setting transmission step, the base station transmits the random access setting to the terminal.

[0258] The operation based on the random access configuration transmission steps S1310 to S1320 described above can be realized by the device shown in Figure 14. For example, the base station 100 can control one or more transceivers 130 and / or one or more memories 140 to perform the operation based on S1310 to S1320 and the random access configuration transmission steps.

[0259] In the following section, the apparatus to which the embodiments of this specification can be applied (apparatus that realizes the methods / operations according to the embodiments of this specification) will be described with reference to Figure 14.

[0260] Figure 14 shows the configurations of the first and second apparatus according to embodiments of this specification.

[0261] The first device 100 may include a processor 110, an antenna unit 120, a transceiver 130, and a memory 140.

[0262] The processor 110 performs baseband-related signal processing and may include a higher-level processing unit 111 and a physical-level processing unit 115. The higher-level processing unit 111 can process MAC layer, RRC layer, or higher-level layer operations. The physical-level processing unit 115 can process PHY layer operations. For example, if the first device 100 is a base station device in base station-terminal communication, the physical-level processing unit 115 can perform uplink received signal processing, downlink transmitted signal processing, etc. For example, if the first device 100 is a first terminal device in terminal-terminal communication, the physical-level processing unit 115 can perform downlink received signal processing, uplink transmitted signal processing, sidelink transmitted signal processing, etc. In addition to performing baseband-related signal processing, the processor 110 can also control the overall operation of the first device 100.

[0263] The antenna unit 120 may include one or more physical antennas, and if it includes multiple antennas, it can support MIMO transmission and reception. The transceiver 130 may include an RF (Radio Frequency) transmitter and an RF receiver. The memory 140 can 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.

[0264] The processor 110 of the first device 100 can be configured to implement the operation of the base station in base station-terminal communication (or the operation of the first terminal device in terminal-terminal communication) in the embodiments described herein.

[0265] The second device 200 may include a processor 210, an antenna unit 220, a transceiver 230, and a memory 240.

[0266] The processor 210 performs baseband-related signal processing and may include a higher-level processing unit 211 and a physical-level processing unit 215. The higher-level processing unit 211 can process MAC layer, RRC layer, or higher-level layer operations. The physical-level processing unit 215 can process PHY layer operations. For example, if the second device 200 is a terminal device in base station-terminal communication, the physical-level processing unit 215 can perform downlink received signal processing, uplink transmitted signal processing, etc. For example, if the second device 200 is a second terminal device in terminal-to-terminal communication, the physical-level processing unit 215 can perform downlink received signal processing, uplink transmitted signal processing, sidelink received signal processing, etc. In addition to performing baseband-related signal processing, the processor 210 can also control the overall operation of the second device 200.

[0267] The antenna unit 220 may include one or more physical antennas, and if it includes multiple antennas, it can support MIMO transmission and reception. The transceiver 230 may include an RF transmitter and an RF receiver. The memory 240 can store information processed by the processor 210, and software, an operating system, applications, etc., related to the operation of the second device 200, and may also include components such as buffers.

[0268] The processor 210 of the second device 200 can 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 herein.

[0269] In the operation of the first device 100 and the second device 200, the matters described in the examples of this 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 applied in the same way, and redundant explanations will be omitted.

[0270] Here, the wireless communication technologies implemented in the devices 100 and 200 of this disclosure may include not only LTE, NR, and 6G, but also Narrowband Internet of Things (NB-IoT) for low-power communication. For example, NB-IoT technology is an example of LPWAN (Low Power Wide Area Network) technology and can be implemented using standards such as LTE Cat NB1 and / or LTE Cat NB2, and is not limited to the aforementioned names.

[0271] Additionally or alternatively, the wireless communication technology implemented in the devices 100, 200 of this disclosure can communicate based on LTE-M technology. For example, LTE-M technology is an example of LPWAN technology and is known by various names such as eMTC (enhanced Machine Type Communication). For example, LTE-M technology can be implemented using 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 names mentioned above.

[0272] Additionally or alternatively, the wireless communication technologies implemented in the devices 100, 200 of this disclosure may include, but are not limited to, at least one of ZigBee, Bluetooth (registered trademark), and Low Power Wide Area Network (LPWAN) technologies, with regard to low-power communication. For example, ZigBee technology can generate personal area networks (PANs) related to small / low-power digital communication based on various standards such as IEEE 802.15.4, and can be referred to by a variety of names.

[0273] [Claims when filing an international application] 〔Claim 1〕 A method executed by a terminal in a wireless communication system, comprising: transmitting a Physical Random Access Channel (PRACH) based on the number of preamble repetitions; receiving a Random Access Response (RAR); where the PRACH is transmitted based on at least one set determined within a time period, each set includes valid PRACH occasions based on the number of preamble repetitions, and the time period is defined such that for all configured numbers related to the number of preamble repetitions, at least one set can be determined within the time period. 〔Claim 2〕 The method according to claim 1, wherein the time period is based on the smallest integer multiple of association pattern periods in which at least one set can be determined for all the configured numbers. 〔Claim 3〕 The association period is the smallest integer number within a set determined by a PRACH configuration period that allows the Synchronization Signal / Physical Broadcast Channel (SS / PBCH) block index to be mapped at least once within the association period. The method according to claim 2, characterized in that each association pattern period includes one or more association periods. [Claim 4] The method according to claim 3, characterized in that the at least one set that can be determined within the time period is associated with each of the SS / PBCH block indices. [Claim 5] The method according to claim 2, characterized in that each association pattern period is 10, 20, 40, 80, or 160 (msec). [Claim 6] The method according to claim 1, characterized in that the at least one set is repeated each time period. [Claim 7] The steps include receiving random access settings; Random access settings include information about multiple preamble sets. The method according to claim 1, characterized in that each preamble set includes a preamble related to a feature combination. [Claim 8] The method according to claim 7, characterized in that the number of preamble repetitions is one of the number of preamble repetitions associated with the plurality of preamble sets. [Claim 9] The method according to claim 1, characterized in that the number of repetitions of the preamble is 2, 4, or 8. [Claim 10] The aforementioned at least one set is i) First set, and ii) The method according to claim 1, characterized by comprising one or more subsequent sets. [Claim 11] The method according to claim 10, characterized in that each of the one or more subsequent sets of first valid PRACH occasions is after the valid PRACH occasion of the previous set. [Claim 12] A terminal that operates in a wireless communication system, One or more transceivers, One or more processors, The system comprises one or more memories connected to one or more processors for storing instructions, A terminal characterized in that, based on the fact that the instructions are performed by the one or more processors, the one or more processors are configured to perform all the steps of the method according to any one of claims 1 to 11. [Claim 13] It is a device, One or more memory devices, The system comprises one or more memory units and one or more processors functionally connected to them, The apparatus is characterized in that the one or more memory stores instructions that, based on being executed by the one or more processors, cause the one or more processors to perform all the steps of the method described in any one of claims 1 to 11. [Claim 14] One or more non-temporary computer-readable media for storing instructions, One or more non-transitory computer-readable media, characterized in that instructions executable by one or more processors are configured to enable the one or more processors to perform all steps of the method described in any one of claims 1 to 11. [Claim 15] A method performed by a base station in a wireless communication system, The steps include: receiving a Physical Random Access Channel (PRACH) based on the number of preamble repetitions; The process comprises the steps of: transmitting a Random Access Response (RAR); The PRACH is received based on at least one set determined within a time period. Each set includes valid PRACH occasions based on the number of preamble iterations, The method is characterized in that the time period is defined such that, for all configured numbers related to the number of preamble iterations, at least one set can be determined within the time period. [Claim 16] A base station operating in a wireless communication system, One or more transceivers, One or more processors, It comprises one or more processors connected to one or more memories for storing instructions, A base station characterized in that, based on the fact that the instructions are performed by the one or more processors, the one or more processors are configured to perform all the steps of the method according to claim 15.

Claims

1. A method performed by a terminal in a wireless communication system, The steps include: transmitting a Physical Random Access Channel (PRACH) based on the number of preamble repetitions; The process includes the step of receiving a Random Access Response (RAR); The PRACH is transmitted based on at least one set determined within a time period. Each set includes valid PRACH opportunities based on the number of preamble iterations, The method is characterized in that the time period is defined such that, for all configured numbers related to the number of preamble iterations, at least one set can be determined within the time period.

2. The method according to claim 1, characterized in that the time period is based on the smallest integer number multiple of association pattern periods, of which at least one set can be determined for all the set number of times.

3. The association period is the smallest integer number in the set determined by the PRACH configuration period, which ensures that the Synchronization Signal / Physical Broadcast Channel block index (SS / PBCH, block index) is mapped to a PRACH opportunity at least once within the association period. The method according to claim 2, characterized in that each association pattern period includes one or more association periods.

4. The method according to claim 3, characterized in that the at least one set that can be determined within the time period is associated with each of the SS / PBCH block indices.

5. The method according to claim 2, characterized in that each association pattern period is 10, 20, 40, 80, or 160 (msec).

6. The method according to claim 1, characterized in that the at least one set is repeated each time period.

7. The steps include receiving random access settings; Random access settings include information about multiple preamble sets. The method according to claim 1, characterized in that each preamble set includes a preamble related to a feature combination.

8. The method according to claim 7, characterized in that the number of preamble repetitions is one of the number of preamble repetitions associated with the plurality of preamble sets.

9. The method according to claim 1, characterized in that the number of repetitions of the preamble is 2, 4, or 8.

10. The aforementioned at least one set is i) First set, and ii) The method according to claim 1, characterized by comprising one or more subsequent sets.

11. The method according to claim 10, characterized in that each of the one or more subsequent sets of first valid PRACH opportunities is after the valid PRACH opportunity of the previous set.

12. A terminal that operates in a wireless communication system, One or more transceivers, One or more processors, The system comprises one or more memories connected to one or more processors for storing instructions, A terminal characterized in that, based on the fact that the instructions are executed by one or more processors, one or more processors are configured to perform all the steps of the method according to any one of claims 1 to 11.

13. It is a device, One or more memory devices, The system comprises one or more memory units and one or more processors functionally connected to them, The apparatus is characterized in that the one or more memory stores instructions that, based on being executed by the one or more processors, cause the one or more processors to perform all the steps of the method according to any one of claims 1 to 11.

14. One or more non-temporary computer-readable media for storing instructions, One or more non-transitory computer-readable media, characterized in that instructions executable by one or more processors are configured to cause the one or more processors to perform all steps of the method according to any one of claims 1 to 11.

15. A method performed by a base station in a wireless communication system, The steps include: receiving a Physical Random Access Channel (PRACH) based on the number of preamble repetitions; The process includes the steps of: transmitting a Random Access Response (RAR); The PRACH is received based on at least one set determined within a time period. Each set includes valid PRACH opportunities based on the number of preamble iterations, The method is characterized in that the time period is defined such that, for all configured numbers related to the number of preamble iterations, at least one set can be determined within the time period.

16. A base station operating in a wireless communication system, One or more transceivers, One or more processors, It comprises one or more processors connected to one or more memories for storing instructions, A base station characterized in that, based on the fact that the instructions are performed by the one or more processors, the one or more processors are configured to perform all the steps of the method according to claim 15.

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