Method and apparatus for contention-free random access in wireless communication system

Abstract

A method of a terminal for performing a random access (RA) procedure may comprise the steps of: receiving, from a base station, contention-free RA (CFRA) configuration information for a CFRA procedure and a system information request, and contention-based random access (CBRA) configuration information for a CBRA procedure; measuring a reception strength of a synchronization signal block (SSB) received from the base station; determining the number of repetitions for transmission of message 1 (Msg1) on the basis of the measured reception strength; and repeatedly transmitting the Msg1 according to the determined number of repetitions in a first random access occasion (RO) group set determined by the CFRA configuration information and / or the CBRA configuration information.

Description

Method and device for non-contention-based random access in a wireless communication system

[0001] The present disclosure relates to a random access procedure in a wireless communication system, and more particularly, to a method and device for non-contention-based random access.

[0002] With the advancement of information and communication technology, various wireless communication technologies are being developed. Representative wireless communication technologies include LTE (long term evolution) and NR (new radio), both of which are defined by the 3rd generation partnership project (3GPP) standards. LTE can be one of the 4th generation (4G) wireless communication technologies, and NR can be one of the 5th generation (5G) wireless communication technologies.

[0003] To handle the rapidly increasing volume of wireless data following the commercialization of 4G communication systems (e.g., communication systems supporting LTE), 5G communication systems (e.g., communication systems supporting NR) that utilize higher frequency bands (e.g., frequency bands higher than 6 GHz) than the frequency bands of 4G communication systems (e.g., frequency bands below 6 GHz) are being considered. 5G communication systems can support enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low Latency Communication (URLLC), and massive Machine Type Communication (mMTC). Discussions are ongoing regarding 6G communication systems that will follow 5G communication systems.

[0004] In mobile communication systems, contention-free random access procedures can be implemented for a variety of purposes and environments. However, significant improvements to contention-free random access procedures are needed for environments such as requesting on-demand system information, non-terrestrial networks, or multi-transmission and reception point (TRP) communication scenarios.

[0005] The purpose of the present disclosure to solve the above problems is to provide a method and device for performing a non-contention random access procedure in a wireless communication system.

[0006] According to one embodiment of the present invention for achieving the above object, a method of a terminal performing a random access (RA) procedure may include: receiving, from a base station, first RA configuration information for a contention-free RA (CFRA) procedure or a system information request and second RA configuration information for a contention-based random access (CBRA) procedure; measuring a reception strength of a synchronization signal block (SSB) received from the base station; determining a repetition number for transmission of message 1 (Msg1) based on the measured reception strength; and repeatedly transmitting Msg1 according to the determined repetition number in a first random access occasion (RO) group set determined by the first RA configuration information and / or the second RA configuration information.

[0007] The first RO group set is derived by the first RA setting information, and the first RO group set may be composed of ROs independent of the ROs for the CBRA procedure set by the second RA setting information.

[0008] A time offset may not be applied between RO groups belonging to the above first RO group set.

[0009] If resources for the CFRA procedure are not set in the first RA setting information, the first RO group set is derived by the second RA setting information, and the time offset between RO groups belonging to the first RO group set can be indicated by the CBRA setting information.

[0010] The above first RA setting information includes mask information, the validity of ROs belonging to the first RO group set is determined based on the mask information, and the Msg1 can be transmitted from the valid RO(s) determined based on the mask information.

[0011] The above time offset may be selected based on the number of repetitions from among a plurality of values ​​indicated by the first RA setting information or the second RA setting information.

[0012] At least a portion of the above first RA setting information may share at least a portion of the above second RA setting information.

[0013] The number of repetitions may be determined based on the reception intensity section to which the measured reception intensity belongs, obtained by comparing the measured reception intensity with at least one threshold value.

[0014] The step of repeatedly transmitting the above Msg1 may be performed to request system information from the base station.

[0015] According to one embodiment of the present invention for achieving the above object, a method of a base station for a random access (RA) procedure may include: transmitting, to a terminal, first RA configuration information for a contention-free RA (CFRA) procedure or a system information request and second RA configuration information for a contention-based random access (CBRA) procedure; transmitting a synchronization signal block (SSB) to the terminal; and repeatedly receiving, from the terminal, a message 1 (Msg1) according to a repetition number determined based on a reception strength of the SSB at the terminal in a first random access occasion (RO) group set determined by the first RA configuration information and / or the second RA configuration information.

[0016] The first RO group set is derived by the first RA setting information, and the first RO group set may be composed of ROs independent of the ROs for the CBRA procedure set by the second RA setting information.

[0017] A time offset may not be applied between RO groups belonging to the above first RO group set.

[0018] If the resources for the CFRA procedure are not set in the first RA setting information, the first RO group set is derived by the second RA setting information, and the time offset between the RO groups belonging to the first RO group set can be indicated by the second RA setting information.

[0019] The above first RA setting information includes mask information, the validity of ROs belonging to the first RO group set is determined based on the mask information, and the Msg1 can be received from valid RO(s) determined based on the mask information.

[0020] The above time offset may be selected based on the number of repetitions from among a plurality of values ​​indicated by the first RA setting information or the second RA setting information.

[0021] At least a portion of the above first RA setting information may share at least a portion of the above second RA setting information.

[0022] According to one embodiment of the present invention for achieving the above object, a terminal for performing a random access (RA) procedure includes at least one processor, and the at least one processor may perform the steps of: receiving, from a base station, first RA configuration information for a contention-free RA (CFRA) procedure or a system information request and second RA configuration information for a contention-based random access (CBRA) procedure; measuring a reception strength of a synchronization signal block (SSB) received from the base station; determining a repetition number for transmission of message 1 (Msg1) based on the measured reception strength; and repeatedly transmitting Msg1 according to the determined repetition number in a first random access occasion (RO) group set determined by the first RA configuration information and / or the second RA configuration information.

[0023] The first RO group set is derived by the first RA setting information, and the first RO group set may be composed of ROs independent of the ROs for the CBRA procedure set by the second RA setting information.

[0024] If resources for the CFRA procedure are not set in the first RA configuration information, the first RO group set is derived by the second RA configuration information, and the time offset between RO groups belonging to the first RO group set can be indicated by the second RA configuration information.

[0025] The above first RA setting information includes mask information, the validity of ROs belonging to the first RO group set is determined based on the mask information, and the Msg1 can be transmitted from the valid RO(s) determined based on the mask information.

[0026] According to various embodiments of the present disclosure, a non-contention-based random access procedure suitable for environments such as requesting on-demand system information, non-terrestrial networks, or multi-transmission and reception point (TRP) communication scenarios can be performed. Accordingly, the performance of the overall communication system can be improved.

[0027] Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0028] Figure 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0029] FIG. 3 is a flowchart illustrating a method for a terminal to trigger a base station on which the terminal is camped to transmit SIB1 or SIBx using UL DRS according to one embodiment of the present invention.

[0030] FIG. 4 is a flowchart illustrating a method for a terminal to trigger a base station on which the terminal is camped to transmit SIB1 or SIBx using UL DRS according to another embodiment of the present invention.

[0031] FIG. 5 is a flowchart illustrating a response monitoring procedure for a terminal to receive RAR or SIB1 or SIBx according to another embodiment of the present invention.

[0032] FIG. 6 and FIG. 7 are flowcharts for explaining the operation of a terminal when SIB1 or SIBx transmission is triggered by multiple terminals according to embodiments of the present invention.

[0033] FIGS. 8 and 9 are timing diagrams illustrating a method for determining whether to drop a preamble according to embodiments of the present invention.

[0034] Figure 10 is a conceptual diagram illustrating an example of listing valid ROs derived from selected SSBs in chronological order.

[0035] Figures 11 and 12 are conceptual diagrams showing examples in which sets of RO groups overlap and a set of RO groups is expressed as a union of these sets.

[0036] Figure 13 is a conceptual diagram illustrating an embodiment in which a set of RO groups are mapped to overlap temporally at the boundary of the second period.

[0037] Figure 14 is a conceptual diagram illustrating an embodiment in which a set of RO groups are mapped without temporal overlap at the boundary of the second period.

[0038] Figure 15 is a conceptual diagram illustrating the Rx GoB and Tx GoB of a terminal.

[0039] Figures 16 and 17 are conceptual diagrams for explaining the relationship between the receiving beam of SSB and the transmitting beam of Msg1.

[0040] Figure 18 is a conceptual diagram explaining improvement in reception quality of Msg1 due to repeated transmission of Msg1 through the same beam.

[0041] Figures 19 and 20 are conceptual diagrams for explaining a case where four transmission beams are derived from one reception beam for Msg1 sweeping.

[0042] Figures 21 and 22 are conceptual diagrams illustrating examples in which gaps are reflected in the RO group.

[0043] Figure 23 is a conceptual diagram illustrating a case where a base station indicates a specific RO within an RO group.

[0044] Figure 24 is a flowchart illustrating Msg5 transmission and its preceding procedures.

[0045] This disclosure may be subject to various modifications and various embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the disclosure to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the disclosure.

[0046] While terms such as "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present disclosure, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component." The term "and / or" encompasses any combination of multiple related items or any one of multiple related items.

[0047] In embodiments of the present disclosure, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.” Furthermore, in embodiments of the present disclosure, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B.”

[0048] When a component is referred to as being "connected" or "connected" to another component, it should be understood that it may be directly connected or connected to that other component, but that there may be other components intervening. Conversely, when a component is referred to as being "directly connected" or "connected" to another component, it should be understood that there are no other components intervening.

[0049] The terminology used in this disclosure is only used to describe specific embodiments and is not intended to limit the present disclosure. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this disclosure, it should be understood that the terms "comprises" or "has" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0050] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0051] Hereinafter, preferred embodiments of the present disclosure will be described in more detail with reference to the attached drawings. In order to facilitate an overall understanding in describing the present disclosure, identical reference numerals will be used for identical components in the drawings, and redundant descriptions of identical components will be omitted.

[0052] A communication system to which embodiments according to the present disclosure are applied will be described. The communication system to which embodiments according to the present disclosure are applied is not limited to the scope described below, and embodiments according to the present disclosure can be applied to various communication systems. Here, the term "communication system" may be used interchangeably with "communication network."

[0053] In an embodiment, "an operation (e.g., a transmission operation) is set" may mean that "setting information for the operation (e.g., an information element, a parameter)" and / or "information instructing performance of the operation" are signaled. "An information element (e.g., a parameter) is set" may mean that the information element is signaled. The signaling may be at least one of system information (SI) signaling (e.g., transmission of a system information block (SIB) and / or a master information block (MIB)), RRC signaling (e.g., transmission of an RRC message, an RRC parameter, and / or an upper layer parameter), MAC control element (CE) signaling (e.g., transmission of a MAC message and / or a MAC CE and / or a MAC subPDU), or PHY signaling (e.g., transmission of downlink control information (DCI), uplink control information (UCI), and / or sidelink control information (SCI)).

[0054] Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.

[0055] Referring to FIG. 1, the communication system (100) may include a plurality of communication nodes (110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). In addition, the communication system (100) may further include a core network (e.g., a serving-gateway (S-GW), a packet data network (PDN)-gateway (P-GW), a mobility management entity (MME)). If the communication system (100) is a 5G communication system (e.g., a new radio (NR) system), the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), etc.

[0056] A plurality of communication nodes (110 to 130) can support a communication protocol (e.g., LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.) specified in the 3GPP (3rd generation partnership project) standard. The plurality of communication nodes (110 to 130) may support CDMA (code division multiple access) technology, WCDMA (wideband CDMA) technology, TDMA (time division multiple access) technology, FDMA (frequency division multiple access) technology, OFDM (orthogonal frequency division multiplexing) technology, Filtered OFDM technology, CP (cyclic prefix)-OFDM technology, DFT-s-OFDM (discrete Fourier transform-spread-OFDM) technology, OFDMA (orthogonal frequency division multiple access) technology, SC (single carrier)-FDMA technology, NOMA (non-orthogonal multiple access) technology, GFDM (generalized frequency division multiplexing) technology, FBMC (filter bank multi-carrier) technology, UFMC (universal filtered multi-carrier) technology, SDMA (space division multiple access) technology, etc. Each of the plurality of communication nodes may have the following structure.

[0057] Figure 2 is a block diagram illustrating a first embodiment of a communication node constituting a communication system.

[0058] Referring to FIG. 2, a communication node (200) may include at least one processor (210), a memory (220), and a transmission / reception device (230) that is connected to a network and performs communication. In addition, the communication node (200) may further include an input interface device (240), an output interface device (250), a storage device (260), etc. Each component included in the communication node (200) may be connected by a bus (270) and communicate with each other.

[0059] However, each component included in the communication node (200) may be connected through an individual interface or individual bus centered around the processor (210), rather than a common bus (270). For example, the processor (210) may be connected to at least one of a memory (220), a transmission / reception device (230), an input interface device (240), an output interface device (250), and a storage device (260) through a dedicated interface.

[0060] The processor (210) can execute program commands stored in at least one of the memory (220) and the storage device (260). The processor (210) may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor in which the methods according to embodiments of the present disclosure are performed. Each of the memory (220) and the storage device (260) may be configured with at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory (220) may be configured with at least one of a read-only memory (ROM) and a random access memory (RAM).

[0061] Referring again to FIG. 1, the communication system (100) may include a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) and a plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6). Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) may form a macro cell. Each of the fourth base station (120-1) and the fifth base station (120-2) may form a small cell. The fourth base station (120-1), the third terminal (130-3), and the fourth terminal (130-4) may be within the cell coverage of the first base station (110-1). The second terminal (130-2), the fourth terminal (130-4), and the fifth terminal (130-5) may be within the cell coverage of the second base station (110-2). The fifth base station (120-2), the fourth terminal (130-4), the fifth terminal (130-5), and the sixth terminal (130-6) may be within the cell coverage of the third base station (110-3). The first terminal (130-1) may be within the cell coverage of the fourth base station (120-1). The sixth terminal (130-6) may be within the cell coverage of the fifth base station (120-2).

[0062] Here, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be referred to as a NodeB (NB), an evolved NodeB (eNB), a gNB, an advanced base station (ABS), a high reliability-base station (HR-BS), a base transceiver station (BTS), a radio base station, a radio transceiver, an access point, an access node, a radio access station (RAS), a mobile multihop relay-base station (MMR-BS), a relay station (RS), an advanced relay station (ARS), a high reliability-relay station (HR-RS), a home NodeB (HNB), a home eNodeB (HeNB), a road side unit (RSU), a radio remote head (RRH), a transmission point (TP), a transmission and reception point (TRP), etc.

[0063] Each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) may be referred to as a user equipment (UE), terminal equipment (TE), advanced mobile station (AMS), high reliability-mobile station (HR-MS), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, OBU (on board unit), etc.

[0064] Meanwhile, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may operate in a different frequency band or may operate in the same frequency band. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to each other via an ideal backhaul link or a non-ideal backhaul link, and may exchange information with each other via the ideal backhaul link or the non-ideal backhaul link. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may be connected to the core network via the ideal backhaul link or the non-ideal backhaul link. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit a signal received from the core network to the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6), and can transmit a signal received from the corresponding terminal (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) to the core network.

[0065] Additionally, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may support multi-input multi-output (MIMO) transmission (e.g., single user (SU)-MIMO, multi user (MU)-MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, device to device communication (D2D) (or, proximity services (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), etc. Here, each of the plurality of terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) can perform an operation corresponding to the base station (110-1, 110-2, 110-3, 120-1, 120-2) and an operation supported by the base station (110-1, 110-2, 110-3, 120-1, 120-2). For example, the second base station (110-2) can transmit a signal to the fourth terminal (130-4) based on the SU-MIMO scheme, and the fourth terminal (130-4) can receive a signal from the second base station (110-2) by the SU-MIMO scheme. Alternatively, the second base station (110-2) can transmit signals to the fourth terminal (130-4) and the fifth terminal (130-5) based on the MU-MIMO method, and each of the fourth terminal (130-4) and the fifth terminal (130-5) can receive signals from the second base station (110-2) based on the MU-MIMO method.

[0066] Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can transmit a signal to the fourth terminal (130-4) based on the CoMP scheme, and the fourth terminal (130-4) can receive a signal from the first base station (110-1), the second base station (110-2), and the third base station (110-3) based on the CoMP scheme. Each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) can transmit and receive a signal with terminals (130-1, 130-2, 130-3, 130-4, 130-5, 130-6) within its cell coverage based on the CA scheme. Each of the first base station (110-1), the second base station (110-2), and the third base station (110-3) can control D2D between the fourth terminal (130-4) and the fifth terminal (130-5), and each of the fourth terminal (130-4) and the fifth terminal (130-5) can perform D2D under the control of the second base station (110-2) and the third base station (110-3).

[0067] Next, the operating methods of communication nodes in a communication system will be described. Even if a method (e.g., signal transmission or reception) performed by a first communication node among communication nodes is described, a corresponding second communication node can perform a method (e.g., signal reception or transmission) corresponding to the method performed by the first communication node. In other words, if the operation of a terminal is described, the corresponding base station can perform an operation corresponding to the operation of the terminal. Conversely, if the operation of a base station is described, the corresponding terminal can perform an operation corresponding to the operation of the base station.

[0068]

[0069] To reduce data error rates, a lower modulation and coding scheme (MCS) level (e.g., a lower MCS index) can be applied. To prevent the size of the field indicated by the downlink control information (DCI) from increasing, the most frequently used MCS(s) can be selected. Subsequently, to apply a lower MCS, a repetitive transmission operation can be supported. Since quadrature phase shift keying (QPSK) has the lowest modulation rate, this can further reduce the code rate. In particular, since the transmit power in uplink (UL) transmission is limited, the repetitive transmission operation can be performed in the time domain rather than the frequency domain.

[0070] eMBB (enhanced Mobile Broadband) traffic and URLLC (Ultra-Reliable and Low Latency Communication) traffic can use low MCS for different purposes. eMBB traffic can use low MCS to extend the reach. On the other hand, URLLC traffic can use low MCS to reduce latency and achieve low error rates. Because of their different requirements, eMBB traffic can be transmitted repeatedly even if latency occurs, while URLLC traffic can be transmitted using a new MCS (e.g., a lower MCS) rather than repeated transmissions. The new MCS can be set by an RRC message and / or DCI.

[0071] To support repetitive transmissions for eMBB traffic in the time domain, physical uplink shared channel (PUSCH) repetition (e.g., PUSCH repetition type A) may be introduced. In this case, PUSCH allocated in slot units may be repeatedly transmitted. To extend the reach, time resources may be allocated to multiple slots. When PUSCH repetition type A is used, the time resources may be configured by an RRC message and / or a DCI. The number of repeated PUSCH transmissions may be indicated by an RRC message, and the time resource in which the PUSCH is transmitted in the first slot may be indicated by a DCI (e.g., a type 2 CG (configured grant) or a dynamic grant) or an RRC message (e.g., a type 1 CG).

[0072] Repeated transmission of URLLC traffic may not be appropriate because it incurs delay. However, if a sufficiently low MCS is used, the delay for decoding URLLC traffic can be reduced. That is, if a sufficiently low MCS is used, the number of REs (resource elements) to which URLLC traffic is mapped may increase, and the base station (e.g., the base station decoder) must wait until all REs are received. In this case, the delay for decoding URLLC traffic can be reduced.

[0073] On the other hand, if a PUSCH with a relatively high MCS is repeatedly transmitted, the base station can perform a decoding operation using only some REs. Therefore, the time point of first successful decoding in a PUSCH repeated transmission (e.g., a PUSCH repeated transmission with a relatively high MCS) may be earlier than the time point of first successful decoding in a PUSCH transmission without repetition (e.g., a PUSCH transmission with a low MCS). If PUSCH repetition type A is used, unnecessary delay may occur, and PUSCH repetition type B may be introduced to reduce the delay time for repeated transmission. If PUSCH repetition type B is used, a PUSCH allocated in units of mini-slots may be repeatedly transmitted. If PUSCH repetition type B is used, the time resource may be set by an RRC message and / or DCI. The combination of the reference time resource and the number of repeated transmissions of a PUSCH instance can be indicated by a DCI (e.g., Type 2 CG and / or dynamic grant) or an RRC message (e.g., Type 1 CG).

[0074] In order to control the transmit power of SRS resources indicated by SRI (SRS (sounding reference signal) resource indicator), the base station can estimate the path attenuation for each SRS resource. The base station can control the transmit power for the SRS resource(s) using DCI. The transmit power of the SRS resource(s) can be controlled based on the estimated path attenuation. The DCI can be scheduling DCI (e.g., DCI format 0_0, DCI format 0_1, DCI format 0_2, DCI format 1_0, DCI format 1_1, or DCI format 1_2) or GC (group common)-DCI (e.g., DCI format 2_2 or DCI format 2_3). The DCI can include a field indicating a transmit power control (TPC) command, and the TPC command can be used to control the transmit power of a terminal. For example, the transmission power of a terminal may be increased or decreased based on a TPC command included in the DCI. To determine the transmission power of a PUSCH, the terminal may consider a value obtained based on path attenuation, a value according to a TPC command included in the DCI, and / or a PUSCH bandwidth indicated by the DCI.

[0075] A base station can configure two or more sets for a terminal using higher layer signaling. The terminal can receive configuration information for the two or more sets from the base station. Each element constituting the two or more sets can be a transmit power parameter(s), which can be designated to suit different scenarios (e.g., a URLLC scenario, an eMBB scenario). The terminal can receive a scheduling DCI or an activating DCI from the base station that allocates PUSCH resources, and the scheduling DCI or the activating DCI can indicate a set for interpreting the transmit power parameter(s). If the sets of transmit power parameter(s) are different, the magnitude of the increase or decrease in transmit power designated by the same TPC command can be different.

[0076] When Type 1 CG or Type 2 CG is used, the transmit power may be determined based on DCI format 2_3 for the SRI associated with the PUSCH instance. When Type 2 CG is used, the activation DCI may indicate a set of transmit power parameter(s) applicable to a PUSCH occasion. A PUSCH occasion may mean a PUSCH instance. The UE may obtain a TPC command for the SRI by receiving a GC (group common)-DCI, interpret the TPC command to be suitable for the set of transmit power parameter(s) indicated by the base station, and derive the transmit power applicable to the PUSCH instance based on the interpretation result.

[0077] In a dynamically scheduled PUSCH transmission, the UE can derive the transmit power applied to the PUSCH instance based on a combination of GC-DCI and scheduling DCI. The UE can identify the TPC command of the SRI by receiving the GC-DCI and store the identified TPC command. In a dynamically scheduled PUSCH transmission, a set of transmit power parameter(s) and / or TPC command applied to the PUSCH occasion can be indicated by scheduling DCI. The UE can derive the transmit power applied to the PUSCH instance based on the transmit power of the SRI associated with the PUSCH instance.

[0078] Repeated HARQ-ACK transmissions can be indicated (or configured) by higher-layer signaling for each physical uplink control channel (PUCCH) format. The number of repeated transmissions for PUCCH format i can be independently configured. i can be 1, 3, or 4. A terminal can repeatedly transmit a PUCCH format in slots. In this case, the PUCCH format can be transmitted using the same time resource in each slot.

[0079] Uplink control information (UCI) types can be classified according to the type of information included in the UCI. UCI can include at least one of scheduling request (SR), L1-RSRP (reference signal received power), HARQ-ACK, or channel state information (CSI). In embodiments, UCI and UCI type can be used interchangeably. In a repeated transmission operation of UCI, only one UCI type can be transmitted. To support this operation, the priority of UCI types can be defined in the technical specification. One UCI type can be selected, and a PUCCH including one UCI type can be repeatedly transmitted. In this case, the UE can assume that no other UCI types are transmitted before the transmission of the corresponding UCI type is completed. To support this operation, the base station can instruct the UE to transmit UCI (e.g., SR or HARQ-ACK) after the PUCCH transmission is completed. The latency for a given UCI transmission may be high, and this latency may act as a scheduling constraint for the base station.

[0080] When "transmission of HARQ-ACKs in the same slot (or the same sub-slot)" or "PUCCH time resources indicated by DCI and / or RRC message allocating PDSCH (physical downlink shared channel) overlap each other," a terminal may generate a HARQ codebook to be transmitted in one PUCCH (e.g., one PUCCH time resource). Within the HARQ codebook, HARQ-ACK bits may be arranged according to an order defined in a technical specification. Information bits may be generated by the above-described operation. The terminal may generate coded bits by performing an coding operation.

[0081] Reed-Muller codes or polar codes can be used in encoding operations. The code rate applied in encoding operations can be indicated by higher-layer signaling. For example, in the PUCCH format, a single value can be the code rate and can be indicated to the terminal.

[0082] A codeword can be mapped to a PUCCH. In a PUCCH repeated transmission operation, a UCI type can be generated as a codeword. When a PUCCH is transmitted once, information bits of one UCI type or two or more UCI types can be concatenated, and the terminal can generate a codeword by performing the same encoding operation on the information bits. When a Reed-Muller code or a polar code is used, performing a soft combining operation may be difficult in implementation. Therefore, even when a PUCCH is repeatedly transmitted, the same codeword can be transmitted, and the base station can perform a chase combining operation on the same codeword. The encoded bits or codeword can mean a bit string in which multiple code blocks (code blocks) are concatenated. A modulation operation can be performed on the codeword, and the result of the modulation operation can be mapped to an RE.

[0083] Meanwhile, identical UCI types may be considered different information. Identical UCI types that are considered different information can be mapped. For example, UCIs may be created to support traffic with different priorities. UCIs supporting eMBB traffic (e.g., SR or HARQ-ACK) may be considered distinct information from UCIs supporting URLLC traffic (e.g., SR or HARQ-ACK). In this case, even if UCI types are identical, they may be distinguished as different information.

[0084] Encoded UCI can be mapped to PUCCH. The same preprocessing scheme (e.g., spatial information, spatial relation) can be maintained in PUCCH transmission operations. Alternatively, the use of different preprocessing schemes for each PUCCH can be permitted through RRC signaling from the base station in PUCCH transmission operations.

[0085] To support URLLC traffic, it may be desirable for a terminal to perform frequent reception operations on downlink (DL) resources and / or frequent transmission operations on uplink (UL) resources. In a time division duplex (TDD) system, a terminal may operate based on a half-duplex scheme. Therefore, the support time for DL ​​traffic and / or UL traffic may increase depending on the slot pattern. On the other hand, in a frequency division duplex (FDD) system, a terminal can utilize DL resources and UL resources. Therefore, the above-described problem in a TDD system may not occur in an FDD system. An FDD system can use two or more carriers. If two or more serving cells are configured for a terminal in a TDD system, the terminal can utilize DL resources and UL resources.

[0086] In a communication system including at least one carrier to which FDD is applied (hereinafter referred to as an "FDD carrier"), there may be no problem with the delay time of the terminal. In a communication system including only carrier(s) to which TDD is applied (hereinafter referred to as "TDD carrier(s)"), there may be a problem with the delay time of the terminal. To solve the above problem, slots in TDD carriers may be configured according to different patterns.

[0087] Carrier aggregation (CA) can be configured in the UE, and PCell and SCell(s) can be activated. Depending on whether a cell includes a common search space (CSS) set, it can be classified as a PCell or SCell. For example, a PCell may include a CSS set, and an SCell may not include a CSS set. To reduce latency in a communication system supporting URLLC traffic, slots with different patterns can be configured and / or indicated to the UE.

[0088] eMBB or URLLC traffic can be supported in licensed bands, but can also be supported in unlicensed bands. Carriers in either the licensed or unlicensed bands can be utilized independently, but depending on base station configuration, carriers in both licensed and unlicensed bands can be utilized through frequency aggregation.

[0089] In an embodiment, two or more terminals may receive data from one or more TRPs and transmit data to one or more TRPs. It may be assumed that one base station or one server performs management operations and / or scheduling operations for one or more TRPs among the plurality of TRPs. The TRPs may be directly connected. Alternatively, the TRPs may be connected via a base station. The above-described connection may be a connection according to an Xn interface or a wireless interface (e.g., an interface of 3GPP NR).

[0090] Shadow regions can occur between the areas supported by TRPs. Therefore, TRPs can resolve shadow regions through cooperative transmission. Cooperative transmission can be performed on terminals located between TRPs. Even if shadow regions do not occur, wireless link quality can be improved by installing numerous TRPs (or base stations) to transmit and receive large amounts of data.

[0091] Depending on the cooperative transmission and reception of TRPs, communication methods can be classified into dynamic point selection (DPS) and joint transmission (JT). For a specific set of physical resource blocks (PRBs), DPS may be a method of receiving data through a single TRP, and JT may be a method of receiving data through two or more TRPs. Dynamic point blanking (DPB) may be a type of JT. When DPB is used, the terminal may not receive data from some TRPs and may receive data from the remaining TRPs. JT can be classified into coherent JP and noncoherent JP. Depending on whether a coherent combining operation is performed on signals received from TRPs, either coherent JP or noncoherent JP may be used.

[0092] Depending on the latency and traffic capacity of the backhaul network to which base stations or TRPs are connected, TRPs may or may not participate in real-time cooperative transmission and reception. A terminal can support JT through a single DCI (i.e., single DCI (sDCI)). Alternatively, a terminal can support JT through multiple DCIs (i.e., multi-DCI (mDCI)).

[0093] When using sDCI, a terminal can transmit and receive data with TRPs. When using sDCI, it is desirable for TRPs to be able to collaborate without delay through a backhaul network. When using mDCI, a terminal can transmit and receive data with some TRPs. When a terminal transmits and receives data with other TRPs, it is difficult for these TRPs to collaborate in real time through the backhaul network. Therefore, it is desirable to allocate semi-fixed resources to these TRPs.

[0094] In the existing technical specifications, the CORESET pool index was introduced to identify a TRP. A CORESET pool is a set of CORESETs, and the transmission configuration indication (TCI) state applied to each CORESET can be independently indicated to the UE via RRC signaling and / or MAC control element (CE). Therefore, the CORESET pool index may not necessarily correspond to a TRP. More specifically, if a TRP is divided into a transmission point (TxP) and a reception point (RxP), the CORESET pool index can correspond to an RxP. For example, an Rx beam received from a TxP can be derived from the TCI state, and uplink signals / channels scheduled from DCIs discovered in CORESETs belonging to a CORESET pool indicated by a single CORESET pool index can be interpreted as being received by the same RxP.

[0095] For a terminal to benefit from coherent combining, the TRPs for that terminal must be synchronized to a certain degree, and CSI reports for those TRPs must be shared. If this is not the case, performing noncoherent combining at the terminal is more advantageous in terms of performance.

[0096] When a terminal is mounted on a vehicle, constraints on its size and weight can be relaxed. However, for terminals carried by a person, portability may also be a consideration.

[0097] To expand the signal coverage area, small cells or IAB nodes can be deployed. The throughput of small cells or IAB nodes can be affected by the quality of the backhaul link, and securing a backhaul network can be expensive. As an alternative, wireless relay devices can be deployed to deliver higher-quality signals to terminals. Wireless relay devices can be categorized into several types depending on the method of signal transmission. Wireless relay devices that support more functions can exhibit performance similar to that of a base station, while wireless relay devices that support fewer functions can be deployed at a lower cost. The wireless relay device considered in the present invention allows beamforming to terminals, but can perform the minimum function of transmitting data. The base station must transmit wireless signals to control these wireless relay devices. These wireless signals can be used to set appropriate parameters for the wireless relay devices.

[0098] In the present disclosure, transmission of a channel may mean transmission of a message, data, signal, and / or information through the channel, and reception of a channel may mean transmission of a message, data, signal, and / or information through the channel. The channel may be a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH), a physical random access channel (PRACH), a physical sidelink broadcast channel (PSBCH), a physical sidelink control channel (PSCCH), a physical sidelink shared channel (PSSCH), and / or a physical sidelink feedback channel (PSFCH).

[0099] In a communication system supporting TDD (time division duplex), downlink (DL) communication and uplink (UL) communication can be performed in different time resources. The ratio between the DL time, in which DL communication is performed, and the UL time, in which UL communication is performed, can be determined based on the ratio of traffic (e.g., DL traffic and / or UL traffic). For example, in an NR system, since the amount of DL traffic is greater than the amount of UL traffic, more DL slots can be allocated than UL slots. For example, slots (e.g., slot patterns) can be configured to repeat a DDDSU pattern. D can denote a DL slot, S can denote a slot including DL symbol(s), FL (flexible) symbol(s), and UL symbol(s), and U can denote a UL slot. The arrangement order of symbols in an S slot can be DL symbol(s)-FL symbol(s)-DL symbol(s). The base station can instruct or set the slot pattern to the terminal(s) through signaling (e.g., RRC signaling). The base station can indicate some FL symbol(s) among the FL symbols set by the RRC signaling as DL symbol(s) or UL symbol(s). The some FL symbol(s) can be indicated as DL symbol(s) or UL symbol(s) through DCI.

[0100]

[0101] [Non-contention based random access procedure]

[0102] A terminal located at the edge of a cell may repeatedly transmit a UL signal / channel to transmit UL traffic to a base station. In this case, the signal to interference plus noise ratio (SINR) at the base station may be improved and the block error rate (BLER) may be reduced. In the present disclosure, a UL signal / channel may refer to a UL signal and / or a UL channel, and a DL signal / channel may refer to a DL signal and / or a DL channel. The base station may instruct the terminal to repeatedly transmit the UL signal / channel, and the terminal may repeatedly transmit the UL signal / channel based on the instruction of the base station. The base station may instruct the terminal to repeatedly transmit the DL signal / channel, and the terminal may repeatedly receive the DL signal / channel based on the instruction of the base station. If UL slots do not occur frequently, a significant delay may occur for the terminal to obtain sufficient UL slots for repeated transmission. For example, if the DDDSU pattern is set and the subcarrier spacing (SCS) is 30 kHz, UL slots may occur every 2.5 ms. In this case, the time required for four repetitions of the UL signal / channel may be 10 ms.

[0103] When there is little coupling between DL communication and UL communication, a separate Rx filtering operation or Rx processing operation may be performed at the base station, but a separate Tx filtering operation or Tx processing operation may not be necessary at the terminal. The filtering operation may be a radio frequency (RF) filtering operation. When the RF filtering operation is performed, spectral emission (e.g., out-of-band emission (OOB) or adjacent channel leakage ratio (ACLR)) affecting adjacent PRB(s) can be reduced, and saturation of RF components can be prevented.

[0104] A base station can establish an RRC connection with a terminal to handle the traffic demand of the terminal. An unspecified number of terminals can select or reselect a base station through a cell search procedure. The base station (or cell) can periodically transmit a synchronization signal and / or system information. System information is divided into a master information block (MIB) and a system information block (SIB), and the SIBs can be further classified as SIB1, SIB2, etc. Various SIBs can be referred to as SIBx. A terminal can camp on a specific base station (or cell) using the MIB and SIBx. The synchronization signal and MIB can be combined and transmitted as a synchronization signal block (SSB). Hereinafter, SIBx mainly refers to SIB1, but is not necessarily limited thereto.

[0105] When DL traffic to be transmitted to a specific terminal occurs in a network or base station, the network or base station can transmit a paging message to an unspecified number of terminals to establish an RRC connection with the specific terminal. The specific terminal can receive the paging message and perform random access with the base station to establish an RRC connection.

[0106] When UL traffic to be transmitted from a terminal to a network or base station occurs, the terminal can perform random access to establish an RRC connection with the base station on which it is camping. After the RRC connection is established, the terminal can be controlled by the serving cell or base station and can transmit and receive data with the serving cell or base station.

[0107] Since the base station cannot know the status of the terminals camped on it, it may transmit SSB and / or SIB1 and / or SIBx periodically, which may not reduce power consumption. For example, when the base station operates in normal mode, SIB1 and / or SIBx may be transmitted at a predetermined period. When the base station operates in low power mode, SIB1 and / or SIBx may be transmitted at a longer period, or SIB1 and / or SIBx may not be transmitted at all.

[0108] The base station may transmit SIB1 and / or SIBx upon request of the terminal(s). Since the SSB is transmitted periodically, it may be broadcast that SIB1 and / or SIBx is not transmitted through the MIB transmitted in the SSB. In this case, the MIB may include separate information indicating that SIB1 and / or SIBx is not transmitted, or may include information implicitly indicating that SIB1 and / or SIBx is not transmitted. Alternatively, SIB1 and / or SIBx may not be transmitted due to the fact that the control channel (or CORESET 0 and Type0-PDCCH CSS set) for scheduling SIB1 and / or SIBx is not transmitted.

[0109] In one embodiment, the MIB may indicate whether the SSB including the MIB is a cell-defining (CD)-SSB or a non-cell-defining (NCD)-SSB. The MIB may include information for deriving a CORESET including a Type0-PDCCH CSS set set in ControlResourceSetZero and a PDCCH occasion set in SearchSpaceZero. The MIB may include an index indicating a multiplexing pattern of the SSB and the CORESET, a bandwidth of the CORESET, a number of symbols of the CORESET, and / or an RB offset. If the SSB and the CORESET are not multiplexed, the SSB may be referred to as a NCD-SSB. k, which determines the frequency location of the SSB in an NR system SSB If the value of k is less than a certain value, SSB The SSB transmitted at the frequency location determined by can be classified as CD-SSB, and the terminal can search the Type0-PDCCH CSS set. On the other hand, k SSB If the value of k falls within the remaining range (i.e., is greater than or equal to a certain value), then k SSB An SSB transmitted at a frequency location determined by may be classified as an NCD-SSB, and the terminal may not search the Type0-PDCCH CSS set. If the received SSB is an NCD-SSB, the terminal may perform a cell reselection procedure again to receive a CD-SSB. The base station may transmit an NCD-SSB in a mode in which it does not transmit SIB1, and may transmit a CD-SSB in a mode in which it transmits SIB1.

[0110] In one embodiment, the UE may determine whether SIB1 and / or SIBx are transmitted based on whether a DM-RS of a CORESET (or a DM-RS of a PDCCH) exists. For example, the UE may assume that SIB1 is transmitted if a CORESET DM-RS (or a DM-RS of a PDCCH) exists, and may assume that SIB1 and / or SIBx are not transmitted if the CORESET DM-RS (or a DM-RS of a PDCCH) is absent. If SIB1 is not transmitted, the UE may perform a cell reselection procedure again.

[0111] In one embodiment, k determines the frequency position at which the SSB is transmitted. SSB The above specific value or k compared to SSB The value of may change. For example, if a certain counter is used and the counter expires, the specific value or k SSB This may be changed. The changed specific value means CD-SSB or NCD-SSB, which may mean a different format of SSB (i.e. CD-SSB or NCD-SSB) than the specific value before the change.

[0112] or k meaning NCD-SSB (or CD-SSB) SSB has been changed to mean CD-SSB (or NCD-SSB) SSB can be changed to k, which is within the range corresponding to NCD-SSB (or CD-SSB). SSB may be changed to fall within the range corresponding to CD-SSB (or NCD-SSB). Therefore, the terminal may change the value of the counter or k SSB The change in can be used to predict the time at which the base station transmits SIB1 and / or SIBx.

[0113] According to the above methods, the base station may or may not transmit SIB1 and / or SIBx as needed. Condition(s) for switching from a mode of not transmitting SIB1 and / or SIBx (or a mode of transmitting SIB1 and / or SIBx) to a mode of transmitting SIB1 and / or SIBx (or a mode of not transmitting SIB1 and / or SIBx) may be defined, and the base station and / or terminal may determine whether the condition(s) are met.

[0114] Additionally or alternatively, the UE may request the base station to change the transmission mode of SIB1 and / or SIBx by transmitting an UL DRS (discovery signal) or PRACH. In order for the UE to transmit the UL DRS, it may be necessary to establish an RRC connection with the base station or use the PRACH. The base station must indicate the UE with the UL DRS resources and various configuration information. Similarly, in order to transmit the PRACH, it is necessary to indicate to the UE information about RA occasions (ROs). Hereinafter, a method for changing the transmission mode of SIBx using the PRACH (or PRACH preamble or preamble) will be described in detail.

[0115] To transmit a PRACH, a terminal can generate and modulate a preamble based on a sequence defined in the technical specification and configuration information of an information element (IE) included in SIBx, and allocate appropriate transmission power. In addition, the terminal can derive information about a set of ROs from SIB1 and / or other IEs included in SIBx, and select a specific RO from the set of ROs to transmit the PRACH. Therefore, a RACH configuration capable of deriving a PRACH and / or RO must be transmitted to an unspecified number of terminals.

[0116] A terminal can derive the resource location of an RO in the time domain using a PRACH configuration index. The PRACH configuration index can be interpreted depending on the frequency band and duplex method in which the PRACH is transmitted. For example, in a frequency domain duplexing (FDD) system (e.g., an FDD system supporting FR1), the PRACH configuration index can be interpreted differently from the PRACH configuration index in a time domain duplexing (TDD) system (e.g., a TDD system supporting FR1). The PRACH configuration index in FR1 can be interpreted differently from the PRACH configuration index in FR2. Table 1 below may represent some of the PRACH configuration indices in a communication system supporting FR1.

[0117]

[0118]

[0119] Additionally, Table 2 below may represent some of the PRACH configuration indices in a communication system supporting FR2.

[0120]

[0121]

[0122] Since the PRACH configuration index is received through system information, terminals performing a random access procedure (e.g., an initial access procedure) can interpret the same PRACH configuration index. The base station can indicate one or two PRACH formats to the terminal, and the two PRACH formats can coexist. In order for the two PRACH formats to coexist, the two PRACH formats can include cyclic prefixes (CPs) with different lengths and / or guard times (GTs) with different lengths. In this case, the lengths of the PRACH preambles of the two PRACH formats can be the same.

[0123] According to Table 1, when the PRACH configuration index is indicated as 106 and the result of (system frame number (SFN) mod 1) is 0, the terminal can select subframes having subframe indices 0 to 9. In Table 1 and Table 2, can represent SFN. That is, the terminal can transmit PRACH in all subframes. One subframe can correspond to two PRACH slots, and one PRACH slot can have six ROs. The terminal can transmit PRACH in six positions (e.g., six ROs) within one PRACH slot. The PRACH can use the preamble format A1, and the duration of the PRACH can correspond to two symbols.

[0124] When the PRACH configuration index is indicated as 114, the terminal can use preamble format A1 or preamble format B1. The number of locations (e.g., ROs) where PRACH can be transmitted within a PRACH slot can be 7.

[0125] The base station can instruct or set an association pattern period for the terminal. An association pattern period may include one or more association periods. One association pattern period, including an RO, may repeat within 160 milliseconds (ms). Here, 160 ms may be related to the transmission period of SIB1.

[0126] When a correlation period is used for a system information request, the base station may indicate the index of the correlation period to the terminal. The minimum integer multiple of a pattern containing all ROs corresponding to all SSBs can be derived using the number of SSBs indicated to the terminal via radio resource control (RRC) signaling (e.g., based on ssb-PositionsInBurst). The minimum derivable value can be defined in the technical specifications, as shown in Table 3 below.

[0127]

[0128]

[0129] For example, the PRACH configuration period can be derived based on the PRACH configuration index indicated to the terminal. In Table 2, if the PRACH configuration index is indicated as 11, x is 2, so the length of the PRACH configuration period can be considered as 20 ms. Thereafter, the time required to map all SSBs to ROs can be derived depending on the number of SSBs. In Table 3, one of {1, 2, 4, 8} can be selected, and if 4 is selected in Table 3, the length of the period that does four association periods can be interpreted as 80 ms. In this case, the length of each of the four association periods can be 20 ms, and the association pattern period can be repeated twice.

[0130] One SSB can be mapped to multiple ROs. Alternatively, multiple SSBs can be mapped to one RO. The base station can indicate mapping information between SSB(s) and RO(s) to the UE through RRC signaling. Here, the mapping information between SSB(s) and RO(s) can be ssb-perRACH-OccasionAndCB-PreamblesPerSSB. The UE can derive (N, R) based on the ssb-perRACH-OccasionAndCB-PreamblesPerSSB value. In (N, R), N can denote the number of SSBs mapped to one RO, and R can denote the number of PRACH preambles. N can be 1 or greater. If N>1, multiple SSBs can be mapped to one RO. Alternatively, N can be less than 1. If N<1, one SSB can be mapped to multiple ROs.

[0131]

[0132] According to the conventional technical specifications, an integer number of association periods can be combined to form one association pattern period. The association pattern period can be introduced so that the same SSB-RO mapping is repeated in terms of the radio frame number with a maximum period of 160ms. However, the association pattern period may not exactly match the integer number of association periods, and some RO(s) may not be included in the association period. In such a case, the SSB may not be mapped to the corresponding RO. This can also be extended to ROs mapped in SBFD resources. That is, an RO mapped in SBFD resources can be considered a valid RO only if it belongs to an association period mapped in UL resources.

[0133]

[0134] The random access (RA) procedure performed by a UE can be either contention-based (CBRA) or contention-free (CFRA). In a contention-free RA procedure, the UE may be informed of the preamble generation information and the resource location of the resource resource provider (RO). Furthermore, if the resource location of the RO is not set or indicated to the UE in a CFRA procedure, the RO may be shared with the resources used in the contention-based RA procedure.

[0135] CFRA may be performed when the UE has not established an RRC connection with the base station. For example, this may be when the UE transmits a preamble to the base station where it is camped in order to receive SIBx. Conversely, CFRA may be performed when the UE has established an RRC connection with the base station. For example, this may be when the UE transmits a preamble to request RRC connection reestablishment to the serving cell.

[0136] For example, a base station may transmit SIBx at very long intervals or not at all, and terminals camped on that base station can receive RACH configuration information via SIB1. If some of these terminals transmit PRACH, the base station can transmit SIB1 at a shorter interval. In other words, this means a method in which the base station adjusts the SIB transmission interval by having the terminals transmit PRACH, and thus changes the SIB transmission mode.

[0137] SIB1, which is transmitted at very long intervals or at the request of a UE, may only contain simplified information. That is, the SIB1 may not contain all the information required for performing random access, but may only contain the information necessary to derive the PRACH and the associated set of ROs for requesting SIB1. This may be a simplified SIB, or it may be separately defined and may contain the information required for transmitting the PRACH. After the UE transmits the PRACH in a specific RO, the base station may subsequently transmit SIB1 at a shorter interval or initiate transmission.

[0138]

[0139] FIG. 3 is a flowchart illustrating a method for a terminal to trigger a base station on which the terminal is camped to transmit SIB1 or SIBx using UL DRS according to one embodiment of the present invention.

[0140] Referring to FIG. 3, configuration information of UL DRS or RACH preamble can be indicated from the base station to the terminal via DCI (downlink control information), RRC signaling, SSB, and / or SIB1 (S310).

[0141] For example, a base station can transmit a separate DCI format to provide unspecified UEs with the information necessary to derive a PRACH sequence and RO set that can be derived from a RACH configuration. The proposed DCI format may or may not schedule a PDSCH. The proposed DCI format may be scrambled with a system information RNTI (SI-RNTI). Alternatively, a separate RNTI may be applied to the proposed DCI format. For example, a CORESET or search space set including a DCI format may be derived from a time resource (e.g., a slot or a symbol) in which the DCI format is received. Alternatively, a value signaled from a higher layer may be applied.

[0142] The resource where the proposed DCI format is received may belong to the Type0-PDCCH CSS set and may be received in two radio frame periods. Alternatively, it may be received in separate periods. For example, the proposed DCI format may have different reception periods in a system operating in FR1 and a system operating in FR2. In the case of a system operating in FR2, the reception period of the proposed DCI format may be the same as the period at which the SSB is received. Here, the SSB may provide quasi-co-location (QCL) information or reception beam-related information associated with the DCI format.

[0143] The proposed DCI format may include at least preamble information, UL symbol location, RO set information, and SSB index. Since the proposed DCI format indicates the PRACH and RO set for triggering SIB1 transmission, it may consist of simpler information than SIB1. For example, if a base station triggers SIB1 transmission using On-Off Keying (OOK), there may be no need to resolve collisions between unspecified UEs. Alternatively, even if a collision occurs, it may be considered a contention-free based RA (CFRA). Therefore, the preamble index may be indicated in the DCI.

[0144] The PRACH configuration index can indicate the UL resources on which the RO can be transmitted. By deriving the UL symbol location based on slot pattern information in the UL resources indicated by the PRACH configuration index, only valid ROs can be selected. In addition, by separately indicating the frequency resources of the ROs, the number of ROs that can be frequency-division multiplexed (FDM) in the same time resource can be derived. Through this process, the terminal can recognize the necessary parameters, derive the RO set, and select the RO corresponding to the selected SSB (S320). The necessary parameters here are derived from the RACH configuration information and can be obtained from the information included in SIB1. However, when configuring the PRACH and RO to change the transmission mode of SIB1, simplified information may be sufficient.

[0145] Additionally, the terminal can transmit a RACH preamble (Msg1) or UL DRS from the RO selected as the base station (S330), and can receive SSB / DCI / SIB1 / SIBx in response to Msg1 from the base station (S340).

[0146] Meanwhile, the proposed DCI format can indicate whether SIB1 or SIBx is scheduled for future transmission or is currently being transmitted. For this purpose, a separate information field can be used in the DCI, or the corresponding information can be derived from other values ​​in existing information fields. For example, the information indicating that SIB1 or SIBx is scheduled for transmission can be expressed as a counter. In this case, when the counter expires, SIB1 or SIBx can be expected to be transmitted.

[0147] Additionally, a transmission time window of SIB1 or SIBx can be defined. For example, based on the length of the time window (e.g., 160 ms) and the radio frame offset or subframe offset, if a specific information field of the DCI has a specific value, SIB1 or SIBx will not be transmitted in the time window in which the DCI is received, but it can be expected that SIB1 or SIBx will be transmitted in the next time window. Using this information, the UE can wait for the next time window without transmitting the PRACH even if SIB1 or SIBx is not received. Here, the length of the time window can be the reception period (P) of SIB1 derived from the existing technical specification or the reception period of the Type0-PDCCH CSS set.

[0148]

[0149] Alternatively, if the terminal triggers SIB1 or SIBx transmission to the base station where the terminal is camped using UL DRS (or PRACH preamble), the base station may transmit SIB1 or SIBx to the terminal in response to the UL DRS (or PRACH preamble).

[0150] FIG. 4 is a flowchart illustrating a method for a terminal to trigger a base station on which the terminal is camped to transmit SIB1 or SIBx using UL DRS according to another embodiment of the present invention.

[0151] The procedure in FIG. 4 may be similar to the CFRA procedure, in which a terminal transmits a PRACH preamble to a base station where the terminal is camped, instructing the base station to transmit other system information (OSI) according to conventional technical standards. According to conventional technical standards, a base station that receives a PRACH preamble from a terminal transmits an RAR, and the terminals can expect the OSI to be transmitted by receiving this. If the RAR is not received within a predetermined time period, the terminal can retransmit the preamble to the base station.

[0152] In the proposed method, steps (S410) and (S420) can be performed in a similar manner to steps (S310) and (S320) of FIG. 3. The terminal can perform a CFRA that transmits a preamble (S430). A response to the CFRA performed by the terminal can be received as SIBx included in Msg2 (S440).

[0153] The camping base station transmits SIB1 or SIBx to the terminal, so that the terminal can receive SIB1 or SIBx. The terminal can monitor searchSpaceSIB1 or searchSpaceOtherSystemInformation to receive SIBx and decode the scheduled SIBx without having to monitor ra-SearchSpace to receive RAR.

[0154]

[0155] In another proposed method, a response to a CFRA performed by a terminal may be received as SIB1 or SIBx or RAR.

[0156] FIG. 5 is a flowchart illustrating a response monitoring procedure for a terminal to receive RAR or SIB1 or SIBx according to another embodiment of the present invention.

[0157] Referring to FIG. 5, a terminal may transmit a preamble to a base station (S510) and receive SIB1 or SIBx or RAR in response to the preamble (S520). The terminal may monitor ra-SearchSpace, searchSpaceSIB1, or searchSpaceOtherSystemInformation to receive a response to the preamble transmitted to the base station. The terminal may consider that a response has been received when it receives RAR or SIB1 or SIBx. Once a response is received, the terminal may not search other search spaces for a response to trigger transmission of SIB1 or SIBx after a predetermined period of time. Here, the predetermined period of time may be derived in relation to the processing time for the terminal to demodulate and / or decode DCI scheduling RAR or SIB1 or SIBx.

[0158] Meanwhile, in the proposed method, when a terminal repeatedly transmits a preamble, a search space in which a response is scheduled can be explored based on the first RO.

[0159]

[0160] The terminal receives an SSB from a base station, and if the reception strength of the SSB (e.g., reference signal received power (RSRP) or reference signal received quality (RSRQ)) exceeds a specific threshold, the terminal may receive SIB1 or SIBx. Alternatively, if the RSRP or RSRQ derived by the terminal does not exceed a specific threshold, the terminal may not receive SIB1 or SIBx.

[0161] Here, the threshold applied to SIBx can be derived from the SIB1 of the corresponding base station. If the terminal does not receive SIB1 or SIBx from the base station, it may not be able to camp on that base station. Alternatively, the threshold applied to SIB1 or SIBx can be determined by the terminal based on a value derived from SIB1 or SIBx received from another base station.

[0162] Accordingly, the terminal can derive a specific SSB index. This threshold can be used to determine the set of ROs when the terminal performs a random access procedure. Alternatively, this threshold can be used to determine the number of preamble transmissions when performing RA.

[0163] For example, the terminal can derive the number of preamble transmissions and / or the size of an RO group corresponding to a selected SSB index using multiple thresholds. The number of transmissions can include at least 1, 2, 4, or 8. The RO group can be composed of valid ROs, and can be composed of the same number as the number of transmissions.

[0164] Valid ROs within an RO group may have identical frequency resources or may have temporally contiguous resources. However, they may not necessarily have temporally contiguous resources, depending on the parameters and slot patterns associated with the SSB-RO mapping.

[0165]

[0166] FIG. 6 and FIG. 7 are flowcharts for explaining the operation of a terminal when SIB1 and / or SIBx transmission is triggered by multiple terminals according to embodiments of the present invention.

[0167] Referring to FIG. 6, a first terminal may transmit a preamble to a base station (S610). The first terminal may be configured to transmit the preamble at least twice. Alternatively, the first terminal may transmit the preamble at least once. The base station may transmit a response (RAR and / or SIB1 and / or SIBx) to the first terminal and the second terminal(s) (S620, S630). The RAR and / or SIB1 and / or SIBx transmitted in steps (S620, S630) may be transmitted by triggering of the second terminal(s), and the second terminal(s) may receive the response.

[0168] The first terminal may receive a response (S620) regardless of step S610. However, the RAR and / or SIB1 and / or SIBx transmitted in step S620 may be unrelated to the triggering of the first terminal according to step S610. Therefore, the first terminal must transmit at least one additional preamble, and may transmit all or part of the remaining preamble in step S640.

[0169] Meanwhile, the RAR and / or SIB1 and / or SIBx transmitted in step (S620) may not be triggered by step (S610), but may contain the same content as the requested information according to the triggering in step (S610) of the first terminal. For example, the presence of a response (RAR and / or SIB1 and / or SIBx) received and decoded by the L1 layer of the first terminal may be notified to the L2 layer of the first terminal. Accordingly, the L2 layer of the first terminal may instruct the L1 layer of the first terminal to drop an additional preamble transmission.

[0170] Referring to FIG. 7, after receiving a response to a preamble transmission (S610) (S620), the first terminal may drop the remaining preamble to be transmitted (S650). According to the proposed method, if the preamble dropping operation is performed, all or part of the first terminal's preamble may be dropped, but this may not affect the power ramping counter, backoff indicator, other timers, or other counters.

[0171] Referring back to FIGS. 6 and 7, the response demodulated and decoded by the first terminal may be a response to the second terminal(s). If the response can be considered as SIB1 and / or SIBx, the response may be a DL-SCH scheduled by DCI scrambled with SI-RNTI. If the response can be considered as RAR, the response may be a DL-SCH scheduled by DCI scrambled with RA-RNTI. That is, the first terminal may receive the response by deriving an RNTI that may be unrelated to the step of transmitting the preamble (S610). Therefore, in order to receive a response to the preamble transmitted by the second terminal(s), the first terminal may need to search a separate search space and apply a separate RNTI.

[0172] Additionally, regarding preamble indices, the first terminal may receive a response from the base station using all or part of the preamble indices that the first terminal has not used but are considered to have been used by the second terminal(s). For example, the first terminal may use two or more RAPIDs to determine the validity of the RAR.

[0173] FIGS. 8 and 9 are timing diagrams illustrating a method for determining whether to drop a preamble according to embodiments of the present invention.

[0174] Referring to FIG. 8, when CFRA is triggered, the first terminal may select the first SSB and transmit the preamble twice using RO 2 and RO 10 belonging to the RO set associated therewith. The terminal may have a slot (820) for receiving SIB1 and / or SIBx and / or RAR between the slot (810) for transmitting RO 2 and the slot (830) for transmitting RO 10. According to the proposed method, depending on the interval between the slots (820) and (830), the terminal may transmit or drop the preamble in RO 10. may include not only the processing time required for the terminal to demodulate and decode the DCI and the response, but also the time required for the L1 layer of the terminal and the L2 layer of the terminal to be notified of the presence of the response and the subsequent procedures. The value may be determined for each SCS in the technical specifications, or one value may be determined from the reference SCS and converted to an appropriate value by applying the SCSs of the active DL / UL BWP, or may be indicated to the terminals through RRC signaling.

[0175] Referring to FIG. 9, a slot (910) for receiving SIB1 and / or SIBx and / or RAR may occur before a slot (920) in which a first terminal starts transmitting a preamble one or more times using RO 2 belonging to a RO set associated with a selected first SSB. In this case, the terminal may transmit or drop the preamble in RO 2. By applying the proposed method, depending on the interval between slots (910) and (920), the terminal may transmit or drop the preamble in RO 2. The conditions or instructions for deriving are described above. Here, the terminal may transmit the preamble more than once. In this case, RO 2 may represent the RO in which the first transmission of the preamble is performed.

[0176]

[0177] After the CFRA triggered terminal transmits the preamble, it waits for a predetermined first time ( ) can receive scheduling information of SIB1 and / or SIBx after a predetermined second time (2) has elapsed since transmitting the preamble. In addition, if RAR is received, the terminal can receive scheduling information of SIB1 and / or SIBx after a predetermined second time (2) has elapsed since transmitting the preamble.

[0178] In one example, class may be different from each other. This may be related to the time required to demodulate the preamble and to modulate and encode SIB1 and / or SIBx at the camping base station and schedule it. Alternatively, the camping base station may transmit SIB1 and / or SIBx in response to a SIB1 and / or SIBx trigger from another terminal without receiving the preamble from the terminal. Therefore, it may be the same time as the gap symbol between SSB and RO.

[0179] It may be related to the time required to demodulate the preamble and to modulate and encode the RAR at the camping base station and schedule it. Alternatively, the camping base station may transmit the RAR in response to a SIB1 and / or SIBx trigger from another terminal without receiving the preamble from the terminal.

[0180]

[0181] Figure 10 is a conceptual diagram illustrating an example of listing valid ROs derived from selected SSBs in chronological order.

[0182] Referring to Fig. 10, a set of ROs derived by the selected first SSB is illustrated. Here, RO 1 may indicate an index at which a mapping cycle is newly started and restarted. In Fig. 10, only one frequency resource is defined for convenience of explanation, but embodiments of the present invention are not limited thereto. When the number of transmissions is 2, 4, or 8, the terminal may use RO 1 to RO 2, RO 1 to RO 4, or RO 1 to RO 8 as an RO group to perform CFRA.

[0183] In the CFRA procedure, the time offset may be separately indicated to the UEs via RRC signaling, or may be derived from SIB1 or SIBx. In this case, the time offset may be indicated as a separate value for each preamble transmission count (i.e., the size of the RO group). Here, the time offset may refer to the interval between the first ROs of the RO groups. For example, the time offset may be indicated by msg1-RepetitionTimeOffsetROGroup.

[0184] An RO group can be composed of ROs belonging to a previous mapping period and ROs belonging to a different mapping period. However, two adjacent RO groups can maintain a time offset interval even if the mapping periods are different. Therefore, even if a new mapping period starts, an RO group may not be mapped from RO 1. However, in order to save power consumption of the base station, a function that can align the starting ROs of the RO groups is required. That is, although the set of RO groups (RO group set, grid of RO groups) is derived differently for each transmission number, it is desirable to be able to align the starting ROs of the sets of RO groups even if the sizes of the RO groups are different when a new mapping period starts.

[0185] Figures 11 and 12 are conceptual diagrams showing examples in which sets of RO groups overlap and a set of RO groups is expressed as a union of these sets.

[0186] Once the terminal selects the first SSB and the number of transmissions is derived accordingly, the size of the RO group can be determined. Accordingly, when the CFRA procedure is performed, the terminal can select a set of RO groups based on the mapping period and transmit the preamble in the RO group starting from RO 1. If the size of the RO group is large and the mapping period is short, a single RO group can be included in two or more mapping periods.

[0187] Referring to FIG. 11, when the CFRA procedure is triggered in the first mapping period, the terminal can transmit a preamble using an RO group belonging to a set of RO groups (1120). The selected RO group here can start from RO 1. Similarly, when the CFRA procedure is triggered in the second mapping period, the terminal can transmit a preamble using an RO group belonging to a set of RO groups (1130). The selected RO group here can start from RO 1.

[0188] Referring to Fig. 12, RO N-1, RO N, RO 1, and RO 2 can form an RO group. Since a new mapping cycle starts, the index for RO can start again from 1 from the newly started mapping cycle. Alternatively, ROs can be indexed as a set of RO groups, and ROs belonging to the RO group can be indexed as RO N-1, RO N, RO N+1, and RO N+2.

[0189] The CFRA procedure can be performed to trigger the transmission of SIB1 or SIBx. According to the proposed method, the time offset is taken into account when triggering the transmission of SIB1 or SIBx, but the time offset can be reapplied when the mapping period changes.

[0190] In another proposed method, instead of including separate information in the existing DCI format, a separate DCI format can be defined that includes information on which SIB1 or SIBx is to be scheduled. The Type0-PDCCH CSS set or the Type0A-PDCCH CSS set can be reused as the space set in which the DCI format is searched, or a separate search space set can be indicated to the terminals as the space set in which the DCI format is searched. In one example, if the search space set is not indicated, the Type0-PDCCH CSS set or the Type0A-PDCCH CSS set is used, but if the search space set is indicated, the Type0-PDCCH CSS set or the Type0A-PDCCH CSS set can be used. In one example, the terminal can search both search space sets by monitoring the Type0-PDCCH CSS set or the Type0A-PDCCH CSS set even if the search space set is indicated.

[0191]

[0192] When the number of transmissions is fixed to a certain value (L), the set of RO groups can consider a first period (N) in which RO groups related to all SSBs are mapped at least once. The first period can be different for each number of transmissions (L). A second period can be formed by multiple first periods. The second period can be a period in which RO groups are mapped at least once for all SSBs for all number of transmissions. Therefore, the second period can be interpreted as a minimum period that is included in at least one integer multiple of the first period (N), and the integer multiple here can be derived differently for each L. The second period can be generated periodically based on the radio frame number (or SFN). Here, the terminal can derive the second period without being instructed with a time offset, or without considering the time offset even if it is instructed.

[0193] When considering the second cycle, the terminal may consider the time offset. If the time offset is indicated differently for each transmission, the terminal may not use some RO group(s) in the last first cycle that constitutes the second cycle. While some of the RO group(s) may be determined to be valid RO groups, the terminal may not transmit the preamble using them.

[0194] Unused RO groups may be RO groups that cross the boundaries of the second cycle. That is, for a set of ROs that repeat in the second cycle, some RO groups may be distributed across the boundaries of the second cycle. In one example, a single RO group may belong to different second cycles, and each may belong to a different SFN.

[0195] Figure 13 is a conceptual diagram illustrating an embodiment in which a set of RO groups are mapped to overlap temporally at the boundary of the second period.

[0196] Referring to Figure 13, the RO groups are represented as RO N-1, RO N, RO 1, and RO 2, but the RO groups may be mapped to the boundaries of the second period. These RO groups may not be used by the terminal. This is because orphan ROs are generated due to the consideration of time offset. In this case, the terminal can transmit the preamble using the RO groups belonging to the new second period (i.e., RO 1, RO 2, RO 3, and RO 4).

[0197] When the number of transmissions constituting an RO group is given as one of 2, 4, and 8, the RO groups corresponding to different transmission numbers can be derived to overlap each other. That is, the overlapping ROs in the RO groups correspond to shared ROs between the RO groups, and the number of transmissions can be regarded as different feature combinations. A time offset can be indicated for each number of transmissions, and the time offset can be given as an integer multiple of the number of transmissions. In particular, the time offset can have restrictions depending on the number of transmissions (L). For example, when L=8, the time offset can be 16. For example, when L=4, the time offset can be 8 or 16. For example, when L=2, the time offset can be 4, 8, or 16.

[0198] Considering the second cycle, the set of final RO groups can be illustrated in Fig. 14.

[0199] Figure 14 is a conceptual diagram illustrating an embodiment in which a set of RO groups are mapped without temporal overlap at the boundary of the second period.

[0200] Referring to FIG. 14, for a set of general RO groups, time offsets for cases where the number of transmissions is 2, 4, or 8 can be indicated differently. For example, the time offsets for cases where the number of transmissions is 2, 4, or 8 can be 8 (difference between RO group 10 and RO group 20), 16 (difference between RO group 60 and RO group 70), or 16 (difference between RO group 90 and RO group 100), respectively.

[0201] However, the time offsets for the sets of the last RO groups (30, 40, 50, 70, 80, 100, 110) belonging to the second period may be derived differently from the time offsets (8 or 16) described above. This is because the second period is derived by applying the same number of associated periods or associated pattern periods (i.e., the first periods described above), but unused ROs occur in the associated period or associated pattern period. Since the number of ROs required for each RO group corresponding to the number of transmissions is different, the last RO groups in the second period may not be nested.

[0202] Referring again to FIG. 14, when the number of transmissions is 2, the difference between the starting RO of RO group 40 and the starting RO of RO group 50 is 6, which may be different from the time offset 8 described above. When the number of transmissions is 4, the difference between the starting RO of RO group 70 and the starting RO of RO group 80 is 14, which may be different from the time offset 16 described above. When the number of transmissions is 8, the difference between the starting RO of RO group 100 and the starting RO of RO group 110 is 14, which may be different from the time offset 16 described above.

[0203] That is, according to the proposed method, the difference between the starting RO of the last RO group belonging to the second cycle and the starting RO of the first RO group may be different from the time offset determined by the number of transmissions.

[0204] According to another proposed method, a set of RO groups can be derived by considering time offsets according to the number of transmissions. Then, a single timing period can be derived from the set of RO groups.

[0205] If this method is applied, a situation like that in Fig. 14 may not occur. Since the value of the time offset allowed depending on the number of transmissions can be interpreted as another number of transmissions, the sets of RO groups corresponding to different numbers of transmissions can be aligned on the boundary of the second period.

[0206]

[0207] When CFRA is triggered, a time offset value may be set or indicated to the UE via RRC signaling. If the UE transmits the same preamble more than once, the mask index may not be set or indicated. Alternatively, even if the mask index is indicated, the UE may ignore it. Here, CFRA can be interpreted as a concept that includes the ReconfigurationWithSync, SI-RequestConfig, or SI-RequestConfigRepetition procedures.

[0208] Table 4 illustrates examples of time offsets applicable to specific cases of Contention-Based Random Access (CBRA) and CFRA. According to this table, the time offset can be indicated by msg1-RepetitionTimeOffsetROGroup. This may imply that a single time offset value can be derived based on one or more feature combinations supported by a terminal or BWP in a CBRA environment.

[0209] The resource on which CFRA is performed may belong to a separately designated first set of RO groups. Alternatively, the resource on which CFRA is performed may belong to a second set of RO groups for which CBRA is designated. This distinction may be determined from CFRA-related configuration information designated to the terminal. If CFRA is performed in the first set of RO groups, a time offset may be set separately from the time offset of the CBRA configuration information in the configuration information of the CFRA (hereinafter, the first time offset) or may not be set. If CFRA is performed in the second set of RO groups, a value corresponding to a specific number of transmissions of the CBRA (hereinafter, the second time offset) may be applied to the CFRA as is.

[0210] According to the proposed method, if CFRA is performed in the first RO group set, the first time offset may be applied if the first time offset is set. If CFRA is performed in the second RO group set, it may be desirable to apply the second time offset, which is a separate value not used in CFRA. Here, the terminal may be configured so that CFRA is not performed in the first RO group set. Alternatively, the terminal may be configured so that CFRA can be performed in the first RO group set, and the first time offset may be set. Alternatively, the terminal may be configured so that CFRA can be performed in the first RO group set, and the first time offset may not be set. The above time offset setting methods may be applied in combination with each other.

[0211] Table 5 is a table that describes examples of time offsets that can be applied to specific cases of CFRA, and shows the structure of an IE for CFRA configuration.

[0212] When a terminal performs CFRA in the first RO group set, a cfra IE containing occasions may be indicated. In this case, the corresponding RO group set (i.e., the first RO group set) can be derived based on the RACH-ConfigGeneric indicated in the occasions and the technical specifications.

[0213] On the other hand, if a cfra IE without occasions is indicated, the terminal can derive the second RO group set based on the RACH-ConfigCommon and technical specifications set in the first activated UL BWP (i.e., the first active UL BWP).

[0214] According to the proposed method, the terminal can apply the time offset derived from RACH-ConfigCommon to the second RO group set, which can correspond to the second time offset described above. When multiple transmission counts are indicated, the second time offset and the first time offset can be applied as time offset values ​​corresponding to the same number of transmissions.

[0215] A terminal can perform CFRA by selecting any one RO group from the derived RO group set. According to the configuration information of CFRA, in addition to information about the RO set, one or more SSB (or CSI-RS) identifiers or indices may be included, indicating which RO group associated with which SSB (or CSI-RS) should be selected from the RO set. If the CFRA procedure is performed after the terminal establishes an RRC connection, the identifier of the CSI-RS is indicated, so that Msg1 can be transmitted from the RO (or RO group) associated with the corresponding CSI-RS. The CFRA procedure using SSB can be performed before the terminal establishes an RRC connection, when the RRC connection is re-established, or when the terminal requests SIB1 and / or SIBx from the base station.

[0216] Additionally, the configuration information of CFRA may indicate, in the form of a mask (or mask index), resources that are allowed to transmit Msg1 or not among the RO groups (or ROs) associated with a specific SSB (or CSI-RS) belonging to the RO set. The terminal can determine from the mask whether an RO belonging to the RO set can be validly used for the CFRA procedure or not.

[0217] A mask can represent an index of an RO group (or RO), and the mask can be reset and assigned at each mapping cycle derived from the PRACH association index. The order in which RO indices are assigned follows the technical specifications for mapping SSB and RO, and can be derived from the indices of the frequency and time resources possessed by the RO.

[0218] According to another proposed method, instead of applying the time offset derived from RACH-ConfigCommon to the second RO group set, the terminal can apply a separate time offset included in the cfra IE to the second RO group set. In this case, the applied time offset may correspond to the third time offset.

[0219]

[0220] The information indicated in the cfra IE can be applied to the parameters required for a single transmission. A camping cell can configure or instruct a UE to configure up to three cfra IEs, which can be configured from the RACH-ConfigDedicated IE derived through the ReconfigurationWithSync procedure.

[0221] When the SI-RequestConfig IE or SI-RequestConfigRepetition IE is set, the RO group set can be derived from the RACH-ConfigGeneric contained in the IE. However, according to existing technical specifications, it may be difficult to clearly derive the RO group set using this method.

[0222] A method may be proposed for the terminal to derive a first set of RO groups from the SI-RequestConfig IE or the SI-RequestConfigRepetition IE. A time offset may be included in the SI-RequestConfigRepetition IE, which may be considered as the first time offset.

[0223] Additionally, each transmission may include a different first time offset. Table 6 illustrates examples of time offsets that may be applied to specific SI requests. According to Table 6, combinations of 2, 4, 8, or fewer transmissions may be supported, and the time offsets may be set in a 1:1 correspondence depending on these combinations.

[0224] Another proposed method allows the time offset to be specified as a single value, which can be applied universally regardless of the number of transmissions. In this case, the time offset value is set to an integer multiple of the largest transmission count, ensuring that the integer multiple relationship is satisfied under all transmission count conditions.

[0225] According to another proposed method, the value of the time offset is not indicated in the SI-RequestConfigRepetition IE, and the time offset value applied in the CBRA can be reused.

[0226] When multiple transmission counts are indicated to a terminal, the applicable time offset may be limited to cases where the number of transmissions indicated in the SI request and the number of transmissions to which the time offset is applied in the CBRA are identical. That is, for different transmission counts, the value of the time offset applied to the SI request may be the value of the time offset derived from the method of the CBRA having the same number of transmissions.

[0227]

[0228] Referring back to Tables 5 and 6, Cond Msg1Rep3 to Cond Msg1Rep6 may indicate conditions under which the time offset may be included in the IE. Here, Cond Msg1Rep3 may indicate a case where msg1-Repetitions is included in the FeatureCombination. Here, Cond Msg1Rep4 to Cond Msg1Rep6 may indicate conditions under which si-RequestResourcesRepetitionNum2 to si-RequestResourcesRepetitionNum8 corresponding to the respective number of transmissions may be included in the IE.

[0229]

[0230]

[0231]

[0232]

[0233] [Msg1 Sweeping]

[0234] The terminal can measure the RSRPs of the SSBs and select one of the SSBs. The RSRP of the selected SSB can belong to one of the intervals determined by several boundary values. For example, if boundary values ​​1 to 3 are indicated to the terminal in decreasing order, if the RSRP of the selected SSB belongs to the interval 0 to boundary value 1, the number of transmissions is set to 1, if it belongs to the interval 1 to boundary value 2, the number of transmissions is set to 2, if it belongs to the interval 2 to boundary value 3, the number of transmissions is set to 3, and if it belongs to the interval greater than or equal to boundary value 3, the number of transmissions can be set to 4. Here, the number of transmissions can indicate the number of times the terminal repeatedly transmits Msg1 to the camping base station (or serving base station). Here, the number of transmissions 1 to 4 can correspond to the number of transmissions 1 to 4 in increasing order, and they can all be values ​​greater than 1. Here, the number of transmissions and the boundary values ​​can be indicated to the terminal through RRC signaling. The number of transmissions and threshold values ​​can be included in SIB1 and also indicated to terminals in RRC idle state.

[0235] In one example, the values ​​to be utilized in the Msg1 iteration may be reused as the above boundary values ​​and applied to the Msg1 sweeping as well. In one example, the above boundary values ​​may be designated independently from the boundary values ​​utilized in the Msg1 iteration and applied to the Msg1 sweeping.

[0236] The terminal can determine an RO group corresponding to the number of transmissions of Msg1. An RO group may be composed of multiple ROs located on the same frequency but at different temporal locations, and the multiple ROs may be associated with the same SSB.

[0237] Here, one RO can be interpreted as a unit resource that allows a terminal to transmit Msg1 once, and only valid ROs according to conventional technical specifications can be considered for an RO group.

[0238] A terminal can maintain the same transmit beam (Tx beam) across different ROs. Alternatively, the terminal can apply different transmit beams to different ROs. According to conventional technical specifications, a terminal can maintain the same transmit beam across all ROs within an RO group.

[0239] The base station can gain benefits during the reception processing by combining and demodulating all Msg1s corresponding to the number of transmissions. Conversely, the terminal may not be able to maintain the same transmission beam across some ROs within the RO group. Alternatively, the terminal may intentionally transmit Msg1s using different transmission beams.

[0240] The base station can attempt to demodulate Msg1 on the corresponding RO for each transmit beam, thereby identifying the RO that provides the best reception quality. This RO can be interpreted as corresponding to the best transmit beam among the transmit beams used by the terminal.

[0241] Here, the definition of a "good transmission beam" can vary depending on the implementation. For example, the transmission beam with the highest RSRP value in a specific RO may be determined as a good transmission beam. Alternatively, the transmission beam with the highest value measured based on a predetermined metric may be determined as a good transmission beam. Preferably, a good transmission beam refers to a transmission beam that can be received with high reception intensity at the base station's receiving end.

[0242]

[0243] The terminal can perform both a repeat transmission operation in which Msg1 is repeatedly transmitted while maintaining the Tx beam, and a sweeping operation in which Msg1 is transmitted in different beams without maintaining the Tx beam. Alternatively, the terminal can perform only one of the Msg1 repeat transmission operation and the Msg1 sweeping operation.

[0244] For example, the above-described operating method may be determined based on the capabilities of the terminal. Alternatively, the above-described operating method may be determined based on the frequency range (FR) of the system in which the terminal operates. For example, a system operating in FR1 may perform repeated transmission of Msg1, while a system operating in FR2 may perform Msg1 sweeping.

[0245] A terminal's capabilities can be reported to the serving base station via RRC signaling. However, a terminal in RRC idle state may not be able to share information about its capabilities with a camping cell or the serving base station. Therefore, the terminal can use the Msg1 preamble to convey this capability information to the serving base station.

[0246] A serving base station can designate a set of preambles or a group of preambles that a terminal can use. If a terminal uses a preamble belonging to a specific set or group, the base station can assume that the terminal supports a specific feature, such as Msg1 sweeping. This behavior can be applied when a separate feature combination is assigned for Msg1 sweeping.

[0247] When a separate function combination is assigned and the function combination is activated in the corresponding uplink BWP, the terminal can select one of the preamble sets or preamble groups configured by the base station. Thereafter, the terminal can select and use a specific Msg1 preamble within the selected preamble set or preamble group. In addition, the terminal can also select a set of boundary values ​​corresponding to the selected preamble set or group. That is, the terminal can recognize which boundary values ​​should be applied when performing Msg1 repeat transmission or Msg1 sweeping.

[0248]

[0249] Msg1 repeat transmission and Msg1 sweeping can be defined within the same RO group. Alternatively, Msg1 repeat transmission and Msg1 sweeping can be defined in different RO groups. If Msg1 repeat transmission and Msg1 sweeping are defined within the same RO group, the terminal can use different preambles for Msg1 repeat transmission and Msg1 sweeping.

[0250] The terminal can determine a single receive beam (Rx beam) by selecting SSB. Based on the determined receive beam, the terminal can determine a transmit beam (Tx beam) to be used for Msg1 transmission.

[0251] When the number of transmit antennas (Tx antennas) is less than the number of receive antennas (Rx antennas) in the terminal, the area where the Rx beam is expressed and the area where the Tx beam is expressed on the grid of beams (GoB) may be configured to have different sizes.

[0252] Figure 15 is a conceptual diagram illustrating the Rx GoB and Tx GoB of a terminal.

[0253] Referring to FIG. 15, beams mapped to smaller areas can be formed according to Rx GoB, and beams mapped to larger areas can be formed according to Tx GoB.

[0254] When a terminal has the same number of transmit antennas (Tx antennas) and receive antennas (Rx antennas), the Tx GoB and the Rx GoB may be configured as beams having the same size. Here, the first and second axes of the angle may be defined according to the configuration of the array antenna or antenna panel arranged in the terminal.

[0255] For example, even if a terminal has x number of receive antenna ports (Rx antenna ports) and y number of transmit antenna ports (Tx antenna ports), it may not be able to form an orthogonal Tx GoB with only the transmit antenna ports. In this case, in FIG. 15, beams on the Tx GoB may be displayed as overlapping areas. Alternatively, a single beam belonging to the Tx GoB may be displayed using only the main lobe of each transmit beam.

[0256] Referring again to FIG. 15, reciprocity between a downlink beam (DL beam) and an uplink beam (UL beam) can be established on the terminal side not only when the terminal performs uplink beam management (UL Beam Management, UL BM) but also when UL BM is not performed depending on the terminal's capabilities.

[0257] When the terminal determines one reception beam (Rx beam) in the Rx GoB, a corresponding transmission beam (Tx beam) can be selected in the Tx GoB, and they can be in a beam reciprocity relationship.

[0258] Figures 16 and 17 are conceptual diagrams for explaining the relationship between the receiving beam of SSB and the transmitting beam of Msg1.

[0259] As illustrated in Fig. 16, when there is no beam reciprocity relationship, the terminal can independently derive the receiving beam and the transmitting beam. The terminal can transmit Msg1 with one transmitting beam applied, which can mean that Msg1 is transmitted once in one RO.

[0260] As illustrated in Fig. 17, according to conventional technical specifications, a terminal transmits Msg1 once, and the transmission beam for Msg1 can be derived from the selected SSB. When Msg1 repetition is performed, it can be considered that the terminal can derive an appropriate transmission beam from the reception beam of the selected SSB.

[0261] Referring to FIG. 17, the terminal can derive a transmit beam 1 (Tx beam 1), but since UL BM is not performed, the transmit beam 1 may correspond to a wider angle area than the receive beam. Therefore, a method for further improving the gain or directivity of the beam may be applied.

[0262] Figure 18 is a conceptual diagram explaining improvement in reception quality of Msg1 due to repeated transmission of Msg1 through the same beam.

[0263] Referring to FIG. 18, it is desirable for the terminal to repeatedly apply transmission beam 1 to improve the reception quality of Msg1 at the base station.

[0264] On the other hand, when Msg1 sweeping is performed, the terminal can derive two or more appropriate transmission beams, and one transmission beam can be applied based on feedback from the base station.

[0265] Figures 19 and 20 are conceptual diagrams for explaining a case where four transmission beams are derived from one reception beam for Msg1 sweeping.

[0266] Referring to FIG. 19, the terminal can derive four transmit beams (i.e., transmit beam 0 to transmit beam 3) from one receive beam. The terminal can repeatedly transmit Msg1 in an RO group consisting of at least four ROs.

[0267] Referring to FIG. 20, different transmit beams in different ROs can be applied to the transmission of Msg1.

[0268] Among the four transmission beams, transmission beam 0 can be selected based on feedback from the base station. The feedback from the base station will be described later. The terminal can consider that UL BM has been performed, and transmission beam 0 can be applied when PUSCH is transmitted in other stages of initial access. For example, transmission beam 0 can be applied to transmit Msg3 and / or Msg5. Alternatively, transmission beam 0 can be applied to PUCCH transmitting HARQ-ACK for Msg4.

[0269]

[0270] When a terminal performs Msg1 sweeping or Msg1 repeat transmission, the terminal may transmit Msg1 using the same or different transmission beams (transmission beams) in ROs or RO groups that are mapped differently in time. An example related to Msg1 repeat transmission may be referred to FIG. 18, and an example related to Msg1 sweeping may be referred to FIG. 20.

[0271] A terminal can transmit Msg1 from each RO belonging to an RO group by applying four different transmission beams from valid ROs. The ROs included in an RO group can be arranged sequentially or spaced apart in time.

[0272] The terminal can change the transmission beam to perform Msg1 sweeping. Furthermore, the terminal can perform Msg1 sweeping using two or more transmission panels (Tx panels). In this case, the terminal transmits Msg1 using only one transmission panel in a Radio Access Point (RO), and only one transmission panel can be involved in that RO. Therefore, the terminal can perform Msg1 sweeping by switching the transmission panels.

[0273] For example, the terminal can transmit Msg1 using the first transmit beam of the first transmit panel in the first RO within the RO group while simultaneously preparing the second transmit beam of the second transmit panel. Subsequently, the terminal can transmit Msg1 using the second transmit beam of the second transmit panel in the second RO within the RO group while simultaneously preparing the third transmit beam of the first or third transmit panel. This operation can be repeatedly performed for all ROs within the RO group. In this case, the terminal may not need a separate time to switch the transmit panels.

[0274] A terminal may perform either Msg1 sweeping or Msg1 repeat transmission. If Msg1 sweeping and Msg1 repeat transmission have the same number of transmissions, they may not be distinguished in the technical specifications. This is because the transmit beam applied to Msg1 by a terminal performing Msg1 repeat transmission may always be the same, but may differ slightly during the implementation process. This can be considered Msg1 sweeping in the broad sense.

[0275] The number of repetitions can be derived by comparing the RSRP (or RSRQ) derived by the terminal upon receiving the SSB with a threshold value. Similarly, the sweeping coefficient can be derived using the same RSRP (or RSRQ). The terminal can be instructed on the threshold values ​​required to derive the number of repetitions or sweeping coefficient from system information.

[0276] In one example, the threshold values ​​used to derive the sweeping coefficient may be identical to the threshold values ​​from which the repetition count is derived. Even if separate threshold values ​​are not specified, once the repetition count or sweeping coefficient is derived, the terminal can derive an RO group using the derived values ​​and determine whether to perform Msg1 repeated transmission or Msg1 sweeping.

[0277] In another example, the thresholds used to derive the sweeping coefficient and the thresholds from which the number of iterations is derived may be different. In this case, for the same RSRP (or RSRQ), the derived number of iterations L and the sweeping coefficient L' may be different.

[0278] By following the proposed method, the terminal can select a method that can transmit Msg1 faster. For example, if L > L', the terminal can decide to perform Msg1 sweeping. If L <L'인 경우, 단말은 Msg1 반복전송을 수행하도록 판단할 수 있다. 만일 L=L'인 경우, 단말은 임의의 동작을 수행하도록 판단할 수 있다. 예를 들어, L=L'인 경우, 단말은 Msg1 스위핑 또는 Msg1 반복전송 중에 어느 한 동작을 수행하도록 판단할 수 있다.

[0279] If a terminal that has determined to perform Msg1 sweeping does not receive an RAR from the base station, it can perform Msg1 sweeping again. The maximum number of times Msg1 sweeping can be indicated from system information. In one example, if the number of times Msg1 sweeping of the terminal has failed exceeds the number, the terminal can increase the Msg1 sweeping coefficient. If the increased Msg1 sweeping coefficient exceeds the maximum value, the terminal can perform Msg1 repeated transmission instead of Msg1 sweeping. Alternatively, in another example, the terminal can perform Msg1 repeated transmission without considering Msg1 sweeping, and the number of repetitions at this time can be equal to the Msg1 sweeping coefficient.

[0280] When the terminal performs Msg1 sweeping, the amount of power applied to each transmission of Msg1 may be the same. Retransmission of Msg1 sweeping may be performed when the terminal does not receive RAR in ra-SearchSpaceSet (or Type1-PDCCH CSS set, or RAR window), and the amount of power applied to Msg1 at this time may increase. In this case, the amount of increase may be indicated to the terminal separately in system information as a ramp-up value, or the ramp-up value applied during repeated transmission of Msg1 may be reused.

[0281] This section discusses how to determine the transmission power when a terminal changes from performing Msg1 sweeping to Msg1 repeat transmission, or vice versa when it changes from performing Msg1 repeat transmission to Msg1 sweeping.

[0282] In one example, even if the terminal changes the transmission method for Msg1, the ramp-up value can remain the same. To achieve this, the ramping counter value can be maintained. Alternatively, the ramping counter can be reset, but only the ramp-up value can remain the same.

[0283] In another example, if the terminal changes the transmission method of Msg1, the ramp-up value may be reset and considered as 0.

[0284]

[0285] Meanwhile, even if a terminal has only one transmit panel or two or more transmit panels, Msg1 sweeping can be performed while changing the transmit beam within a single transmit panel. In this case, according to conventional technical specifications, the terminal may require a certain processing time to change the transmit beam. This processing time may be the time required to activate the transmit panel. Alternatively, this processing time may be the time required to adjust the parameters of the RF (radio frequency) circuit to change the transmit beam within an already activated transmit panel. The processing time may be set to different values ​​depending on the UL BWP or the subcarrier spacing.

[0286] According to the proposed method, gaps may occur during the Msg1 sweep process. While a terminal may have more than one transmit panel, it is not necessary to use only one receive panel (Rx panel) to receive a single SSB. Here, the Rx panel and transmit panel may be structured to utilize the same physical panel for either Rx or Tx purposes.

[0287] According to conventional technical standards, the terminal repeatedly transmits Msg1 while maintaining the same transmission beam, enabling continuous transmission in adjacent ROs. However, when Msg1 sweeping is performed, the terminal may require a certain amount of time to switch to a different transmission beam. Therefore, Msg1 sweeping is not always possible in adjacent ROs.

[0288] Figures 21 and 22 are conceptual diagrams illustrating examples in which gaps are reflected in the RO group.

[0289] Referring to Figures 21 and 22, adjacent ROs can be considered a single subgroup. For example, Msg1 may be transmitted from only one RO. Alternatively, Msg1 may be transmitted from a fixed RO. In another example, Msg1 may be transmitted from all ROs within a subgroup.

[0290] A single transmit beam (transmit beam) can correspond to a single RO subgroup. For example, if two ROs are considered a single subgroup, Msg1 can be transmitted from either one RO or all ROs.

[0291] Referring to Figure 21, the occurrence of gaps in RO subgroups can be explained. Gaps may be required between RO subgroups, but no gap may be required for the last subgroup within an RO group.

[0292] For a sweeping factor of 2, a terminal may require three ROs to transmit two transmit beams. For a sweeping factor of 4, seven ROs may be required, and for a sweeping factor of 8, fifteen ROs may be required.

[0293] Referring to Figure 22, a case where a gap is always required for RO subgroups can be described. All RO subgroups can be configured to have the same size. In this case, if the sweeping factor is 2, an RO group consisting of four ROs can be used. If the sweeping factor is 4, an RO group consisting of eight ROs can be used, and if the sweeping factor is 8, an RO group consisting of sixteen ROs can be used.

[0294] When two ROs form a single subgroup, the UE can transmit Msg1 only on one RO. In this case, it may be desirable for the base station to more clearly indicate which RO (e.g., the first RO or the second RO) to use in the corresponding RO subgroup. This indication can be derived from a specific field in the RAR UL grant information. For example, the CSI request field can indicate this information through a specific value.

[0295]

[0296] According to existing technical specifications, a terminal can use an RO group consisting of up to eight ROs. Based on this configuration, a time period can be determined. Since Msg1 is repeatedly transmitted, the same transmission beam can be applied to all ROs in the RO group.

[0297] Based on the above method, there may be cases where up to 16 ROs are required. However, the proposed method below allows up to 8 ROs to be used to sweep only up to 4 transmit beams. In such cases, the association period, association pattern period, and time period can be derived by reusing the Msg1 iteration procedure defined in the existing technical specifications.

[0298] According to the proposed method, Msg1 sweeping can be performed within a single RO group consisting of up to eight ROs. If gaps are required, the terminal can use seven or eight of the eight ROs.

[0299] The terminal can perform Msg1 sweeping using a subgroup of up to four ROs, i.e., up to four transmission beams. In addition, when partitioning the Modulation and Coding Scheme (MCS) field of the RAR UL grant information, up to two bits can be used to identify the best transmission beam used for Msg1 transmission.

[0300]

[0301] Msg1 may be indicated to use one of multiple preamble formats. According to conventional technical specifications, various information related to Msg1 can be derived from a single index included in SIB1, and the information may indicate the preamble format.

[0302] According to conventional technical specifications, preamble formats can be categorized into long and short formats. Long format means that Msg1 is transmitted once every 1ms or more. Conversely, short format means that Msg1 can be transmitted once every 1ms or less.

[0303] The preamble format classified as a short format may consist of a cyclic prefix (CP), a sequence, and a guard period (GP), and in some cases, the GP may be omitted.

[0304] Therefore, in a configuration where a preamble format already includes GP, there may be no need to allocate a separate gap RO (gap RO) to interpret RO subgroups within an RO group. In this case, as in the conventional technical specification, the size of the RO group (k) may be equal to the number of transmissions (k) of Msg1.

[0305] According to the proposed method, depending on the preamble format, an RO group including or excluding a gap RO may be derived. Therefore, even for the same sweeping factor (k), the required RO group size may vary depending on the preamble format. Consequently, the RO group size may be set to 2k, 2k-1, or k. Here, the sweeping factor k may be one or more of 2, 4, or 8, and a maximum value of 16 or higher may be indicated.

[0306] According to the existing technical specifications, preamble formats B1, B2, B3, and B4, as well as preamble formats C0, C1, and C2, can include GPs, so at least some of these formats can form an RO group without a gap RO. On the other hand, other preamble formats can form an RO group that includes a gap RO. The terminal can determine the presence of a gap RO based on the information contained in SIB1.

[0307]

[0308] After the terminal transmits Msg1, the base station can transmit Msg2 based on it. According to the existing technical specifications, when the terminal performs repeated transmission of Msg1, the base station can derive the RA-RNTI (Random Access-Radio Network Temporary Identifier) ​​based on the last RO in the RO group.

[0309] According to the proposed method, even when a terminal performs Msg1 sweeping, the base station can derive the RA-RNTI based on the last RO in the RO group. Furthermore, the start point of the RA search space set can be the same when Msg1 sweeping is performed and when Msg1 repeat transmission is performed.

[0310]

[0311] [Msg3 Repetition]

[0312] When a terminal performs Msg1 sweeping, the camping base station or serving base station can select the best transmission beam among the transmission beams (transmission beams) of Msg1 used by the terminal. The selected transmission beam can also be used when the terminal transmits Msg3 or PUCCH transmitting HARQ-ACK for Msg4. Therefore, the base station can indicate the transmission beam to be applied to the terminal.

[0313] According to the proposed method, the base station can select the best transmission beam among the multiple transmission beams used for Msg1 transmission and designate it as the transmission beam to be used by the terminal for Msg3 transmission. In this case, since the terminal transmits multiple uplink beams (UL beams) to the base station and receives feedback from the base station indicating that it should select one UL beam, the terminal can consider that uplink beam management (UL beam management, UL BM) has been performed.

[0314] Therefore, even if the base station receives only one Msg3, decoding can be facilitated. The terminal may not perform repeated Msg3 transmissions. Alternatively, even if it does perform repeated Msg3 transmissions, it can utilize a higher MCS by applying the best transmission beam, resulting in savings in uplink resources.

[0315] The base station can explicitly or implicitly provide information about the transmission beam to the terminal. For example, if the base station informs the terminal of a specific RO within the RO group selected by the terminal, the terminal can derive the transmission beam used when transmitting that RO.

[0316] According to the conventional technical specifications, when repeated transmission of Msg3 is performed, some bits (upper 2 bits, 2 MSBs) of the MCS field included in the uplink grant information of RAR (RAR UL grant) may indicate the number of transmissions of Msg3, and the remaining bits (lower 2 bits, 2 LSBs) may indicate the MCS of Msg3. In addition, even when scheduling Msg3 using DCI format 0_0 scrambled with TC-RNTI, the upper 2 bits of the MCS field may indicate the number of transmissions of Msg3.

[0317] Here, the MCS field may not be reused, and other fields of the UL grant may be used. Additionally, the bit order within the MCS field may be reversed, so that the number of Msg3 transmissions may be indicated by the lower bit.

[0318] According to the proposed method, a portion of the MCS field can be used to derive the index of one of the ROs included in the RO group. In this case, the terminal may not perform repeated transmission of Msg3. In other words, this information can be used to indicate which RO has been selected within the RO group selected by the terminal.

[0319] Figure 23 is a conceptual diagram illustrating a case where a base station indicates a specific RO within an RO group.

[0320] Referring to Figure 23, when 2 bits of information can be utilized, any one of up to 4 ROs can be indicated. When the sweeping factor of Msg1 is 4, any RO belonging to the RO group can be indicated.

[0321] When the number of sweeps is two, one bit of information may be required for the terminal to be directed to one of the two ROs. When the number of sweeps is eight, three bits of information may be required for the terminal to be directed to one of the eight ROs.

[0322] According to the proposed method, sweeping factors of 2 or 4 can be supported. In this case, the terminal can determine a specific RO within an RO group with only 2 bits.

[0323] In the previously described FIGS. 21 and 22, the configuration of an RO group for four Tx beams or two Tx beams, respectively, is described. Referring to FIG. 21 or FIG. 22, when an RO group includes or does not include a gap RO, two bits of information can be used to select one of up to four ROs.

[0324] Additionally, the location of the RO can be indicated using part of the MCS field of the RAR UL grant, and 2 bits can be utilized in this case.

[0325] According to the proposed method, sweeping coefficients of 2, 4, and 8 can be supported. In this case, the terminal can also use part of the MCS field to indicate the position of the RO. Three or fewer bits can be used to indicate the RO position, and one or more bits can be used to indicate the MCS.

[0326] For example, if the sweep factor is 8, the MCS can be represented using only 1 bit. In this case, the MCS can be restricted to one of two values.

[0327] For example, other fields may be utilized in addition to the MCS field within the RAR UL grant. According to conventional technical specifications, the CSI request field is set to a reserved state, so that the terminal may not reference its value. According to the proposed method, some bits of the CSI request field and the MCS field can be combined to indicate 3 bits of information to the terminal. In this case, one of the 8 ROs can be selected, thereby supporting a sweeping factor of 8.

[0328] When gap ROs exist, the size of the RO group can be larger. For example, when the sweeping coefficient is K, 2K-1 or 2K ROs may be required. When the sweeping coefficient is 8, referring to FIG. 21 or FIG. 22, the size of the RO group can be 15 or 16. In this case, 3 bits of information may be required to represent any one of the 8 ROs.

[0329] On the other hand, even when gap ROs exist, the maximum size of the RO group may be limited to four. If the sweep factor is four, as shown in FIG. 21 or FIG. 22 , the size of the RO group may be seven or eight. In this case, two bits of information may be required to indicate any one of the four ROs.

[0330] Since this is the same size (2 bits) of information used to indicate the Msg1 repetition factor in conventional technical specifications, it can be applied in a similar way to the method of partitioning the MCS field in RAR UL grant or DCI format 0_0.

[0331]

[0332] Scheduling information for the initial transmission of Msg3 can be included in the RAR UL grant. The terminal can transmit Msg3 to the base station using the TC-RNTI. If the base station successfully decodes Msg3 and the CRC of the transport block (TB) matches (e.g., in the ACK case), the terminal can perform the initial access procedure.

[0333] On the other hand, if the base station fails to verify the CRC of the TB (e.g., in the case of NACK), the base station can retransmit scheduling information for retransmission based on the TC-RNTI. The causes of TB CRC errors can be diverse. For example, if multiple terminals transmit Msg3 using the same RA-RNTI in a contention situation, the base station may receive multiple Msg3s simultaneously, resulting in a CRC error. Alternatively, CRC errors may occur due to fading of the wireless channel or incorrect MCS instructions.

[0334] The base station can transmit DCI format 0_0 containing scheduling information to the terminal for Msg3 retransmission.

[0335] According to the proposed method, the TCI state and the number of transmissions (repetition factor or sweeping factor) can be indicated to the terminal from the scheduling information of Msg3. Alternatively, only the TCI state may be indicated, without indicating the number of transmissions. In this case, the terminal may interpret this to mean that Msg3 is transmitted once.

[0336] To apply the TCI state to Msg3, the terminal may store the transmission beam (transmission beam) used in the previous Msg1 sweeping process.

[0337] According to another proposed method, the scheduling information of Msg3 is divided into initial transmission and retransmission, and in each case, only one of the TCI status or the number of transmissions can be included. For example, the TCI status can be indicated from the scheduling information of the initial transmission, and the number of transmissions can be indicated from the scheduling information of the retransmission. Alternatively, the number of transmissions can be indicated from the scheduling information of the initial transmission, and the TCI status can be indicated from the scheduling information of the retransmission.

[0338] Scheduling information for the initial transmission is included in the RAR UL grant, and according to the proposed method, specific fields can be partitioned to include information indicating the TCI status. For example, the most significant bit (MSB) of the MCS field can indicate the TCI status, and the least significant bit (LSB) can indicate the MCS.

[0339] Scheduling information for retransmissions can be included in DCI format 0_0, and according to the proposed method, information indicating the number of transmissions can be included by dividing a specific field. For example, the MSB of the MCS field can indicate the number of transmissions, and the LSB can indicate the MCS.

[0340] When the base station indicates the number of transmissions, the terminal can repeatedly transmit Msg3 while maintaining the same TCI state. According to conventional technical standards, Msg3 can be repeatedly transmitted without a TCI state. However, the proposed method supports the function of transmitting Msg3 more than twice by performing uplink beam management (UL BM) and applying the selected transmission beam.

[0341] When retransmitting, the MCS can be set by changing the modulation order. At this time, the encoding process of the transport block (TB) is not re-performed, and only rate matching or subsequent procedures can be performed.

[0342] Tables 7 and 8 are examples of MCS tables according to conventional technical specifications. If the terminal does not apply transform precoding when transmitting an uplink physical channel (PUSCH), the CP-OFDM waveform is applied, in which case Table 7 may be applied. On the other hand, if transform precoding is applied, the DFT-s-OFDM waveform is applied, in which case Table 8 may be applied.

[0343] The modulation order for retransmission can be expressed as three values ​​in Table 7, and as three or four values ​​in Table 8. For example, the q value is provided to the terminal through a separate RRC signaling and can be interpreted as 1 or 2 when tp-piBPSK is indicated. Therefore, there can be up to four MCS values ​​available for retransmission, which can be expressed as two bits.

[0344]

[0345]

[0346]

[0347]

[0348] To distinguish whether a scheduling information is a first transmission or a retransmission, the New Data Indicator (NDI) field can be utilized. When the value of the NDI field toggles for the same HARQ process number (HARQ Process Number (HPN) or HARQ Process ID (HPID)), the terminal can recognize that the corresponding transport block (TB) has been first transmitted.

[0349] Accordingly, the terminal can either regard the existing TB stored in the circular buffer as previously transmitted data or reconfigure the circular buffer based on the new TB. Conversely, if the value of the NDI field remains unchanged, the terminal can reuse the TB stored in the circular buffer and perform rate matching or subsequent procedures based on the received scheduling information.

[0350] For Msg3, the NDI field may not be used in general. Information scheduled based on TC-RNTI can be considered retransmitted information. This is because the terminal is performing the initial access procedure and has no history of uplink shared channel (PUSCH) transmissions other than the initial transmission of Msg3, so there is no need for the terminal to refer to the HARQ process number (HPN) or redundancy version (RV).

[0351] If the TCI status of Msg3 is indicated in the RAR UL grant, the TCI status may be applied equally to retransmissions of Msg3. To this end, the terminal may store the transmission beam (transmission beam) used in the Msg1 sweeping procedure until the procedure related to Msg3 is terminated.

[0352] For example, the terminal may apply the same TCI state applied in Msg3 to transmit Msg5. In this case, the terminal may also store the transmission beam used in the Msg1 sweep process until the procedure related to Msg5 is completed.

[0353] The serving base station may indicate a separate TCI status, spatial relation information, or other relevant information to the terminal, taking into account the capability information reported by the terminal in Msg5.

[0354]

[0355] To indicate the number of transmissions, a specific field included in DCI format 0_0 or RAR UL grant information may be partitioned. For example, the field may be an MCS field. Alternatively, two or more fields may be combined to provide information for deriving the number of transmissions. According to the proposed method, the partitioning method of the MCS field may vary depending on the number of transmissions (sweeping factor or repetition factor).

[0356] When the number of transmissions is 2, one bit in the MCS field can be used to indicate the Random Access Opportunity (RO), and the remaining bits can be used to indicate the MCS.

[0357] When the number of transmissions is 4, 2 bits in the MCS field can be used to indicate RO, and the remaining bits can be used to indicate MCS.

[0358] When the number of transmissions is 8, 3 bits in the MCS field can be used to indicate RO, and the remaining bits can be used to indicate MCS, provided that the serving cell or BWP supports it.

[0359] Here, the number of transmissions is a value that the terminal can determine based on RSRP, and the base station can also determine the number of transmissions through feature combinations or the preamble of Msg1. Therefore, the MCS field division method can be derived from the number of transmissions without separate RRC signaling.

[0360]

[0361] The number of PUCCH transmissions for Msg4 may be set to some or all of the following values: 2, 4, 8, or more. The serving base station may transmit or broadcast a list of allowed values ​​for the number of PUCCH transmissions for Msg4 via SIB1.

[0362] The value contained in the DAI (Downlink Assignment Index) field of DCI format 1_0 scrambled with TC-RNTI can be interpreted as the number of PUCCH transmissions, which can also be applied to the number of PUCCH transmissions for Msg4.

[0363] According to the proposed method, a terminal can transmit Msg4 PUCCH more than twice not only in a specific scenario but also in a general mobile communication scenario.

[0364] The PUCCH time resource for Msg4 is defined by the start symbol and the number of symbols within a single slot, and this setting can be applied equally to multiple slots corresponding to the number of repeated transmissions. This setting can be applied not only to the PUCCH for Msg4, but also to cases where the UE transmits PUCCH without being instructed to configure dedicated PUCCH resources via RRC signaling.

[0365] Information provided in SIB1 and / or information included in the scheduling DCI format may be combined to correspond to a PUCCH resource configuration defined in the technical specification, resulting in a single PUCCH resource.

[0366] According to the conventional technical specifications, the transmit beam (transmission beam) of the PUCCH for Msg4 may not be separately indicated. For example, the terminal may reuse the transmit beam of Msg1 or Msg3 as the transmit beam of the PUCCH for Msg4. In another example, the transmit beam of the PUCCH for Msg4 may be determined depending on the implementation of the terminal, and may be the transmit beam of Msg1 or Msg3, or a different transmit beam.

[0367] Furthermore, conventional technical specifications require that a terminal maintain the same PUCCH transmission beam for Msg4. However, according to the proposed method, the terminal may not necessarily maintain the same PUCCH transmission beam for Msg4.

[0368] According to the proposed method, when the terminal performs Msg1 sweeping, the terminal can select the best transmission beam among the transmission beams of Msg1 and set it as the transmission beam for PUCCH transmission for Msg4. In this case, the selected transmission beam may be the same as the transmission beam used for transmission of Msg3, and the transmission beam may be interpreted as a TCI state and applied as the TCI state of the PUCCH for Msg4.

[0369] Additionally, the DAI field of DCI format 1_0 scheduling Msg4 can be interpreted as the number of PUCCH transmissions for Msg4. For example, if a terminal performs Msg1 sweeping and Msg3 repeated transmissions, the terminal can consider that uplink beam management has been performed and apply the PUCCH repeated transmission procedure for Msg4.

[0370]

[0371] According to another proposed method, a sweeping procedure can also be applied to the PUCCH for Msg4. That is, sweeping can be applied to the PUCCH for Msg4 similar to the sweeping for Msg1.

[0372] The terminal can derive two or more transmission beams from the selected SSB, and these transmission beams can be sequentially applied to transmit the PUCCH for Msg4.

[0373] The DAI field of DCI format 1_0, which schedules Msg4, can be interpreted as the number of Msg4 PUCCH transmissions. This method can be applied not only to Msg4 but also to cases where the UE is not instructed to configure dedicated PUCCH resources via RRC signaling. In such cases, the UE may transmit HARQ-ACK for the scheduled PDSCH more than twice.

[0374] According to the proposed method, the number of PUCCH transmissions can be indicated by the DAI field. That is, even for a general PDSCH other than Msg4, the DAI field can simultaneously indicate the number of HARQ-ACK bits and the number of PUCCH transmissions. In this case, the number of PUCCH transmissions can increase in proportion to the number of HARQ-ACK bits.

[0375] According to another proposed method, the terminal can derive the transmit beam to be used for HARQ-ACK transmission for Msg4 from the TCI state of the CORESET in which the DCI scheduling Msg4 is discovered. Since this method derives the transmit beam from the receive beam, it can be applied to terminals that support beam reciprocity even if uplink beam management is not performed.

[0376] If the terminal can transmit the PUCCH for Msg4 more than twice, it can perform repetition transmission while maintaining the transmission beam derived from CORESET. Alternatively, the terminal can perform sweeping, applying different transmission beams without necessarily maintaining a single transmission beam.

[0377]

[0378] [Msg5 repetition]

[0379] Figure 24 is a flowchart illustrating Msg5 transmission and its preceding procedures.

[0380] Referring to Figure 24, repetition or sweeping may be performed when transmitting Msg1 (S2410). As another example, repetition may be performed when transmitting Msg3 (S2420). Additionally, repetition or sweeping may be performed when transmitting PUCCH for Msg4 (S2430). These operations may be performed independently or in combination.

[0381] Meanwhile, the Msg5 PUSCH includes information transmitted during the initial access procedure and may include at least a capability report of the UE. For example, in addition to UE capability information, the Msg5 PUSCH may include other information required during the initial access procedure, such as security. The information may be mapped to a single uplink shared channel (UL-SCH) and transmitted via the Msg5 PUSCH through a single scheduling. Alternatively, the information may be mapped to two or more UL-SCHs and transmitted via multiple Msg5 PUSCHs through two or more scheduling. For convenience of explanation, the expression "Msg5" may be considered to mean the Msg5 PUSCH.

[0382] After receiving Msg5 containing the capability information of the UE, the serving base station can instruct the UE on the PUSCH repetition mode (Type A or Type B). According to the existing technical specifications, the UE can receive PUSCH repetition type A or type B from the serving base station in the RRC connection state. This is because the PUSCH repetition mode can be set after the UE reports its capabilities to the base station via Msg5.

[0383] However, since Msg5 itself transmitted by the terminal may be transmitted in an environment with limited coverage, it is desirable to perform repeated transmission or sweeping for Msg5 as well (S2440).

[0384] For terminals that have performed Msg1 sweeping, a certain level of uplink beam management has already been performed. Therefore, the base station can achieve sufficient reception quality by transmitting Msg5 once, applying specific TCI status or spatial relationship information to the terminal. However, if these conditions are not met, a function is required to indicate that Msg5 should be transmitted more than twice.

[0385] Additionally, if a terminal performs repeated transmissions of Msg3, the base station can recognize that the terminal is located at the edge of cell coverage. In this case, the number of transmissions for Msg5 can be explicitly specified, thereby reinforcing the transmission of Msg5 in a repeated and / or sweeping manner.

[0386]

[0387] According to conventional technical specifications, a terminal can derive the number of transmissions of a scheduled PUSCH from a time domain resource assignment (TDRA). The TDRA is applied by selecting an index of one of multiple settings indicated by RRC signaling through scheduling information, and the starting symbol, number of symbols, and / or number of consecutive slots to which the PUSCH is mapped can be determined based on the selected TDRA.

[0388] According to the proposed method, when DCI format 0_0 is transmitted scrambled with C-RNTI or MCS-C-RNTI, some bits of the MCS field of the corresponding DCI format can be used to derive the number of PUSCH transmissions. The remaining bits can be used to derive the MCS of the PUSCH.

[0389] According to another proposed method, the field can be interpreted differently for initial transmissions and retransmissions. Whether a PUSCH is initialized can be determined by toggling the NDI field. If the initial TB is scheduled, the entire MCS field can be used to derive the MCS.

[0390] On the other hand, if the retransmitted TB is scheduled, some bits of the MCS field can be used to derive the number of PUSCH transmissions, and the remaining bits can be used to derive the MCS. This is because the MCS information used for retransmission typically only includes information on changes in the modulation order.

[0391] For example, if an MCS table supporting three modulation methods, QPSK, 16QAM, and 64QAM, is used, only three values, 29, 30, and 31, can be allowed in the MCS field of DCI for retransmission. As another example, if an MCS table supporting four modulation methods, QPSK, 16QAM, 64QAM, and 256QAM, only four values, 28, 29, 30, and 31, can be allowed in the MCS field of DCI for retransmission.

[0392]

[0393] Since the value 0b11100 is calculated as 16 + 8 + 4 = 28, the value expressed in the 0b000xx format thereafter can be interpreted as the lower 2 bits (2 LSBs). For example, the lower 2 bits of the MCS field can mean the MCS, and the upper 3 bits (3 MSBs) can mean the number of PUSCH transmissions. The PUSCH to which this method is applied can be scheduled with one of the DCI formats searched in the common search space (CSS set), the DCI formats searched in the dedicated search space (USS set), DCI format 0_0, or DCI format 0_1. The proposed method can be applied through one of these or a combination of these. For example, it can be scheduled through DCI format 0_0 searched in the CSS set.

[0394] For example, the number of transmissions can be indicated in a manner suggested only for Msg5. Since Msg5 contains terminal capability information, after the base station successfully receives Msg5, the number of transmissions for PUSCH for general data transmission can be derived from the TDRA. Subsequent scheduling can then indicate an appropriate number of transmissions to the terminal.

[0395]

[0396] To apply the proposed methods, the terminal must store information about the transmission beam used for Msg1 transmission. Then, if a value is indicated in the UL grant of the RAR, the terminal can consider this as a TCI state and apply it to the transmission beams of Msg3 and / or Msg5.

[0397] If the base station fails to decode the initially transmitted Msg3, it can reschedule Msg3 to the terminal using a DCI format scrambled with TC-RNTI. The maximum time for which the terminal can store the transmission beam can be determined based on its capabilities. If the base station indicates a TCI state beyond this time, the terminal may not apply the transmission beam derived from Msg1 sweeping.

[0398] According to another proposed method, the transmission beams of Msg1 and the transmission beam mathematical formulas used for PUCCH transmission for Msg4 can be corresponded one-to-one. That is, the number of transmissions of Msg1 and the number of PUCCH transmissions for Msg4 are the same, and the respective transmission beams can be applied identically or correspondingly. Accordingly, the terminal can transmit the PUCCH for Msg4 in multiple slots or subslots.

[0399]

[0400] [Maintaining Ramp-up Values]

[0401] The terminal can determine the amount of transmission power applied to the Msg1 preamble during the process of transmitting Msg1 to the base station by performing repeated single transmissions of Msg1, repeated Msg1 transmissions, or repeated Msg1 sweeping. For example, when retransmission is performed, a ramp-up value can be applied in addition to the value derived by applying path attenuation and using various offsets indicated by upper layer signaling.

[0402] The transmission power of Msg1 can be derived from the mathematical expression 1 below.

[0403]

[0404]

[0405] The difference between the transmission power of Msg1 and the transmission power of PUSCH is that the value of the target transmission power can be determined from a value (PREAMBLE_RECEIVED_TARGET_POWER) indicated by a higher layer. The value can be derived from the product of the ramping counter and the value of the ramping step ((PREAMBLE_POWER_RAMPING_COUNTER - 1) Х PREAMBLE_POWER_RAMPING_STEP) at a fixed value of the transmission power (preambleReceivedTargetPower + DELTA_PREAMBLE) in relation to the ramping counter. Therefore, the target value of the transmission power can be interpreted as a value proportional to the ramping counter. Here, the ramping counter can mean a counter that increases by 1 when the terminal transmits Msg1 and fails to receive Msg2 from the base station within an appropriate time.

[0406] The interpretation of the ramp-up value may differ between cases where Msg1 sweeping is performed and cases where Msg1 repeat transmission is performed. This may be related to the interpretation of the ramp-up value (or ramping counter) or the number of ramp-up values ​​(ramping counters).

[0407] If the transmission method used in Msg1 is applied consistently (i.e., only Msg1 sweeping is performed or only Msg1 repeat transmission is performed), the conventional technical specifications can be applied.

[0408] When both Msg1 sweeping and Msg1 repeat transmission are performed, the ramp-up value (or ramping counter) may be reused or reset, so that a different value may be applied to the ramp-up value (or ramping counter). For example, the value of the ramp-up value (or ramping counter) may be applied regardless of the transmission method of Msg1, so that the terminal may receive the same ramp-up value (or ramping counter) derived from Msg1 sweeping transmission even if Msg1 repeat transmission is performed.

[0409] The ramp-up value may be reset when the transmission method of Msg1 changes. In this case, the terminal must perform Msg1 sweeping or Msg1 repeat transmission again from the beginning to find the appropriate transmission power. To reduce the delay in this process, a power offset can be introduced.

[0410] By using a separate power offset, if the transmission method of Msg1 changes, the amount of power derived from the power offset can be subtracted from the ramp-up value. This reduces the transmit power, but has the advantage of starting from a non-zero value, which can help reduce delay time.

[0411] If the ramping counter remains constant, a change in the transmission method of Msg1 could result in exceeding the maximum power value of the PUSCH. If a power offset is applied, the PUSCH transmit power can again be reduced to a value less than the maximum power value.

[0412]

[0413] The power control applied for transmission of Msg3 can be given as in the following mathematical expression 2, and the dynamic update part can be examined in detail.

[0414]

[0415]

[0416] Here, or can represent an output value set to the terminal. PUSCH is transmitted on carrier f of serving cell c, and can mean the kth TCI state. The transmission time of the PUSCH is represented by i, which can be an index utilized in dynamic update. or is a value indicated from the upper layer, and when the terminal performs random access, is considered as, can be expressed as can be indicated by upper layer signaling (preambleReceivedTargetPower) related to the transmit power of Msg1, The value indicated by the upper layer signaling (msg3-DeltaPreamble or deltaPreamble) may be applied, or it may be considered as 0 if no such value is present.

[0417] Is It can be considered as 1 if the value indicated to the terminal from the upper layer (msg3-Alpha) is applied or if no such value is indicated.

[0418] may be the number of RBs allocated to PUSCH. is a value indicating the path attenuation, and is indicated by RS ( ) can be measured.

[0419] is the value indicated in the upper layer (deltaMCS, or ), 0 or It could be. If, = is applied, and BPRE can be derived from the number of REs scheduled on PUSCH and the number of code blocks. If, =0 can be derived.

[0420] In the calculation of, can be considered as.

[0421] Is can be decided by can have one of four values. may be the accumulated value of power control commands received during a given time interval. The transmission point (or occasion) of PUSCH And the transmission time of PUSCH About each The symbol's front (T1) and The symbol's transition (T2) can be considered. Power control commands received between T2 and T1 can be accumulated.

[0422] If the size of the PUSCH transmission power becomes less than 0 or exceeds the maximum allowable value, may not accumulate.

[0423] For Msg3, no separate accumulation is required, can be expressed as a power control command from the fields included in RAR ( ) may be applied. is interpreted more complexly and can be expressed as the first or second value below.

[0424] The first value is, and , and can be greater than or equal to 0. The second value is, and , and can be greater than or equal to 0.

[0425] Here, may be a value indicated from the upper layer and may correspond to a power ramp-up derived after the terminal transmits Msg1 from the beginning to the end.

[0426]

[0427] The operations of the method according to an embodiment of the present invention can be implemented as a computer-readable program or code on a computer-readable recording medium. A computer-readable recording medium includes any type of recording device that stores information readable by a computer system. Furthermore, a computer-readable recording medium can be distributed across network-connected computer systems, allowing the computer-readable program or code to be stored and executed in a distributed manner.

[0428] Additionally, the computer-readable recording medium may include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. The program instructions may include not only machine language codes produced by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc.

[0429] While some aspects of the present invention have been described in the context of a device, they may also represent a description of a corresponding method, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may also be described as a corresponding block or item or a feature of a corresponding device. Some or all of the method steps may be performed by (or using) a hardware device, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, at least one or more of the most important method steps may be performed by such a device.

[0430] In embodiments, a programmable logic device (e.g., a field-programmable gate array) may be used to perform some or all of the functions of the methods described herein. In embodiments, the field-programmable gate array may operate in conjunction with a microprocessor to perform one of the methods described herein. In general, the methods are preferably performed by some hardware device.

[0431] Although the present invention has been described above with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

Claims

1. A method of a terminal performing a random access (RA) procedure, A step of receiving first RA configuration information for a contention-free RA (CFRA) procedure or system information request and second RA configuration information for a contention-based random access (CBRA) procedure from a base station; A step of measuring the reception strength of a synchronization signal block (SSB) received from the base station; A step of determining the number of repetitions for transmitting message 1 (Msg1) based on the measured reception intensity; and A step of repeatedly transmitting the Msg1 according to the determined number of repetitions in a first random access occasion (RO) group set determined by the first RA setting information and / or the second RA setting information, method.

2. In claim 1, The first RO group set is derived by the first RA setting information, and the first RO group set is composed of ROs independent of the ROs for the CBRA procedure set by the second RA setting information. method.

3. In claim 2, No time offset is applied between the RO groups belonging to the above first RO group set. method.

4. In claim 1, If the resources for the CFRA procedure are not set in the first RA setting information, the first RO group set is derived by the second RA setting information, and the time offset between the RO groups belonging to the first RO group set is indicated by the CBRA setting information. method.

5. In claim 4, The above first RA setting information includes mask information, and the validity of ROs belonging to the first RO group set is determined based on the mask information, and the Msg1 is transmitted from the valid RO(s) determined based on the mask information. method.

6. In claim 4, The time offset is selected based on the number of repetitions among a plurality of values ​​indicated by the first RA setting information or the second RA setting information. method.

7. In claim 1, At least a portion of the above first RA setting information shares at least a portion of the above second RA setting information, method.

8. In claim 1, The number of repetitions is determined based on the reception intensity section to which the measured reception intensity belongs, obtained by comparing the measured reception intensity with at least one threshold value. method.

9. In claim 1, The step of repeatedly transmitting the above Msg1 is performed to request system information from the base station. method.

10. As a method of base station for random access (RA) procedure, A step of transmitting first RA configuration information for a contention-free RA (CFRA) procedure or system information request and second RA configuration information for a contention-based random access (CBRA) procedure to a terminal; a step of transmitting a synchronization signal block (SSB) to the terminal; and A step of repeatedly receiving message 1 (Msg1) from the terminal according to a repetition number determined based on the reception strength of the SSB at the terminal in a first random access occasion (RO) group set determined by the first RA setting information and / or the second RA setting information, method.

11. In claim 10, The first RO group set is derived by the first RA setting information, and the first RO group set is composed of ROs independent of the ROs for the CBRA procedure set by the second RA setting information. method.

12. In claim 11, No time offset is applied between the RO groups belonging to the above first RO group set. method.

13. In claim 11, If the resources for the CFRA procedure are not set in the first RA setting information, the first RO group set is derived by the second RA setting information, and the time offset between the RO groups belonging to the first RO group set is indicated by the second RA setting information. method.

14. In claim 13, The above first RA setting information includes mask information, and the validity of ROs belonging to the first RO group set is determined based on the mask information, and the Msg1 is received from the valid RO(s) determined based on the mask information. method.

15. In claim 13, The time offset is selected based on the number of repetitions among a plurality of values ​​indicated by the first RA setting information or the second RA setting information. method.

16. In claim 13, At least a portion of the above first RA setting information shares at least a portion of the above second RA setting information, method.

17. A terminal performing a random access (RA) procedure includes at least one processor, wherein the at least one processor: A step of receiving first RA configuration information for a contention-free RA (CFRA) procedure or system information request and second RA configuration information for a contention-based random access (CBRA) procedure from a base station; A step of measuring the reception strength of a synchronization signal block (SSB) received from the base station; A step of determining the number of repetitions for transmitting message 1 (Msg1) based on the measured reception intensity; and In a first random access occasion (RO) group set determined by the first RA setting information and / or the second RA setting information, a step of repeatedly transmitting the Msg1 according to the determined repetition number is performed. Terminal.

18. In claim 17, The first RO group set is derived by the first RA setting information, and the first RO group set is composed of ROs independent of the ROs for the CBRA procedure set by the second RA setting information. Terminal.

19. In claim 17, If the resources for the CFRA procedure are not set in the first RA setting information, the first RO group set is derived by the second RA setting information, and the time offset between the RO groups belonging to the first RO group set is indicated by the second RA setting information. Terminal.

20. In claim 19, The above first RA setting information includes mask information, and the validity of ROs belonging to the first RO group set is determined based on the mask information, and the Msg1 is transmitted from the valid RO(s) determined based on the mask information. Terminal.

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