KR20250143701A - Random access method and apparatus for low-power communication - Google Patents

Abstract

A method of a terminal performing random access may include the steps of: receiving configuration information of a first PRACH resource including first PRACH occasions from a base station; receiving configuration information of a second PRACH resource including second PRACH occasions from the base station; receiving indication information indicating activation of the second PRACH resource from the base station; identifying an activation period in which the second PRACH resource is activated based on the indication information; and transmitting a preamble to the base station in at least one PRACH occasion among the first PRACH occasions and the second PRACH occasions in the activation period.

Description

Random access method and apparatus for low-power communication

The present invention relates to a method and device for random access in a mobile communication system, and more particularly, to a method and device for performing random access using a plurality of PRACH (physical random access channel) resources in order to reduce power consumption of a network in a mobile communication system.

Mobile communication systems, a core infrastructure driving the development of the ICT industry, are evolving to overcome the shortcomings and limitations of existing communication methods. They can provide advanced services in usage scenarios such as enhanced Mobile Broadband (eMBB), Ultra Reliable Low Latency Communication (URLLC), massive Machine Type Communication (mMTC), ultra-low power, ultra-precision, and ultra-wide coverage. Furthermore, to achieve various performance indicators, mobile communication systems are exploring new communication frequency bands in mid- and high-band and more actively utilizing multi-antenna technology.

While this may increase communication performance and the processing power of communication nodes, it also increases the power consumption of the communication nodes that make up the mobile communication system. In particular, recent global efforts to achieve carbon neutrality and reduce operating costs for telecommunications operators have led to a growing demand for technologies that reduce power consumption not only of terminals but also of networks, specifically base stations.

The purpose of the present invention to solve the above problems is to provide a method and device for performing random access using multiple PRACH resources in order to reduce power consumption of a network in a mobile communication system.

According to embodiments of the present invention for achieving the above object, a method of a terminal performing random access may include: receiving configuration information of a first physical random access channel (PRACH) resource including first PRACH occasions from a base station; receiving configuration information of a second PRACH resource including second PRACH occasions from the base station; receiving indication information indicating activation of the second PRACH resource from the base station; identifying an activation period in which the second PRACH resource is activated based on the indication information; and transmitting a preamble to the base station in at least one PRACH occasion among the first PRACH occasions and the second PRACH occasions in the activation period.

The configuration information of the first PRACH resource and the configuration information of the second PRACH resource may be included in the system information and received.

The above first PRACH occasions and the above second PRACH occasions may be associated with a common set of actually transmitted SSBs (synchronization signal blocks).

The association between the first PRACH occasions and the set of common actually transmitted SSBs may be independent of the association between the second PRACH occasions and the set of common actually transmitted SSBs.

The above instruction information can be received as included in downlink control information (DCI).

The above DCI may additionally include a paging message for the terminal.

The at least one PRACH occasion is a first PRACH occasion among the first PRACH occasions, and the one first PRACH occasion may overlap with one of the second PRACH occasions.

The at least one PRACH occasion is a first PRACH occasion of one of the first PRACH occasions, and the preamble may be retransmitted in a second PRACH occasion of one of the second PRACH occasions.

The transmission power of the preamble retransmitted in the one second PRACH occasion may be a transmission power obtained by applying power ramping to the transmission power applied to the preamble transmitted in the one first PRACH occasion.

Common PRACH transmission power related parameters may be applied to the first PRACH resource and the second PRACH resource.

According to embodiments of the present invention for achieving the above object, a method of a base station for random access of a terminal may include: transmitting configuration information of a first physical random access channel (PRACH) resource including first PRACH occasions to the terminal; transmitting configuration information of a second PRACH resource including second PRACH occasions to the terminal; transmitting indication information indicating activation of the second PRACH resource to the terminal; and receiving a preamble in at least one PRACH occasion among the first PRACH occasions and the second PRACH occasions from the terminal during an activation period of the second PRACH resource, the activation period of which is determined based on the indication information.

The configuration information of the first PRACH resource and the configuration information of the second PRACH resource may be included in the system information and transmitted.

The above first PRACH occasions and the above second PRACH occasions may be associated with a common set of actually transmitted SSBs (synchronization signal blocks).

The association between the first PRACH occasions and the set of common actually transmitted SSBs may be independent of the association between the second PRACH occasions and the set of common actually transmitted SSBs.

The at least one PRACH occasion is a first PRACH occasion among the first PRACH occasions, and the one first PRACH occasion may overlap with one of the second PRACH occasions.

The at least one PRACH occasion is a first PRACH occasion of one of the first PRACH occasions, and the preamble may be retransmitted in a second PRACH occasion of one of the second PRACH occasions.

The transmission power of the preamble retransmitted in the one second PRACH occasion may be a transmission power obtained by applying power ramping to the transmission power applied to the preamble transmitted in the one first PRACH occasion.

According to embodiments of the present invention for achieving the above object, a terminal for performing random access may include: at least one processor, and the at least one processor may cause the terminal to perform the steps of: receiving configuration information of a first physical random access channel (PRACH) resource including first PRACH occasions from a base station; receiving configuration information of a second PRACH resource including second PRACH occasions from the base station; receiving indication information indicating activation of the second PRACH resource from the base station; identifying an activation period in which the second PRACH resource is activated based on the indication information; and transmitting a preamble to the base station in at least one PRACH occasion among the first PRACH occasions and the second PRACH occasions in the activation period.

The above first PRACH occasions and the above second PRACH occasions may be associated with a common set of actually transmitted SSBs (synchronization signal blocks).

The association between the first PRACH occasions and the set of common actually transmitted SSBs may be independent of the association between the second PRACH occasions and the set of common actually transmitted SSBs.

Using embodiments of the present invention, multiple PRACH resources can be configured in a terminal, and some of the PRACH resources can be dynamically activated or deactivated based on network conditions. This reduces the load on the PRACH resources of a mobile communication system and reduces the power consumption of the mobile communication system, depending on network conditions.

Figure 1 is a conceptual diagram illustrating a first embodiment of a communication system.
Figure 2 is a block diagram illustrating a first embodiment of the device.
Figure 3a is a conceptual diagram illustrating the first multiplexing pattern of SSB and CORESET.
Figure 3b is a conceptual diagram illustrating a second multiplexing pattern of SSB and CORESET.
Figure 3c is a conceptual diagram illustrating the third multiplexing pattern of SSB and CORESET.
FIG. 4 is a conceptual diagram illustrating a first embodiment of a random access method based on an SSB-RO association.
FIG. 5 is a conceptual diagram illustrating a first embodiment of a PRACH resource setting method based on multiple PRACH resources.
FIG. 6 is a conceptual diagram illustrating a second embodiment of a PRACH resource setting method based on multiple PRACH resources.
FIG. 7 is a conceptual diagram illustrating a third embodiment of a PRACH resource setting method based on multiple PRACH resources.
FIG. 8 is a conceptual diagram illustrating a fourth embodiment of a PRACH resource setting method based on multiple PRACH resources.
FIG. 9a is a conceptual diagram illustrating a first embodiment of a method for allocating multiple PRACH resources overlapping in RO units.
FIG. 9b is a conceptual diagram illustrating a second embodiment of a method for allocating multiple PRACH resources overlapping in RO units.
FIG. 9c is a conceptual diagram illustrating a third embodiment of a method for allocating multiple PRACH resources overlapping in RO units.
FIG. 10 is a conceptual diagram illustrating a first embodiment of a method for determining a RAR window for multiple PRACH resources.
Fig. 11 is a conceptual diagram illustrating a second embodiment of a method for determining a RAR window for multiple PRACH resources.
FIG. 12 is a conceptual diagram illustrating a first embodiment of an SSB-RO mapping method for multiple PRACH resources.
FIG. 13 is a conceptual diagram illustrating a second embodiment of an SSB-RO mapping method for multiple PRACH resources.

The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the drawings. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

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 invention, 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 described herein or any one of multiple related items described herein.

In the embodiments of the present application, “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 the embodiments of the present application, “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.”

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.

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

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention 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 will not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

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

A communication system to which embodiments of the present invention are applied will be described. The communication system may be a 4G communication system (e.g., a long-term evolution (LTE) communication system, an LTE-A communication system), a 5G communication system (e.g., a new radio (NR) communication system), a 6G communication system, etc. The 4G communication system can support communication in a frequency band below 6 GHz, and the 5G communication system can support communication in a frequency band above 6 GHz as well as a frequency band below 6 GHz. The communication system to which embodiments of the present invention are applied is not limited to the contents described below, and the embodiments of the present invention can be applied to various communication systems. Here, the communication system may be used with the same meaning as a communication network, and “LTE” may indicate a “4G communication system,” an “LTE communication system,” or an “LTE-A communication system,” and “NR” may indicate a “5G communication system” or an “NR communication system.”

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. "A resource (e.g., a resource region) is set" may mean that setting information of the resource 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 RRC parameters and/or higher layer parameters), MAC control element (CE) signaling, or PHY signaling (e.g., transmission of downlink control information (DCI), uplink control information (UCI), and/or sidelink control information (SCI)).

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

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.

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 mean an apparatus or a device. The embodiments may be performed by a device or apparatus. The structure of the apparatus (e.g., device) may be as follows.

Figure 2 is a block diagram illustrating a first embodiment of the device.

Referring to FIG. 2, the device (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 device (200) may further include an input interface device (240), an output interface device (250), a storage device (260), etc. Each component included in the device (200) may be connected by a bus (270) and communicate with each other.

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 methods according to embodiments of the present invention 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).

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).

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.

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, on board unit (OBU), etc.

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.

Additionally, each of the plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2) may support 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.

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).

In a communication system (e.g., NR communication system, 6G communication system), the numerology applied to the physical signal and channel can be variable. The numerology can be variable to meet various technical requirements of the communication system. In a communication system to which CP (cyclic prefix)-based OFDM waveform technology is applied, the numerology can include subcarrier spacing and CP length (or CP type). Table 1 may be a first embodiment of a method for configuring a numerology for a CP-OFDM-based communication system. Adjacent subcarrier spacings can have a relationship of exponentiation of 2 with each other, and the CP length can be scaled at the same rate as the OFDM symbol length. At least some of the numerologies in Table 1 may be supported depending on the frequency band in which the communication system operates. In addition, the communication system may additionally support numerologies not listed in Table 1. Additional CP types (e.g., extended CP) not listed in Table 1 may be supported for specific subcarrier spacing (e.g., 60 kHz).

Table 1 relates to a first embodiment of a numerology configuration method for a CP-OFDM based communication system.

Below, the frame structure of a communication system will be described. In the time domain, elements that constitute the frame structure may include subframes, slots, mini-slots, and symbols. A subframe may be used as a unit for transmission, measurement, etc., and the length of a subframe may have a fixed value (e.g., 1 ms) regardless of the subcarrier spacing. A slot may include consecutive symbols (e.g., 14 OFDM symbols). The length of a slot may be variable, unlike the length of a subframe. For example, the length of a slot may be inversely proportional to the subcarrier spacing.

A slot can be used as a unit for transmission, measurement, scheduling, resource configuration, timing (e.g., scheduling timing, hybrid automatic repeat request (HARQ) timing, channel state information (CSI) measurement and reporting timing, etc.). The length of the actual time resource used for transmission, measurement, scheduling, resource configuration, etc. may not match the length of the slot. A minislot can include consecutive symbol(s), and the length of a minislot can be shorter than the length of a slot. A minislot can be used as a unit for transmission, measurement, scheduling, resource configuration, timing, etc. A minislot (e.g., minislot length, minislot boundary, etc.) can be predefined in a technical specification. Alternatively, a minislot (e.g., minislot length, minislot boundary, etc.) can be configured (or instructed) to a terminal. It can be configured (or instructed) to a terminal that a minislot is used when a specific condition is satisfied.

A base station can schedule a data channel (e.g., a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), or a physical sidelink shared channel (PSSCH)) using some or all of the symbols constituting a slot. In particular, a data channel can be transmitted using a portion of a slot for URLLC transmission, unlicensed band transmission, transmission in a situation where NR communication systems and LTE communication systems coexist, and multi-user scheduling based on analog beamforming. In addition, the base station can schedule a data channel using a plurality of slots. In addition, the base station can schedule a data channel using at least one mini-slot.

In the frequency domain, elements that constitute a frame structure may include resource blocks (RBs), subcarriers, etc. One RB may include consecutive subcarriers (e.g., 12 subcarriers). The number of subcarriers constituting one RB may be constant regardless of the numerology. In this case, the bandwidth occupied by one RB may be proportional to the subcarrier spacing of the numerology. An RB may be used as a transmission and resource allocation unit for data channels, control channels, etc. Resource allocation for a data channel may be performed in units of RBs or RB groups (e.g., resource block groups (RBGs)). One RBG may include one or more consecutive RBs. Resource allocation for a control channel may be performed in units of control channel elements (CCEs). In the frequency domain, one CCE may include one or more RBs.

In a communication system, a slot (e.g., a slot format) may be composed of a combination of one or more of a downlink (DL) interval, a flexible interval (or unknown interval), and an uplink (UL) interval. Each of the downlink interval, the flexible interval, and the uplink interval may be composed of one or more consecutive symbols. The flexible interval may be located between a downlink interval and an uplink interval, between a first downlink interval and a second downlink interval, between a first uplink interval and a second uplink interval, etc. When a flexible interval is inserted between a downlink interval and an uplink interval, the flexible interval may be used as a guard interval.

A slot may include one or more flexible periods. Alternatively, a slot may not include a flexible period. A terminal may perform a predefined operation in a flexible period. Alternatively, the terminal may perform an operation that is semi-statically or periodically configured by a base station in the flexible period. For example, the operation that is periodically configured by the base station may include a physical downlink control channel (PDCCH) monitoring operation, a synchronization signal/physical broadcast channel (SS/PBCH) block reception and measurement operation, a channel state information-reference signal (CSI-RS) reception and measurement operation, a downlink semi-persistent scheduling (SPS) PDSCH reception operation, a sounding reference signal (SRS) transmission operation, a physical random access channel (PRACH) transmission operation, a periodically configured physical uplink control channel (PUCCH) transmission operation, a PUSCH transmission operation according to a configured grant, etc. A flexible symbol may be overridden by a downlink symbol or an uplink symbol. When a flexible symbol is overridden by a downlink or uplink symbol, the terminal may perform a new operation instead of the existing operation on the flexible symbol (e.g., the overridden flexible symbol).

Meanwhile, in the present disclosure, SSB may refer to a set of signals including a synchronization signal and/or a broadcast channel. The synchronization signal may include PSS, SSS, etc., and the broadcast channel may include a physical broadcast channel (PBCH). In addition, the SSB may further include a reference signal. The reference signal may refer to a demodulation reference signal (DM-RS), a CSI-RS, a tracking reference signal (TRS), a positioning reference signal (PRS), a phase tracking reference signal (PT-RS), etc. for decoding the PBCH. In an NR communication system, the SSB may refer to a synchronization signal/physical broadcast channel (SS/PBCH) block. The SSB may be transmitted periodically, and one or more SSB(s) may be repeatedly transmitted in one period.

The format of a unit time resource (hereinafter referred to as "slot format") can be semi-statically configured by higher layer signaling (e.g., radio resource control (RRC) signaling). Information indicating a semi-static slot format can be included in system information, and the semi-static slot format can be configured cell-specifically. In addition, the semi-static slot format can be additionally configured for each terminal through terminal-specific higher layer signaling (e.g., RRC signaling). The flexible symbol of the cell-specifically configured slot format can be overridden with a downlink symbol or an uplink symbol by terminal-specific higher layer signaling. In addition, the slot format can be dynamically indicated by physical layer signaling (e.g., a slot format indicator (SFI) included in downlink control information (DCI)). A semi-statically configured slot format can be overridden by a dynamically indicated slot format. For example, a semi-statically configured flexible symbol can be overridden with a downlink symbol or an uplink symbol by the SFI.

A base station and a terminal can perform downlink operations, uplink operations, sidelink operations, etc. in a bandwidth part. A bandwidth part can be defined as a set of RBs (e.g., physical resource blocks (PRBs)) having a specific numerology. RBs constituting one bandwidth part can be contiguous in the frequency domain. One numerology can be used for signal transmission (e.g., transmission of a control channel or a data channel) in one bandwidth part. In embodiments, "signal" may refer to any physical signal and channel when used in a broad sense. A terminal performing an initial access procedure can obtain configuration information of an initial bandwidth part from a base station through system information. A terminal operating in an RRC connected state can obtain configuration information of a bandwidth part from a base station through terminal-specific upper layer signaling.

The configuration information of the bandwidth portion may include a numeral applied to the bandwidth portion (e.g., a subcarrier spacing and/or a CP length). In addition, the configuration information of the bandwidth portion may further include information indicating the position of a start RB (e.g., a start PRB) of the bandwidth portion and information indicating the number of RBs (e.g., PRBs) constituting the bandwidth portion. At least one of the bandwidth portion(s) configured for the terminal may be activated. For example, one uplink bandwidth portion and one downlink bandwidth portion may each be activated within one carrier. In a TDD (time division duplex) based communication system, a pair of uplink bandwidth portions and downlink bandwidth portions may be activated. The base station may configure multiple bandwidth portions for the terminal within one carrier and switch the active bandwidth portion of the terminal.

Meanwhile, in the embodiments, "a certain frequency band (e.g., a carrier, a bandwidth portion, a set of RBs, a listen before talk (LBT) subband, a guard band, etc.) is activated" may mean "a base station or a terminal is in a state where it can transmit and receive signals using the corresponding frequency band." In addition, "a certain frequency band is activated" may mean "a state where an RF (radio frequency) filter (e.g., a band-pass filter) of a transceiver is operating including the frequency band."

In embodiments, RB may mean CRB (common RB). Alternatively, RB may mean PRB or VRB (virtual RB). In a communication system, CRB may mean RB that constitutes a set of consecutive RBs (e.g., common RB grid) based on a reference frequency (e.g., point A). Carriers, bandwidth portions, etc. may be arranged on the common RB grid. That is, carriers, bandwidth portions, etc. may be configured as CRB(s). RBs or CRBs that constitute bandwidth portions may be referred to as PRBs, and within bandwidth portions, CRB indices may be appropriately converted to PRB indices. In embodiments, RB may mean IRB (interlace RB).

The PDCCH can be used to transmit DCI or a DCI format to a terminal. The minimum resource unit constituting the PDCCH can be a resource element group (REG). An REG can be composed of one PRB (e.g., 12 subcarriers) in the frequency domain and one OFDM symbol in the time domain. Therefore, one REG can include 12 resource elements (REs). A DM-RS (demodulation reference signal) for decoding (or demodulating) the PDCCH can be mapped to three of the 12 REs constituting the REG, and control information (e.g., modulated DCI) can be mapped to the remaining nine REs. One PDCCH candidate can be composed of one CCE or aggregated CCEs. One CCE can be composed of multiple REGs. The NR communication system can support CCE aggregation levels 1, 2, 4, 8, 16, etc., and one CCE can be composed of six REGs.

A CORESET (control resource set) may be a resource region in which a terminal performs blind decoding (or blind demodulation) of a PDCCH. A CORESET may be composed of multiple REGs. A CORESET may be composed of one or more PRBs in the frequency domain and one or more symbols (e.g., OFDM symbols) in the time domain. The symbols constituting a CORESET may be consecutive in the time domain. The PRBs constituting a CORESET may be consecutive or discontinuous in the frequency domain. One DCI (e.g., one DCI format, one PDCCH) may be transmitted within one CORESET. Multiple CORESETs may be configured from a cell perspective or a terminal perspective, and the multiple CORESETs may overlap each other in time-frequency resources.

CORESET can be set to the terminal by PBCH (e.g., system information transmitted through PBCH, MIB (master information block)). The ID (identifier) of the CORESET set by the PBCH can be 0. That is, the CORESET set by the PBCH can be referred to as CORESET #0. A terminal operating in an RRC idle state can perform a monitoring operation in CORESET #0 to receive the first PDCCH in the initial access procedure. Not only a terminal operating in an RRC idle state but also a terminal operating in an RRC connected state can perform a monitoring operation in CORESET #0. In addition to the system information transmitted through the PBCH, a CORESET can be set to the terminal by other system information (e.g., SIB1 (system information block type 1)). For example, in order to receive a random access response (or Msg2) in a random access procedure, the terminal can receive SIB1 including configuration information of the CORESET. Additionally, CORESET can be set to the terminal by terminal-specific higher layer signaling (e.g., RRC signaling).

A search space may be a set of PDCCH candidate(s) or a set of resource regions occupied by PDCCH candidate(s). A terminal may perform blind decoding on each PDCCH candidate within a predefined search space. The terminal may determine whether the PDCCH has been transmitted to itself by performing a cyclic redundancy check (CRC) on the blind decoding result. If the PDCCH is determined to be intended for the terminal, the terminal may receive the PDCCH.

One or more search spaces may constitute a search space set. The search spaces may be defined/configured for each CCE aggregation level, and the search space set may refer to a search space for each CCE aggregation level or a sum of search spaces for all CCE aggregation levels. For each CCE aggregation level, the PDCCH candidate may be composed of CCE(s) selected by a predefined hash function within a CORESET or a search space occasion. In an embodiment, the "search space set" may refer to a "search space."

A search space set may be logically associated with or correspond to one CORESET. One CORESET may be logically associated with or correspond to one or more search space sets. A search space set for transmitting common DCI or group common DCI may be referred to as a common search space set (hereinafter, "CSS set"). The common DCI or group common DCI may include at least one of resource allocation information of a PDSCH for transmitting system information, paging, a power control command, an SFI, or a preemption indicator. In the case of NR communication system, common DCI may correspond to DCI format 0_0, 1_0, etc., and the CRC (cyclic redundancy check) of the common DCI may be scrambled and transmitted by SI-RNTI (system information-radio network temporary identifier), P-RNTI (paging-RNTI), RA-RNTI (random access-RNTI), TC-RNTI (temporary cell-RNTI), etc. Group common DCI may correspond to DCI format 2_X (X=0, 1, 2, ??), etc., and the CRC of the group common DCI may be scrambled and transmitted by SFI-RNTI (slot format indicator-RNTI). The CSS set may include Type 0, Type 0A, Type 1, Type 2, and Type 3 CSS sets.

A search space set for transmitting UE-specific DCI may be referred to as a UE-specific search space set (hereinafter, "USS set"). The UE-specific DCI may include scheduling and resource allocation information such as PDSCH, PUSCH, and PSSCH. In the case of an NR communication system, the UE-specific DCI may correspond to DCI formats 0_1, 0_2, 1_1, 1_2, 3_0, and 3_1, and the CRC of the UE-specific DCI may be scrambled and transmitted using C-RNTI, CS-RNTI (configured scheduling-RNTI), MCS-C-RNTI (modulation and coding scheme-C-RNTI). Considering scheduling freedom or fallback transmission, the UE-specific DCI may also be transmitted in the CSS set. In this case, the UE-specific DCI may be transmitted according to a DCI format corresponding to the common DCI. For example, the terminal can monitor a PDCCH (e.g., DCI format 0_0, 0_1) whose CRC is scrambled with C-RNTI, CS-RNTI, MCS-C-RNTI, etc. in the CSS set.

A Type 0 CSS set can be used to receive DCI scheduling a PDSCH containing SIB1, and can be configured via PBCH or cell-specific RRC signaling. The ID of a Type 0 CSS set can be assigned or set to 0. A Type 0 CSS set can be logically combined with CORESET #0.

The terminal can assume that the PDCCH DM-RS has a QCL (quasi co-location) relationship with a certain signal (e.g., SSB, CSI-RS, PDSCH DM-RS, PDCCH DM-RS, etc.). The PDCCH DM-RS can refer to a DM-RS used for modulation and/or demodulation of the PDCCH. The PDSCH DM-RS can refer to a DM-RS used for modulation and/or demodulation of the PDSCH. Since the PDCCH has the same antenna port as the PDCCH DM-RS, the PDCCH and the PDCCH DM-RS can have a QCL relationship with each other. Through the QCL assumption, the terminal can obtain information about the large-scale propagation characteristics of the wireless channel experienced by the PDCCH and PDCCH DM-RS, and can utilize the large-scale propagation characteristics of the wireless channel for channel estimation, reception beamforming, etc. The QCL parameter may include at least one of a delay spread, a Doppler spread, a Doppler shift, an average gain, an average delay, or a spatial Rx parameter. The spatial Rx parameter may correspond to at least one characteristic of a receive beam, a receive channel spatial correlation, or a transmit/receive beam pair. The spatial Rx parameter may be referred to as "spatial QCL." The PDCCH may be used to mean including a PDCCH DM-RS. That the PDCCH has a QCL relationship with a certain signal may mean that the DM-RS of the PDCCH has a QCL relationship with the certain signal. A signal having a QCL relationship with the PDCCH or a resource of the signal may be referred to as a QCL source, a QCL source signal, a QCL source resource, etc.

PDCCHs transmitted in the same CORESET (e.g., a search space set corresponding to the same CORESET, a PDCCH monitoring occasion, etc.) may have the same QCL relationship. In other words, a unit of a set in which a UE assumes the same QCL may be a CORESET, and the QCL assumptions may be independent for each CORESET. In an embodiment, each of a QCL and a QCL source of a CORESET may mean the QCL and a QCL source of a PDCCH received through the corresponding CORESET. Exceptionally, different QCL assumptions may be applied to search space sets corresponding to a single CORESET. For example, a search space set for monitoring RA (random access)-RNTI (e.g., a type 1 CSS set) and a search space set other than the search space set may have different QCL relationships.

The QCL relationship or QCL assumption (e.g., QCL source, QCL type, etc.) of a CORESET can be determined by a predefined method. For example, a UE can assume that a PDCCH DM-RS received through a certain CORESET or a certain search space set has a QCL relationship with respect to an SSB and/or CSI-RS selected during an initial access or random access procedure and a predefined QCL type. A QCL type can mean a set of one or more QCL parameters. The QCL relationship or QCL assumption (e.g., QCL source, QCL type, etc.) of a CORESET can be signaled from a base station to a UE (e.g., RRC signaling, MAC (medium access control) CE (control element) signaling, DCI signaling, a combination of the above signaling, etc.). In other words, the base station can set a transmission configuration information (TCI) state for a CORESET to the UE. In general, a TCI state may include at least one of an ID of a signal having a QCL relationship with a DM-RS of a physical channel to which the TCI is applied (e.g., a PDCCH DM-RS) (e.g., a QCL source of the PDCCH DM-RS, a QCL source resource) or a QCL type for the signal. For example, a base station may configure one or more TCI state candidates for each CORESET to a terminal through RRC signaling, and may indicate (e.g., configure) one TCI state used for CORESET monitoring of the terminal among the one or more TCI state candidates through MAC signaling (or DCI signaling). If there is only one TCI state candidate configured by RRC signaling, the MAC signaling procedure (or DCI signaling procedure) may be omitted. The terminal may perform PDCCH monitoring and reception operations for the corresponding CORESET based on the TCI state configuration information received from the base station.

In the present disclosure, the TCI state may be conveniently referred to as TCI. While TCI may generally refer to a broad concept including a beam or signaling information corresponding to a beam, it may be conveniently used in the present disclosure in a meaning corresponding to a beam. A downlink TCI or a TCI for receiving a downlink signal may correspond to a reception beam, and an uplink TCI or a TCI for transmitting an uplink signal may correspond to a transmission beam. A transmission beam may refer to spatial relation information, a transmission spatial filter, etc.

A terminal may perform a synchronization signal block (SSB) reception operation to camp on a cell or make an initial connection. The terminal may assume that the SSB is transmitted based on a default period value (e.g., 20 ms) during the initial cell search process, and may subsequently receive the SSB period value (periodicity) through system information or an RRC (radio resource control) message. In an NR communication system, the maximum period value of the SSB may be 160 ms. Multiple SSBs may be repeatedly transmitted via multiple beams within one period, and the terminal may receive or attempt to receive the multiple SSBs based on different reception beams (or different QCL assumptions). The terminal may select one SSB with the highest reception quality among one or more SSB(s), and perform subsequent transmission and reception procedures based on the selected SSB (e.g., resources, beams, QCL assumptions, etc. of the selected SSB). The terminal may obtain some system information through the SSB. For example, SSB may include a physical broadcast channel (PBCH) as a component, and a terminal may obtain a master information block (MIB) through PBCH reception.

In addition, the terminal can receive additional system information (e.g., SIB1, SIBx) from the base station in addition to the above-mentioned partial system information (e.g., MIB). For example, the terminal can receive a PDSCH (i.e., SIB1 PDSCH) including a SIB (e.g., SIB1), and can monitor and receive a PDCCH including scheduling information of the PDSCH in a PDCCH search space set. Similar to SSB, the additional system information (e.g., SIB1, SIBx) can be transmitted periodically. For example, SIB1 can be transmitted based on a period value of 160 ms, and can be repeatedly transmitted several times within each period. The transmission period of SIB1 including repeated transmission can coincide with the SSB transmission period. That is, the terminal can monitor a CORESET (hereinafter referred to as a first CORESET) to which the PDCCH search space set is mapped with the same period as the SSB. For example, the first CORESET may be CORESET 0. Additionally, the PDCCH search space set may be a Type 0 PDCCH CSS set.

The first CORESET and/or the PDCCH search space set may be configured through some system information (e.g., MIB). For example, the MIB may include configuration information of CORESET 0 and a type 0 PDCCH CSS set, and the PDCCH may be monitored in the type 0 PDCCH CSS set. Since the SIB is cell-specific information, the configuration information may be included in common DCI (e.g., DCI format 1_0) and transmitted through the PDCCH. The CRC of the common DCI may be scrambled by an RNTI (e.g., SI (system information)-RNTI) predefined in a technical specification and transmitted through the PDCCH. The PDCCH and/or the PDSCH may be received based on a QCL relationship with the received SSB.

Fig. 3a is a conceptual diagram illustrating a first multiplexing pattern of SSB and CORESET, Fig. 3b is a conceptual diagram illustrating a second multiplexing pattern of SSB and CORESET, and Fig. 3c is a conceptual diagram illustrating a third multiplexing pattern of SSB and CORESET.

Referring to FIGS. 3A to 3C, the SSB and the CORESET can be multiplexed in several forms. In FIGS. 3A to 3C, the CORESET can refer to the first CORESET or the SIB1 CORESET. Referring to FIG. 3A, the CORESET can be time division multiplexed (TDM) with the corresponding SSB. At this time, the PDSCH including the SIB1 can be multiplexed with the corresponding SSB in one of the forms of TDM, FDM, and a combination of TDM and FDM. This can be referred to as the first multiplexing pattern. Referring to FIG. 3B, the CORESET can be TDM with the corresponding SSB, and the SIB1 PDSCH can be frequency division multiplexed (FDM) with the corresponding SSB. That is, the CORESET can be mapped to symbols different from the SSB, and the SIB1 PDSCH can be mapped to symbols similar to the SSB. This may be referred to as a second multiplexing pattern. Referring to FIG. 3c, the CORESET and SIB1 PDSCH may be FDM'd with the corresponding SSB. That is, the CORESET and SIB1 PDSCH may be mapped to symbols such as SSB. This may be referred to as a third multiplexing pattern. The multiplexing pattern supported by the terminal may vary depending on the frequency band or the subcarrier spacing applied to the SSB and CORESET. The first multiplexing pattern may be used for a wider frequency range and more diverse subcarrier spacing than the second and third multiplexing patterns.

In the present disclosure, a base station may refer to a base station that manages cell(s), or may refer to any cell(s) included in a base station. Conversely, a cell may refer to a cell included in a base station, or may refer to a base station that includes a cell and manages the cell. For example, when a terminal transmits a signal to or receives a signal from a cell, it may mean that the terminal exchanges signals with a base station that includes the cell. The cell may refer to a cell that performs communication with the terminal, a cell that the terminal has camped on or is attempting an initial connection to, etc. For a terminal in RRC idle/inactive mode, a cell may refer to a cell that the terminal has camped on or is likely to camp on. In addition, for a terminal in RRC connected mode, a cell may refer to a serving cell, a neighboring cell, a cell that performs RRM measurements, a cell that the terminal has connected to or maintains a connected state, a carrier, etc. A terminal that communicates with a base station in the present disclosure may include a terminal in RRC active mode, an RRC idle mode, or an RRC inactive mode. In particular, the random access procedure described in the present disclosure can be performed by both a terminal in RRC idle/inactive mode and a terminal in RRC connected mode.

A terminal may perform a random access procedure to access a camped cell. The random access procedure between the terminal and the base station may consist of four steps. The terminal may transmit Msg1 PRACH to the base station in the first step, receive Msg2 PDCCH/PDSCH including a random access response (RAR) in the second step, transmit Msg3 PUSCH in the third step, and receive Msg4 PDCCH/PDSCH in the fourth step. Alternatively, a two-step random access procedure may be used for rapid random access. The terminal may transmit MsgA PRACH and MsgA PUSCH to the base station in the first step, and receive MsgB PDCCH/PDSCH in the second step. In the first stage, if multiple terminals transmit the same preamble to the same PRACH resource, resulting in a contention, the contention can be resolved by the terminal obtaining a contention resolution message transmitted by the base station during the Msg4 PDSCH reception stage of the fourth stage or the MsgB PDSCH reception stage of the second stage. For example, the contention resolution message may include a higher layer terminal ID (e.g., temporary mobile subscriber identities (TMSI)).

The PRACH resource used for the above Msg1/MsgA transmission may include one or more PRACH occasion(s) and may be arranged in a periodic and repetitive manner. In the present disclosure, the PRACH occasion may be conveniently referred to as a random access occasion (RO). In a multi-beam-based communication system, the PRACH resource may be composed of a plurality of ROs, and the ROs may be multiplexed and mapped to physical resources based on an FDM and/or TDM scheme within a PRACH resource period. The ROs are interrelated with SSBs. The terminal may select one RO based on the SSB-RO association and transmit a PRACH preamble in the selected RO.

FIG. 4 is a conceptual diagram illustrating a first embodiment of a random access method based on an SSB-RO association.

Referring to FIG. 4, a base station can transmit an SSB four times repeatedly using four transmit beams, and can monitor a PRACH in four ROs using four corresponding receive beams. At this time, a correlation relationship can be established between the SSBs and the ROs. According to the present embodiment, an SSB and an RO can correspond one-to-one, and SSB #0 to #3 can be correlated with ROs #0 to #3, respectively. A terminal can transmit a PRACH in an RO correlated with a received optimal SSB (or SSB resource). The terminal can select SSB #1 as the optimal SSB, and can transmit a PRACH in RO #1 correlated with SSB #1.

Meanwhile, network energy saving (NES) technology, a low-power operation technology for the network, can be considered as a method for improving the energy efficiency of communication systems. The network (i.e., base station) can maintain a low-power state by periodically or opportunistically entering a sleep mode where it does not perform transmission or reception operations. The network's power consumption can be reduced in proportion to the time the base station remains in sleep mode.

In the random access procedure described above, the base station must periodically monitor the preamble on the configured PRACH resource to detect the initial access attempt of the terminal. At this time, the PRACH period is set semi-fixed. If the PRACH period is set too short, the base station must frequently wake up from sleep mode to operate the receiver, which may increase the base station's power consumption. On the other hand, if the PRACH period is set excessively long for NES, frequent collisions may occur during the preamble transmission phase when multiple terminals attempt initial access, and the terminal's random access delay may increase. To address the above-described problems, the present disclosure proposes a random access method that supports smooth initial access of the terminal while simultaneously enabling low-power operation of the network.

The proposed method can be performed based on multiple PRACH resources. The terminal can receive configuration information regarding the multiple PRACH resources from the base station. For example, the multiple PRACH resources can include a first PRACH resource and a second PRACH resource. In this case, the category or capability of the terminal can be divided into a legacy terminal and a terminal supporting an enhanced random access method. The latter terminal can be conveniently referred to as a NES terminal. In an embodiment, the first PRACH resource can be a resource applicable to both the legacy terminal and the NES terminal, and the second PRACH resource can be a resource applicable only to the NES terminal. The first PRACH resource can be semi-statically configured based on the legacy PRACH configuration information. The second PRACH resource can be configured additionally in addition to the first PRACH resource.

In the present disclosure, the first PRACH resource and the second PRACH resource may be configured by the first PRACH configuration and the second PRACH configuration, respectively. Each PRACH configuration may include parameters required for PRACH resource mapping and preamble transmission. For example, each PRACH configuration may include parameters regarding a PRACH configuration index, a PRACH root sequence index, zeroCorrelationZoneConfig, restrictedSetConfig, initial preamble transmission power, whether Msg1 is FDM, a frequency starting point of Msg1, a maximum number of preamble transmissions, and the like. The first PRACH configuration and the second PRACH configuration may be configured as RRC messages and may be transmitted to a terminal by an RRC signaling procedure.

The second PRACH resource can be dynamically turned on and off or activated and deactivated depending on the initial access load of the cell. When the initial access load is low, the second PRACH resource can be turned off or deactivated. The random access procedure of the terminal can depend solely on the first PRACH resource, and the UL signal reception interval of the base station can be minimized. On the other hand, when the initial access load is high, the second PRACH resource can be turned on or activated, and the random access attempts of multiple terminals can be distributed across the first and second PRACH resources and performed stably. Depending on the arrangement of the second PRACH resource, the base station can still maintain low-power operation. In the embodiments below, the specific operations of the proposed method will be described.

[PRACH resource setup and Msg1/MsgA transmission method]

FIG. 5 is a conceptual diagram illustrating a first embodiment of a PRACH resource configuration method based on a plurality of PRACH resources, FIG. 6 is a conceptual diagram illustrating a second embodiment of a PRACH resource configuration method based on a plurality of PRACH resources, FIG. 7 is a conceptual diagram illustrating a third embodiment of a PRACH resource configuration method based on a plurality of PRACH resources, and FIG. 8 is a conceptual diagram illustrating a fourth embodiment of a PRACH resource configuration method based on a plurality of PRACH resources.

Referring to FIGS. 5 to 8, a terminal may be configured with a first PRACH resource and a second PRACH resource for random access. The first PRACH resource and the second PRACH resource may be repeatedly arranged according to their respective configured periodicities. The NES terminal may transmit a PRACH preamble in an RO belonging to either the first PRACH resource or the second PRACH resource and initiate a random access procedure. Alternatively, the NES terminal may transmit a PRACH preamble using both an RO belonging to the first PRACH resource (hereinafter referred to as the first RO) and an RO belonging to the second PRACH resource (hereinafter referred to as the second RO). For example, the terminal may repeatedly transmit a PRACH preamble using the first RO and the second RO. For another example, the terminal may initially transmit (or retransmit) a PRACH in the first RO (or the second RO), and if reception of the corresponding RAR fails, may retransmit the PRACH in the second RO (or the first RO).

Referring to FIG. 5, the second PRACH resource may be mapped to a different time resource (e.g., different symbol(s) and/or different slot(s)) than the first PRACH resource. That is, the first PRACH resource and the second PRACH resource may be TDM'd. Referring to FIG. 6, the second PRACH resource may be mapped to a different frequency domain (e.g., different RB(s) and/or different subband(s)) than the first PRACH resource in the same time resource (e.g., same slot(s) and/or same symbol(s)). That is, the first PRACH resource and the second PRACH resource may be FDM'd.

In the above embodiments, the same period value may be applied to the first PRACH resource and the second PRACH resource. More specifically, the period value of the first PRACH resource and the period value of the second PRACH resource are set by separate signaling, but the period values may be stipulated to have the same value. For example, the value of parameter x indicated by the PRACH configuration index included in the first PRACH configuration and the value of parameter x indicated by the PRACH configuration index included in the second PRACH configuration may be identical. The value of parameter x may be a value corresponding to 1/10 of the actual PRACH period value. Alternatively, the period value of the second PRACH resource may not be separately signaled to the terminal, and the period value of the first PRACH resource may be applied to the second PRACH resource as is. For example, the first PRACH configuration and the second PRACH configuration may share the same PRACH configuration index, and the value of parameter x (i.e., PRACH period value) indicated by the same PRACH configuration index may be commonly applied to the first PRACH resource and the second PRACH resource.

The first PRACH resource and the second PRACH resource may not only have the same periodic value, but may also share a common periodicity. That is, the length and starting point of each PRACH period may be consistent between the first PRACH resource and the second PRACH resource. Within the common periodicity, the first PRACH resource and the second PRACH resource may be distinguished by different time offsets (e.g., subframe offset, slot offset, symbol offset) and/or different frequency offsets (e.g., RB offset, subband offset). For example, the y value, subframe number, start symbol, etc. indicated by the PRACH configuration index of the second PRACH configuration may be set to different values from the values indicated by the PRACH configuration index of the first PRACH configuration, thereby applying a different time offset to the second PRACH resource than to the first PRACH resource. Additionally or alternatively, a separate parameter may be defined for applying an additional time offset to the PRACH resource. The above parameter may include information indicating at least one of a subframe offset, a slot offset, and a symbol offset, and may be included in the PRACH configuration information. More specifically, the parameter may be added to a PRACH configuration table, and the parameter may be indicated by a PRACH configuration index. The parameter may be applied only to a certain PRACH resource (e.g., a second PRACH resource). Accordingly, the second PRACH resource may be arranged more flexibly temporally, and the above advantage may be maximized in a TDD system using an asymmetric (unpaired) frequency band.

Alternatively, the period of the second PRACH resource may not coincide with the period of the first PRACH resource, and may start at a time point that temporally shifts the period of the first PRACH resource. That is, the starting point of the second PRACH resource period may not coincide with the starting point of the first PRACH resource period. The y value, subframe number, start symbol, etc. indicated by the PRACH configuration index of the second PRACH configuration may be set to different values from the values indicated by the PRACH configuration index of the first PRACH configuration, so that the starting point of the period of the second PRACH resource and the starting point of the period of the first PRACH resource may be set differently. In this case, the value of the parameter x indicating the period value of the first PRACH resource according to the first PRACH configuration and the value of the parameter x indicating the period value of the second PRACH resource according to the second PRACH configuration may be the same. In this case as well, an additional time offset may be applied to the second PRACH resource based on the separate parameter.

According to the previous embodiments, the second PRACH resource may be adjacent to or overlap with the first PRACH resource in the time domain. Therefore, the base station can monitor both the first and second PRACH resources with a single wake-up and, if no preamble is detected, re-enter a long sleep period. Therefore, it is possible to increase PRACH capacity while minimizing the additional power consumption of the base station due to monitoring the second PRACH resource.

Referring to FIG. 7, the second PRACH resource can be TDM'd with the first PRACH resource. However, unlike the first embodiment, in the present embodiment, the second PRACH resource can be arranged as far as possible from the first PRACH resource. For example, the second PRACH resource can be mapped in the middle of two first PRACH resources arranged in two consecutive periods. This can be possible by appropriately setting the PRACH resource configuration parameters described above. Consequently, the entire PRACH resources can be temporally distributed, and according to the method, the wake-up frequency of the base station increases due to the additional configuration of the second PRACH resource, but from the perspective of the NES terminal, the repetition period of the entire PRACH resources can be halved, and the random access delay time of the NES terminal can be shortened.

Referring to FIG. 8, the second PRACH resource may overlap with the first PRACH resource. For example, the period value of the second PRACH resource may be set to 1/4 of the period value of the first PRACH resource, and every fourth second PRACH resource may overlap with the first PRACH resource. Depending on the frequency domain arrangement of the first PRACH resource and the second PRACH resource, the first PRACH resource and the second PRACH resource may overlap only in time, or may overlap in the time-frequency domain (i.e., may share REs (resource elements)). Hereinafter, the RO(s) belonging to the first PRACH resource may be referred to as the first RO(s), and the RO(s) belonging to the second PRACH resource may be referred to as the second RO(s). Meanwhile, in order for the preamble transmitted in the first RO and the preamble transmitted in the second RO to be distinguished at the base station, the orthogonality or near-orthogonality between the first RO and the second RO must be maintained, and therefore, it is preferable that the first RO and the second RO do not overlap at all or overlap completely. The complete overlap of the first RO and the second RO in the time domain may mean that the symbol(s) and RB(s) to which the first RO is mapped are identical to the symbol(s) and RB(s) to which the second RO is mapped, and the root sequence, PRACH format, etc. of the first RO are identical to the root sequence, PRACH format, etc. of the second RO. In other words, the overlapping first RO and the second RO may completely overlap at least in the time domain. A necessary condition for this may include at least that the first RO and the second RO are set to the same PRACH format. Meanwhile, the first RO and the second RO may completely overlap or not overlap at all in the frequency domain. Alternatively, in the frequency domain, the first RO and the second RO may be allowed to partially overlap. The first RO may be mapped to a resource region including some of the RBs to which the second RO is mapped. In this case, the transmission power applied to the first RO and the second RO may be determined by each PRACH configuration and power ramping operation regardless of whether they overlap. The terminal may not expect that the configured first RO and second RO partially overlap. In addition, if at least some of the first ROs belonging to the first PRACH resource overlap with at least some of the second ROs belonging to the second PRACH resource, the preamble of the first PRACH resource may be generated from the same sequence length and the same root sequence as the preamble of the second PRACH resource.

FIG. 9a is a conceptual diagram illustrating a first embodiment of a method for allocating a plurality of PRACH resources overlapping in RO units, FIG. 9b is a conceptual diagram illustrating a second embodiment of a method for allocating a plurality of PRACH resources overlapping in RO units, and FIG. 9c is a conceptual diagram illustrating a third embodiment of a method for allocating a plurality of PRACH resources overlapping in RO units.

Referring to FIGS. 9A to 9C , the first PRACH resource and the second PRACH resource configured in the terminal may each include four ROs. The first RO(s) and the second RO(s) may completely overlap or not overlap at all using the method described above. That is, the first PRACH resource and the second PRACH resource may overlap in units of ROs in the time domain and/or frequency domain.

In the proposed method, beams of a first RO and a second RO that overlap each other can be aligned. That is, a first RO and a second RO that overlap temporally, or a first RO and a second RO that completely overlap in the time-frequency domain, can be correlated to the same SSB, and a transmit beam of a preamble transmitted in the first RO and the second RO can be determined based on a receive beam of the same SSB. Alternatively, if beam correspondence does not exist between an SSB and a PRACH, at least a transmit beam applied to the second RO can be identical to a transmit beam applied to the first RO. The ROs can be valid ROs. That is, if the overlapping first RO and the second RO are correlated to different SSBs, both of the ROs can be considered invalid. Alternatively, if the overlapping first RO and the second RO are correlated to different SSBs, any one of the ROs determined by a priority rule can be considered invalid.

Referring to FIG. 9A, four first ROs may be interrelated with four SSBs in ascending order of index, and four second ROs may be interrelated with four SSBs in ascending order of index. At this time, the first RO and the second RO interrelated with the same SSB may overlap with each other. For example, the first RO #0 (i.e., the first RO having an index of 0) and the second RO #0 (i.e., the second RO having an index of 0) interrelated with SSB #0 may overlap. All of the four first ROs and the four second ROs may be regarded as valid ROs. At this time, the resource configurations of the first PRACH resource and the second PRACH resource may be the same, and the same SSB-RO mapping rule may be applied to the first PRACH resource and the second PRACH resource. As a result, the same SSB(s) may be mapped to the overlapping first RO and the second RO.

Referring to FIG. 9b, among the four first ROs, the first RO #0 (i.e., the first RO having an index of 0) may be determined to be invalid, and the remaining three valid ROs, the first RO #1, the first RO #2, and the first RO #3 (i.e., the first ROs having indices of 1, 2, and 3), may be correlated with SSBs #0 to SSB #2, respectively. In addition, the four valid second ROs may be correlated with the four SSBs, respectively. Similarly, the first RO and the second RO that are correlated with the same SSB may overlap with each other. For example, the first RO #1 (i.e., the first RO having an index of 1) and the second RO #0 (i.e., the second RO having an index of 0) that are correlated with SSB #0 may overlap. In the above embodiments, the multiple overlapping ROs may be valid ROs. In other words, a valid first RO and a valid second RO may overlap (or completely overlap) with each other. The terminal may select one of the multiple overlapping ROs and transmit a PRACH in the selected RO. For example, the terminal may select the first RO, i.e., the RO belonging to the first PRACH resource. The terminal may select the first RO and transmit a PRACH in the first RO not only when the first RO and the second RO completely overlap but also when they partially overlap.

Referring to FIG. 9c, the four first ROs can be correlated with the four SSBs in ascending order of index, and the four second ROs can be correlated with the four SSBs in ascending order of index. At this time, the first RO #2 (i.e., the first RO with an index of 2) and the second RO #0 (i.e., the second RO with an index of 0) can be correlated with different SSBs, i.e., SSB #2 and SSB #0, respectively. Therefore, the overlapping of the first RO #2 and the second RO #0 as illustrated in FIG. 9c may be considered an incorrect configuration. The terminal may ignore the configuration or not expect the configuration. Alternatively, the terminal may consider only one of the first RO #2 and the second RO #0 to be valid, and may transmit the PRACH using the valid RO. That is, the valid RO may override the non-valid RO. In other words, the invalid first RO and the valid second RO may overlap each other, and only the second RO may be used for PRACH transmission. Alternatively, the terminal may consider the first RO to be valid and transmit the PRACH based on the first RO. In addition, the terminal may consider only one of the first PRACH resource and the second PRACH resource to be available. The valid RO may be determined by the priority between the first PRACH resource and the second PRACH resource.

In another embodiment, the mapping between SSBs and ROs for the first PRACH resource and/or the mapping between SSBs and ROs for the first PRACH resource may be performed based on the overlap between the first RO(s) and the second RO(s). That is, when performing the task of interrelating ROs constituting the PRACH resource with SSBs (e.g., valid SSBs), at least some of the ROs overlapping with other PRACH resources may not be mapped to SSBs. The terminal may interrelate the remaining ROs with SSBs in ascending order of index according to the method described above, excluding the ROs.

As described above, the first PRACH resource can be configured in the terminal by a conventional RRC configuration message (e.g., RACH-ConfigCommon IE, RACH-ConfigDedicated IE). In this case, the configuration information of the second PRACH resource can be defined in a separate RRC message. The configuration information of the second PRACH resource can be defined in a terminal-specific RRC message and transmitted to the terminal that maintains the RRC connection state. However, according to this method, it is impossible for the NES terminal camping on the cell to perform an initial access procedure based on the proposed random access method. Therefore, a method of including the configuration information of the second PRACH resource in the SIB and broadcasting it in the coverage area of the cell can be considered. For example, the configuration information of the second PRACH resource can be included in the RACH-ConfigCommon IE, which can be further included in the ServingCellConfigCommon IE and transmitted to the terminal as a part of SIB1. The above SIB may be transmitted by being included in a PDSCH, and the PDSCH may be scheduled by common DCI (e.g., DCI with CRC scrambled by SI-RNTI and/or DCI format 1_0). The common DCI may be monitored in a type 0-PDCCH CSS set.

Alternatively, the configuration information of the second PRACH resource may be broadcast as system information or other broadcast information other than SIB. In this case, the PDSCH including the configuration information of the second PRACH resource may be scheduled by the first DCI. The first DCI may likewise be a common DCI or a group common DCI. The first DCI may be a DCI in which the PDCCH including the first DCI has a CRC scrambled by SI-RNTI and its purpose is distinguished from legacy SIB transmission by a specific field in the first DCI payload. Alternatively, the first DCI may be transmitted via a PDCCH, and the PDCCH may be a PDCCH in which a CRC (i.e., the CRC of the PDCCH) is scrambled by a different RNTI. By the above-described method, the terminal can distinguish the first DCI from the DCI for SIB transmission, and can obtain the second PRACH resource configuration information by expecting that the PDSCH scheduled through the first DCI will include the second PRACH resource configuration information.

The PDSCH including the configuration information of the second PRACH resource may further include other configuration information. For example, the terminal may perform an operation of requesting transmission of SSB or SIB1 by transmitting an UL WUS (wake-up signal) to the base station (or cell). At this time, the configuration information required for transmission of the UL WUS may be included in the PDSCH together with the configuration information of the second PRACH resource and transmitted to the terminal. The UL WUS may be transmitted based on the second PRACH resource. For example, a PRACH preamble included in the second PRACH resource may be used as the UL WUS, and the UL WUS may be transmitted to the base station (or cell) through the second PRACH resource (i.e., an RO belonging to the second PRACH resource).

When the first PRACH configuration message and the second PRACH configuration message are separated, the lower configuration parameters included in the PRACH configuration message can be independently configured between the first PRACH configuration and the second PRACH configuration. In this case, parameters for some configurations (e.g., PRACH configuration index, sequence length, root sequence, PRACH format, subcarrier spacing, power control parameters, etc.) may not be included in the second PRACH configuration message, and for some of the configurations, the values of the parameters of the first PRACH configuration message may be used as default values.

Alternatively, a conventional RRC configuration message for PRACH configuration (e.g., RACH-ConfigCommon IE, RACH-ConfigDedicated IE) may be extended, and the first PRACH resource and the second PRACH resource may be configured together based on the extended RRC configuration message. That is, the extended RRC configuration message may include both the first PRACH configuration information and the second PRCH configuration information. In this case, some of the lower configuration parameters included in the extended message (e.g., parameters for PRACH period, RO arrangement, etc.) may be configured in multiple numbers, and the multiple parameters may be applied to the multiple PRACH resources, respectively. In addition, other some of the configuration parameters (e.g., parameters for PRACH configuration index, preamble sequence length, root sequence, PRACH format, subcarrier spacing, power control, etc.) may be configured in single numbers, and one parameter may be commonly applied to the multiple PRACH resources.

A method for assigning priorities among multiple PRACH resources configured in a terminal may be considered. From an NES perspective, the primary purpose of configuring multiple PRACH resources (i.e., additional PRACH resources) in a terminal is to dynamically offload random access load. When multiple legacy terminals camped on a cell attempt to access using the first PRACH resource, the NES terminal can distribute the load on the first PRACH resource by preferentially attempting to access using the second PRACH resource. Accordingly, the terminal can assign a higher priority to the second PRACH resource than the first PRACH resource and transmit Msg1/MsgA preferentially on the second PRACH resource.

The above-described priority-based PRACH transmission method can be implemented under certain conditions. For example, when the time offset between the first PRACH resource (or the first RO(s)) and the second PRACH resource (or the second RO(s)) is less than or equal to a reference value, the terminal can select one PRACH resource (or RO) by applying the priority, and transmit a preamble in the selected PRACH resource (or RO). In an embodiment, the time offset can be realized in the form of a time window (e.g., a sliding window). For example, when the terminal moves the sliding window and both the first PRACH resource (or the first RO(s), the slot(s) to which the first PRACH resource belongs) and the second PRACH resource (or the second RO(s), the slot(s) to which the second PRACH resource belongs) are included within the sliding window, the above-described priority-based method can be applied. For another example, if the first PRACH resource (or the first RO(s)) and the second PRACH resource (or the second RO(s)) are mapped to the same slot (or a set of slots) or overlap each other, the above priority application method may be applied. This may be interpreted as a case where the sliding window is a slot (or a set of slots). The overlap may include a partial overlap and a complete overlap. The reference value of the time offset or the configuration information regarding the length of the time window may be signaled to the terminal.

Contrary to the above-described method, the terminal may give a higher priority to the first PRACH resource and transmit the PRACH preferentially on the first PRACH resource. Alternatively, the priority among the PRACH resources may be determined based on the time point at which the PRACH transmission is triggered by the upper layer of the terminal and the time resource region to which the PRACH resources are mapped. For example, the terminal may transmit the preamble on the earliest PRACH resource (or the corresponding earliest RO) that appears after the time point at which the preamble transmission is triggered by the upper layer (or after a predetermined time value has elapsed from the trigger time point).

In the above embodiment, if the PRACH configuration index of the first PRACH resource (or the first RO(s)) is set to a different value from the PRACH configuration index of the second PRACH resource (or the second RO(s)), the priority application method may be implemented. Alternatively, if the first PRACH resource (or the first RO(s)) and the second PRACH resource (or the second RO(s)) have the same PRACH configuration index, i.e., if the first PRACH resource (or the first RO(s)) and the second PRACH resource (or the second RO(s)) are multiplexed or at least partially overlap in the frequency domain, the terminal may select one PRACH resource (or corresponding RO) according to the priority rule and transmit a preamble on the selected resource.

The priority of PRACH resources can be set to the terminal by a signaling procedure from the base station. The base station can selectively instruct the terminal through PRACH resource priority setting information to assign a higher priority to the first PRACH resource, to assign a higher priority to the second PRACH resource, to assign a priority according to a predetermined rule, or to assign no priority (or to apply the same priority to the first PRACH resource and the second PRACH resource). If the first PRACH resource and the second PRACH resource are not assigned a priority or are assigned the same priority, the terminal can select either the first PRACH resource and the second PRACH resource arbitrarily or according to a predetermined rule and perform an initial access procedure. Alternatively, the terminal can be instructed to use only one PRACH resource among a plurality of PRACH resources. Likewise, the terminal may be instructed to turn off or deactivate the remaining PRACH resources except for one of the above-mentioned PRACH resources, and may use only one of the above-mentioned PRACH resources in a random access procedure based on the above-mentioned instruction. The above-mentioned configuration information may be included in the above-mentioned PRACH configuration message.

The priority between PRACH resources can be maintained without change within a random access procedure. That is, if a terminal initially transmits a preamble on a second PRACH resource (or a first PRACH resource), it can transmit a retransmission preamble on the second PRACH resource (or a first PRACH resource) within the same random access procedure. Alternatively, the priority between PRACH resources can be changed within a random access procedure. For example, the priority between PRACH resources can be determined differently (or independently) for each preamble transmission step (or power ramping step) within the same random access procedure. The PRACH resource on which the initial transmission preamble is transmitted and the PRACH resource on which the retransmission preamble is transmitted can be different. Different rules for determining priorities can be applied to each transmission step. For example, the PRACH resource through which the initial transmission preamble is transmitted may be determined based on a priority set by the base station, and the PRACH resource through which the retransmission preamble is transmitted may be determined based on a predefined rule.

The PRACH resource selection and preamble transmission method according to the above-described priority rule can be applied when both the first PRACH resource and the second PRACH resource are available or both are activated. For example, the method can be applied when the first PRACH resource and the second PRACH resource are set to the terminal and at the same time, the second PRACH resource is indicated to the terminal as being available or activated. In other words, the method can be applied in a section in which the second PRACH resource is activated. In addition, the priority can be applied on a PRACH resource basis. In the case where the first PRACH resource and the second PRACH resource overlap each other and the first PRACH resource is selected as a preamble transmission resource according to the priority, all ROs constituting the first PRACH resource can have a higher priority than all ROs constituting the second PRACH resource. In addition, all ROs constituting the second PRACH resource can be dropped. The terminal may not transmit a preamble in any of the ROs belonging to the second PRACH resource. Alternatively, some ROs belonging to the second PRACH resource that satisfy a predetermined condition may be used for the terminal's preamble transmission. The predetermined condition may include a condition that does not overlap with the ROs of the first PRACH resource.

Among the ROs constituting the second PRACH resource, RO(s) that satisfy certain conditions may be considered valid ROs. Only valid RO(s) may have a correlation with SSB(s) and may be used for preamble transmission. For example, an RO that does not precede an SSB in a slot to which the second PRACH resource is mapped may be considered a valid RO. Simultaneously or separately, an RO that has a time gap of at least N symbol(s) with the SSB and/or the last DL symbol immediately preceding the RO may be considered a valid RO. In addition, a valid RO may have a time gap of at least M symbol(s) with other uplink resources (e.g., PUSCH, PUCCH, SRS). N and M may be integers greater than or equal to 0, and may be determined by the subcarrier spacing, frequency band, etc. applied to the PRACH preamble or may be set by the base station. In an embodiment, N may be 0 for a specific subcarrier spacing of the PRACH preamble. In another embodiment, N may be 2.

In addition, a time gap may be provided for determining the validity of the RO of the first PRACH resource and the RO of the second PRACH resource. For example, if the time gap between the first RO and the second RO is less than or equal to a threshold value, at least one RO of the first RO and the second RO may be considered invalid. At this time, the valid RO may be determined by the priority rule described above. The time gap may be defined in the technical specification as L1 symbol(s) and/or L2 slot(s) or may be set by the base station. The method described above may be applied when the first PRACH resource and the second PRACH resource do not overlap. Alternatively, the method described above may be applied when the first PRACH resource and the second PRACH resource are used for random access for different cells or different TRPs, or when the first PRACH resource and the second PRACH resource are associated with different timing advances (TAs) or timing advance groups (TAGs).

For a terminal performing full-duplex operation, for example, subband-based full duplex (SBFD) operation, the symbols constituting a frame (i.e., time resources) can be divided into SBFD symbols and non-SBFD symbols. An SBFD symbol can include both an UL subband and a DL subband, and the terminal can perform either an operation of transmitting a UL signal on a UL subband or an operation of receiving a DL signal on a DL subband in the SBFD symbol. An SBFD symbol can be configured by assigning a UL subband to a DL symbol configured by a slot format setting (hereinafter referred to as a DL SBFD symbol for convenience), or by assigning a UL subband to a flexible symbol configured by a slot format setting (hereinafter referred to as a flexible SBFD symbol for convenience). In the latter case, the SBFD symbol can be interpreted as including a UL subband and a flexible subband. In this case, the first PRACH resource and the second PRACH resource can be configured for different duplex symbol types. For example, the first PRACH resource may be allocated to non-SBFD symbols, and the second PRACH resource may be allocated to SBFD symbols. The first PRACH resource may be shared between a legacy terminal and a terminal performing an SBFD operation. Alternatively, the second PRACH resource may be set to an interval including both SBFD symbols and non-SBFD symbols. At this time, an RO validity check may be performed, and among the ROs belonging to the second PRACH resource, an RO composed only of SBFD symbol(s) may be regarded as a valid RO, and an RO overlapping with a non-SBFD symbol may be regarded as invalid and may not be used for Msg1 transmission. The valid RO may be mapped to both a DL SBFD symbol and a flexible SBFD symbol.

In the two-step random access procedure, the UE can transmit the MsgA PUSCH together with the MsgA PRACH. A correlation can be established between the ROs (or preamble sets) constituting the MsgA PRACH resource and the PUSCH occasions (hereinafter referred to as POs) constituting the MsgA PUSCH resource, and among the POs constituting the MsgA PUSCH resource, the PO on which the PUSCH is transmitted can be a PO that is correlated with the RO (or preamble set) on which the MsgA PRACH is transmitted.

When multiple PRACH resources are configured in a terminal, the multiple PRACH resources may be correlated with the same MsgA PUSCH resource. When the first PRACH resource is a legacy PRACH resource, the MsgA PUSCH resource may be a legacy MsgA PUSCH resource associated with the first PRACH resource. In this case, the additionally configured second PRACH resource may be correlated with the legacy MsgA PUSCH resource. That is, the preambles constituting the valid ROs of the first PRACH resource and the preambles constituting the valid ROs of the second PRACH resource may be mapped to the POs of the same MsgA PUSCH resource. In this case, the preambles belonging to the second PRACH resource may be mapped in a later order than the preambles belonging to the first PRACH resource. For example, the preambles belonging to the plurality of RPACH resources may be sequentially mapped to POs firstly in ascending order of preamble index within the PRACH resource and RO, secondly in frequency arrangement order of ROs within the PRACH resource (e.g., in ascending order of frequency resource index), thirdly in time arrangement order of ROs within the PRACH resource (e.g., in ascending order of time resource index), and fourthly in ascending order (or descending order) of PRACH resource index. For legacy terminal operation, even if the second PRACH resource is dynamically turned on-off or activated-deactivated, the mapping between the preambles (e.g., preambles belonging to the first PRACH resource) and POs may not be changed.

Alternatively, the second PRACH resource may be correlated with a separate MsgA PUSCH resource (hereinafter referred to as the second PUSCH resource) other than the MsgA PUSCH resource to which the first PRACH resource is mapped (hereinafter referred to as the first PUSCH resource). In this way, preambles belonging to valid ROs of the first PRACH resource may be mapped to valid POs of the first PUSCH resource, and preambles belonging to valid ROs of the second PRACH resource may be mapped to valid POs of the second PUSCH resource. The MsgA PUSCH may be transmitted in a PO correlated with the RO in which the MsgA PRACH is transmitted. The second PUSCH resource may be multiplexed with the first PUSCH resource in the time domain and/or the frequency domain. Unlike the case of PRACH resources, overlap between the first PUSCH resource and the second PUSCH resource may not be allowed. Additionally, the PUSCH resource may be configured not to overlap with the interrelated PRACH resource(s). Here, the overlap may refer only to a temporal overlap or may refer to an overlap in the time and frequency domains. Since the MsgA PUSCH is transmitted before the UE acquires uplink synchronization, each PO may include a guard band and/or a guard period for interference control. The first PUSCH resource and the second PUSCH resource may be arranged based on the same period value and/or the same period. The period of the first PUSCH resource and the period of the second PUSCH resource may be determined based on the period value of the first PRACH resource and the period value of the second PRACH resource, respectively.

Meanwhile, PRACH can be repeatedly transmitted to expand UL coverage. Strictly speaking, PRACH resources (or ROs among PRACH resources designated for repeated transmission) can be configured repeatedly, and preambles can be repeatedly transmitted on the repeated PRACH resources (or ROs). When multiple PRACH resources are configured, repeated PRACH transmissions can be performed based on ROs belonging to the same PRACH resource. The ROs can be valid ROs.

The activation or deactivation instruction of the second PRACH resource (or, generally, the PRACH resource) can be dynamically performed based on the DCI. The terminal can be instructed to activate the PRACH resource via the DCI and can transmit a preamble on the PRACH resource that appears after the time point at which the activation instruction is applied. In addition, the terminal can be instructed to deactivate the PRACH resource via the DCI and can consider the PRACH resource that appears after the time point at which the deactivation instruction is applied as unavailable and not transmit a preamble on the PRACH resource. For example, if the DCI indicates that the PRACH resource is available, the terminal can consider the PRACH resource to be turned on or activated, and if the DCI indicates that the PRACH resource is unavailable, the terminal can consider the PRACH resource to be turned off or deactivated. The time point of application of the above activation/deactivation instruction may be any time point after a reference time has passed from the time point at which the terminal receives the DCI or the time point at which the terminal transmits HARQ-ACK for the DCI to the base station. For example, the time point of application of the activation/deactivation instruction may be the first slot (or, the first RO, the first PRACH period, the first SSB-RO association period, or association pattern period, etc.) that appears after X symbols have passed from the symbol at which the terminal receives the DCI (e.g., the last symbol) or the symbol at which the terminal transmits HARQ-ACK for the DCI (e.g., the last symbol).

At this time, considering the time taken for the terminal to prepare for PRACH transmission, a time gap may exist between the time point of application of the activation/deactivation instruction of the PRACH resource (hereinafter referred to as the “first time point”) and the time point at which the terminal can actually transmit a preamble on the PRACH resource (hereinafter referred to as the “second time point”). The time gap may be predefined in the technical specification. The time gap may be defined by the capability of the terminal, and the terminal may report information about the time gap supported by the terminal to the base station. The time gap may be conveniently referred to as a first time gap. The first time gap may mean a predetermined time offset, and may be expressed as a slot offset, a symbol offset, or a time offset defined by a combination of slots and symbols. Depending on the capability or implementation of the terminal, the first time gap may be 0. For example, the terminal can prepare a preamble transmission in advance before receiving a DCI indicating activation of a PRACH resource, and can transmit the prepared preamble on the PRACH resource immediately after obtaining the activation indication information.

Alternatively, the time point at which the PRACH resource activation/deactivation instruction is applied can be defined as a sufficiently late time point, taking into account both the time required for the UE to receive and process the DCI and the time required for the UE to prepare for PRACH transmission. In this case, the first and second time points can be considered to coincide, and defining a first time gap may be unnecessary. Alternatively, the first time gap can be defined or set to 0.

In one embodiment, a terminal may be instructed to either activate or deactivate a PRACH resource via DCI. In other words, the terminal may be instructed via DCI to either enable or disable a PRACH resource. If it is instructed to activate a PRACH resource that is in an active or inactive state, the PRACH resource may be maintained in an activated state until a predetermined condition is satisfied. The predetermined condition may include the terminal receiving a DCI instructing to deactivate the PRACH resource, the bandwidth portion (e.g., a UL bandwidth portion) for which the PRACH resource is configured being deactivated or released, the carrier for which the PRACH resource is configured being deactivated or released, the PRACH resource being released by an RRC configuration or an RRC reset, etc. If it is instructed to deactivate a PRACH resource that is in an inactive or active state, the PRACH resource may be maintained in an inactive state until a predetermined condition is satisfied. The above-described conditions may include the terminal receiving a DCI instructing the terminal to activate the PRACH resource, the bandwidth portion (e.g., the UL bandwidth portion) for which the PRACH resource is set being deactivated or released, the carrier for which the PRACH resource is set being deactivated or released, the PRACH resource being released by RRC configuration or RRC reset, etc.

In this case, the activation/deactivation state transition of the PRACH resource can be performed on a PRACH period basis. That is, the terminal can activate or deactivate the PRACH resource from the first complete PRACH period that appears after the time point at which the dynamic indication of the PRACH resource is applied (e.g., the first time point or the second time point). According to the above operation, the ROs belonging to the first activated PRACH period(s) or the last PRACH period(s) before deactivation can be mapped only to some of the valid SSBs (e.g., SSBs that are actually transmitted). Accordingly, a terminal that performs an initial access based on one of the some SSBs can transmit Msg1 in the PRACH period, whereas a terminal that performs an initial access based on an SSB other than the some SSBs cannot find an RO to transmit Msg1 in the PRACH period, and thus can transmit Msg1 in any of the subsequent PRACH periods.

As a method for solving the above problem, the activation/deactivation state transition of the PRACH resource can be performed in units of SSB-RO association periods or association pattern periods. That is, the UE can activate or deactivate the PRACH resource in the first complete SSB-RO association period or association pattern period that appears after the time point at which the dynamic indication of the PRACH resource is applied (e.g., the first time point or the second time point). According to the above operation, ROs belonging to the first activated SSB-RO association period (or association pattern period) or the last SSB-RO association period (or association pattern period) before deactivation can be mapped to all valid SSBs without omission. When PRACH repeated transmission is performed, RO sets for repeated transmission can be mapped across a plurality of SSB-RO association periods or a plurality of association pattern periods, and can be periodically repeated in units of a first period composed of a plurality of SSB-RO association periods or a plurality of association pattern periods. In this case, the activation/deactivation state transition of the PRACH resource can be performed in units of the first cycle.

Alternatively, the activation/deactivation state transition of the PRACH resource may be performed on a slot-by-slot basis or an RO-by-RO basis. That is, the terminal may activate or deactivate the PRACH resource in the first complete slot or the first complete RO that appears after the time point at which the dynamic indication of the PRACH resource is applied (e.g., the first time point or the second time point). The first complete slot may be a slot including a valid RO. The first complete RO may be a valid RO and may be an RO correlated with an SSB selected by the terminal. When PRACH repeated transmission is used, the slot may be the first slot among slot(s) to which a set of ROs for repeated transmission is mapped, and the RO may be the first RO of the set of ROs for repeated transmission. Alternatively, when PRACH repeated transmission is used, the activation/deactivation state transition of the PRACH resource may be performed on a repetition period basis for the PRACH repeated transmission resource. Within each repetition period for a PRACH repetitive transmission resource, all PRACH repetitive transmission resources may be mapped, and the repetition period may include one or more SSB-RO association period(s) or one or more SSB-RO association pattern period(s).

In another embodiment, the terminal may be instructed to activate a PRACH resource for a predetermined time interval via DCI. The starting point of the activation interval may be indicated by the DCI. Alternatively, the starting point of the activation interval may be the first time point or the second time point. The length of the activation interval may also be predetermined in the technical specification or signaled to the terminal from the base station. Similar to the principle applied to the above-described method, the length of the activation interval may be composed of Y1 slot(s), Y2 RO(s), Y3 PRACH period(s), Y4 SSB-RO association period(s), Y5 SSB-RO association pattern period(s), Y6 first period(s), or a combination of the above units. The terminal may assume that the PRACH resource (e.g., the second PRACH resource) is activated in the activation interval indicated via the DCI, and may assume that the PRACH resource is deactivated in other intervals (i.e., intervals before and after the activation interval).

The terminal may receive a message indicating to activate or deactivate the PRACH resource through a second DCI that is different from the DCI (i.e., the DCI indicating to activate the PRACH resource for a predetermined time period, hereinafter referred to as the first DCI). The second DCI may be received in a period in which the PRACH resource is activated by the first DCI. Simultaneously or separately, the second activation period of the PRACH resource indicated by the second DCI may overlap with the first activation period of the PRACH resource indicated by the first DCI. In this case, the terminal may follow the PRACH activation/deactivation indication by the second DCI and may consider the PRACH resource to be available in the second activation period. That is, the terminal may consider the PRACH resource to be available in both (or the union of) the first activation period and the second activation period, and may transmit a preamble using the PRACH resource. Alternatively, the terminal may consider only one of the indication by the first DCI and the indication by the second DCI to be valid. For example, the terminal may ignore the indication by the second DCI. For another example, the terminal may consider the indication by the second DCI, which was received more recently, to be valid, and may consider the PRACH resource to be available in the second activation period. The terminal may be instructed to deactivate the PRACH resource by the second DCI, and if the time of applying the indication belongs to the first activation period, the terminal may deactivate the PRACH resource from the time of application and may consider the PRACH resource to be no longer available. That is, the first activation period may be terminated by the second DCI. The second DCI may follow a different DCI format from the first DCI or may be a DCI whose CRC is scrambled by a different RNTI from the first DCI, and may be monitored in a different search space set from the first DCI.

The DCI may be transmitted in a CSS set considering that it should be received by an RRC connected mode terminal and an RRC idle/inactive mode terminal. For example, the DCI may follow a group common DCI format (e.g., DCI format 2_X, X=0, 1, 2, ??) and may be monitored in a type 3 CSS set. Alternatively, the DCI may follow a common DCI format (e.g., DCI format 1_0). The DCI may be monitored in a type 0/0A/1/2 CSS set. However, the type 0/0A/1/2 CSS set may be configured to be optimized for other purposes such as system information, RAR, paging transmission, etc., and may limit operations in terms of instructing PRACH adaptation to the terminal. Accordingly, when the DCI is transmitted for PRACH adaptation indication, the DCI may be monitored in a CSS set of a different type that is distinct from the above type, and the PDCCH monitoring occasions constituting the CSS set of the different type may be configured in the terminal separately from the PDCCH monitoring occasions constituting the CSS set of the existing type. Alternatively, the DCI may be transmitted in the CSS set of the existing type, but additional PDCCH monitoring occasions may be configured in the terminal for the purpose of PRACH adaptation indication. For example, the DCI may be transmitted through a PDCCH whose CRC is scrambled by a P-RNTI in a Type 2-PDCCH CSS set. The DCI may be transmitted in a separate PDCCH monitoring occasion(s) that is distinct from the PDCCH monitoring occasion(s) of a Type 2-PDCCH CSS set configured for paging transmission. Information regarding the separate PDCCH monitoring occasion(s) may be additionally signaled to the terminal. For example, the information may be included in SIB1. Alternatively, the DCI may be transmitted over a PDCCH with the CRC scrambled by a new RNTI distinct from the SI/RA/P-RNTI.

As described above, the DCI may follow DCI format 1_0, and the PDCCH including the DCI may have its CRC scrambled by P-RNTI. At this time, the activation/deactivation indication information of the PRACH resource may be transmitted by being mapped to the reserved bit(s) of the DCI format 1_0. Alternatively, the activation/deactivation indication information of the PRACH resource may be transmitted by being mapped to the reserved bit(s) or available bit(s) of the short message field of the DCI format 1_0. Specifically, the short message field may be composed of 8 bits, and the indication information may be mapped to at least one bit(s) of the LSBs of the field. At this time, the DCI may transmit to the terminal information for scheduling a paging PDSCH together with activation/deactivation indication information of PRACH resources, information notifying that system information has been updated, an ETWS (earthquake and tsunami warning system) message, information instructing to stop paging monitoring, etc. The terminal may receive at least some of the above information and perform a corresponding action. Alternatively, if the DCI includes activation/deactivation indication information of PRACH resources, the DCI may not include the other information listed above. That is, the DCI may be transmitted only for the purpose of PRACH adaptation indication. In this case, the short message indicator may be set to '10' or '11'. In addition, the MSB(s) of the short message (e.g., the first MSB, the second MSB, the third MSB, the fourth MSB) may be set to '0'. Alternatively, if the DCI includes activation/deactivation indication information of PRACH resources, the short message indicator of the DCI may be set to '00'. That is, the reserved field of the short message indicator may be used for PRACH adaptation indication.

According to an embodiment, the DCI may include TRS availability indication information. That is, information indicating activation/deactivation of PRACH resources may be transmitted together with the TRS availability indication information in the DCI. When the DCI includes a TRS availability indication field, reserved bits of the DCI may or may not exist depending on the size of the field. Therefore, only when reserved bits of the DCI exist, that is, only when the size of the TRS availability indication field is smaller than the number of reserved bits, the PRACH resource adaptation indication information may be mapped to the reserved bits. Alternatively, regardless of the presence or absence of the TRS availability indication field, the size of the TRS availability indication field, etc., the PRACH resource adaptation indication information may be mapped to the available bit(s) of the short message field by the above-described method. According to another embodiment, when the DCI includes PRACH resource adaptation indication information, the DCI may not include TRS availability indication information.

In addition to the dynamic indication of the activation period by the DCI, the available ROs of the PRACH resources (e.g., the second PRACH resources) may be further restricted by a PRACH mask. That is, the terminal may receive mask configuration information for the PRACH resources from the base station. The mask configuration information may include information indicating RO(s) (or unusable RO(s)) that the terminal can use among a plurality of valid ROs. The plurality of valid ROs may be ROs that are mutually associated with the same SSB. Specifically, the terminal may be indicated by the mask one or more available RO(s) among the valid ROs within an SSB-RO mapping cycle or a PRACH association period (or a PRACH association pattern period). Alternatively, the valid ROs may be ROs that belong to one PRACH configuration period or one radio frame. The above mask setting information may be applied to some PRACH resources among multiple PRACH resources set in the terminal or to specific PRACH resources (e.g., a second PRACH resource, an additional PRACH resource, a PRACH resource for which a dynamic activation/deactivation instruction is set).

[How to receive Msg2/MsgB]

After transmitting Msg1 (or MsgA), the terminal may expect to receive Msg2 (or MsgB). Msg2 (or MsgB) may be composed of a PDSCH including an RAR (hereinafter referred to as Msg2 PDSCH) and a PDCCH (hereinafter referred to as Msg2 PDCCH) that schedules the Msg2 PDSCH. The Msg2 PDCCH may have its CRC scrambled by a random access (RA)-RNTI and may be monitored in a CSS set (e.g., a Type 1-PDCCH CSS set) within the RAR window.

The terminal may transmit a PRACH preamble in an RO belonging to any one of a plurality of PRACH resources, and may monitor the Msg2 PDCCH in a CORESET following the RO in which the preamble is transmitted. Specifically, the terminal may form an RAR window by starting the earliest Msg2 PDCCH monitoring resource appearing after the last symbol of the RO in which the preamble is transmitted, and may monitor the Msg2 PDCCH in the Msg2 PDCCH monitoring resource within the RAR window period. The Msg2 PDCCH monitoring resource may include a Type 1-PDCCH CSS set (or a corresponding CORESET, PDCCH monitoring occasion). An RAR timer may be started at the start time of the RAR window, and an RAR window end time may be determined by the time when the RAR timer expires (i.e., the time when the timer value becomes 0).

FIG. 10 is a conceptual diagram illustrating a first embodiment of a method for determining a RAR window for a plurality of PRACH resources, and FIG. 11 is a conceptual diagram illustrating a second embodiment of a method for determining a RAR window for a plurality of PRACH resources.

Referring to FIGS. 10 and 11, a terminal may be configured with a first PRACH resource including four first ROs and a second PRACH resource including four second ROs, and may transmit a PRACH preamble in any one of the ROs. The terminal may monitor the Msg2 PDCCH in a CORESET following the RO in which the terminal transmitted the preamble. For example, the CORESET may be a Type 1-PDCCH CSS set (or a corresponding CORESET, PDCCH monitoring occasion) and may be conveniently referred to as the Msg2 CORESET.

Specifically, the terminal can set the earliest Msg2 CORESET appearing after the last symbol of the RO in which the preamble is transmitted (i.e., the selected RO) as the start point of the RAR window, and can monitor the Msg2 CORESET within the RAR window until the RAR timer expires. Referring to FIG. 10, the Msg2 CORESETs can be arranged after the first PRACH resource and the second PRACH resource, and the earliest Msg2 CORESET after the first RO and the earliest Msg2 CORESET after the second RO are identical. Therefore, regardless of which PRACH resource's RO the terminal has selected, the terminal can determine the illustrated CORESET as the earliest Msg2 CORESET, and form the RAR window to have the CORESET (or the slot including the CORESET) as the start point. That is, the RAR window can be determined regardless of the PRACH resource in which the terminal transmitted the preamble. Additionally, a common RAR window may be formed for the first PRACH resource and the second PRACH resource. The common RAR window may be formed by the base station appropriately configuring the PRACH resources, CORESET, and search space set. Alternatively, the first PRACH resource and the second PRACH resource may be mandated by technical specifications to have a common RAR window. One method for this may be to apply a rule that Msg2 CORESET is not mapped between the first PRACH resource and the second PRACH resource. This rule may restrict the PRACH configuration or the CORESET/PDCCH configuration. Alternatively, the RAR window may be explicitly configured in the terminal. For example, the RAR window for the first PRACH resource may be determined based on a predefined rule according to the method described above, and the RAR window for the second PRACH resource may be signaled from the base station to the terminal. The base station can appropriately set the start time and/or duration of the RAR window of the second PRACH resource so that the RAR window of the second PRACH resource matches or overlaps with the RAR window of the first PRACH resource.

On the other hand, according to the second embodiment of FIG. 11, Msg2 CORESET can be placed between the first PRACH resource and the second PRACH resource. By the above-described method, when the terminal transmits the PRACH in the first RO, the period after the first PRACH resource can be regarded as the RAR window, and when the terminal transmits the PRACH in the second RO, the period after the second PRACH resource can be regarded as the RAR window. In other words, the RAR window can be determined by the RO in which the terminal transmits the preamble and the corresponding PRACH resource.

Meanwhile, the terminal can determine the next step action by determining whether the received RAR corresponds to the preamble transmitted by the terminal and the RO to which the preamble was transmitted. That is, if the RAPID (random access preamble ID) included in Msg2 matches the ID of the preamble transmitted by the terminal and the RA-RNTI used for Msg2 PDCCH detection is a value corresponding to the RO to which the preamble was transmitted, the terminal can consider the received RAR to be for the terminal and can perform the Msg3 transmission step. Otherwise, the terminal can consider the received RAR not to be for the terminal and can perform an operation of retransmitting Msg1.

The RA-RNTI used for Msg2 PDCCH detection can be given by the following mathematical expression 1. Here, s_id may mean the index of the first symbol of the RO (0 ≤ s_id < 14), t_id may mean the index of the first slot to which the RO is mapped within the radio frame (0 ≤ t_id < 80), f_id may mean the frequency domain index of the RO within the radio frame (0 ≤ f_id < 8), and ul_carrier_id may mean the index of the UL carrier used for PRACH preamble transmission. For example, ul_carrier_id may be 0 for a NUL (normal UL) carrier and 1 for a SUL (supplementary UL) carrier. t_id may be determined based on the subcarrier spacing defined in the technical specification according to the frequency band. The above RO may be an RO in which the terminal transmits a PRACH preamble or an RO selected for PRACH preamble transmission.

However, when multiple PRACH resources are set in a terminal, the above mathematical formula may cause ambiguity in determining RAR. For example, while the s_id and the t_id are indices that directly indicate the location of the physical resource to which the RO is mapped, f_id means the logical index of the RO. Therefore, when the first PRACH resource and the second PRACH resource are FDMed, that is, when multiple ROs belonging to different PRACH resources coexist in the same symbol or the same slot, it may be difficult to specify which PRACH resource the RO is an RO and to inform the terminal of this using only the f_id. In addition, when the start symbol and start slot of multiple ROs belonging to different PRACH resources are the same, it may be difficult to specify which PRACH resource the RO is an RO and to inform the terminal of this using only the s_id and the t_id. Additionally, a method may be used to limit the configuration so that the first PRACH resource and the second PRACH resource are always configured on the same UL carrier (e.g., NUL carrier or SUL carrier) and/or on the corresponding same UL bandwidth portion. In this case, it may be difficult to distinguish multiple ROs using only the ul_carrier_id.

As a proposed method, a method of adding a PRACH resource index to the mathematical formula for deriving the RA-RNTI may be considered. That is, the terminal may generate the RA-RNTI based on the index of the PRACH resource through which the terminal transmitted the preamble. In an embodiment, RA-RNTI = f(r_id), where f(A) denotes a function of A and r_id denotes a PRACH resource index. In an embodiment, RA-RNTI = f(s_id, t_id, f_id, r_id, ul_carrier_id). That is, the RA-RNTI may include all the variables defined in mathematical formula 1 and may additionally include r_id. In another embodiment, RA-RNTI = f(s_id, t_id, f_id, r_id). That is, the RA-RNTI may include s_id, t_id, and f_id among the variables defined in mathematical formula 1 and may additionally include r_id. For example, ul_carrier_id in Equation 1 can be replaced with r_id, and RA-RNTI can be given by Equation 2 below.

For example, a legacy terminal may determine an RA-RNTI based on Equation 1, and a NES terminal may determine an RA-RNTI based on Equation 2. Alternatively, the terminal may receive signaling information from the base station indicating to apply either the method according to Equation 1 or the method according to Equation 2. In a similar manner to the method according to Equation 2, the terminal may use Equation 1 as is, but derive the PRACH resource index to which the RO belongs based on ul_carrier_id. For example, ul_carrier_id may match the PRACH resource index to which the RO belongs.

The above-described methods are only specific examples for implementing RA-RNTI = f(r_id), and the PRACH resource index may be included in the RA-RNTI generation formula in more diverse forms. For example, in the mathematical formula, r_id or its corresponding term may coexist with ul_carrier_id. In addition, the PRACH resource index may be explicitly assigned to multiple PRACH resources or may be an indicator for distinguishing multiple PRACH resources. As an example of the latter, if the UE transmits a preamble on a specific PRACH resource (e.g., a legacy PRACH resource), it may generate an RA-RNTI assuming r_id = 0 or its corresponding mathematical formula, and if the UE transmits a preamble on another specific PRACH resource (e.g., an additional PRACH resource), it may generate an RA-RNTI assuming r_id = 1 or its corresponding mathematical formula.

Alternatively, a method of imposing restrictions on the PRACH resource configuration may be considered. For example, multiple PRACH resources may be configured so as not to include the first RO and the second RO starting in the same symbol and/or the same slot. Furthermore, multiple PRACH resources may be configured so as not to include the first RO and the second RO mapped to the same frequency resource. Additionally or alternatively, a method of extending the interpretation of some variables included in Equation 1 may be applied. For example, f_id may first be mapped to ROs within a PRACH resource in the order of their frequency resource indices (i.e., frequency positions of the ROs) (e.g., in ascending order), and secondly, may be mapped to PRACH resources in the order of their PRACH resource indices (e.g., in ascending order). The number of ROs FDMed in each PRACH resource may be transmitted to the terminal in the form of an RRC message. At this time, the upper limit of the total number of ROs to be FDMed in the same time resource may be constant regardless of the number of PRACH resources set for the terminal. That is, when one PRACH resource is set for the terminal, the maximum value of the number of ROs belonging to the PRACH resource that can be FDMed may match the maximum value of the total number of ROs that can be FDMed when two PRACH resources are set for the terminal (i.e., the sum of the number of ROs belonging to the first PRACH resource and the number of ROs belonging to the second PRACH resource). In addition, as described above, the PRACH resource index may be explicitly assigned to a plurality of PRACH resources or may be an indicator for distinguishing a plurality of PRACH resources.

For example, assuming that the first PRACH resource and the second PRACH resource include four ROs in the frequency domain, f_id = 0, 1, 2, 3 may correspond to ROs FDM'd in the first PRACH resource, respectively, and f_id = 4, 5, 6, 7 may correspond to ROs FDM'd in the second PRACH resource, respectively. In an embodiment, the maximum range of f_id may be [0, 7] regardless of the number of PRACH resources. In this case, the first PRACH resource may be a PRACH resource assigned a low index (e.g., 0), and the second PRACH resource may be a PRACH resource assigned a high index (e.g., 1). Alternatively, the PRACH resources corresponding to the first PRACH resource and the second PRACH resource may be defined in the technical specification. For example, the first PRACH resource and the second PRACH resource may be a legacy PRACH resource and an additional PRACH resource, respectively. Conversely, the first PRACH resource and the second PRACH resource may be an additional PRACH resource and a legacy PRACH resource, respectively.

Alternatively, f_id may be mapped to ROs based on the order in which PRACH resources are mapped in the frequency domain, or the order in which ROs are mapped in the frequency domain regardless of the PRACH resources. For example, two second ROs belonging to a second PRACH resource may be sequentially mapped in a low frequency position, and six first ROs belonging to a first PRACH resource may be sequentially mapped in a high frequency position. In this case, f_id = 0, 1 may be mapped to two second ROs in ascending frequency order (or in ascending frequency resource index order), respectively, and f_id = 2, 3, 4, 5, 6, 7 may be mapped to six first ROs in ascending frequency order (or in ascending frequency resource index order), respectively.

In the above-described method, s_id and t_id can indicate the locations where ROs are mapped in the time domain, regardless of PRACH resources. The FDMed ROs can have the same starting symbol. That is, all of the ROs can correspond to the same s_id and t_id.

Referring back to FIG. 10, the RAR window corresponding to the first PRACH resource (hereinafter referred to as the first RAR window) and the RAR window corresponding to the second PRACH resource (hereinafter referred to as the second RAR window) may overlap (e.g., coincide), and the terminal may receive the Msg2 PDCCH in the overlapping section. At this time, if the preamble transmitted by the terminal is included in both the first PRACH resource and the second PRACH resource (or, more specifically, the valid ROs of the first PRACH resource and the valid ROs of the second PRACH resource), and furthermore, the PRACH resource is not specified by the RA-RNTI used for receiving the Msg2 PDCCH, it is difficult for the terminal to determine whether the RAPID received via the RAR corresponds to the preamble transmitted in the first RO or the preamble transmitted in the second RO. If the RAPID received with the above ambiguity matches the ID of the preamble it transmitted, the terminal can perform Msg3 and Msg4 transmission and reception operations, and the above ambiguity can be resolved at this stage. However, connection collisions between multiple terminals can occur not only within a single PRACH resource but also across multiple PRACH resources, which increases unnecessary Msg3/Msg4 transmissions and may deteriorate contention-based random access performance.

As a method for solving the above problem, the terminal can check which PRACH resource the RAPID acquired in the Msg2 reception step corresponds to through the method proposed below. If the RAPID corresponds to the PRACH resource (or RO) through which the terminal transmitted the PRACH, the terminal can determine that the RAPID matches the ID of the preamble it transmitted and can perform the Msg3 transmission procedure. Conversely, if the RAPID corresponds to a different PRACH resource from the PRACH resource (or RO) through which the terminal transmitted the PRACH, the terminal can determine that the RAPID does not match the ID of the preamble it transmitted and can retransmit the PRACH.

As a first proposed method, a method of including a PRACH resource index in Msg2 and indicating it to the terminal may be considered. The terminal may regard RAPID as being for a PRACH resource having the PRACH resource index and perform the above operation based on this. In this case, the PRACH resource index may be included in the RAR message. If there are no remaining fields in the RAR message, a method of reusing a specific field (or some bits or bytes) already defined for another purpose for the purpose of indicating the PRACH resource index may be used. Alternatively, the PRACH resource index may be included in the RAR UL grant. Although the PRACH resource index is not strictly information related to the UL grant, it may be relatively easy to use or reuse a field constituting the RAR UL grant for the purpose of indicating the PRACH resource index. If there is no available field in the RAR or RAR UL grant, a method of adding a field for indicating the PRACH resource index while maintaining the existing field configuration of the RAR or RAR UL grant may be considered. As a result, the total payload size of the RAR or RAR UL grant may increase, and the RAR or RAR UL grant may only be received by NES terminals. Alternatively, the PRACH resource index may be included in the Msg2 PDCCH and transmitted to the terminal. For example, the PRACH resource index may be indicated by a reserved bit or a specific field of the common DCI (e.g., DCI format 1_0).

As a second method, a method of temporally separating the first RAR window and the second RAR window may be considered. More specifically, the configuration of the PRACH resource and the Msg2 CORESET may be restricted so that the first RAR window and the second RAR window do not include the same Msg2 CORESET. Accordingly, each Msg2 CORESET may be included in only one of the first RAR window and the second RAR window. For example, as illustrated in FIG. 11, different Msg2 CORESETs may be placed after the first PRACH resource and the second PRACH resource, and these may be placed in sections sufficiently far apart in time. In this case, the RAR windows monitored when the terminal transmits the preamble in the first RO and when the terminal transmits the preamble in the second RO may be distinguished from each other. Therefore, the terminal may determine the PRACH resource corresponding to the RAPID based on the RAR window in which the Msg2 PDCCH is received.

In a third way, the set of preambles set in the first PRACH resource and the set of preambles set in the second PRACH resource may not include common elements (i.e., identical preambles). Alternatively, considering that only valid ROs are used for SSB-RO mapping and PRACH transmission, the first PRACH resource and the second PRACH resource may be set such that the set of preambles included in valid ROs belonging to the first PRACH resource and the set of preambles included in valid ROs belonging to the second PRACH resource do not have an intersection. Accordingly, each PRACH preamble can belong to only one of the first PRACH resource (or valid ROs of the first PRACH) and the second PRACH resource (or valid ROs of the second PRACH resource). In this case, RAPID must have a sufficiently wide range to be able to distinguish between all preambles included in the former preamble set and the latter preamble set. For example, when the cardinalities of the former preamble set and the latter preamble set are S1 and S2, respectively, at least (S1+S2) different preambles belonging to the sets can be distinguished through RAPID included in Msg2.

In a fourth method, the terminal can select one PRACH resource according to the priority assigned among the PRACH resources at a specific time point or interval and transmit a preamble on the selected PRACH resource. For example, the terminal can select one PRACH resource if the first PRACH resource (or the ROs constituting the first PRACH resource) and the second PRACH resource (or the ROs constituting the second PRACH resource) overlap at least partially. The overlap may include overlapping in both the time domain and the frequency domain, overlapping only in the time domain and not overlapping in the frequency domain, etc. In the latter case, even though the first PRACH resource and the second PRACH resource do not physically overlap, the ambiguity may still occur, and to resolve the ambiguity, the PRACH resource on which the terminal will transmit the preamble may be specified. As a result, the RAPID acquired by the terminal through Msg2 at each time point or interval can be associated with only one PRACH resource. A base station can distribute potential Msg1/MsgA transmission possibilities across multiple resources by assigning different priorities to multiple terminals.

The method presented for resolving the ambiguity of the above RA-RNTI reception operation and the method presented for resolving the ambiguity of the above RAPID confirmation operation may not be distinguished from each other or may be used together. Alternatively, it may be sufficient to use any one of the above methods. For example, if the ambiguity regarding multiple PRACH resources is resolved in the RA-RNTI reception step by the above-described method, the terminal can perform a procedure for comparing and confirming the ID of the preamble it transmitted with the RAPID included in Msg2 without having to consider multiple PRACH resources in the RAPID confirmation step. Conversely, if the ambiguity regarding multiple PRACH resources is resolved in the RAPID confirmation step by the above-described method, the terminal can generate the RA-RNTI and receive the RAR as in the existing operation described above without having to determine which PRACH resource the RA-RNTI is for.

According to the fourth embodiment described with reference to FIG. 8, multiple PRACH resources can completely overlap in a specific period, and at least some preambles of the multiple PRACH resources can match. Even in this case, the terminal can determine whether the RAR corresponds to the preamble and RO transmitted by itself based on the RAR reception operation by the above-described method, and can determine the next step operation. For example, the PRACH initial transmission and retransmission of the terminal can be restricted to be performed within the same PRACH resource, and in this case, the terminal can determine the next PRACH resource to transmit the retransmission preamble after confirming the PRACH resource corresponding to the received RAR based on the above-described method.

When PRACH resources and Msg2 CORESETs are arranged to be temporally interleaved, a RAR window may include a PRACH slot (i.e., a slot to which at least one RO is mapped). At this time, the counting of the RAR timer may be temporarily suspended (i.e., omitted) during the PRACH slot and resumed from the next slot of the PRACH slot. In this way, the RAR window may be extended by the number of PRACH slot(s) included in the RAR window, and a constant Msg2 transmission opportunity may be guaranteed regardless of whether the RAR window and PRACH resources overlap. Alternatively, the RAR timer may be counted (e.g., decremented by 1) according to the same rule in both slots (or subframes, half-subframes) to which a PRACH is mapped and slots (or subframes, half-subframes) to which a PRACH is not mapped.

The terminal can transmit Msg1 (or MsgA) on the activated second PRACH resource and can retransmit Msg1 (or MsgA) if Msg2 (or MsgB) is not received in the RAR window. However, the second PRACH resource may be deactivated before the terminal retransmits Msg1 (or MsgA). For example, the second PRACH resource may be deactivated or switched to an invalid state by a dynamic indication via DCI. In this case, the terminal can retransmit Msg1 on the first PRACH resource. That is, within the same random access procedure, preamble transmission and retransmission of each power ramping step may be performed on different PRACH resources. Power ramping may be applied to Msg1 retransmitted on the first PRACH resource. In order to ensure continuous power ramping operation even when the PRACH resource for transmitting the preamble by the terminal is switched from the second PRACH resource to the first PRACH resource, the PRACH initial transmission power (or preamble target reception power), power ramping step size, maximum output power, maximum number of transmissions, etc. of the first PRACH resource and the second PRACH resource may be set to be common or identical between the first PRACH resource and the second PRACH resource. That is, the transmission power of the preamble retransmitted in the first RO belonging to the first PRACH may be the transmission power obtained by applying power ramping to the transmission power applied to the preamble transmitted in the second RO belonging to the second PRACH before the PRACH resource was switched. That is, even when the PRACH resource is switched, the power ramping counter may be increased (e.g., increased by 1) without being reset. Alternatively, some of the configuration information listed above may be individually configured for each of the first PRACH resource and the second PRACH resource, and the terminal may determine the transmission power of the preamble to be transmitted based on the configuration value of each PRACH resource to which the preamble is to be transmitted. The configuration information described above may be configured to the same (or common) value for the first PRACH resource and the second PRACH resource only when a switching or switching operation between the first PRACH resource and the second PRACH resource is permitted for PRACH retransmission. If the switching or switching operation is not used, the configuration information described above may be configured to any number of different values for the first PRACH resource and the second PRACH resource.

In the above-described operation, the first PRACH resource may be considered a fallback resource. If the deactivation instruction of the second PRACH resource is dynamically signaled by the DCI, the UE may drop the retransmission Msg1 being prepared for the second PRACH resource. On the other hand, the DCI may include information regarding the deactivation time of the second PRACH resource or the length of the activation period, and the UE may determine the deactivation time of the second PRACH resource in advance based on the information. In this case, the UE may prepare the retransmission Msg1 for the first PRACH resource.

Conversely, after the terminal transmits Msg1 (or MsgA) on the first PRACH resource, the second PRACH resource may be activated. If the terminal does not receive Msg2 (or MsgB), which is a response message to Msg1 (or MsgA), the terminal may perform retransmission of Msg1 (or MsgA) on either the first PRACH resource or the second PRACH resource. Which PRACH resource is selected by the priority rule described above. If which PRACH resource is the second PRACH resource, the PRACH resource on which the terminal transmits the preamble within the same random access procedure may be switched from the first PRACH resource to the second PRACH resource, and the method, such as the power ramping operation described above, may be applied in the same manner. That is, the transmission power of the preamble retransmitted from the second RO belonging to the second PRACH may be the transmission power with power ramping applied to the transmission power applied to the preamble transmitted from the first RO belonging to the first PRACH before the PRACH resource is switched. That is, even when the PRACH resource is switched, the power ramping counter may be increased (e.g., increased by 1) without being reset.

Alternatively, the terminal may terminate the random access procedure and perform a new random access procedure for the first PRACH resource if the second PRACH resource, which is to transmit a retransmission of the preamble transmitted on the second PRACH resource, is deactivated. Alternatively, the terminal may not expect the PRACH resource (i.e., the second PRACH resource) to be deactivated while the random access procedure is being performed. Similarly, if the terminal knows in advance the deactivation time of the second PRACH resource, i.e., if the second PRACH resource is expected to be deactivated until a predetermined time or within a predetermined time interval, the terminal may not initiate the random access procedure for the second PRACH resource. The terminal may initiate the random access procedure for the first PRACH resource. The predetermined time or predetermined time interval may be determined based on the RO, RAR window, Msg4 window, etc., in which the preamble is transmitted. Additionally, the terminal may perform the retransmission on the first PRACH resource even if the second PRACH is activated at the time of transmitting the retransmission of the preamble transmitted on the first PRACH resource.

[SSB-RO Mapping Method]

As described above, valid ROs belonging to a PRACH resource can be correlated with SSBs. When multiple PRACH resources are configured for a terminal, first ROs belonging to a first PRACH resource and second ROs belonging to a second PRACH resource can be independently mapped to SSBs. That is, the terminal can determine mapping, association period, association pattern period, etc. between SSBs and first valid ROs based on configuration information of the first PRACH resource, and separately, can determine mapping, association period, association pattern period, etc. between SSBs and second valid ROs based on configuration information of the second PRACH resource. Alternatively, a common SSB-RO association period and/or association pattern period can be applied to the first PRACH resource and the second PRACH resource.

FIG. 12 is a conceptual diagram illustrating a first embodiment of an SSB-RO mapping method for multiple PRACH resources.

Referring to FIG. 12, a terminal may be configured with a first PRACH resource including four first valid ROs and a second PRACH resource including four second valid ROs. The base station (or cell) may repeatedly transmit SSBs on six SSB resources. The six SSB resources may be resources configured in the terminal as "actually transmitted SSB resources."

At this time, the four first valid ROs and the four second valid ROs can be independently mapped to the SSBs by the above-described method. As illustrated in FIG. 12, the four first valid ROs belonging to the first PRACH period and the first two first valid ROs belonging to the second PRACH period can be sequentially mapped to the six SSBs. An SSB-RO association period (or association pattern period) can be composed of two PRACH periods, and the last two first valid ROs belonging to the second PRACH period may not be mapped to an SSB. That is, the last two first valid ROs may not be used for PRACH transmission. In addition, the four second valid ROs belonging to the first PRACH period and the first two second valid ROs belonging to the second PRACH period can be sequentially mapped to the six SSBs. Similarly, an SSB-RO association period (or association pattern period) may consist of two PRACH periods, and the last two second valid ROs belonging to the second PRACH period may not be mapped to SSB. That is, the last two second valid ROs may not be used for PRACH transmission.

Meanwhile, according to the embodiments of FIGS. 9A to 9C, the second ROs may overlap with ROs belonging to other PRACH resources (e.g., the first ROs). The overlap may refer to overlap in both the time domain and the frequency domain. That is, at least one RE constituting the second RO may overlap with a resource occupied by the first RO. In this case, the second RO overlapping with an RO belonging to other PRACH resources (e.g., the first RO) may be considered an invalid RO and may be excluded from the SSB-RO mapping procedure described above. In addition, an RO that is simultaneously mapped to an SBFD symbol and a non-SBFD symbol may be considered an invalid RO under certain conditions and may be excluded from the SSB-RO mapping procedure described above.

In a different method from the above-described method, the first ROs belonging to the first PRACH resource and the second ROs belonging to the second PRACH resource can be mapped to SSBs together or jointly. To this end, the first PRACH resource and the second PRACH resource can share a common cycle, and both the first valid ROs and the second valid ROs belonging to the common cycle(s) can be used to form an SSB-RO mapping cycle.

FIG. 13 is a conceptual diagram illustrating a second embodiment of an SSB-RO mapping method for multiple PRACH resources.

Referring to FIG. 13, similar to the first embodiment, the terminal may be configured with a first PRACH resource including four first valid ROs and a second PRACH resource including four second valid ROs. The base station (or cell) may repeatedly transmit SSBs on six SSB resources. The six SSB resources may be resources configured in the terminal as "actually transmitted SSB resources."

By the above-described method, the SSB-RO correlation can be determined based on the four first valid ROs and the four second valid ROs belonging to a common PRACH period. Referring to FIG. 13, the four first valid ROs and the first two second valid ROs belonging to the first PRACH period can be sequentially mapped to the six SSBs, and in the same manner, the four first valid ROs and the first two second valid ROs belonging to the second PRACH period can be sequentially mapped to the six SSBs. The last two second valid ROs in each PRACH period may not be mapped to an SSB and may not be used for PRACH transmission. In this case, the SSB-RO correlation period (or association pattern period) can be composed of one PRACH period.

SSB-RO mapping can be performed for all ROs constituting a PRACH resource, regardless of the activation/deactivation status of the PRACH resource (i.e., ROs). That is, the activation or deactivation of a PRACH resource may not affect the SSB-RO mapping. If a PRACH resource is activated or deactivated in the middle of an association period or association pattern period, the ROs participating in the SSB-RO mapping may include both activated RO(s) and deactivated RO(s). Alternatively, the UE may consider only the RO(s) activated within the association period or association pattern period to have a mutual correlation with the SSB.

Different SSB groups (or SSB sets) may be associated with the first PRACH resource and the second PRACH resource. In SBFD operation, SSBs for SBFD symbols (hereinafter, the first SSB group) and SSBs for non-SBFD symbols (hereinafter, the second SSB group) may be configured, and the first SSB group and the second SSB group may be correlated with different PRACH resources. Alternatively, in multi-TRP operation, the first SSB group received from the first TRP and the second SSB group received from the second TRP may be correlated with different PRACH resources. The SSB-RO association rule may be equally applied to each (SSB group, PRACH resource) pair.

[Adaptation Instructions by PDCCH Order]

The above embodiments can be applied to a contention-based random access procedure and a contention-free random access procedure. In the case of a contention-free random access procedure, a base station can allocate a preamble to a terminal through dedicated signaling, and the terminal can transmit the allocated preamble on a PRACH resource. The dedicated signaling can be a DCI and can be referred to as a PDCCH order. The preamble can be indicated by a PRACH preamble index, an SSB index, and/or a RACH mask index included in the DCI. When a first PRACH resource and a second PRACH resource are configured (and activated) for the terminal, the DCI can additionally include information (e.g., a PRACH resource index) indicating a PRACH resource on which the terminal will transmit the preamble or a PRACH resource to which the allocated preamble belongs. Specifically, the terminal can be instructed via the PDCCH order on which PRACH resource among the first PRACH resource and the second PRACH resource to transmit the Msg1 preamble. The information can be indicated by a separately defined DCI field (e.g., a PRACH resource indicator field). According to an embodiment, the field (hereinafter referred to as the first field) can consist of 1 bit. In this case, the terminal can interpret the PRACH preamble index and/or the PRACH mask index included in the PDCCH order as relating to the indicated PRACH resource.

The above operation may be applied only when a non-contention-based random access procedure is triggered by a PDCCH order. Specifically, the above operation may be applied when the PRACH preamble index indicated by the PDCCH order has a non-zero value or the code point of the PRACH preamble index field is not all-zero. In addition, the above operation may be applied when one PRACH occasion (i.e., RO) for which the UE will transmit a preamble is specified by the PRACH mask index field of the PDCCH order.

Additionally or alternatively, the PDCCH order may include information indicating the availability or activation/deactivation of a second PRACH resource. For example, the same function as a PRACH adaptation indication command by a DCI (or paging DCI) in which the CRC is scrambled by the P-RNTI may be performed based on the PDCCH order. The indication information may be indicated to the terminal by a DCI field (hereinafter referred to as the second field) included in the PDCCH order. According to an embodiment, the second field may consist of 1 bit. The second field may be a different field distinct from the first field. The second field may be mapped to the payload of the PDCCH order together with the first field.

The above operation may be applied when the PDCCH order triggers a contention-based random access procedure. Specifically, when the PRACH preamble index indicated by the PDCCH order is 0 or the codepoint of the PRACH preamble index field is all-zero, the terminal may receive an adaptation instruction of the PRACH resource through the PDCCH order, initiate a contention-based random access procedure, and transmit a Msg1 or MsgA preamble on the PRACH resource. Alternatively, the above operation may be applied when a plurality of PRACH occasions (i.e., ROs) on which the terminal will transmit a preamble are designated by the PRACH mask index field of the PDCCH order. In this case, the terminal may ignore other indication information included in the PDCCH order (e.g., PRACH preamble index, SSB index, PRACH mask index, etc.) and may not perform a corresponding operation (e.g., Msg1 or MsgA transmission operation of a non-contention-based random access procedure).

In addition, the above operation can be applied to a non-contention-based random access procedure. For example, the terminal can be instructed about the availability and/or available duration of a second PRACH resource through the PDCCH order, and can initiate a non-contention-based random access procedure using either the first PRACH resource or the second PRACH resource within the available duration. The one PRACH resource can be randomly selected by the terminal, selected by the terminal based on a priority, or indicated to the terminal by the PDCCH order (e.g., the first field). Alternatively, the one PRACH resource can be a second PRACH resource, i.e., an additional PRACH resource. If the terminal is instructed through the PDCCH order that an additional PRACH resource is available, the terminal can perform a Msg1 transmission operation using an RO belonging to the additional PRACH resource within the available duration.

While DCI based on P(paging)-RNTI can be applied to both RRC idle/inactive mode terminals and RRC connected mode terminals regardless of the RRC state, PDCCH order can be transmitted only to RRC connected mode terminals. PDCCH order can follow DCI format 1_0, and CRC can be scrambled by C-RNTI. PDCCH order can be monitored in both CSS set and USS set, which can be distinguished from the search space set monitored by DCI based on P-RNTI.

When configured to monitor the above PDCCH order, the RRC connected mode terminal may receive an adaptation instruction command for the second PRACH resource through the PDCCH order, and may not receive an adaptation instruction command by DCI based on P-RNTI or may ignore the adaptation instruction command of DCI based on P-RNTI. For example, the terminal may not read a field including PRACH adaptation instruction information included in DCI based on P-RNTI or may not perform the corresponding operation.

Alternatively, the terminal may follow both the PRACH adaptation indication by the paging DCI and the PRACH adaptation indication by the PDCCH order. The period in which the PRACH resource (e.g., the second PRACH resource) is activated by the paging DCI (hereinafter, the first activation period) and the period in which the PRACH resource is activated by the PDCCH order (hereinafter, the second activation period) may or may not coincide. If the SSB-RO mapping of the PRACH resource is invariant regardless of whether the PRACH resource is activated/deactivated or available, the mismatch between the first activation period and the second activation period may be allowed. In this case, the minimum configuration unit of the first activation period and the minimum configuration unit of the second activation period may be the same. For example, the first activation period and the second activation period may include N1 and N2 PRACH association period(s) (or PRACH association pattern period(s), radio frame(s)), respectively. The terminal may consider the PRACH resource as valid in the union of the first and second activation periods. Alternatively, the terminal may consider only one activation period as valid based on the priority between PRACH resources, the priority between DCIs, the priority between DCI reception points, etc.

Alternatively, the terminal may expect that the multiple PRACH adaptation instructions will instruct the first and second activation periods to always coincide. Alternatively, the terminal may expect that the multiple PRACH adaptation instructions will instruct the first and second activation periods to not overlap.

When multiple PRACH resources are set, for example, when a first PRACH resource and a second PRACH resource are set, the terminal may consider that the DCI includes a field indicating the PRACH resource. That is, the payload size of the DCI may be determined based on the number of PRACH resources set in the terminal. At this time, whether or not the field indicating the PRACH resource is included may be unrelated to the availability or activation/deactivation of the PRACH resource (e.g., the second PRACH resource). For example, when the first PRACH resource and the second PRACH resource are set in the terminal, the PRACH resource indication field may be included in the DCI regardless of the activation/deactivation status of the second PRACH resource. When the second PRACH resource is indicated by the DCI in a section in which the second PRACH resource is activated, the terminal may transmit a preamble belonging to the second PRACH resource according to the indication. On the other hand, if the second PRACH resource is indicated by the DCI in the section where the second PRACH resource is deactivated, the terminal may regard the indication as an error and may ignore the PDCCH order. That is, the terminal may not perform the PRACH transmission operation according to the indication. Alternatively, in the above case, the terminal may transmit a preamble belonging to the first PRACH resource even though the second PRACH resource is indicated. The preamble belonging to the first PRACH resource may be determined by the PRACH preamble index, the SSB index, and/or the RACH mask index included in the DCI. That is, the terminal may regard the PRACH preamble index, the SSB index, and/or the RACH mask index included in the DCI as relating to the first PRACH resource in the section where the second PRACH resource is deactivated. In another embodiment, the terminal may not expect to be instructed to perform a Msg1 transmission operation according to a non-contention-based random access procedure on a deactivated PRACH resource (e.g., the second PRACH resource) via the PDCCH order. In another embodiment, in this case, the terminal may consider the second PRACH resource to be activated and transmit a preamble belonging to the second PRACH resource according to the instruction of the DCI.

The operation 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. The computer-readable recording medium includes all types of recording devices that store information that can be read by a computer system. In addition, the computer-readable recording medium can be distributed over network-connected computer systems so that the computer-readable program or code can be stored and executed in a distributed manner.

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.

Although some aspects of the invention have been described in the context of an apparatus, this 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 represented as a feature of a corresponding block or item or a feature of a corresponding apparatus. 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 significant method steps may be performed by such an apparatus.

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, a 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.

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 (20)

As a method of performing random access to a terminal,
A step of receiving configuration information of a first PRACH resource including first PRACH (physical random access channel) occasions from a base station;
A step of receiving configuration information of a second PRACH resource including second PRACH occasions from the base station;
A step of receiving instruction information indicating activation of the second PRACH resource from the base station;
A step of confirming an activation period in which the second PRACH resource is activated based on the above instruction information; and
Including a step of transmitting a preamble to the base station in at least one of the first PRACH occasions and the second PRACH occasions in the activation period,
method. In claim 1,
The configuration information of the first PRACH resource and the configuration information of the second PRACH resource are received as included in the system information.
method. In claim 1,
The above first PRACH occasions and the above second PRACH occasions are associated with a common set of actually transmitted SSBs (synchronization signal blocks).
method. In claim 3,
The association between the first PRACH occasions and the set of common actually transmitted SSBs is independent of the association between the second PRACH occasions and the set of common actually transmitted SSBs.
method. In claim 1,
The above instruction information is received as included in downlink control information (DCI).
method. In claim 5,
The above DCI additionally includes a paging message for the terminal,
method. In claim 1,
wherein said at least one PRACH occasion is a first PRACH occasion among said first PRACH occasions, and said one first PRACH occasion overlaps with one of said second PRACH occasions.
method. In claim 1,
wherein said at least one PRACH occasion is a first PRACH occasion of one of said first PRACH occasions, and said preamble is retransmitted in a second PRACH occasion of one of said second PRACH occasions.
method. In claim 8,
The transmission power of the preamble retransmitted in the above one second PRACH occasion is a transmission power obtained by applying power ramping to the transmission power applied to the preamble transmitted in the above one first PRACH occasion.
method. In claim 1,
Common PRACH transmission power related parameters are applied to the first PRACH resource and the second PRACH resource.
method. As a method of base station for random access of terminals,
A step of transmitting configuration information of a first PRACH resource including first PRACH (physical random access channel) occasions to the terminal;
A step of transmitting configuration information of a second PRACH resource including second PRACH occasions to the terminal;
A step of transmitting instruction information indicating activation of the second PRACH resource to the terminal; and
A step of receiving a preamble in at least one of the first PRACH occasions and the second PRACH occasions from the terminal in an activation period of the second PRACH resource, which is determined based on the instruction information,
method. In claim 11,
The configuration information of the first PRACH resource and the configuration information of the second PRACH resource are included in the system information and transmitted.
method. In claim 11,
The above first PRACH occasions and the above second PRACH occasions are associated with a common set of actually transmitted SSBs (synchronization signal blocks).
method. In claim 13,
The association between the first PRACH occasions and the set of common actually transmitted SSBs is independent of the association between the second PRACH occasions and the set of common actually transmitted SSBs.
method. In claim 11,
wherein said at least one PRACH occasion is a first PRACH occasion among said first PRACH occasions, and said one first PRACH occasion overlaps with one of said second PRACH occasions.
method. In claim 11,
wherein said at least one PRACH occasion is a first PRACH occasion of one of said first PRACH occasions, and said preamble is retransmitted in a second PRACH occasion of one of said second PRACH occasions.
method. In claim 16,
The transmission power of the preamble retransmitted in the above one second PRACH occasion is a transmission power obtained by applying power ramping to the transmission power applied to the preamble transmitted in the above one first PRACH occasion.
method. A terminal performing random access, comprising at least one processor, wherein the at least one processor comprises:
A step of receiving configuration information of a first PRACH resource including first PRACH (physical random access channel) occasions from a base station;
A step of receiving configuration information of a second PRACH resource including second PRACH occasions from the base station;
A step of receiving instruction information indicating activation of the second PRACH resource from the base station;
A step of confirming an activation period in which the second PRACH resource is activated based on the above instruction information; and
In the above activation period, a step of transmitting a preamble to the base station in at least one of the first PRACH occasions and the second PRACH occasions is performed.
Terminal. In claim 18,
The above first PRACH occasions and the above second PRACH occasions are associated with a common set of actually transmitted SSBs (synchronization signal blocks).
Terminal. In claim 19,
The association between the first PRACH occasions and the set of common actually transmitted SSBs is independent of the association between the second PRACH occasions and the set of common actually transmitted SSBs.
Terminal.