Patent Description:
Generally, a wireless communication system is developing to diversely cover a wide range to provide such a communication service as an audio communication service, a data communication service and the like. The wireless communication is a sort of a multiple access system capable of supporting communications with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). For example, the multiple access system may be any of a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, and a single carrier frequency division multiple access (SC-FDMA) system.

<CIT> discloses a method for processing data in a wireless communication system. The method includes receiving a first uplink scheduling command indicating a first radio resource, receiving a second uplink scheduling command indicating a second radio resource through a random access response, and stopping a procedure associated with the second uplink scheduling command when the first radio resource and the second radio resource collide.

Accordingly, the present disclosure is directed to a method and apparatus for transmitting and receiving a signal in a wireless communication system that substantially obviates one or more problems due to limitations and disadvantages of the related art.

Features of certain embodiments are defined in the dependent claims.

An object of the present disclosure is to provide a method of efficiently performing wireless signal transmission/reception procedures and an apparatus therefor.

It is to be understood that both the foregoing general description and the following detailed description of the present disclosure are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed.

The invention made is disclosed in the embodiments relating to <FIG>. Reference will now be made in detail to the preferred embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings.

Embodiments of the present disclosure are applicable to a variety of wireless access technologies such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), and single carrier frequency division multiple access (SC-FDMA). CDMA can be implemented as a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented as a radio technology such as Global System for Mobile communications (GSM)/General Packet Radio Service (GPRS)/Enhanced Data Rates for GSM Evolution (EDGE). OFDMA can be implemented as a radio technology such as Institute of Electrical and Electronics Engineers (IEEE) <NUM> (Wireless Fidelity (Wi-Fi)), IEEE <NUM> (Worldwide interoperability for Microwave Access (WiMAX)), IEEE <NUM>, and Evolved UTRA (E-UTRA). UTRA is a part of Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is part of Evolved UMTS (E-UMTS) using E-UTRA, and LTE-Advanced (A) is an evolved version of 3GPP LTE. 3GPP NR (New Radio or New Radio Access Technology) is an evolved version of 3GPP LTE/LTE-A.

As more and more communication devices require a larger communication capacity, there is a need for mobile broadband communication enhanced over conventional radio access technology (RAT). In addition, massive Machine Type Communications (MTC) capable of providing a variety of services anywhere and anytime by connecting multiple devices and objects is another important issue to be considered for next generation communications. Communication system design considering services/UEs sensitive to reliability and latency is also under discussion. As such, introduction of new radio access technology considering enhanced mobile broadband communication (eMBB), massive MTC, and Ultra-Reliable and Low Latency Communication (URLLC) is being discussed. In the present disclosure, for simplicity, this technology will be referred to as NR (New Radio or New RAT).

For the sake of clarity, 3GPP NR is mainly described, but the technical idea of the present disclosure is not limited thereto.

In the present disclosure, the term "set/setting" may be replaced with "configure/configuration", and both may be used interchangeably. Further, a conditional expression (e.g., "if", "in a case", or "when") may be replaced by "based on that" or "in a state/status". In addition, an operation or software/hardware (SW/HW) configuration of a user equipment (UE)/base station (BS) may be derived/understood based on satisfaction of a corresponding condition. When a process on a receiving (or transmitting) side may be derived/understood from a process on the transmitting (or receiving) side in signal transmission/reception between wireless communication devices (e.g., a BS and a UE), its description may be omitted. Signal determination/generation/encoding/transmission of the transmitting side, for example, may be understood as signal monitoring reception/decoding/determination of the receiving side. Further, when it is said that a UE performs (or does not perform) a specific operation, this may also be interpreted as that a BS expects/assumes (or does not expect/assume) that the UE performs the specific operation. When it is said that a BS performs (or does not perform) a specific operation, this may also be interpreted as that a UE expects/assumes (or does not expect/assume) that the BS performs the specific operation. In the following description, sections, embodiments, examples, options, methods, schemes, and so on are distinguished from each other and indexed, for convenience of description, which does not mean that each of them necessarily constitutes an independent invention or that each of them should be implemented only individually. Unless explicitly contradicting each other, it may be derived/understood that at least some of the sections, embodiments, examples, options, methods, schemes, and so on may be implemented in combination or may be omitted.

In a wireless communication system, a user equipment (UE) receives information through downlink (DL) from a base station (BS) and transmit information to the BS through uplink (UL). The information transmitted and received by the BS and the UE includes data and various control information and includes various physical channels according to type/usage of the information transmitted and received by the UE and the BS.

<FIG> illustrates physical channels used in a 3GPP NR system and a general signal transmission method using the same.

When a UE is powered on again from a power-off state or enters a new cell, the UE performs an initial cell search procedure, such as establishment of synchronization with a BS, in step S101. To this end, the UE receives a synchronization signal block (SSB) from the BS. The SSB includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). The UE establishes synchronization with the BS based on the PSS/SSS and acquires information such as a cell identity (ID). The UE may acquire broadcast information in a cell based on the PBCH. The UE may receive a DL reference signal (RS) in an initial cell search procedure to monitor a DL channel status.

After initial cell search, the UE may acquire more specific system information by receiving a physical downlink control channel (PDCCH) and receiving a physical downlink shared channel (PDSCH) based on information of the PDCCH in step S102.

The UE may perform a random access procedure to access the BS in steps S103 to S106. For random access, the UE may transmit a preamble to the BS on a physical random access channel (PRACH) (S103) and receive a response message for preamble on a PDCCH and a PDSCH corresponding to the PDCCH (S104). In the case of contention-based random access, the UE may perform a contention resolution procedure by further transmitting the PRACH (S105) and receiving a PDCCH and a PDSCH corresponding to the PDCCH (S106).

After the foregoing procedure, the UE may receive a PDCCH/PDSCH (S107) and transmit a physical uplink shared channel (PUSCH)/physical uplink control channel (PUCCH) (S108), as a general downlink/uplink signal transmission procedure. Control information transmitted from the UE to the BS is referred to as uplink control information (UCI). The UCI includes hybrid automatic repeat and request acknowledgement/negative-acknowledgement (HARQ-ACK/NACK), scheduling request (SR), channel state information (CSI), etc. The CSI includes a channel quality indicator (CQI), a precoding matrix indicator (PMI), a rank indicator (RI), etc. While the UCI is transmitted on a PUCCH in general, the UCI may be transmitted on a PUSCH when control information and traffic data need to be simultaneously transmitted. In addition, the UCI may be aperiodically transmitted through a PUSCH according to request/command of a network.

The purpose of the random access procedure (RACH procedure) is not limited to initial network access (e.g., S103 to S106). That is, the random access procedure may be used for various purposes. For example, the random access procedure may be used for at least one of an RRC connection re-establishment procedure, handover, UE-triggered UL data transmission, transition from RRC_INACTIVE, SCell time alignment, system information request, beam failure recovery, or UL resource request. However, the random access procedure is not limited thereto. The UE may acquire UL synchronization and/or UL transmission resources from the random access procedure. The random access procedure may be divided into <NUM>) a contention-based random access procedure and <NUM>) a contention-free random access procedure.

The CBRA may be referred to as CB-RACH, and the CFRA may be referred to as CF-RACH.

<FIG> illustrates a radio frame structure. In NR, uplink and downlink transmissions are configured with frames. Each radio frame has a length of <NUM> and is divided into two <NUM>-ms half-frames (HF). Each half-frame is divided into five <NUM>-ms subframes (SFs). A subframe is divided into one or more slots, and the number of slots in a subframe depends on subcarrier spacing (SCS). Each slot includes <NUM> or <NUM> Orthogonal Frequency Division Multiplexing (OFDM) symbols according to a cyclic prefix (CP). When a normal CP is used, each slot includes <NUM> OFDM symbols. When an extended CP is used, each slot includes <NUM> OFDM symbols.

Table <NUM> exemplarily shows that the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary according to the SCS when the normal CP is used.

Table <NUM> illustrates that the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary according to the SCS when the extended CP is used.

The structure of the frame is merely an example. The number of subframes, the number of slots, and the number of symbols in a frame may vary.

In the NR system, OFDM numerology (e.g., SCS) may be configured differently for a plurality of cells aggregated for one UE. Accordingly, the (absolute time) duration of a time resource (e.g., an SF, a slot or a TTI) (for simplicity, referred to as a time unit (TU)) consisting of the same number of symbols may be configured differently among the aggregated cells. Here, the symbols may include an OFDM symbol (or a CP-OFDM symbol) and an SC-FDMA symbol (or a discrete Fourier transform-spread-OFDM (DFT-s-OFDM) symbol).

<FIG> illustrates a resource grid of a slot. A slot includes a plurality of symbols in the time domain. For example, when the normal CP is used, the slot includes <NUM> symbols. However, when the extended CP is used, the slot includes <NUM> symbols. A carrier includes a plurality of subcarriers in the frequency domain. A resource block (RB) is defined as a plurality of consecutive subcarriers (e.g., <NUM> consecutive subcarriers) in the frequency domain. A bandwidth part (BWP) may be defined to be a plurality of consecutive physical RBs (PRBs) in the frequency domain and correspond to a single numerology (e.g., SCS, CP length, etc.). The carrier may include up to N (e.g., <NUM>) BWPs. Data communication may be performed through an activated BWP, and only one BWP may be activated for one UE. In the resource grid, each element is referred to as a resource element (RE), and one complex symbol may be mapped to each RE.

<FIG> illustrates exemplary mapping of physical channels in a slot. A PDCCH may be transmitted in a DL control region, and a PDSCH may be transmitted in a DL data region. A PUCCH may be transmitted in a UL control region, and a PUSCH may be transmitted in a UL data region. A guard period (GP) provides a time gap for transmission mode-to-reception mode switching or reception mode-to-transmission mode switching at a BS and a UE. Some symbol at the time of DL-to-UL switching in a subframe may be configured as a GP.

Each physical channel will be described below in greater detail.

The PDCCH delivers DCI. For example, the PDCCH (i.e., DCI) may carry information about a transport format and resource allocation of a DL shared channel (DL-SCH), resource allocation information of an uplink shared channel (UL-SCH), paging information on a paging channel (PCH), system information on the DL-SCH, information on resource allocation of a higher-layer control message such as an RAR transmitted on a PDSCH, a transmit power control command, information about activation/release of configured scheduling, and so on. The DCI includes a cyclic redundancy check (CRC). The CRC is masked with various identifiers (IDs) (e.g., a radio network temporary identifier (RNTI)) according to an owner or usage of the PDCCH. For example, if the PDCCH is for a specific UE, the CRC is masked by a UE ID (e.g., cell-RNTI (C-RNTI)). If the PDCCH is for a paging message, the CRC is masked by a paging-RNTI (P-RNTI). If the PDCCH is for system information (e.g., a system information block (SIB)), the CRC is masked by a system information RNTI (SI-RNTI). When the PDCCH is for an RAR, the CRC is masked by a random access-RNTI (RA-RNTI).

The PDCCH includes <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> control channel elements (CCEs) according to its aggregation level (AL). A CCE is a logical allocation unit used to provide a PDCCH with a specific code rate according to a radio channel state. A CCE includes <NUM> resource element groups (REGs), each REG being defined by one OFDM symbol by one (P)RB. The PDCCH is transmitted in a control resource set (CORESET). A CORESET is defined as a set of REGs with a given numerology (e.g., an SCS, a CP length, and so on). A plurality of CORESETs for one UE may overlap with each other in the time/frequency domain. A CORESET may be configured by system information (e.g., a master information block (MIB)) or UE-specific higher-layer signaling (e.g., radio resource control (RRC) signaling). Specifically, the number of RBs and the number of symbols (<NUM> at maximum) in the CORESET may be configured by higher-layer signaling.

For PDCCH reception/detection, the UE monitors PDCCH candidates. A PDCCH candidate is CCE(s) that the UE should monitor to detect a PDCCH. Each PDCCH candidate is defined as <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> CCEs according to an AL. The monitoring includes (blind) decoding PDCCH candidates. A set of PDCCH candidates decoded by the UE are defined as a PDCCH search space (SS). An SS may be a common search space (CSS) or a UE-specific search space (USS). The UE may obtain DCI by monitoring PDCCH candidates in one or more SSs configured by an MIB or higher-layer signaling. Each CORESET is associated with one or more SSs, and each SS is associated with one CORESET. An SS may be defined based on the following parameters.

Table <NUM> shows the characteristics of each SS.

Table <NUM> shows DCI formats transmitted on the PDCCH.

DCI format 0_0 may be used to schedule a TB-based (or TB-level) PUSCH, and DCI format 0_1 may be used to schedule a TB-based (or TB-level) PUSCH or a code block group (CBG)-based (or CBG-level) PUSCH. DCI format 1_0 may be used to schedule a TB-based (or TB-level) PDSCH, and DCI format 1_1 may be used to schedule a TB-based (or TB-level) PDSCH or a CBG-based (or CBG-level) PDSCH (DL grant DCI). DCI format 0_0/0_1 may be referred to as UL grant DCI or UL scheduling information, and DCI format 1_0/1_1 may be referred to as DL grant DCI or DL scheduling information. DCI format 2_0 is used to deliver dynamic slot format information (e.g., a dynamic slot format indicator (SFI)) to a UE, and DCI format 2_1 is used to deliver DL pre-emption information to a UE. DCI format 2_0 and/or DCI format 2_1 may be delivered to a corresponding group of UEs on a group common PDCCH which is a PDCCH directed to a group of UEs.

DCI format 0_0 and DCI format 1_0 may be referred to as fallback DCI formats, whereas DCI format 0_1 and DCI format 1_1 may be referred to as non-fallback DCI formats. In the fallback DCI formats, a DCI size/field configuration is maintained to be the same irrespective of a UE configuration. In contrast, the DCI size/field configuration varies depending on a UE configuration in the non-fallback DCI formats.

The PDSCH conveys DL data (e.g., DL-shared channel transport block (DL-SCH TB)) and uses a modulation scheme such as quadrature phase shift keying (QPSK), <NUM>-ary quadrature amplitude modulation (16QAM), 64QAM, or 256QAM. A TB is encoded into a codeword. The PDSCH may deliver up to two codewords. Scrambling and modulation mapping may be performed on a codeword basis, and modulation symbols generated from each codeword may be mapped to one or more layers. Each layer together with a demodulation reference signal (DMRS) is mapped to resources, and an OFDM symbol signal is generated from the mapped layer with the DMRS and transmitted through a corresponding antenna port.

The PUCCH delivers uplink control information (UCI). The UCI includes the following information.

Table <NUM> illustrates exemplary PUCCH formats. PUCCH formats may be divided into short PUCCHs (Formats <NUM> and <NUM>) and long PUCCHs (Formats <NUM>, <NUM>, and <NUM>) based on PUCCH transmission durations.

PUCCH format <NUM> conveys UCI of up to <NUM> bits and is mapped in a sequence-based manner, for transmission. Specifically, the UE transmits specific UCI to the BS by transmitting one of a plurality of sequences on a PUCCH of PUCCH format <NUM>. Only when the UE transmits a positive SR, the UE transmits the PUCCH of PUCCH format <NUM> in PUCCH resources for a corresponding SR configuration.

PUCCH format <NUM> conveys UCI of up to <NUM> bits and modulation symbols of the UCI are spread with an orthogonal cover code (OCC) (which is configured differently whether frequency hopping is performed) in the time domain. The DMRS is transmitted in a symbol in which a modulation symbol is not transmitted (i.e., transmitted in time division multiplexing (TDM)).

PUCCH format <NUM> conveys UCI of more than <NUM> bits and modulation symbols of the DCI are transmitted in frequency division multiplexing (FDM) with the DMRS. The DMRS is located in symbols #<NUM>, #<NUM>, #<NUM>, and #<NUM> of a given RB with a density of <NUM>/<NUM>. A pseudo noise (PN) sequence is used for a DMRS sequence. For <NUM>-symbol PUCCH format <NUM>, frequency hopping may be activated.

PUCCH format <NUM> does not support UE multiplexing in the same PRBS, and conveys UCI of more than <NUM> bits. In other words, PUCCH resources of PUCCH format <NUM> do not include an OCC. Modulation symbols are transmitted in TDM with the DMRS.

PUCCH format <NUM> supports multiplexing of up to <NUM> UEs in the same PRBS, and conveys UCI of more than <NUM> bits. In other words, PUCCH resources of PUCCH format <NUM> include an OCC. Modulation symbols are transmitted in TDM with the DMRS.

The PUSCH delivers UL data (e.g., UL-shared channel transport block (UL-SCH TB)) and/or UCI based on a CP-OFDM waveform or a DFT-s-OFDM waveform. When the PUSCH is transmitted in the DFT-s-OFDM waveform, the UE transmits the PUSCH by transform precoding. For example, when transform precoding is impossible (e.g., disabled), the UE may transmit the PUSCH in the CP-OFDM waveform, while when transform precoding is possible (e.g., enabled), the UE may transmit the PUSCH in the CP-OFDM or DFT-s-OFDM waveform. A PUSCH transmission may be dynamically scheduled by a UL grant in DCI, or semi-statically scheduled by higher-layer (e.g., RRC) signaling (and/or Layer <NUM> (L1) signaling such as a PDCCH) (configured scheduling or configured grant). The PUSCH transmission may be performed in a codebook-based or non-codebook-based manner.

<FIG> illustrates an exemplary ACK/NACK transmission process. Referring to <FIG>, the UE may detect a PDCCH in slot #n. The PDCCH includes DL scheduling information (e.g., DCI format 1_0 or DCI format 1_1). The PDCCH indicates a DL assignment-to-PDSCH offset, K0 and a PDSCH-to-HARQ-ACK reporting offset, K1. For example, DCI format 1_0 and DCI format 1_1 may include the following information.

After receiving a PDSCH in slot #(n+K0) according to the scheduling information of slot #n, the UE may transmit UCI on a PUCCH in slot #(n+K1). The UCI may include an HARQ-ACK response to the PDSCH. <FIG> is based on the assumption that the SCS of the PDSCH is equal to the SCS of the PUCCH, and slot #n1=slot #(n+K0), for convenience, which should not be construed as limiting the present disclosure. When the SCSs are different, K1 may be indicated/interpreted based on the SCS of the PUCCH.

In the case where the PDSCH is configured to carry one TB at maximum, the HARQ-ACK response may be configured in one bit. In the case where the PDSCH is configured to carry up to two TBs, the HARQ-ACK response may be configured in two bits if spatial bundling is not configured and in one bit if spatial bundling is configured. When slot #(n+K1) is designated as an HARQ-ACK transmission timing for a plurality of PDSCHs, UCI transmitted in slot #(n+K1) includes HARQ-ACK responses to the plurality of PDSCHs.

Whether the UE should perform spatial bundling for an HARQ-ACK response may be configured for each cell group (e.g., by RRC/higher layer signaling). For example, spatial bundling may be configured for each individual HARQ-ACK response transmitted on the PUCCH and/or HARQ-ACK response transmitted on the PUSCH.

When up to two (or two or more) TBs (or codewords) may be received at one time (or schedulable by one DCI) in a corresponding serving cell (e.g., when a higher layer parameter maxNrofCodeWordsScheduledByDCI indicates <NUM> TBs), spatial bundling may be supported. More than four layers may be used for a <NUM>-TB transmission, and up to four layers may be used for a <NUM>-TB transmission. As a result, when spatial bundling is configured for a corresponding cell group, spatial bundling may be performed for a serving cell in which more than four layers may be scheduled among serving cells of the cell group. A UE which wants to transmit an HARQ-ACK response through spatial bundling may generate an HARQ-ACK response by performing a (bit-wise) logical AND operation on A/N bits for a plurality of TBs.

For example, on the assumption that the UE receives DCI scheduling two TBs and receives two TBs on a PDSCH based on the DCI, a UE that performs spatial bundling may generate a single A/N bit by a logical AND operation between a first A/N bit for a first TB and a second A/N bit for a second TB. As a result, when both the first TB and the second TB are ACKs, the UE reports an ACK bit value to a BS, and when at least one of the TBs is a NACK, the UE reports a NACK bit value to the BS.

For example, when only one TB is actually scheduled in a serving cell configured for reception of two TBs, the UE may generate a single A/N bit by performing a logical AND operation on an A/N bit for the one TB and a bit value of <NUM>. As a result, the UE reports the A/N bit for the one TB to the BS.

There are plurality of parallel DL HARQ processes for DL transmissions at the BS/UE. The plurality of parallel HARQ processes enable continuous DL transmissions, while the BS is waiting for an HARQ feedback indicating successful or failed reception of a previous DL transmission. Each HARQ process is associated with an HARQ buffer in the medium access control (MAC) layer. Each DL HARQ process manages state variables such as the number of MAC physical data unit (PDU) transmissions, an HARQ feedback for a MAC PDU in a buffer, and a current redundancy version. Each HARQ process is identified by an HARQ process ID.

<FIG> illustrates an exemplary PUSCH transmission procedure. Referring to <FIG>, the UE may detect a PDCCH in slot #n. The PDCCH includes DL scheduling information (e.g., DCI format 1_0 or 1_1). DCI format 1_0 or 1_1 may include the following information.

The UE may then transmit a PUSCH in slot #(n+K2) according to the scheduling information in slot #n. The PUSCH includes a UL-SCH TB.

<FIG> illustrates exemplary multiplexing of UCI in a PUSCH. When a plurality of PUCCH resources overlap with a PUSCH resource in a slot and a PUCCH-PUSCH simultaneous transmission is not configured in the slot, UCI may be transmitted on a PUSCH (UCI piggyback or PUSCH piggyback), as illustrated. In the illustrated case of <FIG>, an HARQ-ACK and CSI are carried in a PUSCH resource.

A semi-static configured grant (CG) may be configured for the UE by RRC signaling. Regarding a corresponding BWP of a serving cell, up to <NUM> active CGs may be configured for the UE.

Each CG may be type <NUM> or type <NUM>. Type-<NUM> CGs may be activated/deactivated independently between serving cells. When a plurality of type-<NUM> CGs are configured, each type-<NUM> CG may be activated individually by DCI. One DCI may deactivate one type-<NUM> CG or a plurality of type-<NUM> CGs.

For a CG-based transmission in NR-U (i.e., shared spectrum channel access), configured grant uplink control information (CG-UCI) is transmitted on a CG PUSCH (i.e., a PUSCH scheduled by a CG). In NR-U, multiplexing between a PUCCH carrying CG-UCI and a PUCCH carrying an HARQ-ACK may be configured/allowed by the BS. When a PUCCH carrying an HARQ-ACK overlaps with a CG PUSCH in a PUCCH group, multiplexing between a PUCCH carrying CG-UCI and a PUCCH carrying an HARQ-ACK may not be configured. In this case, the CG PUSCH transmission is dropped.

<FIG> illustrates a wireless communication system supporting an unlicensed band. For convenience, a cell operating in a licensed band (hereinafter, L-band) is defined as an LCell and a carrier of the LCell is defined as a (DL/UL) LCC. A cell operating in an unlicensed band (hereinafter, U-band) is defined as a UCell and a carrier of the UCell is defined as a (DL/UL) UCC. A carrier of a cell may represent an operating frequency (e.g., a center frequency) of the cell. A cell/carrier (e.g., CC) may generically be referred to as a cell.

When carrier aggregation is supported, one UE may transmit and receive signals to and from a BS in a plurality of aggregated cells/carriers. If a plurality of CCs is configured for one UE, one CC may be configured as a primary CC (PCC) and the other CCs may be configured as secondary CCs (SCCs). Specific control information/channels (e.g., a CSS PDCCH and PUCCH) may be configured to transmit and receive signals only in the PCC. Data may be transmitted and received in the PCC and/ or the SCCs. In <FIG>, the UE and the BS transmit and receive signals in the LCC and the UCC (non-standalone (NSA) mode). In this case, the LCC may be configured as the PCC and the UCC may be configured as the SCC. If a plurality of LCCs is configured for the UE, one specific LCC may be configured as the PCC and the other LCCs may be configured as the SCCs. <FIG> corresponds to LAA of the 3GPP LTE system. <FIG> illustrates the case in which the UE and the BS transmit and receive signals in one or more UCCs without the LCC (SA mode). In this case, one of the UCCs may be configured as the PCC and the other UCCs may be configured as the SCCs. To this end, PUCCH, PUSCH, PRACH transmission can be supported. Both the NSA mode and the SA mode may be supported in an unlicensed band of the 3GPP NR system.

Unless otherwise mentioned, the definitions below are applicable to terms as used in the present disclosure.

<FIG> illustrates a method of occupying resources in an unlicensed band. According to regional regulations concerning the unlicensed band, a communication node in the unlicensed band needs to determine, before signal transmission, whether other communication nodes use a channel. Specifically, the communication node may first perform carrier sensing (CS) before signal transmission to check whether other communication nodes transmit signals. If it is determined that other communication nodes do not transmit signals, this means that clear channel assessment (CCA) is confirmed. When there is a predefined CCA threshold or a CCA threshold configured by higher layer (e.g., RRC) signaling, if energy higher than the CCA threshold is detected in a channel, the communication node may determine that the channel is in a busy state and, otherwise, the communication node may determine that the channel is in an idle state. For reference, in Wi-Fi standard (<NUM>. 11ac), the CCA threshold is set to -62dBm for a non-Wi-Fi signal and to -82dBm for a Wi-Fi signal. Upon determining that the channel is in an idle state, the communication node may start to transmit signals in the UCell. The above processes may be referred to as listen-before-talk (LBT) or a channel access procedure (CAP). LBT and CAP may be used interchangeably.

In Europe, two LBT operations are defined: frame based equipment (FBE) and load based equipment (LBE).

Referring to <FIG>, in FBE-based LBT, one fixed frame is made up of a channel occupancy time (e.g., <NUM> to <NUM>), which is a time period during which once a communication node succeeds in channel access, the communication node may continue transmissions, and an idle period corresponding to at least <NUM>% of the channel occupancy time, and CCA is defined as an operation of monitoring a channel during a CCA slot (at least <NUM>) at the end of the idle period. The communication node performs CCA periodically on a fixed frame basis. When the channel is unoccupied, the communication node transmits during the channel occupancy time, whereas when the channel is occupied, the communication node defers the transmission and waits until a CCA slot in the next period.

Referring to <FIG>, in LBE-based LBT, the communication node may set q ∈ {<NUM>, <NUM>,. , <NUM>} and then perform CCA for one CCA slot. When the channel is unoccupied in the first CCA slot, the communication node may secure a time period of up to (<NUM>/<NUM>)q ms and transmit data in the time period. When the channel is occupied in the first CCA slot, the communication node randomly selects N∈{<NUM>, <NUM>,. , q}, stores the selected value as an initial value, and then senses a channel state on a CCA slot basis. Each time the channel is unoccupied in a CCA slot, the communication node decrements the stored counter value by <NUM>. When the counter value reaches <NUM>, the communication node may secure a time period of up to (<NUM>/<NUM>)q ms and transmit data.

Table <NUM> illustrates exemplary CAPs supported in NR-U.

In the 3GPP standardization, Type <NUM> CAP may be referred to as Category <NUM> (CAT4)-LBT, Type 2A CAP and Type 2B CAP may be referred to as CAT2-LBT, and Type 2C CAP may be referred to as CAT1-LBT. CAT2-LBT (i.e., Type 2A CAP and Type 2B CAP) are FBE-based LBT, and CAT4-LBT is LBE-based LBT.

Referring to Table <NUM>, the BS may perform one of the following CAPs to transmit a DL signal in an unlicensed band.

In a Type <NUM> DL CAP, a time duration spanned by sensing slots that are sensed to be idle before DL transmission(s) is random. The Type <NUM> DL CAP is applicable to the following transmissions.

Type <NUM> DL CAP in Table <NUM> will be described in greater detail with reference to <FIG>. The BS may sense whether a channel is idle during sensing slot durations of a defer duration Td and then when a counter N is zero, the BS may perform a transmission (S1234). The counter N is adjusted by sensing the channel during additional sensing slot duration(s) according to the following procedure:.

In a Type 2A/2B DL CAP, when sensing a channel to be idle during at least a sensing duration of <NUM>, the BS may perform a DL transmission in an unlicensed band immediately after the sensing is completed. In a Type 2C DL CAP, the BS may immediately access a channel without sensing.

As described before with reference to Table <NUM>, a plurality of CAP types (i.e., LBT types) may be defined for UL transmissions in an unlicensed band. For example, Type <NUM> CAP or Type <NUM> CAP may be defined for UL transmissions. The UE may perform a CAP (e.g., Type <NUM> or Type <NUM>) configured/indicated by the BS, for a UL signal transmission.

With reference to <FIG>, the Type <NUM> UL CAP of Table <NUM> will be described in greater detail. For a signal transmission in an unlicensed band, a UE may initiate a CAP (S1510). The UE may select a backoff counter N randomly within a CW according to step <NUM>. N is set to an initial value Ninit (S1520). Ninit is a value randomly selected between <NUM> and CWp. Subsequently, when the backoff counter value N is <NUM> according to step <NUM> (S1530; Y), the UE ends the CAP (S1532). The UE may then transmit a Tx burst (S1534). On the other hand, if the backoff counter value is not <NUM> (S1530; N), the UE decrements the backoff counter value by <NUM> according to step <NUM> (S1540). Subsequently, the UE checks whether a channel of UCell(s) is idle (S1550). If the channel is idle (S1550; Y), the UE checks whether the backoff counter value is <NUM> (S1530). On the contrary, if the channel is not idle, that is, the channel is busy (S1550; N), the UE checks whether the channel is idle for a defer duration Td (of 25usec or more) longer than a slot duration (e.g., 9usec) according to step <NUM> (S1560). If the channel is idle for the defer duration (S1570; Y), the UE may resume the CAP. The defer duration may include a duration of 16µsec and following Mp consecutive slot durations (e.g., <NUM>). On the contrary, when the channel is busy during the defer duration (S1570; N), the UE checks whether the channel is idle during a new defer duration by performing step S1560 again.

Table <NUM> illustrates that mp, a minimum CW CWmin,p, a maximum CW CWmax,p, a maximum channel occupancy time (MCOT) Tulmcot,p, and an allowed CW size for a CAP vary according to a channel access priority class.

A CW size (CWS) applied to the Type <NUM> CAP may be determined in various ways. For example, the CWS may be adjusted based on whether a new data indicator (NDI) value for at least one HARQ process related to the HARQ process ID, HARQ_ID_ref of a UL-SCH within a predetermined time period (e.g., a reference TU) is toggled. In the case where the UE performs a signal transmission on a carrier by using a Type <NUM> CAP related to a channel access priority class p, when an NDI value for at least one HARQ process related to HARQ_ID_ref is toggled, the UE sets CWp = CWmin,p for all priority classes p ∈{<NUM>,<NUM>,<NUM>,<NUM>}. Otherwise, the UE increments CWp for all priority classes p ∈ {<NUM>,<NUM>,<NUM>,<NUM>} to the next higher allowed value.

A reference frame nref (or reference slot nref) is determined as follows.

When the UE receives a UL grant in subframe (or slot) ng, and performs a transmission including a UL-SCH without gaps, starting from subframe (or slot) n<NUM> in a subframe (or slot) n<NUM>, n<NUM>, ··· , nw, the reference subframe (or slot) nref is subframe (or slot) n<NUM>.

When sensing a channel to be idle at least during a sensing duration Tshort_ul of <NUM>, the UE may perform a UL transmission (e.g., PUSCH) in an unlicensed band immediately after the sensing is completed. Tshort_ul may be Tsl (=<NUM>) + Tf (=<NUM>).

<FIG> illustrates an exemplary case in which a plurality of LBT-subbands (LBT-SBs) are included in an unlicensed band. Referring to <FIG>, a plurality of LBT-SBs may be included in a BWP of a cell (or carrier). An LBT-SB may have, for example, a band of <NUM>. An LBT-SB may include a plurality of consecutive (P)RBs in the frequency domain, and may be referred to as a (P)RB set. While not shown, a guard band (GB) may be included between LBT-SBs. Accordingly, a BWP may be configured in the form of {LBT-SB #<NUM> (RB set #<NUM>) + GB #<NUM> + LBT-SB #<NUM> (RB set #<NUM> + GB #<NUM>) +. + LBT-SB #(K-<NUM>) (RB set (#K-<NUM>))}. For convenience, LBT-SBs/RBs may be configured/defined to be indexed increasingly from a lower frequency band to a higher frequency band.

To support an FBE-based U-band (e.g., shared spectrum) operation, a fixed frame period (FFP) starting with a BS-initiated COT (e.g., Type 2A/2B CAP) has been introduced in NR Rel-<NUM>. Table <NUM> summarizes the core of the FFP transmission structure.

As described in Table <NUM>, the UE may be (semi-statically) configured with the length of the FFP duration through higher layer signaling (e.g., RRC). The term FFP used herein may be simply replaced with a period or a semi-static period. In addition, channel occupancy based on the FFP may be referred to as semi-static channel occupancy.

In Rel-<NUM>, an FFP transmission structure starting with a UE-initiated COT may be introduced to efficiently support a URLLC service in an FBE-based U-band environment. In this context, an FBE transmission operation method is proposed in consideration of both of a UE-initiated COT and a BS-initiated COT. In the following description, a DL signal may refer to the specific DL signal, and a BS may be, but not limited to, a <NUM> NR BS, that is, a gNB.

For UE-initiated COT-based and BS-initiated COT-based FBE operations, the following UE/BS transmission operations may be basically considered.

In this FBE operation situation, the following UE transmission operation methods may be considered depending on whether a UE detects a DL signal from a BS.

In a situation in which the BS generates/configures a BS-initiated COT for a specific FFP-g (e.g., FFP-g #<NUM> in <FIG>), the following operations may be performed.

<FIG> is a diagram illustrating a UL signal transmission/reception according to an embodiment of the present disclosure. As described before, to perform a scheduled UL transmission in a shared-COT, the UE should (basically) check that the BS succeeds in occupying/securing a corresponding FFP-g (e.g., the BS starts with a BS-initiated COT), and may perform a UL transmission by sharing the remaining duration of the FFP-g only after a DL transmission of the BS is completed in the FFP-g which the BS succeeds in occupying/securing. However, when determining that Opt <NUM> is (exceptionally) applicable, the UE may skip an operation H20 of confirming that the BS has succeeded in occupying/securing the FFP-g.

Referring to <FIG>, the UE receives DCI (H10). The DCI may be, but not limited to, UL grant DCI that schedules a UL transmission. For example, because a PUCCH transmission of the UE in a PUCCH resource indicated by DL grant DCI is also a scheduled UL transmission, the DCI may also be DL grant DCI. An FFP carrying the DCI is assumed to be FFP_a. The FFP_a may be an FFP-g starting with a BS-initiated COT. The DCI may indicate channel access parameters for the UL transmission. The UE may determine whether the scheduled UL transmission is for an FFP-g (a BS-initiated COT corresponding to the FFP-g) or an FFP-u (a UE-initiated COT corresponding to the FFP-u) based on the DCI. The UE may determine whether to perform channel sensing for the scheduled UL transmission based on network signaling, for example, the DCI. Hereinbelow, it is assumed that a UL transmission (starting with a BS-initiated COT) scheduled by DCI is included in an FFP_g, and the UE is instructed to perform the scheduled UL transmission in a shared-COT in the FFP-g starting with the BS-initiated COT.

Upon receipt of the DCI, the UE checks whether the scheduled UL resource is confined within the FFP_a in which the DCI has been received (H15)
When the scheduled UL resource is included in the FFP_a, in other words, when the scheduled UL transmission is scheduled in the same FFP as the DCI (e.g., intra-period scheduling), the UE may perform the scheduled UL transmission based on Opt <NUM> (H25). The scheduled UL transmission based on Opt <NUM> may be performed based on a shared COT. In the scheduled UL transmission based on Opt <NUM>, the UE may skip a DL detection/sensing process for determining whether the FFP is an FFP-g starting with a BS-initiated COT. <FIG> is a diagram illustrating an exemplary case of a UL transmission based on a shared COT. For example, <FIG> may be related to H25 or H30 of <FIG>. Referring to <FIG>, the UE determines whether to perform the scheduled UL transmission within a time gap of up to <NUM> from a previous UL transmission time (in the presence of a UL transmission before the scheduled UL transmission) (J15). For example, when there is any UL transmission performed before the time gap of up to <NUM> from the scheduled UL transmission, the UE may perform the scheduled UL transmission without additional channel sensing (LBT). In the absence of any UL transmission performed before the time gap of up to <NUM> from the scheduled UL transmission, the UE may perform additional channel sensing (LBT) (J20), and when determining a channel to be idle, perform the scheduled UL transmission (J30).

Referring back to <FIG>, when the scheduled UL resource is not included in the FFP_a, in other words, when the scheduled UL resource is scheduled in the FFP_a different from the FFP carrying the DCI (e.g., cross-period scheduling), the UE may perform the scheduled UL transmission based on Opt <NUM> (H15, No). According to Opt <NUM>, the UE should perform a DL detection/sensing process for an FFP_b to which the scheduled UL resource belongs (H20). It is not obvious to the UE/BS whether the FFP_b may be occupied by the BS, at the time of the FFP_a carrying the DCI. This is because the corresponding frequency spectrum is a shared spectrum/unlicensed band and thus coexistence with other devices/standards (e.g., IEEE802. <NUM> and so on) is needed. For example, even though the FFP_b is pre-agreed to be configured as an FFP-g starting with a BS-initiated COT (e.g., at the time of the FFP_a at the latest), a third device which does not comply to the 3GPP standards or a third device without knowledge of the pre-agreement between the 3GPP UE and the BS is likely to occupy the FFP_b. For example, the 3GPP BS/UE has no right to exclusively occupy the frequency band, and thus the possibility of a third device occupying the FFP_b may not be excluded completely. Accordingly, the UE should check whether the BS has actually succeeded in occupying the FFP_b at the starting time of the FFP_b to which the scheduled UL resource belongs. In other words, the UE needs to perform the DL detection/sensing process to check the presence of a DL signal related to a BS-initiated COT at the starting time of the FFP_b (H20). In the absence of a DL signal related to a BS-initiated COT at the starting time of the FFP_b (H20, non-pass), the UE is not sure whether the FFP_b is occupied by the BS (in other words, there is a possibility that a third device occupies the FFP_b), and thus does not perform the scheduled UL transmission probable to collide with the third device (H25, drop). In the presence of a DL signal related to a BS-initiated COT at the starting time of the FFP_b (H20, pass), the UE performs the scheduled UL transmission based on a shared COT, determining that the FFP_b is occupied/reserved by the BS (H30 and <FIG>).

It may be further considered whether the DCI overlaps with the scheduled UL resource in the time domain (intra-period scheduling) and whether the DCI overlaps with the scheduled UL resource in the frequency domain (intra-frequency scheduling). Further, it may be considered whether to apply Opt <NUM>/<NUM>, when the cell carrying the (UL/DL grant) DCI is identical to the cell to which the scheduled UL (e.g., PUSCH/PUCCH/SRS) resource is allocated.

For example, even though the transmitted cell is identical to the cell in which the scheduled UL resource is allocated, Opt <NUM> may be applied, when one or more RB sets (requiring individual/independent LBT) are configured in the corresponding cell
Alternatively, in the case where the cell carrying the DCI is identical to the cell in which the scheduled UL resource is allocated, when one or more RB sets are configured in the corresponding cell, the operation of Opt <NUM> and the operation of Opt <NUM> may be separately applied as follows.

<FIG> is a diagram illustrating a UL signal transmission/reception according to an embodiment of the present disclosure. <FIG> may be understood as an example of specifying the UL signal transmission/reception of <FIG> described before. In other words, because <FIG> is a higher-layer concept of <FIG> and <FIG> do not conflict with each other. <FIG> is an implementation of <FIG>, and thus the description of <FIG> is not interpreted as limited by <FIG>. However, a redundant description of <FIG> to that of <FIG> may be avoided herein. The UE receives DCI (e.g., UL grant DCI or DL grant DCI) scheduling a UL transmission (H10a). It is assumed that an FFP carrying the DCI is FFP_a. FFP_a may be an FFP-g starting with a BS-initiated COT. The DCI may indicate channel access parameters for a UL transmission. The UE may determine based on the DCI whether a scheduled UL transmission is for an FFP-g (a BS-initiated COT corresponding to the FFP-g) or a FFP-u (a UE-initiated COT corresponding to the FFP-u). The UE may determine whether to perform channel sensing for the scheduled UL transmission based on network signaling, for example, the DCI. In the following description, it is assumed that the UL transmission scheduled by the DCI is included in the FFP-g (starting with the BS-initiated COT), and the UE is instructed to perform the scheduled UL transmission in a shared-COT in the FFP-g starting with BS initiated COT.

Upon receipt of the DCI, the UE checks whether the scheduled UL resource is (fully) confined in FFP_a carrying the DCI (intra-period scheduling) or in a frequency resource area (e.g., an RB set or carrier) carrying the DCI (intra-frequency scheduling) (H15a).

In the case of intra-period & intra-frequency scheduling, the UE may perform the scheduled UL transmission based on Opt <NUM> (H25 in <FIG>). For example, the Opt <NUM>-based operation of UE/BS may be performed in the same frequency resource region (RB set/carrier) and the same FFP-g, (e.g., when the DCI is received in the RB set in which the UL resource is allocated, the DL signal detection process is skipped).

In the case of cross-period scheduling & cross-frequency scheduling, the UE may perform the scheduled UL transmission based on Opt <NUM> (H15a, No).

In <FIG>, in the case of cross-period scheduling or cross-frequency scheduling, the UE is exemplarily implemented as performing a scheduled UL transmission based on Opt <NUM>, which should not be construed as limiting the present disclosure, and the UE may operate as follows (the following i/ii may be understood as a result similar to the embodiment of <FIG> in which no distinction is made between cross-frequency scheduling and intra-frequency scheduling).

<NUM>) In a situation in which DCI indicates whether a scheduled UL transmission is performed based on a UE-initiated COT or a shared-COT (DCI indicates a transmission type), the following UE operations may be additionally considered.

In a situation in which a carrier (i.e., cell) including a plurality of RB sets and/or a plurality of cells (including one or more RB sets) are configured for the UE (i.e., CA situation), the following operations may be considered in relation to determination of a COT initiator (e.g., a UE-initiated COT or a BS-initiated COT) (from the perspective of the UE).

In a characteristic example, for an RB group including a plurality of RB sets configured in the same cell (e.g., intra-carrier scheduling) or the same BWP (and/or a cell (RB set) group including a plurality of cells (a plurality of RB sets included in the cells) configured in the same frequency band (e.g., intra-band scheduling), the following operations may be performed.

The UL transmission may be allowed/enabled in the following case: when the same COT initiator, COT initiator A (e.g., either a UE-initiated COT or a BS-initiated COT) is determined/assumed/indicated for the corresponding (allocated) RB set(s) (in particular, when it is detected/validated that COT initiator A is indicated by DCI for all of the (allocated) set(s) if the UL transmission is a scheduled UL transmission), and when there is no COT initiator determined/assumed/indicated for the remaining RB set(s) (except for the corresponding allocated RB set(s)) or when a COT initiator determined/assumed/indicated for the remaining RB set(s) (except for the corresponding allocated RB set(s)) is identical to COT initiator A.

Operation <NUM>: For an RB set group consisting of multiple RB sets configured on the same cell (e.g., intra-carrier) or on the same BWP, it is assumed that (at least) some (allocated) RB set(s) in the RB set group are configured/indicated as a specific (e.g., configured or scheduled) UL transmission resource.

As long as the same COT initiator (e.g., either a UE-initiated COT or a BS-initiated COT) is configured for the corresponding (allocated) RB set(s) (in particular, when it is detected/validated that a COT initiator is indicated by DCI for all (allocated) RB set(s) if the UL transmission is a scheduled UL transmission), the UL transmission may be allowed/enabled, regardless of whether the corresponding COT initiator is identical to a COT initiator determined/assumed/indicated for the remaining RB set(s) (except for the corresponding (allocated) RB set(s)).

Operation <NUM>: For an RB set group consisting of multiple RB sets configured on the same cell (e.g., intra-carrier) or on the same BWP, it is assumed that specific some (allocated) RB set(s) in the RB set group are configured/indicated as a specific (e.g., configured or scheduled) UL transmission resource.

The UL transmission may be allowed/enabled, regardless of whether the same or different COT initiators (e.g., either a UE-initiated COT or a BS-initiated COT) are determined/assumed/indicated for the corresponding (allocated) RB set(s).

<FIG> illustrates an exemplary UL signal transmission and reception process based on determination of a COT initiator according to an embodiment of the present disclosure. The embodiment of <FIG> is an exemplary application method of the above-described proposal(s), not limiting the scope of the present disclosure. Further, the foregoing description may be referred to in order to understand the embodiment of <FIG>.

Referring to <FIG>, a COT initiator is determined for RB set(s) in which a UL transmission is to be performed (K10). The COT initiator determination may include a process of detecting/sensing a signal. A COT initiator may be determined for each RB set. The UE may determine the COT initiator of each RB set in an FFP to which RB sets (allocated at least for a UL transmission) belong. In the case of a configured UL transmission, the UE may perform the UL transmission (K25 in which the UE performs a channel access procedure (required) for the UL transmission), depending on whether the COT initiators of (allocated) RB sets are all the same (K15). In the case of a scheduled UL transmission, the UE receives DCI indicating a COT initiator, and thus determines whether the COT initiators of all (allocated) RB sets are the same as the COT initiator indicated by the DCI (K15). When the COT initiators of all (allocated) RB sets are the same as the COT initiator indicated by the DCI, the UE performs the UL transmission (K25 in which the UE performs a channel access procedure (required) for the UL transmission). When determining that the CPT initiator of at least one of the (allocated) RB sets is different from the COT initiator indicated by the DCI, the UE may drop the UL transmission (K20). As described above, for example, even though there is no COT initiator specifically determined/assumed/indicated for the remaining RB set(s) (of the corresponding RB set group in addition to the allocated RB sets), the UL transmission may be allowed/enabled. In a more specific implementation example, when the COT initiator of the allocated RB set(s) is different from the COT initiators of the remaining RB set(s), the UL transmission may not be allowed/enabled. (That is, the UE may drop the UL transmission.

For example, referring to <FIG>, while performing a CBRA procedure, the UE may perform UL transmission(s) only based on COT sharing for FFP-g#<NUM> (e.g., UL transmissions including a UL transmission related to the CBRA procedure) (regardless of whether the UE is in the RRC connected mode or RRC inactive/idle mode). That is, the UE may not be allowed to initiate a UE-initiated COT or to perform a UL transmission based on the UE-initiated COT in FFP-u#<NUM>. Since the start of FFP-u#<NUM> overlaps with the CBRA procedure, UE-initiated channel occupancy may not be allowed to the UE at the start of FFP-u#<NUM>. Thus, the UE may not perform a UL transmission associated with the UE-initiated channel occupancy for the entirety of FFP-u#<NUM>, which is available only when it starts with the UE-initiated channel occupancy. That is, during FFP-u#<NUM>, the UE may perform a UL transmission only based on COT sharing for FFP-g#<NUM>. For an FFP-u after FFP-u#<NUM>, the UL transmission associated with the UE-initiated channel occupancy based may be allowed. During the entirety of FFP-u#<NUM> including a timing t2 at which the CBRA procedure ends, the UL transmission associated with the UE-initiated channel occupancy may not be allowed. During FFP-u#<NUM> including a timing t1 at which the CBRA procedure starts, the UE may not perform the UL transmission associated with the UE-initiated channel occupancy after the timing t1, but the UE may perform the transmission only based on COT sharing for FFP-g#<NUM>. For example, even if the UE succeeds in the UE-initiated channel occupancy at the start of FFP-u#<NUM>, the UE may not be allowed to maintain the UE-initiated channel occupancy until after the timing t1 at which the CBRA procedure starts within FFP-u#<NUM>.

For example, referring to <FIG>, when the UE is not in the RRC connected mode (N in A05), the UE needs to attempt channel access by sharing an FFP-g starting with a BS-initiated COT. When COT sharing is allowed, the UE may perform a UL transmission (A30). When the UE is in the RRC connected mode (Y in A05), the UE may perform a channel access procedure for the UL transmission, based on whether the UE receives a channel access configuration related to a UE-initiated COT (A10). When the UE has no capability for the UE-initiated COT or does not receive the channel connection configuration related to the UE-initiated COT (N in A10), the UE may attempt the channel access by sharing the FFP-g starting with the BS-initiated COT (A30). When the UE is configured with channel access based on the UE-initiated COT (Y in A10), if corresponding UL transmission is related to the UE-initiated COT, whether the UL transmission is for a CBRA procedure may be considered (A15). When the corresponding UL transmission related to the UE-initiated COT is for the CBRA procedure (Y in A15) (for example, when a corresponding FFP-u is an FFP-u for the CBRA procedure), even if the UE is configured with the channel access based on the UE-initiated COT (Y in A10), the UE needs to attempt the channel access by sharing the FFP-g starting with the BS-initiated COT, instead of performing the channel access based on the UE-initiated COT. If the corresponding UL transmission is not for the CBRA (N in A15), the UE may attempt the channel access based on the UE-initiated COT (A25 and A35). Specifically, the UE may determine whether the UE is capable of initiating UE-initiated channel occupancy in the corresponding FFP-u through channel sensing (A25). When it is determined by the channel sensing that the UE is incapable of initiating the UE-initiated channel occupancy in the corresponding FFP-u (N in A25), the UE may attempt the channel access by sharing the FFP-g starting with the BS-initiated COT (A30). When it is determined by the channel sensing that the UE is capable of initiating the UE-initiated channel occupancy in the corresponding FFP-u (Y in A25), the UE may perform the channel access in the FFP-u starting with the UE-initiated COT (A35).

In the example above, the UE-initiated COT-based UL transmission in the FFP-u for the CBRA may not be performed based on the UE-initiated channel occupancy, but the UE-initiated COT-based UL transmission in the FFP-u for the CFRA may be performed based on the UE-initiated channel occupancy (e.g., N in A15, A20, Y in A25, and A35). As described above in '<NUM>) Problem Situation', when a Rel. <NUM> NR BS does not start channel occupancy in an FFP-g period including RACH resources, the BS may assume that there are no UL transmissions based on COT sharing during the corresponding FFP-g (that is, there are no UL transmissions from all UEs up to Rel. <NUM> including UL transmissions for RACH). Depending on the implementation, the BS may be configured to omit a UL reception process in the corresponding FFP-g period. If the above BS assumption is capable of being effectively applied to a Rel. <NUM> BS during CBRA, the complexity and power of the BS may be reduced. When the RACH resources are related to CFRA, if the BS indicates to the UE a dedicated RACH preamble for the CFRA, the BS may expect to receive the dedicated RACH preamble. Specifically, the BS at least needs to receive the dedicated RACH preamble in UL (regardless of whether a UE FFP-u is generated), and thus, the BS may not skip the UL reception process on the corresponding time resource. When the RACH resources are related to CBRA, if there is a restriction that the UE-initiated COT is not allowed during the CBRA and if the BS does not start channel occupancy in the FFP-g period including the RACH resources as in the above example, the BS may assume that there are no UL transmissions based on the UE-initiated COT and/or COT sharing during the corresponding FFP-g. Depending on the implementation, the BS may be configured to skip the UL reception process in the corresponding FFP-g period.

<FIG> is a diagram for explaining UL signal transmission and reception according to an embodiment of the present disclosure.

Comparing the example of <FIG> and <FIG>, a scheduled UL signal in <FIG> may be scheduled by scheduling DCI (H10), and a scheduled UL signal in <FIG> may be related to an RAR (B10) (e.g., scheduled by an RAR message). For example, the scheduled UL signal in <FIG> may be a (Msg3) PUSCH transmitted based on an RAR, but the present disclosure is not limited thereto. The RAR message may include channel access parameters necessary for transmitting the PUSCH on a shared spectrum. For example, the RAR may indicate whether a scheduled UL signal (e.g., PUSCH) is associated with a BS-initiated COT or a UE-initiated COT (that is, whether the UE performs a scheduled UL transmission in an FFP-g starting with the BS-initiated COT based on a shared COT). Specifically, an RAR PDSCH may include a MAC PDU related to the RAR message. The MAC PDU related to the RAR message may include at least one MAC sub-PDU. It is assumed that the corresponding MAC sub-PDU includes both a MAC subheader including an RA preamble ID and a MAC RAR. The MAC RAR may include (i) a timing advance command, (ii) a UL grant for PUSCH transmission, and (iii) a temporary C-RNTI. (ii) The UL grant for PUSCH transmission may include a frequency hopping flag field, a PUSCH frequency resource allocation field, a PUSCH time resource allocation field, an MCS field, a TPC command for a PUSCH field, a CSI request field, and a ChannelAccess-CPext field, where the ChannelAccess-CPext field may indicate whether a scheduled UL signal (e.g., PUSCH) is related to a BS-initiated COT or a UE-initiated COT (e.g., whether the UE performs a scheduled UL transmission in an FFP-g starting with the BS-initiated COT based on a shared COT). In summary, an RAR PDSCH scheduled by an RAR PDCCH includes a UL grant for a PUSCH, and the UL grant for the PUSCH may indicate whether the PUSCH needs to be transmitted based on a BS-initiated COT or a UE-initiated COT.

Hereinafter, it is assumed that the UE is instructed to perform a scheduled UL transmission (e.g., PUSCH) in an FFP-g starting with a BS-initiated COT based on COT sharing.

As described above, in order to perform a scheduled UL transmission based on COT sharing, the UE needs to confirm that the BS successfully occupies/secures a corresponding FFP-g (e.g., the UE needs to confirm that it starts with a BS-initiated COT). Only after the BS ends a DL transmission in the FFP-g that the BS successfully occupies/secures, the UE may perform a UL transmission by sharing the rest of the FFP-g period. However, when it is determined that Opt <NUM> is applicable, the UE may (exceptionally) skip a process for confirming that the BS successfully occupies/secures the corresponding FFP-g (B20).

Referring to <FIG>, the UE receives an RAR (H10). The RAR may include at least one of a PDCCH/DCI related to an RAR grant (e.g., a PDCCH scheduling a Msg2 (RAR) PDSCH) or a Msg2 (RAR) PDSCH. For convenience, an FFP in which the RAR is received is assumed to be an FFP_a. The FFP_a may be an FFP-g starting with a BS-initiated COT. The RAR PDCCH and RAR PDSCH may be received in the same FFP as shown in <FIG>, but the present disclosure is not limited thereto. The RAR PDCCH and RAR PDSCH may be received in different FFPs as shown in <FIG>, and in this case, an FFP to which the RAR PDSCH belongs may be the FFP_a.

Upon receiving the RAR, the UE may check whether a scheduled UL resource is confined in the FFP_a in which the RAR is received (H15). For example, referring to <FIG>, it is assumed that the UE transmits a random access preamble (Msg1) before receiving the RAR. The random access preamble (Msg1) may be transmitted in FFP-g#<NUM>, but the present disclosure is not limited thereto. Specifically, the random access preamble (Msg1) may be transmitted in an FFP-g/u located before FFP-g#<NUM>. In <FIG>, the RAR PDCCH and the RAR PDSCH scheduled by the RAR PDCCH belong to the same FFP, FFP-g#<NUM>, and thus, FFP-g#<NUM> becomes the FFP_a. Therefore, when the scheduled UL transmission is a UL signal transmission <NUM> in FFP-g#<NUM>, it may be determined that the scheduled UL resource is included in the FFP_a in which the RAR is received. On the other hand, when the scheduled UL transmission is a UL signal transmission <NUM> in FFP-g#<NUM>, it may be determined that the scheduled UL resource is not included in the FFP_a in which the RAR is received. In <FIG>, the RAR PDCCH and the RAR PDSCH scheduled by the RAR PDCCH may belong to different FFP-gs, and FFP-g#<NUM> in which the RAR PDSCH is received may be included in the FFP_a. Assuming that the scheduled UL transmission is a UL signal transmission <NUM> in FFP-g#<NUM>, it may be determined that the UL signal transmission <NUM> is included in the FFP_a in which the RAR (RAR PDSCH) is received. On the other hand, when the scheduled UL transmission is a UL signal transmission <NUM> in FFP-g#<NUM> (e.g., in this case, the scheduled UL transmission may be a UL signal other than Msg3, for example, non-Msg3 PUSCH), it may be determined that the UL signal transmission <NUM> is included in the FFP_a in which the corresponding RAR (RAR PDCCH) is received. Assuming that the scheduled UL transmission is a UL signal transmission <NUM> in FFP-g#<NUM>, it may be determined that the UL signal transmission <NUM> is not included in the FFP_a in which the RAR is received.

When the scheduled UL resource is included in the FFP_a, that is, when the scheduled UL resource is included in FFP(s) (e.g., FFP_a) to which the RAR belongs (e.g., intra-period scheduling), the UE performs the scheduled UL transmission according to Opt <NUM> (B25). The scheduled UL transmission according to Opt <NUM> may be performed based on COT sharing. In the scheduled UL transmission according to Opt <NUM>, a DL detection/sensing process for confirming that the corresponding FFP is the FFP-g starting with the BS-initiated COT may be omitted. <FIG> illustrates an example in which the UE performs a UL transmission based on COT sharing. For example, <FIG> may be related to B25 or B30 of <FIG>. Referring to <FIG>, (if there is a previous UL transmission performed before a scheduled UL transmission), the UE may determine whether the scheduled UL transmission is performed within a maximum time gap of <NUM> from a time at which the previous UL transmission is performed (J15). For example, if there is a previous UL transmission performed before the maximum time gap of <NUM> from the scheduled UL transmission, the UE may perform the scheduled UL transmission without separate channel sensing (LBT) (J25). If there is no previous UL transmission performed before the maximum time gap of <NUM> from the scheduled UL transmission, the UE may perform a separate channel sensing (LBT) process (J20) and then perform the scheduled UL transmission if the cannel is idle (J30).

Referring back to <FIG>, when the scheduled UL resource is not included in the FFP_a, that is, when the scheduled UL resource is scheduled on a different FFP_b from that of the RAR (e.g., cross-period scheduling), the UE performs the scheduled UL transmission according to Opt <NUM> (No in B15). According to Opt <NUM>, the UE needs to perform a DL detection/sensing process for the FFP_b to which the scheduled UL resource belongs (B20). The UE/BS may not be sure whether the FFP_b will be capable of being occupied by the BS at the time of the FFP_a in which DCI is transmitted and received. The reason for this is that the corresponding frequency band is a shared spectrum/unlicensed band and coexistence with other devices/other standards (e.g., IEEE802. <NUM>, etc.) is required. For example, even though it is predetermined between a 3GPP UE and a BS operating a serving cell that an FFP_b is set to an FFP-g starting with a BS-initiated COT (e.g., starting at the time of an FFP_a at the latest), it is difficult to exclude the possibility that a third device that does not follow the 3GPP protocols or a third device that does not know the predetermined arrangement between the 3GPP UE and the BS occupies at least part of the FFP_b. For example, since the 3GPP BS/UE does not have the right to monopolize the corresponding frequency band, it is difficult to completely exclude the possibility that the FFP_b is occupied by the third device. Therefore, the UE needs to check whether the BS actually succeeds in occupying the FFP_b at the start time of the FFP_b to which the scheduled UL resource belongs. In other words, the UE needs to perform a DL detection/sensing process for checking whether a DL signal related to the BS-initiated COT exists at the start time of the FFP_b (B20). If there is no DL signal related to the BS-initiated COT at the start of the FFP_b (Non-pass in B20), the UE may not be sure whether the FFP_b is occupied by the BS (due to the possibility of channel occupation by the third device). Thus, the UE may not perform the scheduled UL transmission which may collide with the third device (Drop in B25). If there is a DL signal related to the BS-initiated COT at the start of the FFP_b (Pass in B20), the UE may determine that the FFP_b is occupied/reserved by the BS and then perform the scheduled UL transmission based on COT sharing (B30 and <FIG>).

Although it is assumed that a PDCCH/DCI related to an RAR grant is included in scheduling DCI (H10) in <FIG> by interpreting the corresponding scheduling DCI (H10) in a broad sense, the operations of the UE in <FIG> may be the same as the operations of the UE in <FIG>. Thus, it may be understood by those skilled in the art that the examples of <FIG> and <FIG> do not contradict each other and are applied together to one UE (e.g., <FIG>). For example, in C10 and C15 of <FIG>, corresponding DL may be corresponding scheduling DCI or a corresponding RAR. On the other hand, even though the scheduling DCI (H10) in <FIG> is broadly interpreted to include DCI scheduling a Msg2 (RAR) PDSCH, the scheduling DCI (H10) in <FIG> may not be interpreted to include even the Msg2 (RAR) PDSCH.

In the examples of <FIG>, <FIG>, and/or <NUM>, (i) a cell in which corresponding DL (e.g., corresponding scheduling DCI or corresponding RAR) is received may be the same as (ii) a cell in which a scheduled UL transmission is performed, but (i) the cell in which the corresponding DL (e.g., corresponding scheduling DCI or corresponding RAR) is received may be different from (ii) the cell in which the scheduled UL transmission is performed. In this case, whether FFPs are the same or different (whether an FFP_a is used) may depend on an FFP-related configuration (e.g., semi-static channel occupancy configuration) configured for the cell in which the scheduled UL transmission is performed. For example, referring to <FIG>, it is assumed that (i) the corresponding DL (e.g., corresponding scheduling DCI or corresponding RAR) is received in cell A. It is also assumed that (ii) the scheduled UL transmission is performed in cell B, and cell A and cell B are different. If (i) the corresponding DL is a DL signal <NUM>, it may be determined that (i) the corresponding DL and (ii) the scheduled UL belong to different FFPs (i.e., cross-period scheduled UL). If (i) the corresponding DL is a DL signal <NUM> or a DL signal <NUM>, it may be determined that (i) the corresponding DL and (ii) the scheduled UL belong to the same FFP (i.e., intra-period scheduled UL).

The PUSCH mentioned in the example of <FIG> above may include a Msg3 PUSCH.

<FIG> is a diagram for explaining operations of a UE on a shared spectrum in a wireless communication system according to an embodiment of the present disclosure. <FIG> shows an exemplary application method of the above-described proposal(s), and the scope of the present disclosure is not limited to <FIG>. In addition, the above-described contents may be referred to for understanding of the embodiment of <FIG>.

Referring to <FIG>, the UE transmits a random access preamble to the BS (D05).

The UE receives an RAR from the BS (D10).

The UE performs a channel access procedure for a scheduled UL transmission on the shared spectrum based on the RAR (D15).

In a state where the scheduled UL transmission is indicated as being associated with channel occupancy initiated by the BS and the UE is indicated to perform channel sensing for the scheduled UL transmission, the UE performs the channel access procedure for the scheduled UL transmission, based on whether the reception of the RAR and the scheduled UL transmission are confined in a same period among periods configured in the shared spectrum.

For example, based on that the scheduled UL transmission and the reception of the RAR are confined within the same period, the UE may determine that channel occupancy on the same period is initiated by the BS and perform the scheduled UL transmission. Based on that the scheduled UL transmission and the reception of the RAR are confined within the same period, the UE skips a specific procedure for determining whether the channel occupancy in a corresponding period has been initiated by the BS.

For example, the scheduled UL transmission may be a PUSCH transmission scheduled by the RAR.

For example, the RAR may include an RAR-PDCCH and an RAR-PDSCH scheduled by the RAR-PDCCH. The RAR-PDSCH may include a UL grant for scheduling a PUSCH. The UE may transmit the PUSCH scheduled by the RAR-PDSCH, based on whether at least one of the RAR-PDCCH or the RAR-PDSCH is confined within the same period as the scheduled UL transmission. Based on that the RAR-PDSCH and the PUSCH scheduled by the RAR-PDSCH are confined in the same period, the UE may skip a specific procedure for determining whether channel occupancy in the corresponding period is initiated by the BS and transmit the PUSCH.

For example, regardless of whether a cell for the reception of the RAR is equal to or different from a cell for the scheduled UL transmission, the UE may perform the channel access procedure for the scheduled UL transmission, based on whether the scheduled UL transmission and the reception of the RAR are confined within the same period. When a first cell for the reception of the RAR is different from a second cell for the scheduled UL transmission, based on that both the reception of the RAR and the scheduled UL transmission are confined in a first period among a plurality of periods configured in the second cell, the UE may perform the scheduled UL transmission without performing a specific procedure for determining whether the first period starts with the channel occupancy of the BS.

Based on that the reception of the RAR and the scheduled UL transmission are not confined in the same period, the UE performs a specific procedure for determining whether channel occupancy in a corresponding period for the scheduled UL transmission is initiated by the BS. The UE performs the channel access procedure for the scheduled UL transmission only when it is determined as a result of the specific procedure that the channel occupancy in the corresponding period is initiated by the BS. The UE may drop the scheduled UL transmission when it is determined as a result of the specific procedure that the channel occupancy in the corresponding period is not initiated by the BS.

<FIG> is a diagram for explaining operations of a BS on a shared spectrum in a wireless communication system according to an embodiment of the present disclosure. <FIG> shows an exemplary application method of the above-described proposal(s), and the scope of the present disclosure is not limited to <FIG>. In addition, the above-described contents may be referred to for understanding of the embodiment of <FIG>.

Referring to <FIG>, the BS may receive a random access preamble from the UE (E05)
The BS may transmit an RAR to the UE (E10).

The BS may receive a scheduled UL signal on the shared spectrum based on the RAR (E15).

When the BS has indicated that the scheduled UL signal is associated with channel occupancy initiated by the BS and indicated the UE to perform channel sensing for the scheduled UL signal, the BS may assume that the UE is going to transmit the scheduled UL signal without performing a specific procedure, based on that the transmission of the RAR and the scheduled UL signal are confined within a same period among periods configured in the shared spectrum, where the specific procedure is to determine whether channel occupancy in the corresponding period is initiated by the BS.

For example, the scheduled UL signal may be a PUSCH scheduled by the RAR.

For example, the RAR may include an RAR-PDCCH and an RAR-PDSCH scheduled by the RAR-PDCCH. The RAR-PDSCH may include a UL grant for scheduling a PUSCH. The BS may receive the PUSCH scheduled by the RAR-PDSCH, based on that at least one of the RAR-PDCCH or the RAR-PDSCH is confined within a same period as the scheduled UL signal. Based on that the RAR-PDSCH and the PUSCH scheduled by the RAR-PDSCH are confined in a same period, the BS may assume that the UE will skip a specific procedure for determining whether channel occupancy in the corresponding period is initiated by the BS and transmit the PUSCH.

For example, regardless of whether a cell for the transmission of the RAR is equal to or different from a cell for the scheduled UL signal, the BS may assume that the UE will perform the channel access procedure for the scheduled UL signal, based on whether the transmission of the scheduled UL signal and the RAR are confined within a same period. When a first cell for the transmission of the RAR is different from a second cell for the scheduled UL signal, based on that both the transmission of the RAR and the scheduled UL signal are confined in a first period among a plurality of periods configured on the second cell, the BS may assume that the UE will transmit the scheduled UL signal without performing a specific procedure for determining whether the first period starts with the channel occupancy of the BS.

For example, based on that the transmission of the RAR and the scheduled UL signal are not confined in the same period, the BS may assume that the UE will perform a specific procedure for determining whether channel occupancy in the corresponding period for the scheduled UL signal is initiated by the BS. The BS may assume that the UE will perform the channel access procedure for the scheduled UL signal only when the UE determined as a result of the specific procedure that the channel occupancy in the corresponding period is initiated by the BS. The BS may assume that the UE will drop the scheduled UL transmission when the UE determined as a result of the specific procedure that the channel occupancy in the corresponding period is not initiated by the BS.

Referring to <FIG>, a communication system <NUM> applied to the present disclosure includes wireless devices, Base Stations (BSs), and a network. Herein, the wireless devices represent devices performing communication using Radio Access Technology (RAT) (e.g., <NUM> New RAT (NR)) or Long-Term Evolution (LTE)) and may be referred to as communication/radio/SG devices. The wireless devices may include, without being limited to, a robot 100a, vehicles 100b-<NUM> and 100b-<NUM>, an eXtended Reality (XR) device 100c, a hand-held device 100d, a home appliance 100e, an Internet of Things (IoT) device 100f, and an Artificial Intelligence (AI) device/server <NUM>. Herein, the vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may include an Augmented Reality (AR)/Virtual Reality (VR)/Mixed Reality (MR) device and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). For example, the BSs and the network may be implemented as wireless devices and a specific wireless device 200a may operate as a BS/network node with respect to other wireless devices.

For example, the vehicles 100b-<NUM> and 100b-<NUM> may perform direct communication (e.g., Vehicle-to-Vehicle (V2V)/Vehicle-to-everything (V2X) communication).

Wireless communication/connections 150a, 150b, or 150c may be established between the wireless devices 100a to 100f/BS <NUM>, or BS <NUM>/BS <NUM>. Herein, the wireless communication/connections may be established through various RATs (e.g., <NUM> NR) such as uplink/downlink communication 150a, sidelink communication 150b (or, D2D communication), or inter BS communication (e.g., relay, Integrated Access Backhaul (IAB)). The wireless devices and the BSs/the wireless devices may transmit/receive radio signals to/from each other through the wireless communication/connections 150a and 150b. For example, the wireless communication/connections 150a and 150b may transmit/receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, and resource mapping/demapping), and resource allocating processes, for transmitting/receiving radio signals, may be performed based on the various proposals of the present disclosure.

<FIG> illustrates another example of a wireless device applied to the present disclosure.

<FIG> illustrates a vehicle or an autonomous driving vehicle applied to the present disclosure. The vehicle or autonomous driving vehicle may be implemented by a mobile robot, a car, a train, a manned/unmanned Aerial Vehicle (AV), a ship, etc..

Referring to <FIG>, a vehicle or autonomous driving vehicle <NUM> may include an antenna unit <NUM>, a communication unit <NUM>, a control unit <NUM>, a driving unit 140a, a power supply unit 140b, a sensor unit 140c, and an autonomous driving unit 140d.

The control unit <NUM> may perform various operations by controlling elements of the vehicle or the autonomous driving vehicle <NUM>. The driving unit 140a may cause the vehicle or the autonomous driving vehicle <NUM> to drive on a road. The driving unit 140a may include an engine, a motor, a powertrain, a wheel, a brake, a steering device, etc. The power supply unit 140b may supply power to the vehicle or the autonomous driving vehicle <NUM> and include a wired/wireless charging circuit, a battery, etc. The sensor unit 140c may acquire a vehicle state, ambient environment information, user information, etc. The sensor unit 140c may include an Inertial Measurement Unit (IMU) sensor, a collision sensor, a wheel sensor, a speed sensor, a slope sensor, a weight sensor, a heading sensor, a position module, a vehicle forward/backward sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illumination sensor, a pedal position sensor, etc. The autonomous driving unit 140d may implement technology for maintaining a lane on which a vehicle is driving, technology for automatically adjusting speed, such as adaptive cruise control, technology for autonomously driving along a determined path, technology for driving by automatically setting a path if a destination is set, and the like.

For example, the communication unit <NUM> may receive map data, traffic information data, etc. from an external server. The autonomous driving unit 140d may generate an autonomous driving path and a driving plan from the obtained data. The control unit <NUM> may control the driving unit 140a such that the vehicle or the autonomous driving vehicle <NUM> may move along the autonomous driving path according to the driving plan (e.g., speed/direction control). In the middle of autonomous driving, the communication unit <NUM> may aperiodically/periodically acquire recent traffic information data from the external server and acquire surrounding traffic information data from neighboring vehicles. In the middle of autonomous driving, the sensor unit 140c may obtain a vehicle state and/or surrounding environment information. The autonomous driving unit 140d may update the autonomous driving path and the driving plan based on the newly obtained data/information. The communication unit <NUM> may transfer information about a vehicle position, the autonomous driving path, and/or the driving plan to the external server. The external server may predict traffic information data using AI technology, etc., based on the information collected from vehicles or autonomous driving vehicles and provide the predicted traffic information data to the vehicles or the autonomous driving vehicles.

<FIG> is a diagram illustrating a DRX operation of a UE according to an embodiment of the present disclosure.

The UE may perform a DRX operation in the afore-described/proposed procedures and/or methods. A UE configured with DRX may reduce power consumption by receiving a DL signal discontinuously. DRX may be performed in an RRC_IDLE state, an RRC_INACTIVE state, and an RRC_CONNECTED state. The UE performs DRX to receive a paging signal discontinuously in the RRC_IDLE state and the RRC_INACTIVE state. DRX in the RRC _CONNECTED state (RRC_CONNECTED DRX) will be described below.

Referring to <FIG>, a DRX cycle includes an On Duration and an Opportunity for DRX. The DRX cycle defines a time interval between periodic repetitions of the On Duration. The On Duration is a time period during which the UE monitors a PDCCH. When the UE is configured with DRX, the UE performs PDCCH monitoring during the On Duration. When the UE successfully detects a PDCCH during the PDCCH monitoring, the UE starts an inactivity timer and is kept awake. On the contrary, when the UE fails in detecting any PDCCH during the PDCCH monitoring, the UE transitions to a sleep state after the On Duration. Accordingly, when DRX is configured, PDCCH monitoring/reception may be performed discontinuously in the time domain in the afore-described/proposed procedures and/or methods. For example, when DRX is configured, PDCCH reception occasions (e.g., slots with PDCCH SSs) may be configured discontinuously according to a DRX configuration in the present disclosure. On the contrary, when DRX is not configured, PDCCH monitoring/reception may be performed continuously in the time domain. For example, when DRX is not configured, PDCCH reception occasions (e.g., slots with PDCCH SSs) may be configured continuously in the present disclosure. Irrespective of whether DRX is configured, PDCCH monitoring may be restricted during a time period configured as a measurement gap.

Table <NUM> describes a DRX operation of a UE (in the RRC_CONNECTED state). Referring to Table <NUM>, DRX configuration information is received by higher-layer signaling (e.g., RRC signaling), and DRX ON/OFF is controlled by a DRX command from the MAC layer. Once DRX is configured, the UE may perform PDCCH monitoring discontinuously in performing the afore-described/proposed procedures and/or methods, as illustrated in <FIG>.

MAC-CellGroupConfig includes configuration information required to configure MAC parameters for a cell group. MAC-CellGroupConfig may also include DRX configuration information. For example, MAC-CellGroupConfig may include the following information in defining DRX.

When any of drx-OnDurationTimer, drx-InactivityTimer, drx-HARQ-RTT- TimerDL, and drx-HARQ-RTT-TimerDL is running, the UE performs PDCCH monitoring in each PDCCH occasion, staying in the awake state.

Those skilled in the art will appreciate that the present disclosure may be carried out in other specific ways than those set forth herein. The above embodiments are therefore to be construed in all aspects as illustrative and not restrictive. The scope of the invention is determined by the appended claims, not by the above description.

Claim 1:
A method performed by a user equipment, UE, (<NUM>) in a wireless communication system (<NUM>), the method comprising:
transmitting (D05) a random access preamble to a base station, BS (<NUM>);
receiving (D10) a random access response from the BS; and
performing (D15) a scheduled uplink, UL, transmission in a first period including a channel occupancy time, COT, and an idle time, based on the random access response,
wherein, the scheduled UL transmission is associated with channel occupancy initiated by the BS (<NUM>) and the UE (<NUM>) is indicated to perform the scheduled UL transmission based on channel sensing in shared spectrum,
characterized in that
wherein, based on the random access response being received in a second period different from the first period, the scheduled UL transmission in the first period is performed after determining, through a downlink, DL, signal detection procedure, that the channel occupancy of the first period is initiated by the BS (<NUM>), and
wherein, based on the random access response being received in the first period, the scheduled UL transmission in the first period is performed without the DL signal detection procedure.