Method and apparatus for performing uplink channel access in a wireless communication system

Abstract

The present invention relates to a method and apparatus for performing uplink channel access in a wireless communication system. In particular, the present invention includes the following steps: receiving an uplink grant for scheduling uplink transmission in at least one subframe from a base station; and performing uplink transmission in at least one subframe by using at least one of a first type of channel access and / or a second type of channel access. When all of the at least one subframe is included in a predetermined interval determined based on downlink transmission from the base station through an unlicensed cell, uplink transmission is performed by using the second type of channel access.

Description

[0001] This application is a divisional application of a patent application with application number 201780018454.3 (PCT / KR2017 / 003084), which was submitted to the China Patent Office on September 19, 2018, with an international application date of March 22, 2017, and the invention name is "Method and device for accessing unlicensed uplink channels in a wireless communication system". Technical Field

[0002] The present invention relates to a wireless communication system, and in particular to a method and apparatus for accessing an uplink channel in an unlicensed band in a wireless communication system. Background Art

[0003] In recent years, as mobile services have exploded due to the popularity of smart devices, it has been difficult to handle the increased data usage for providing cellular communication services only through conventional licensed spectrum or LTE licensed frequency bands.

[0004] In this case, a solution to provide cellular communication services using unlicensed (alternatively, unlicensed, unauthorized, or license-unnecessary) spectrum or LTE unlicensed bands (e.g., 2.4 GHz band, 5 GHz band, etc.) has been designed as a solution to the spectrum shortage problem.

[0005] However, unlike the authorized band in which a communication service provider secures exclusive frequency use rights through a process in the unlicensed band (such as auction, etc.), when only a predetermined level of adjacent band protection rules are followed, multiple communication facilities can be used simultaneously without restriction. Therefore, when the unlicensed band is used in a cellular communication service, it is difficult to guarantee the communication quality at the level provided in the authorized band, and interference problems with common wireless communication devices (e.g., wireless LAN devices) using the unlicensed band may occur.

[0006] Therefore, it is necessary to prioritize the research on coexistence schemes with respect to conventional unlicensed band devices and schemes for efficiently sharing radio channels in order to address LTE technology in the unlicensed band. That is, it is necessary to develop a robust coexistence mechanism (RCM) to prevent devices using LTE technology in the unlicensed band from affecting conventional unlicensed band devices. Summary of the invention

[0007] Technical issues

[0008] The present invention has been devoted to providing a method for efficiently sending signals in a wireless communication system (particularly, a cellular wireless communication system and its equipment). Further, the present invention has been devoted to providing a method for efficiently sending signals in a specific frequency band (e.g., an unlicensed band) and its equipment.

[0009] The technical objectives expected to be achieved in the present invention are not limited to the aforementioned objectives, and other technical objectives not described above will be clearly understood by those skilled in the art from the following disclosure.

[0010] Technical Solution

[0011] According to one aspect of the present invention, there is provided a method for a user equipment to perform uplink transmission to a base station through an unlicensed cell in a wireless communication system, the method comprising: receiving an uplink grant for scheduling uplink transmission in at least one subframe from the base station; and performing uplink transmission in at least one subframe by using at least one of a first type of channel access or a second type of channel access. When all of the at least one subframe are included in a predetermined interval determined based on downlink transmission from the base station through the unlicensed cell, uplink transmission is performed by using the second type of channel access.

[0012] In addition, according to one aspect of the present invention, a user equipment of a wireless communication system is provided, the user equipment comprising: a wireless communication module; and a processor, the processor being configured to receive an uplink grant for scheduling uplink transmission in at least one subframe from a base station, and perform uplink transmission in at least one subframe by using at least one of a first type of channel access or a second type of channel access. The processor is configured to: when all of the at least one subframe are included in a predetermined interval determined based on downlink transmission from the base station through an unlicensed cell, perform uplink transmission by using the second type of channel access.

[0013] Preferably, the uplink grant may indicate a channel access type to be used in uplink transmission among the first type channel access or the second type channel access. Preferably, when at least one subframe is not included in the predetermined interval or only a portion of at least one subframe is included in the predetermined interval, uplink transmission may be performed by using the channel access of the type indicated in the uplink grant.

[0014] On the other hand, the predetermined interval may be determined based on a maximum channel occupancy time set by downlink transmission, and information on whether at least one subframe is the last subframe for uplink transmission may be received through a common control channel.

[0015] In addition, when uplink transmission is performed in a next subframe of downlink transmission in an unlicensed cell, uplink transmission may be performed by using the second type channel access.

[0016] On the other hand, according to another aspect of the present invention, there is provided a method for a base station to receive uplink transmission from a user equipment through an unlicensed cell in a wireless communication system, the method comprising: scheduling the transmission of an uplink signal in at least one subframe, and transmitting to the user equipment an uplink grant indicating a channel access type to be used in a first type of channel access or a second type of channel access when the user equipment transmits an uplink signal; and receiving the uplink signal in at least one subframe. The method further comprises: when all of at least one subframe are included in a predetermined interval determined based on downlink transmission through an unlicensed cell, transmitting common downlink control information indicating that the second type of channel access is performed in the uplink transmission.

[0017] In addition, according to another aspect of the present invention, a base station in a wireless communication system is provided, the base station comprising: a wireless communication module; and a processor, the processor being configured to schedule the transmission of an uplink signal through an unauthorized cell in at least one subframe, transmit to a user equipment an uplink permission indicating a channel access type to be used when the user equipment transmits an uplink signal among the first type of channel access or the second type of channel access, and receive an uplink signal from the user equipment in at least one subframe, and when all of at least one subframe are included in a predetermined interval determined based on the downlink transmission through the unauthorized cell, the processor is configured to transmit common downlink control information indicating that the second type of channel access is to be performed in the uplink transmission.

[0018] In addition, when at least one subframe is not included in the predetermined interval or only a portion of at least one subframe is included in the predetermined interval, the uplink grant may indicate the first type channel access. In addition, the common downlink control information may include information on whether the at least one subframe is the last subframe for uplink transmission.

[0019] Beneficial Effects

[0020] According to an exemplary embodiment of the present invention, a method for efficiently sending a signal in a wireless communication system (particularly, a cellular wireless communication system and its equipment) is provided. Further, a method for efficiently accessing a channel in a specific frequency band (e.g., an unlicensed band) and its equipment are provided.

[0021] Effects obtained in the present invention are not limited to the aforementioned effects, and other effects not described above will be clearly understood by those skilled in the art from the following disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] To help understanding of the present invention, the accompanying drawings, which are included as a part of the detailed description, provide embodiments of the present invention and, together with the detailed description, describe the technical problems of the present invention.

[0023] Figure 1 Illustrated are physical channels used in a 3rd Generation Partnership Project (3GPP) system and a general signal transmission method using the physical channels.

[0024] Figure 2 An example of a radio frame structure used in a wireless communication system is illustrated.

[0025] Figure 3 An example of a downlink (DL) / uplink (UL) slot structure used in a wireless communication system is illustrated.

[0026] Figure 4 The structure of a downlink subframe (SF) is shown.

[0027] Figure 5 The structure of an uplink subframe is illustrated.

[0028] Figure 6 It is a schematic diagram used to describe single-carrier communication and multi-carrier communication.

[0029] Figure 7 An example of applying the cross-carrier scheduling technology is illustrated.

[0030] Figure 8 The diagram illustrates an ACK / NACK (A / N) transmission process in the case of a single cell.

[0031] Fig. 9 The diagram illustrates a License Assisted Access (LAA) service environment.

[0032] Fig.10 The diagram illustrates the deployment scenario of user equipment and base stations in the LAA service environment.

[0033] Fig.11 A communication scheme (eg, wireless LAN) operating in an unlicensed band in the related art is illustrated.

[0034] Figure 12 to Figure 13 The diagram illustrates the listen-before-talk (LBT) process for downlink transmission.

[0035] Fig.14 Downlink transmission in the unlicensed band is illustrated.

[0036] Fig.15 : is a schematic diagram illustrating a case where a PDCCH including only an uplink grant is transmitted without PDSCH transmission as an embodiment of the present invention.

[0037] Fig.16: is a schematic diagram illustrating a case where an EPDCCH including only an uplink grant is transmitted without PDSCH transmission as an embodiment of the present invention.

[0038] Fig.17 is a diagram illustrating a case where LBT is independently performed for a subframe for transmitting only a UL grant without PDSCH transmission and a subframe(s) for performing PDSCH transmission according to an embodiment of the present invention.

[0039] Fig.18 is a diagram illustrating a case where LBT is independently performed for a subframe for transmitting only a UL grant without PDSCH transmission and a subframe(s) for performing PDSCH transmission according to an embodiment of the present invention.

[0040] Fig.19 is a diagram illustrating an example of switching an LBT type according to an embodiment of the present invention when DL scheduling occurs between UL grant transmission and corresponding UL traffic transmission.

[0041] Fig. 20 is a diagram illustrating another example of switching an LBT type according to an embodiment of the present invention when DL scheduling occurs between UL grant transmission and corresponding UL traffic transmission.

[0042] Fig.21 is a diagram illustrating another example of switching an LBT type according to an embodiment of the present invention when DL scheduling occurs between UL grant transmission and corresponding UL traffic transmission.

[0043] Fig. 22 is a schematic diagram illustrating a method of performing UL channel access for consecutive UL transmissions following DL transmissions in an LAA cell.

[0044] Fig.23 An example of a terminal transmitting a data channel to a base station according to another embodiment of the present invention is shown.

[0045] Fig.24 The diagram illustrates configurations of a user equipment and a base station according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] By considering the functions in the present invention, the terms used in this specification try to adopt the common terms widely used at present, but the terms can be changed according to the intentions, habits, and emergence of new technologies of the technicians in this field. Further, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, their meanings will be described in the corresponding description part of the present invention. Therefore, the present invention is intended to show that the terms used in this specification should be analyzed, and the analysis is not only based on the name of the term, but also based on the substantive meaning of the term and the content throughout the present specification.

[0047] Throughout this specification and the claims that follow, when an element is described as being "coupled" to another element, the element may be "directly coupled" to the other element or "electrically coupled" to the other element through a third element. Further, unless expressly described to the contrary, the word "include" and variations (such as, "comprises" or "comprising") will be understood to mean the inclusion of the stated elements but not the exclusion of any other elements. Moreover, in some exemplary embodiments, it may be appropriate to replace the limitation with "greater than" or "less than", such as, "equal to or greater than" or "equal to or less than" based on a particular threshold, respectively.

[0048] The following technologies, such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier FDMA (SC-FDMA), etc., can be used in various wireless access systems. CDMA can be implemented by radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA 2000. TDMA can be implemented by 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 by radio technology such as IEEE 802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA), etc. UTRA is part of Universal Mobile Telecommunications System (UMTS). The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is a part of Evolved UMTS (E-UMTS) using Evolved UMTS Terrestrial Radio Access (E-UTRA), and Advanced LTE (A) is an evolved version of 3GPP LTE. 3GPP LTE / LTE-A is mainly described for clarity of description, but the technical spirit of the present invention is not limited thereto.

[0049] Figure 1The diagram illustrates physical channels used in the 3GPP system and a general signal transmission method using the physical channels. The user equipment receives information from the base station through the downlink (DL), and the user equipment transmits information to the base station through the uplink (UL). The information transmitted / received between the base station and the user equipment includes data and various control information, and various physical channels exist according to the type / purpose of the information transmitted / received between the base station and the user equipment.

[0050] When the power of the user equipment is turned on or the user equipment enters a cell in a new way, the user equipment performs an initial cell search operation including synchronization with the base station, etc. (S301). To this end, the user equipment receives a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from the base station to synchronize with the base station and obtain information including a cell ID, etc. Thereafter, the user equipment receives a physical broadcast channel from the base station to obtain intra-cell broadcast information. The user equipment receives a downlink reference signal (DL RS) in the initial cell search step to verify the downlink channel state.

[0051] The user equipment that has completed the initial cell search receives a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to information loaded on the PDCCH to obtain more detailed system information (S302).

[0052] When there is no radio resource for initial access to the base station or signal transmission, the user equipment may perform a random access procedure (RACH procedure) for the base station (S303 to S306). To this end, the user equipment may transmit a preamble through a physical random access channel (PRACH) (S303) and receive a response message to the preamble through a PDCCH and a PDSCH corresponding thereto (S304). In the case of a contention-based RACH, a contention resolution procedure may also be performed.

[0053] Thereafter, the user equipment may receive PDCCH / PDSCH (S307) and transmit a physical uplink shared channel (PUSCH) / physical uplink control channel (PUCCH) (S308) as a general process. The user equipment receives downlink control information (DCI) through PDCCH. DCI includes control information (such as resource allocation information) for the user equipment, and the format varies according to the purpose of use. The control information transmitted by the user equipment to the base station is designated as uplink control information (UCI). UCI includes acknowledgement / negative acknowledgement (ACK / NACK), channel quality indicator (CQI), precoding matrix index (PMI), rank indicator (RI), etc. UCI can be transmitted through PUSCH and / or PUCCH.

[0054] Figure 2An example of a radio frame structure used in a wireless communication system is illustrated. Figure 2 (a) illustrates a frame structure for frequency division duplex (FDD), and Figure 2 (b) illustrates a frame structure for time division duplex (TDD).

[0055] Reference Figure 2 , the frame structure may have a length of 10 ms (307200 Ts) and may be composed of 10 subframes (SFs). Ts represents a sampling time and is expressed as Ts=1 / (2048*15kHz). Each subframe may have a length of 1 ms and may be composed of 2 time slots. Each time slot has a length of 0.5 ms. The time used to transmit one subframe is defined as a transmission time interval (TTI). Time resources may be distinguished by a radio frame number / index, a subframe number / index #0 to #9, and a time slot number / index #0 to #19.

[0056] The radio frame can be configured in different ways according to the duplex mode. In FDD mode, downlink transmission and uplink transmission are distinguished by frequency, and the radio frame includes only one of the downlink subframe and uplink subframe for a specific frequency band. In TDD mode, downlink transmission and uplink transmission are distinguished by time, and the radio frame includes both of the downlink subframe and uplink subframe for a specific frequency band.

[0057] Figure 3 The structure of the downlink / uplink time slot is shown.

[0058] Reference Figure 3 , a time slot includes multiple orthogonal frequency division multiplexing (OFDM) symbols in the time domain and multiple resource blocks (RBs) in the frequency domain. OFDM symbol also means one symbol period. According to the multiple access scheme, OFDM symbol can be called OFDMA symbol, single carrier frequency division multiple access (SC-FDMA) symbol, etc. The number of OFDM symbols included in a time slot can be variously modified according to the length of the cyclic prefix (CP). For example, in the case of standard CP, one time slot includes 7 OFDM symbols, and in the case of extended CP, one time slot includes 6 OFDM symbols. RB is defined as N in the time domain. DL / UL symb (e.g., 7) consecutive OFDM symbols and N in the frequency domain RB sc (For example, 12) consecutive subcarriers. A resource consisting of one OFDM symbol and one subcarrier is called a resource element (RE) or tone. One RB consists of N DL / UL symb *N RB scResource elements.

[0059] The resources of the time slot can be represented by N DL / UL RB *N RB sc subcarriers and N DL / UL symb OFDM symbols form a resource grid. Each RE in the resource grid is uniquely defined by a pair of indexes (k, 1) at each time sequence. K represents a 0 to N in frequency domain. DL / UL RB *N RB sc -1 for a given index, and 1 for a given index in the time domain from 0 to N DL / UL symb -1 given index. Here, N DL RB represents the number of resource blocks (RBs) in a downlink slot, and N UL RB N represents the number of RBs in the UL slot. DL RB and N UL RB Depends on the DL transmission bandwidth and UL transmission bandwidth respectively. DL symb represents the number of symbols in a downlink slot, and N UL symb N represents the number of symbols in the UL slot. RB sc Indicates the number of subcarriers that make up one RB. A resource grid is set for each antenna port.

[0060] Figure 4 The structure of a downlink subframe is illustrated.

[0061] Reference Figure 4 , a subframe can be composed of 14 OFDM symbols. According to the subframe setting, the first 1 to 3 (alternatively, 2 to 4) OFDM symbols are used as the control region, and the remaining 13 to 11 (alternatively, 12 to 10) OFDM symbols are used as the data region. R1 to R4 represent reference signals for antenna ports 0 to 3. The control channels allocated to the control region include the Physical Control Format Indicator Channel (PCFICH), the Physical Hybrid ARQ Indicator Channel (PHICH), the Physical Downlink Control Channel (PDCCH), etc. The data channels allocated to the data region include PDSCH, etc. When the enhanced PDCCH (EPDCCH) is set, PDSCH and EPDCCH are multiplexed in the data region by frequency division multiplexing (FDM).

[0062] The PDCCH as a physical downlink control channel is allocated to the first n OFDM symbols of a subframe, and n is represented by PCFICH as an integer of 1 (alternatively, 2) or more. The PDCCH announces information associated with resource allocation of a paging channel (PCH) and a downlink shared channel (DL-SCH) as transmission channels, uplink scheduling permissions, HARQ information, etc. to each user equipment or user equipment group. The data (i.e., transport blocks) of the PCH and DL-SCH are transmitted through the PDSCH. In addition to specific control information or specific service data, each of the base station and the user equipment generally transmits and receives data through the PDSCH.

[0063] Information indicating to which user equipment (one or more user equipment) the data of the PDSCH is transmitted, information indicating how the user equipment receives the PDSCH data and decodes the PDSCH data, etc. are transmitted, and the information is included in the PDCCH / EPDCCH. For example, it is assumed that the PDCCH / EPDCCH is CRC-masked using a radio network temporary identifier (RNTI) called "A" and information about data transmitted by using a radio resource (e.g., frequency position) called "B" and a DCI format called "C" (i.e., transmission format information (e.g., transport block size, modulation scheme, coding information, etc.) is transmitted through a specific subframe). In this case, the user equipment in the cell monitors the PDCCH / EPDCCH by using its RNTI information, and when one or more user equipments with the "A" RNTI are provided, the user equipment receives the PDCCH / EPDCCH, and receives the PDSCH represented by "B" and "C" through the information about the received PDCCH / EPDCCH.

[0064] Figure 5 The structure of an uplink subframe is illustrated.

[0065] Reference Figure 5 , a subframe can be divided into a control region and a data region in the frequency domain. PUCCH is allocated to the control region and carries UCI. PUSCH is allocated to the data region and carries user data.

[0066] The following control information may be transmitted using the PUCCH.

[0067] - Scheduling Request (SR): Information for requesting UL-SCH resources. The SR is transmitted by using an On-Off Keying (OOK) scheme.

[0068] -HARQ-ACK: A response to the PDCCH and / or a response to a downlink data packet (e.g., a codeword) on the PDSCH. A codeword is a coding format for a transport block. HARQ-ACK indicates whether the PDCCH and PDSCH were successfully received. The HARQ-ACK response includes a positive ACK (simply, ACK), a negative ACK (NACK), a discontinuous transmission (DTX), or NACK / DTX. DTX indicates that the user equipment loses the PDCCH (alternatively, a semi-persistent scheduling (SPS) PDSCH) and NACK / DTX refers to the case of NACK or DTX. HARQ-ACK is used in combination with HARQ-ACK / NACK and ACK / NACK.

[0069] - Channel State Information (CSI): Feedback information about downlink channels. Feedback information related to Multiple Input Multiple Output (MIMO) includes RI and PMI.

[0070] Hereinafter, carrier aggregation will be described. Carrier aggregation means a method in which a wireless communication system uses multiple frequency blocks as one larger logical frequency band in order to use a wider frequency band. When the entire system band is extended by carrier aggregation, the frequency band used to communicate with each user equipment is defined by a component carrier (CC) unit.

[0071] Figure 6 It is a schematic diagram used to describe single-carrier communication and multi-carrier communication. Figure 6 (a) illustrates a subframe structure of a single carrier, and Figure 6 (b) illustrates a subframe structure of a multi-carrier of carrier aggregation.

[0072] Figure 6 (b) illustrates a subframe structure of a multi-carrier of carrier aggregation.

[0073] Reference Figure 6 (a) In a single carrier system, a base station and a user equipment perform data communication through one DL band and one UL band corresponding thereto. The DL / UL band is divided into a plurality of orthogonal subcarriers, and each band operates at one carrier frequency. In FDD, the DL and UL bands operate at different carrier frequencies, respectively, and in TDD, the DL and UL bands operate at the same carrier frequency. The carrier frequency refers to the center frequency of the frequency band.

[0074] Reference Figure 6 (b) of the present invention distinguishes carrier aggregation from an OFDM system that performs DL / UL communication in a baseband divided into a plurality of subcarriers by using one carrier frequency, because carrier aggregation performs DL / UL communication by using a plurality of carrier frequencies. Figure 6(b) of the present invention aggregates three 20MHz CCs in each of the UL and DL to support a bandwidth of 60MHz. CCs may be adjacent to each other or not adjacent to each other in the frequency domain. For convenience, Figure 6 (b) illustrates a case where the bandwidth of the UL CC and the bandwidth of the DL CC are the same and symmetrical to each other, but the bandwidth of the corresponding CC can be determined independently. Further, asymmetric carrier aggregation in which the number of UL CCs and the number of DL CCs are different from each other is also available. (Multiple) DL / UL CCs are independently allocated / configured for each user equipment, and the (multiple) DL / UL CCs allocated / configured for the user equipment are designated as (multiple) serving UL / DL CCs of the corresponding user equipment.

[0075] The base station may start some or all of the service CCs of the user equipment or disable some CCs. When the base station allocates (multiple) CCs to the user equipment, if the CC allocation to the user equipment is completely reconfigured or if the user equipment is not switched, at least one specific CC in the (multiple) CCs configured for the corresponding user equipment is not disabled. The specific CC that is always started is called the primary CC (PCC), and the CC that the base station can start / disable arbitrarily is called the secondary CC (SCC). The PCC and SCC can be distinguished based on control information. For example, specific control information can be set to be sent / received only through a specific CC, and the specific CC can be called the PCC, and the remaining (multiple) CCs can be called (multiple) SCCs. PUCCH is transmitted only on the PCC.

[0076] In 3GPP, the concept of cells is used to manage radio resources. A cell is defined as a combination of DL resources and UL resources, that is, a combination of DL CCs and UL CCs. A cell can be configured only by DL resources or a combination of DL resources and DL resources. When carrier aggregation is supported, system information can be used to indicate the link between the carrier frequency of DL resources (alternatively, DL CCs) and the carrier frequency of UL resources (alternatively, UL CCs). For example, a system information block type 2 (SIB2) link can be used to indicate the combination of DL resources and UL resources. The carrier frequency refers to the center frequency of each cell or CC. The cell corresponding to the PCC is called the primary cell (PCell), and the cell corresponding to the SCC is called the secondary cell (SCell). The carrier corresponding to the PCell is the DL PCC in the downlink, and the carrier corresponding to the PCell is the UL PCC in the uplink. Similarly, the carrier corresponding to the SCell is the DL SCC in the downlink, and the carrier corresponding to the SCell is the UL SCC in the uplink. Depending on the user equipment capability, (multiple) service cells can be composed of a PCell and 0 or more SCells. For a user equipment in RRC_CONNECTED state but without any configuration of carrier aggregation or not supporting carrier aggregation, there is only one serving cell consisting of only PCell.

[0077] Figure 7 An example of applying cross-carrier scheduling is illustrated. When cross-carrier scheduling is configured, a control channel transmitted through a first CC can schedule a data channel transmitted through a first CC or a second CC by using a carrier indicator field (CIF). The CIF is included in the DCI. In other words, a scheduling cell is configured, and the DL grant / UL grant transmitted in the PDCCH area of ​​the scheduling cell schedules the PDSCH / PUSCH of the scheduled cell. That is, the search space of multiple component carriers exists in the PDCCH area of ​​the scheduling cell. The PCell can basically be a scheduling cell, and a specific SCell can be designated as a scheduling cell by an upper layer.

[0078] exist Figure 7In this paper, it is assumed that three DL CCs are aggregated. In this article, DL component carrier #0 is assumed to be DL PCC (alternatively, PCell), and DL component carrier #1 and DL component carrier #2 are assumed to be DL SCC (alternatively, SCell). Further, it is assumed that the DL PCC is set to monitor the PDCCH of the CC. When CIF is disabled, according to the LTE PDCCH rules (non-cross-carrier scheduling and self-carrier scheduling), the corresponding DL CC can transmit only the PDCCH that schedules its PDSCH without CIF. On the contrary, when CIF is enabled by UL-specific (alternatively, UL group-specific or cell-specific) upper layer signaling, a specific CC (e.g., DL PCC) can transmit the PDCCH that schedules the PDSCH of DL CC A and the PDCCH that schedules the PDSCH of another CC by using CIF (cross-carrier scheduling). On the contrary, in another DL CC, PDCCH is not transmitted.

[0079] Figure 8 The figure illustrates an ACK / NACK (A / N) transmission process in the case of a single cell. (i) PDSCH scheduled by PDCCH, (ii) PDSCH without corresponding PDCCH (i.e., SPS PDSCH), and (iii) PDCCH indicating SPS release. The figure illustrates a process of transmitting ACK / NACK for PDSCH of (i). PDCCH includes EPDCCH.

[0080] Reference Figure 8 , the user equipment receives the PDCCH (or EPDCCH) (S802) in subframe #nk, and receives the PDSCH indicated by the PDCCH in the same subframe (S804). The PDCCH transmits scheduling information (i.e., DL grant), and the PDSCH transmits one or more (e.g., two) transport blocks TB (or codewords CW) according to the transmission mode. Thereafter, the user equipment may transmit ACK / NACK for the PDSCH (i.e., transport block) in subframe #n (S806). In response to a single transport block, one bit of ACK / NACK may be transmitted, and in response to two transport blocks, two bits of ACK / NACK may be transmitted. Basically, ACK / NACK is transmitted via PUCCH, but when there is PUSCH transmission in subframe #n, ACK / NACK is transmitted via PUSCH. k represents the time interval between a DL subframe and a UL subframe. In FDD, K=4, and k in TDD may be given by a downlink association set index (DASI). ACK / NACK represents HARQ-ACK. HARQ-ACK responses include ACK, NACK, DTX, and NACK / DTX.

[0081] When a plurality of cells are configured for a user equipment, ACK / NACK information may be transmitted by using PUCCH format 3, or may be transmitted by using a channel selection scheme based on PUCCH format 1b.

[0082] Each cell is configured with an ACK / NACK payload of PUCCH format 3, and the cascaded ACK / NACK payload is ordered according to the cell index. The ACK / NACK payload is configured for all cells configured for user equipment, regardless of whether actual data is transmitted in each cell. Each bit in the ACK / NACK payload represents the HARQ-ACK feedback for the transport block (or codeword). The HARQ-ACK feedback indicates ACK or NACK, and DTX is processed as NACK. NACK and DTX have the same HARQ-ACK feedback value. If necessary, the base station can distinguish NACK from DTX by using information about the control channel that the base station has transmitted to the user equipment.

[0083] When two cells are aggregated, a channel selection scheme based on PUCCH format 1b may be configured for ACK / NACK transmission. In the channel selection scheme based on PUCCH format 1b, ACK / NACK responses to multiple transport blocks (or codewords) are identified by combining a PUCCH resource index and a bit value.

[0084] Fig. 9 The diagram illustrates a License Assisted Access (LAA) service environment.

[0085] Reference Fig. 9 , a service environment can be provided to users, in which the LTE technology (11) in the conventional authorized band and LTE unlicensed (LTE-U) or LAA as the LTE technology (12) in the unlicensed band, which have been actively discussed, can be connected to each other. For example, the LTE technology (11) in the authorized band and the LTE technology (12) in the unlicensed band in the LAA environment can be integrated by using technologies (such as carrier aggregation, etc.), which can help expand network capacity. Further, in an asymmetric service structure in which the amount of downlink data is greater than the amount of uplink data, LAA can provide optimized LTE services according to various requirements or environments. For convenience, the LTE technology in the authorized (alternatively, authorized or allowed) band is referred to as LTE authorized (LTE-L), and the LTE technology in the unlicensed (alternatively, unauthorized, unlicensed, not necessarily authorized) band is referred to as LTE unlicensed (LTE-U) or LAA.

[0086] Fig.10The diagram illustrates the layout scenarios of user equipment and base stations in the LAA service environment. The frequency band targeted by the LAA service environment has a short wireless communication reach distance due to its high frequency characteristics. Taking this into account, the layout scenarios of user equipment and base stations in an environment where conventional LTE-L services and LAA services coexist can be an overlapping model and a co-location model.

[0087] In the overlapping model, the macro base station can perform wireless communication with X UE and X'UE in the macro area (32) by using a licensed carrier, and connect with multiple remote radio heads (RRH) through the X2 interface. Each RRH can perform wireless communication with X UE or X'UE in a predetermined area (31) by using an unlicensed carrier. The frequency bands of the macro base station and the RRH are different from each other and do not interfere with each other, but data needs to be quickly exchanged between the macro base station and the RRH through the X2 interface so that the LAA service can be used as an auxiliary downlink channel for the LTE-L service through carrier aggregation.

[0088] In the co-location model, the pico / femto base station can perform wireless communication with the Y UE by using a licensed carrier and an unlicensed carrier. However, the pico / femto base station may be limited in downlink transmission using the LTE-L service and the LAA service. The coverage (33) of the LTE-L service and the coverage (34) of the LAA service may be different depending on the frequency band, transmission power, etc.

[0089] When LTE communication is performed in an unlicensed band, a conventional device (e.g., a wireless LAN (Wi-Fi) device) that performs communication in the corresponding unlicensed band may not demodulate an LTE-U message or data, and determine the LTE-U message or data as a type of energy for performing interference avoidance operations through an energy detection technique. That is, when the energy corresponding to the LTE-U message or data is less than -62dBm, the wireless LAN device may perform communication by ignoring the corresponding message or data. Therefore, the user device that performs LTE communication in the unlicensed band may be frequently interfered with by the wireless LAN device.

[0090] Therefore, it is necessary to allocate or reserve a specific frequency band within a specific time in order to effectively implement LTE-U technology / services. However, since peripheral devices that perform communication through unlicensed bands attempt to access based on energy detection technology, there is a problem that it is difficult to perform efficient LTE-U services. Therefore, it is necessary to give priority to the research on coexistence schemes for conventional unlicensed band devices and schemes for efficiently sharing radio channels in order to solve LTE-U technology. That is, it is necessary to develop a robust coexistence mechanism in which LTE-U devices do not affect conventional unlicensed band devices.

[0091] Fig.11A communication scheme (eg, wireless LAN) operating in an unlicensed band in the prior art is illustrated. Since most devices operating in an unlicensed band operate based on listen-before-talk (LBT), a clear channel assessment (CCA) technique of sensing a channel before data transmission is performed.

[0092] Reference Fig.11 , a wireless LAN device (e.g., an AP or a STA) checks whether a channel is busy by performing carrier sensing before transmitting data. When a radio signal of a predetermined strength or greater is sensed in a channel transmitting data, the corresponding channel is determined to be busy, and the wireless LAN device delays access to the corresponding channel. This process is called idle channel assessment, and the signal level used to determine whether a signal is sensed is called a CCA threshold. At the same time, when no radio signal is sensed in the corresponding channel or a radio signal with a strength less than the CCA threshold is sensed, the channel is determined to be idle.

[0093] When it is determined that the channel is idle, the terminal with data to be transmitted performs a backoff process after a delay period (e.g., arbitration interframe space (AIFS), PCF IFS (PIFS), etc.). The delay period refers to the minimum time that the terminal needs to wait after the channel is idle. The backoff process allows the terminal to further standby within a predetermined time after the delay period. For example, while the channel is in an idle state, the terminal stands by while reducing the slot time for the slot time corresponding to the random number allocated to the terminal in the contention window (CW), and the terminal that completely runs out of the slot time can attempt to access the corresponding channel.

[0094] When the terminal successfully accesses the channel, the terminal can transmit data through the channel. When data is successfully transmitted, the CW size (CWS) is reset to the initial value (CWmin). On the contrary, when data is not successfully transmitted, the CWS is doubled. Therefore, the terminal is assigned a new random number in a range twice as large as the previous random number range to perform a backoff process in the next CW. In a wireless LAN, only ACK is defined as receiving response information to data transmission. Therefore, when ACK is received for data transmission, CWS is reset to the initial value, and when no feedback information is received for data transmission, CWS is doubled.

[0095] As mentioned above, since most communications in unlicensed bands in the prior art operate based on LBT, LTE also considers LBT in LAA to coexist with conventional devices. Specifically, in LTE, channel access methods on unlicensed bands can be divided into the following 4 categories according to the presence / application scheme of LBT.

[0096] (1) Category 1: No LBT

[0097] -The LBT process performed by the Tx entity is not performed.

[0098] (2) Category 2: LBT without random backoff

[0099] -Determines the time interval during which the Tx entity needs to sense the channel in an idle state before performing a transmission on the channel. No random backoff is performed. This may be referred to as Type 2 channel access.

[0100] (3) Category 3: LBT with random backoff of fixed-size CW

[0101] -LBT method that performs random backoff by using a fixed-size CW. The Tx entity has a random number N in the CW, and the CW size is defined by a minimum / maximum value. The CW size is fixed. The random number N is used to determine the time interval that the Tx entity needs to sense the channel in an idle state before performing a transmission on the channel.

[0102] (4) Category 4: LBT with random backoff of CW with variable size

[0103] -LBT method that performs random backoff by using a variable-sized CW. The Tx entity has a random number N in the CW, and the CW size is defined by the minimum / maximum value of N. The Tx entity can change the CW size when the random number N is generated. The random number N is used to determine the time interval that needs to sense the channel in an idle state before the Tx entity performs transmission on the channel. This can be called Type 1 channel access.

[0104] Fig.12 and Fig.13 The figure shows the downlink transmission process based on Category 4 LBT. Category 4 LBT can be used to ensure fair channel access using Wi-Fi. Fig.12 and Fig.13 , the LBT process includes initial CCA (ICCA) and extended CCA (ECCA). In ICCA, random backoff is not performed, and in ECCA, random backoff is performed by using a CW of variable size. ICCA is applicable to the case where the channel is idle when signal transmission is required, and ECCA is applicable to the case where the channel is busy when downlink transmission is performed just before.

[0105] Reference Fig.12 , the downlink transmission process based on Category 4 LBT, Type 1 channel access can be performed as follows.

[0106] Initial CCA

[0107] - S1202: The base station verifies that the channel is idle.

[0108] - S1204: The base station verifies whether signal transmission is required. When signal transmission is not required, the process returns to S1202, and when signal transmission is required, the process continues to S1206.

[0109] -S1206: The base station verifies whether the channel is idle within the ICCA delay period (BCCA). The ICCA delay period is configurable. As an implementation example, the ICCA delay period may be composed of an interval of 16 μs and n consecutive CCA slots. In this document, n may be a positive integer, and one CCA slot interval may be 9 μs. Depending on the QoS level, the number of CCA slots may be configured in different ways. The ICCA delay period may be set to an appropriate value by considering the delay period of Wi-Fi (e.g., DIFS or AIFS). For example, the ICCA delay period may be 34 μs. When the channel is idle within the ICCA delay period, the base station may perform a signal transmission process (S1208). When it is determined that the channel is busy during the ICCA delay period, the process proceeds to S1212 (ECCA).

[0110] - S1208: The base station may perform a signal transmission process. When signal transmission is not performed, the process proceeds to S1202 (ICCA), and when signal transmission is performed, the process proceeds to S1210. Even in the case where the backoff count N reaches 0 in S1218 and S1208 is performed, when signal transmission is not performed, the process proceeds to S1202 (ICCA), and when signal transmission is performed, the process proceeds to S1210.

[0111] - S1210: When additional signal transmission is not required, the process proceeds to S1202 (ICCA), and when additional signal transmission is required, the process proceeds to S1212 (ECCA).

[0112] Extended CCA

[0113] -S1212: The base station generates a random number N in the CW. N is used as a count during the backoff process, and N is generated from [0, q-1]. The CW may consist of q ECCA slots, and the ECCA slot size may be 9 μs or 10 μs. In S1214, the CW size (CWS) may be defined as q and may be variable. Thereafter, the base station proceeds to S1216.

[0114] -S1214: The base station may update the CWS. The CWS q may be updated to a value between X and Y. The X and Y values ​​are configurable parameters. The CWS update / adjustment may be performed whenever N is generated (dynamic backoff), and may be performed semi-statically within a predetermined time interval (semi-static backoff). The CWS may be updated / adjusted based on an exponential backoff or a binary backoff. That is, the CWS may be updated / adjusted in the form of a square of 2 or a multiple of 2. In conjunction with PDSCH transmission, the CWS may be updated / adjusted based on feedback / reporting from the user equipment (e.g., HARQ ACK / NACK) or may be updated / adjusted based on base station sensing.

[0115] -S1216: The base station verifies whether the channel is idle within the ECCA delay period (DeCCA). The ECCA delay period is configurable. As an implementation example, the ECCA delay period may consist of an interval of 16 μs and n consecutive CCA slots. In this article, n may be a positive integer, and one CCA slot interval may be 9 μs. Depending on the QoS level, the number of CCA slots may be configured in different ways. The ECCA delay period may be set to an appropriate value by considering the delay period of Wi-Fi (e.g., DIFS or AIFS). For example, the ECCA delay period may be 34 μs. When the channel is idle within the ECCA delay period, the base station proceeds to S1218. When it is determined that the channel is busy during the ECCA delay period, the base station repeats S1216.

[0116] - S1218: The base station verifies whether N is 0. When N is 0, the base station may perform the signal transmission process (S1208). In this case, (N=0), the base station may not perform transmission immediately, and perform a CCA check within at least one time slot to continue the ECCA process. When N is not 0 (i.e., N>0), the process continues to S1220.

[0117] - S1220: The base station senses the channel during one ECCA time slot interval (T). The ECCA time slot size may be 9 μs or 10 μs, and the actual sensing time may be at least 4 μs.

[0118] - S1222: When it is determined that the channel is idle, the process proceeds to S1224. When it is determined that the channel is busy, the process returns to S1216. That is, an ECCA delay period is applied again after the channel is idle, and N is not counted during the ECCA delay period.

[0119] -S1224: N minus 1 (ECCA count down)

[0120] Fig.13 Generally speaking Fig.12 The transmission process is the same / similar to that of Fig.12 Therefore, you can refer to Fig.12 to describe the problem in detail.

[0121] - S1302: The base station verifies whether signal transmission is required. When signal transmission is not required, S1302 is repeated, and when signal transmission is required, the process proceeds to S1304.

[0122] - S1304: The base station verifies whether the time slot is idle. When the time slot is idle, the process continues to S1306, and when the time slot is busy, the process continues to S1312 (ECCA). The time slot can be Fig.12 Corresponding to the CCA time slot in.

[0123] - S1306: The base station verifies whether the channel is idle within the delay period (D). D can be Fig.12 When the channel is idle during the delay period, the base station may perform a signal transmission process (S1308). When it is determined that the channel is busy during the delay period, the process proceeds to S1304.

[0124] - S1308: If necessary, the base station may perform a signal transmission process.

[0125] - S1310: When signal transmission is not performed, the process proceeds to S1302 (ICCA), and when signal transmission is performed, the process proceeds to S1312 (ECCA). Even in the case where the backoff count N reaches 0 in S1318 and S1308 is performed, when signal transmission is not performed, the process proceeds to S1302 (ICCA), and when signal transmission is performed, the process proceeds to S1312 (ECCA).

[0126] Extended CCA

[0127] - S1312: The base station generates a random number N in the CW. N is used as a count during the backoff process, and N is generated from [0, q-1]. In S1314, the CW size (CWS) may be defined as q and may be variable. Thereafter, the base station proceeds to S1316.

[0128] -S1314: The base station may update the CWS. The CWS q may be updated to a value between X and Y. The X and Y values ​​are configurable parameters. The CWS update / adjustment may be performed whenever N is generated (dynamic backoff), and may be performed semi-statically within a predetermined time interval (semi-static backoff). The CWS may be updated / adjusted based on an exponential backoff or a binary backoff. That is, the CWS may be updated / adjusted in the form of a square of 2 or a multiple of 2. In conjunction with PDSCH transmission, the CWS may be updated / adjusted based on feedback / reports from the user equipment (e.g., HARQ ACK / NACK) or may be updated / adjusted based on base station sensing.

[0129] - S1316: The base station verifies whether the channel is idle within the delay period (D). D can be Fig.12 The D in S1306 and the D in S1316 may be the same. When the channel is idle during the delay period, the base station proceeds to S1318. When it is determined that the channel is busy during the delay period, the base station repeats S1316.

[0130] - S1318: The base station verifies whether N is 0. When N is 0, the base station may perform a signal transmission process (S1308). In this case, (N=0), the base station may not perform transmission immediately, and perform a CCA check during at least one time slot to continue the ECCA process. When N is not 0 (i.e., N>0), the process continues to S1320.

[0131] - S1320: The base station selects one of an operation of N minus 1 and an operation of not decreasing N (self-delay). The self-delay operation may be performed according to the implementation / selection of the base station, and in the self-delay the base station does not perform energy detection sensing and does not even perform ECCA countdown.

[0132] - S1322: The base station may select one of not performing an operation of energy detection sensing and an energy detection operation. When energy detection sensing is not performed, the process proceeds to S1324. When the energy detection operation is performed, if the energy level is equal to or less than the energy detection threshold (i.e., idle), the process proceeds to S1324. If the energy level is greater than the energy detection threshold (i.e., busy), the process returns to S1316. That is, a delay period is applied again after the channel is idle, and N is not calculated during the delay period.

[0133] -S1324: The process continues to enter S1318.

[0134] Fig.14The figure shows an example in which a base station performs downlink transmission in an unlicensed band. The base station can aggregate one or more cells in the licensed band (for convenience, LTE-L cells) and one or more cells in the unlicensed band (for convenience, LTE-U cells). Fig.14 In the present invention, it is assumed that one LTE-L cell and one LTE-U cell are aggregated to communicate with a user equipment. The LTE-L cell may be a PCell, and the LTE-U cell may be an SCell. In the LTE-L cell, the base station may use only frequency resources and perform operations according to LTE in the prior art. Therefore, all radio frames may be composed of a regular subframe (rSF) having a length of 1 ms (see Figure 2 ), and DL transmission (eg, PDCCH and PDSCH) may be performed in each subframe (see Figure 1 ). Meanwhile, in the LTE-U cell, downlink transmission is performed based on LBT for coexistence with conventional devices (e.g., Wi-Fi devices). Furthermore, it is necessary to allocate or reserve a specific frequency band within a specific time in order to effectively implement LTE-U technology / services. Therefore, in the LTE-U cell, downlink transmission may be performed through a set of one or more consecutive subframes (DL transmission bursts) after LBT. Depending on the LBT situation, the DL transmission burst may start with a regular subframe (rSF) or a partial subframe (pSF). The pSF may be part of a subframe and may include the second time slot of the subframe. Further, the downlink transmission burst may end with an rSF or a pSF.

[0135] <Method of performing LBT in uplink-only grant transmission>

[0136] Hereinafter, a channel access method for performing transmission of a downlink control channel (e.g., PDCCH or EPDCCH) will be described, taking into account the transmission of only an uplink grant (UL grant only), and the transmission of an uplink grant and uplink services scheduled by an uplink grant when channel access is performed for an uplink signal and uplink data transmission via an unlicensed band.

[0137] In particular, the present invention focuses on an LBT method performed on transmission of a downlink control channel in consideration of uplink grant-only transmission and uplink traffic transmission scheduled by the corresponding uplink grant.

[0138] Fig.15 : is a schematic diagram illustrating a case where a PDCCH including only an uplink grant is transmitted without PDSCH transmission as an embodiment of the present invention.

[0139] Reference Fig.15, when the uplink data service transmitted in the LAA SCell is self-carrier scheduled by the control channel transmitted in the corresponding LAA SCell, a control channel for transmitting only the uplink grant may be transmitted in the PDCCH of the DL subframe, that is, when there is no PDSCH transmission in a subframe, only the uplink grant transmission may be performed in the PDCCH. In this case, the OFDM symbols that the PDSCH region may have in the subframe may be invalidated without transmitting any signal, and channel access from other nodes or Wi-Fi nodes may be allowed in the (multiple) corresponding invalidated OFDM symbols of the unlicensed carrier.

[0140] Therefore, although the base station attempts to ensure the transmission of the base station by configuring the maximum channel occupation time (MCOT) configuration differently according to the channel access priority level and the LBT performed on the uplink grant transmission only is also successful, due to the transmission and interference of other nodes due to the fact that the PDSCH transmission does not occur in the corresponding subframe, for the transmission of PDSCH and the scheduled PUSCH in the next subframe, as in Fig.15 As shown in , transmission of PDSCH and scheduled PUSCH may not be possible.

[0141] exist Fig.15 In the present invention, the case where the starting subframe of the LAA burst on the unlicensed carrier is configured as a partial subframe for performing only uplink grant transmission is described as an embodiment, but the present invention is not limited to this. As another embodiment, there may be a case where the last subframe of the LAA burst is configured as a partial subframe for performing only uplink grant transmission. In another embodiment, even in the starting subframe of the LAA burst in the unlicensed carrier or in a subframe that is not the last subframe of the LAA burst, an invalidated OFDM symbol may be generated in a subframe for performing only UL grant transmission, and therefore, the above-mentioned problem may occur. Hereinafter, a method for solving the above-mentioned problem will be described.

[0142] Method A)

[0143] Fig.16 The diagram illustrates the case where an EPDCCH including only UL grant is transmitted without PDSCH transmission. Accordingly, since the EPDCCH is allocated in the PDSCH region in the FDM scheme using PDSCH, even if only UL grant is transmitted without PDSCH, (multiple) invalidated OFDM symbols can be prevented from appearing in the PDSCH region, and other nodes can be prevented from performing channel access through LBT.

[0144] Moreover, as a method for performing LBT used by (multiple) UEs when transmitting UL services corresponding to corresponding UL grants, by executing an LBT scheme performed during transmission of the UL grant, or performing a single interval LBT such as 16us, 25us, 34us, or 43us when transmitting UL services in the MCOT ensured in the UL grant transmission (hereinafter referred to as type 2 channel access for ease of explanation), fast channel access for UL data transmission can be achieved.

[0145] Alternatively, as a method for LBT used in (multiple) UEs when transmitting UL services corresponding to a UL grant, an LBT scheme performed during transmission of the UL grant is performed, or cat-4 LBT (hereinafter referred to as type 1 channel access for ease of explanation) is performed when UL services are transmitted outside the MCOT obtained during UL grant transmission [t1].

[0146] Alternatively, in this case, the following method can be considered: by this method, the base station notifies with a signal whether to perform type 2 channel access to allow the user equipment to have fast channel access as LBT for UL services, or whether to perform type 1 channel access to perform backoff. The channel access type that the base station can notify the user equipment can be transmitted through a UL grant, and the base station can notify type 1 channel access or type 2 channel access in the corresponding UL grant. Here, type 1 channel access refers to Cat-4 LBT, and type 2 channel access refers to LBT of 25us.

[0147] Method B)

[0148] Fig.17 is a diagram illustrating a case where LBT is independently performed for a subframe for transmitting only a UL grant without PDSCH transmission and a subframe(s) for performing PDSCH transmission according to an embodiment of the present invention.

[0149] As in Fig.17 As shown in, even when PDCCH or EPDCCH for UL grant transmission only is transmitted in one subframe, in the next subframe for transmitting PDSCH, independent of the LBT in the subframe for UL grant transmission only, a method for configuring the LBT to be performed according to the channel access priority level of PDSCH can be considered.

[0150] In this case, when LBT in a subframe transmitting PDSCH succeeds, MCOT from the corresponding subframe is configured. When a UL subframe transmitting UL traffic corresponding to a previously scheduled UL grant exists in the corresponding MCOT, type 2 channel access can be performed to achieve fast channel access for UL data transmission.

[0151] Alternatively, as a method for performing LBT for use in (multiple) UEs during transmission of UL traffic corresponding to a UL grant, the method can be configured to perform an LBT scheme performed during transmission of an UL grant, or to perform type 1 channel access when UL traffic is transmitted outside of the MCOT obtained by LBT in a subframe transmitting a PDSCH.

[0152] Alternatively, in this case, the following method may be considered: by which the base station notifies with a signal whether to perform type 2 channel access to allow the user equipment to have fast channel access as LBT for UL services, or whether to perform type 1 channel access to perform backoff. The channel access type that the base station may notify the terminal of may be transmitted through a UL grant, and the base station may notify type 1 channel access or type 2 channel access in the corresponding UL grant. Here, type 1 channel access may refer to Cat-4 LBT, and type 2 channel access may refer to an LBT of 25us.

[0153] Method C)

[0154] Fig.18 It is a schematic diagram illustrating the case of independently performing LBT for a subframe for transmitting only UL grant without PDSCH transmission and (multiple) subframes for performing PDSCH transmission according to an embodiment of the present invention. It is possible to prevent (multiple) invalidated OFDM symbols from appearing in the PDSCH region by transmitting a reservation signal, and to prevent other nodes from performing channel access through LBT. Moreover, due to this, the PDSCH transmitted in the next subframe can be transmitted in MCOT without additional LBT.

[0155] As an example of a reserved signal, there may be one EPDCCH transmission common to all UEs, and as another example, a method of extending CRS port 0 and port 1 to extend the transmission in OFDM symbol indexes #0, #4, #5, and #7 to the remaining symbols may be considered. In addition, a form of extending and transmitting CRS ports 0 to 4 may also be considered, and a method of transmitting dummy data as a reserved signal to an RB in a specific frequency region may be considered.

[0156] Moreover, as a method for performing LBT used in (multiple) UEs when transmitting UL services corresponding to UL grants, type 2 channel access can be performed when UL services are transmitted in MCOT ensured in transmission of UL grants, thereby achieving fast channel access for UL data transmission.

[0157] Alternatively, as a method for performing LBT for use in (multiple) UEs during transmission of UL traffic corresponding to a UL grant, the method can be configured as a scheme for performing LBT performed during transmission of a UL grant, or for performing type 1 channel access when UL traffic is transmitted outside of the MCOT obtained in the UL grant transmission.

[0158] Alternatively, in this case, the following method can be considered: by this method, the base station notifies with a signal whether to perform type 2 channel access to allow the user equipment to have fast channel access as LBT for UL services, or whether to perform type 1 channel access to perform backoff. The channel access type that the base station can notify the user equipment can be transmitted through a UL grant, and the base station can notify type 1 channel access or type 2 channel access in the corresponding UL grant. Here, type 1 channel access refers to Cat-4 LBT, and type 2 channel access refers to LBT of 25us.

[0159] exist Figures 16 to 18 In the embodiment, there is a case where the starting subframe of the LAA burst based on the unlicensed carrier is set to a partial subframe for performing only UL grant transmission, but the present invention is not limited to this. As another embodiment, there may be a case where the last subframe of the LAA burst is set to a partial subframe for performing only UL grant transmission. In another embodiment, even in the starting subframe of the LAA burst in the unlicensed carrier or in a subframe that is not the last subframe of the LAA burst, an invalidated OFDM symbol may be generated in a subframe for performing only UL grant transmission, and therefore, the above-mentioned problem may occur.

[0160] Furthermore, although the conventional subframe is described Figures 15 to 18 ,but Figures 15 to 18 It can be equally applied to the case where the start subframe is a partial subframe (for example, a subframe consisting of less than 14 OFDM symbols) and the case where the last subframe is a partial subframe.

[0161] Below, during UL grant transmission only, taking into account the channel access priority level of the UL service corresponding to the UL grant, a DL control channel (e.g., PDCCH, EPDCCH) including the UL grant and an LBT method and an LBT scheme for UL service transmission corresponding to the UL grant will be described. In addition, an LBT scheme for UL service transmission corresponding to the UL grant when the UL grant is transmitted together with the PDSCH transmission will be described.

[0162] First, when UL grant is transmitted together with PDSCH transmission, LBT for PDCCH and EPDCCH which are control channels through which UL grant is transmitted includes: performing channel access by using LBT parameters according to the channel access priority level (hereinafter referred to as CAPC for convenience) of PDSCH.

[0163] Table 1 below shows LBT parameters according to channel access priority levels for transmitting PDSCH as downlink transmission.

[0164] [Table 1] Channel access priority categories

[0165]

[0166] As an example, when the CAPC of the PDSCH is 1 or 2, since the MCOT is 2ms or 3ms, when it is assumed that the minimum time delay between the UL grant and the UL service transmission is 4ms, the UL service transmission corresponding to the UL grant is performed outside the MCOT of the downlink burst to which the UL grant is transmitted. Therefore, the LBT of the UL service transmission corresponding to the UL grant can be configured to perform the LBT according to the CAPC of the UL service to be transmitted by the user equipment. When there are multiple CAPCs for the UL service to be transmitted instead of one CAPC, the user equipment is configured to perform type 1 channel access based on the CAPC with the lowest priority among the multiple CAPCs.

[0167] As another example, when the CAPC of the PDSCH transmitted with the UL grant is 3 or 4, since the MCOT is 8ms or 10ms, the UL service transmission corresponding to the UL grant can be transmitted within the MCOT, but the UL service transmission corresponding to the UL grant can also be transmitted outside the MCOT. Therefore, when downlink transmission and UL LBT and UL service transmission can occur within the MCOT, a single interval (e.g., 16us, 25us, 34us, 43us or 16+9*N, N can be 1 or a greater value) LBT is performed, regardless of the CAPC of the UL service. That is, UL service transmission is performed through type 2 channel access. On the other hand, in the case where DL transmission and UL LBT and UL service transmission do not occur within the MCOT, type 2 channel access is performed for UL transmission that may occur within the MCOT, regardless of the CAPC of the UL service, but for UL service transmission scheduled to be transmitted outside the MCOT, the user equipment can be configured to perform LBT according to the CAPC of the UL service to be transmitted by the user equipment. When there are a plurality of CAPCs for UL traffic to be transmitted by the corresponding user equipment, the corresponding user equipment may perform type 1 channel access based on a CAPC having the lowest priority among the plurality of CAPCs.

[0168] As another example, in the case where the CAPC of the PDSCH transmitted with the UL grant is set to 3 and the UL grant is also performed according to CAPC 3, if the CAPC of the UL service that the user equipment actually wants to transmit is set to 3 or less, the UL service is transmitted through type 2 channel access regardless of the CAPC of the UL service. However, if the CAPC of the UL service is 4, regardless of whether the corresponding UL service transmission occurs within the MCOT, the user equipment can be set to perform type 1 channel access using LBT parameters according to CAPC4 of the UL service to perform UL transmission. Moreover, when the CAPC of the PDSCH transmitted with the UL grant is configured to 4 and the transmission of the UL grant is also performed according to CAPC 4, regardless of the CAPC of the UL service that the user equipment actually wants to transmit, the user equipment can perform UL service transmission through type 2 channel access.

[0169] As another example, when LBT is performed by using a CAPC value X of a PDSCH transmitted using a UL grant, UL service transmission through a type 2 channel access may be performed for a CAPC value of the UL service that is less than or equal to X. In other cases, the user equipment may be configured to perform LBT according to the CAPC of the UL service to be transmitted by the user equipment. When there are multiple CAPCs of the UL service to be transmitted by the corresponding user equipment, the corresponding user equipment may be configured to perform type 1 channel access based on a CAPC having the lowest priority among the multiple CAPCs.

[0170] <ul lbt类型切换>

[0171] Hereinafter, a method of switching the type of UL LBT when performing UL channel access will be described.

[0172] The base station notifies the user equipment of the LBT type and parameters for the LBT that the user equipment should perform. The base station may specify the LBT type through a UL grant and notify type 1 channel access, type 2 channel access, or no LBT as the LBT type.

[0173] Fig.19 1 is a schematic diagram illustrating a method for switching LBT type according to an embodiment of the present invention when DL scheduling occurs between UL grant transmission and corresponding UL service transmission. Fig.19 In the present invention, the base station notifies the user equipment of the LBT type through a UL grant, but it is assumed that DL scheduling occurs between the UL grant transmission and the corresponding UL transmission.

[0174] Fig.19 (a) notifies that type 1 channel access is performed for UL service transmission through UL grant in the sixth subframe or the tenth subframe starting from the first DL subframe. In this case, the user equipment can perform type 1 channel access and perform UL transmission. Fig.19 In (a), since the MCOT is set to 3 ms by the first DL subframe, the UL traffic transmission scheduled in the sixth or tenth subframe does not exist within the MCOT set in the DL. Therefore, the base station can instruct the user equipment to perform type 1 channel access for UL transmission.

[0175] In contrast, when UL service transmission exists in the MCOT set in the DL, for example, when the configured MCOT from the first DL subframe is 8ms, the base station can instruct the user equipment to perform type 2 channel access through UL permission, and the instructed user equipment can perform type 2 channel access to transmit UL service.

[0176] exist Fig.19 In (b), under the assumption that type 1 channel access is indicated to be performed by UL grant for transmission of UL traffic configured in the sixth subframe or the tenth subframe starting from the first DL subframe, before scheduled UL traffic transmission has been performed as in Fig.19 When DL scheduling is performed as in the fifth subframe in (b), the following method may be considered, in which the user equipment that has performed DL reception may change the channel access type indicated in the UL grant received by the user equipment from the first DL subframe.

[0177] In other words, when there is UL transmission in the MCOT configured in the DL, since the base station can transmit the UL service through the type 2 channel access, the base station can be configured to transmit the UL service through the type 2 channel access instead of the indicated type 1 channel access. Therefore, the base station can provide a trigger message to enable the user equipment to perform the type 2 channel access, so that the user equipment receiving the trigger message can perform the type 2 channel access to transmit the UL service.

[0178] However, when Fig.19 (a) and Fig.19 When the UL grant indicated by the base station is configured to perform scheduling of multiple consecutive subframes via one UL grant as in (b) of the present invention, that is, it is necessary to consider configuring the first DL subframe to perform Fig.19 (a) and Fig.19 The case of scheduling the sixth UL subframe and the seventh UL subframe in (b). In particular, when a DL service to be transmitted by the base station occurs and DL scheduling is performed in the 5th subframe and the MCOT is set to 2ms in the DL transmission, for the UE scheduled for the sixth and seventh consecutive multiple UL subframes in the first DL subframe, the UL LBT configured for the UL transmission in the sixth and seventh consecutive subframes is located within the newly set MCOT (2ms). Therefore, by switching from type 1 channel access to type 2 channel access, UL service transmission may be possible. However, since the LBT time point of the sixth subframe is located in the MCOT of 2ms although the LBT for the seventh subframe is located outside the MCOT of 2ms, it is possible to benefit from performing fast channel access, so that fairness issues will arise between systems using other unlicensed bands. In order to improve this, according to an embodiment of the present invention, a user equipment that schedules UL transmission of multiple subframes in the sixth subframe may consider a method of performing type 1 channel access on the UL transmission of the seventh subframe.

[0179] On the other hand, when the length of the entire UL burst (ie, the sixth and seventh subframes) is not included in the newly set DL MCOT, Fig.19 In (b), a method of performing a channel access type configured by a previous UL grant (ie, type 1 channel access configured by a UL grant from a first DL subframe) may be considered.

[0180] Although the reference Fig.19 The UL bursts in the sixth and seventh subframes are described, but Fig.19 The same may be applied to the UL bursts in the tenth subframe and the eleventh subframe.

[0181] Fig. 20 is a schematic diagram illustrating another example of switching channel access type according to another embodiment of the present invention when DL scheduling occurs between UL grant transmission and corresponding UL service transmission. Fig. 20 In , the base station notifies the user equipment of the channel access type through a UL grant, but it is assumed that DL scheduling occurs between the UL grant transmission and the corresponding UL transmission. Fig. 20 In the present invention, it is assumed that the channel access type for the UL burst is notified when scheduling multiple subframes, and the user equipment performs the corresponding LBT.

[0182] exist Fig. 20 In (a), the base station schedules the tenth UL subframe and the eleventh UL subframe in the first, second or third DL subframe, i.e., by UL grant on the previous DL burst, and indicates to perform type 1 channel access and transmission of UL traffic as the associated channel access type.

[0183] By the way, as in Fig. 20 As shown in (b), when DL scheduling (e.g., the eighth and ninth subframes) occurs between UL grant transmission and corresponding UL service transmission, when the MCOT of the DL burst includes the tenth and eleventh UL subframes as UL bursts, the UL service transmission exists in the MCOT of the DL. Therefore, the channel access type for the tenth and eleventh UL subframes is switched to type 2 channel access to transmit the UL service.

[0184] On the other hand, as in Fig. 20 As shown in (c), if the MCOT of a DL burst occurring between a UL grant transmission and a corresponding UL service transmission does not include a UL burst (i.e., the tenth UL subframe and the eleventh UL subframe), type 2 channel access is allowed only for the UL subframes included in the MCOT among the UL bursts, and if not, the UL service is transmitted by performing type 1 channel access on the eleventh subframe.

[0185] Moreover, as in Fig. 20 As shown in (d), when the length of the entire UL burst scheduled for multiple subframes is not included in the newly formed MCOT, UL burst LBT is performed by using the channel access type previously indicated by the base station through the UL grant to transmit the UL service.

[0186] Finally, in Fig. 20 In (e), when DL scheduling occurs between UL grant transmission and the corresponding UL service transmission (the eighth subframe and the ninth subframe), if the MCOT of the DL burst does not include any part of the UL burst, UL burst LBT is performed by using the channel access type previously indicated by the base station through the UL grant to transmit the UL service.

[0187] Fig.21 1 is a schematic diagram illustrating another example of switching channel access type according to an embodiment of the present invention when DL scheduling occurs between UL grant transmission and corresponding UL service transmission. Fig.21 In , the base station notifies the user equipment of the channel access type through a UL grant, but it is assumed that DL scheduling occurs between the UL grant transmission and the corresponding UL transmission. Fig.21 In the present invention, it is assumed that a channel access type of each UL subframe used to constitute a UL burst is notified when scheduling multiple subframes or a single subframe, and the user equipment performs corresponding LBT.

[0188] exist Fig.21 In (a), the base station schedules the tenth UL subframe and the eleventh UL subframe in the first, second or third DL subframe, i.e., through UL grant on the previous DL burst, and instructs type 1 channel access and transmission of UL traffic for each UL subframe.

[0189] However, as in Fig.21 As shown in (b), if the MCOT of a DL burst occurring between a UL grant transmission and a corresponding UL service transmission does not include the UL burst (i.e., the tenth UL subframe and the eleventh UL subframe), the UL service is transmitted by allowing type 2 channel access to be performed on the UL subframe included in the MCOT among the UL burst and not performing type 1 channel access to the eleventh subframe not included in the MCOT.

[0190] Moreover, as in Fig.21 As shown in (c), when the length of the entire UL burst scheduled for multiple subframes is not included in the newly formed MCOT, LBT is performed to transmit UL traffic by using the channel access type previously indicated by the base station through the UL grant.

[0191] It is possible to consider the signal from the base station for switching through Figures 19 to 21 The described LBT type implicit or explicit signaling method, and as implicit signaling, by determining whether there is transmission of a UL burst in the MCOT newly formed by receiving the first DL subframe on the DL burst, the channel access type used for UL transmission can be changed, and LBT is performed to transmit UL traffic.

[0192] Alternatively, as explicit signaling, if DL scheduling occurs between UL grant transmission and the corresponding UL service transmission, the base station may transmit signaling for changing the channel access type to the user equipment, and the user equipment may change the channel access type to transmit UL service by receiving the corresponding signaling. Alternatively, the base station notifies the user equipment of the MCOT for each DL burst, and if the UL burst is configured to be completed within the MCOT configured by the base station, the user equipment may change the channel access type to perform LBT through type 2 channel access and transmit UL service.

[0193]

[0194] Meanwhile, if the base station schedules UL transmissions for multiple user equipments, the base station may know whether the UL subframe to be scheduled is the last UL subframe for the UE in the cell when transmitting the UL grant. Therefore, preferably, the base station signals whether the subframe to be scheduled for the UE is the last subframe. As a signaling method, when transmitting the UL grant, there may be a notification method through the DL common control signal for DL or a notification method through the UL common control signal.

[0195] As an example of the above common control signal, it may represent a PDCCH with DCI scrambled by CC-RNTI. The base station may notify the UE of the last subframe in the UL subframe through the common control signal. If the (multiple) scheduled UL subframes are all included before the last subframe indicated by the common control signal in the cell, the user equipment may perform type 2 channel access to perform UL transmission in the (multiple) scheduled UL subframes, regardless of the channel access type indicated by the base station for the (multiple) scheduled UL subframes.

[0196] On the other hand, when the (multiple) scheduled UL subframes are only partially included or not fully included before the last subframe indicated by the common control signal in the cell, the user equipment may perform channel access according to the channel access type indicated for the (multiple) UL subframes scheduled by the base station and perform UL transmission in the (multiple) scheduled UL subframes.

[0197] <Method for Performing LBT for Consecutive UL Transmissions after DL Transmission>

[0198] Hereinafter, a UL channel access method for consecutive UL transmissions after DL transmission in an LAA cell will be described.

[0199] Fig. 22 is a schematic diagram illustrating a method for performing UL channel access for consecutive UL transmissions after DL transmission in an LAA cell.

[0200] As Fig. 22 Even if the base station transmits a UL grant to the user equipment in subframe #n and schedules UL transmission in subframe #(n+4), any user equipment can recognize through PDCCH / EPDCCH that the PDSCH for the user equipment itself is included in the DL transmission in subframe #(n+3) from the base station, or recognize its DL scheduling through PDCCH / EPDCCH and successful decoding of PDSCH.

[0201] In this case, DL reception is completed, and UL traffic transmission of the user equipment may be performed without UL LBT immediately after a certain interval (e.g., 16us, 20us, or 25us, or any other value) from the time when DL reception is completed, or only type 2 channel access may be performed. Since LBT is performed once in DL during UL grant transmission, for UL transmission expected by UL grant, the user equipment may not additionally perform UL LBT, or perform a simple LBT operation without backing off to transmit UL traffic.

[0202] Here, when UL traffic is transmitted after a certain interval, transmission after a specific period may be considered regardless of the subframe boundary, or transmission may be performed corresponding to an OFDM symbol (or SC-FDMA symbol) boundary. Alternatively, there may be a method of transmitting UL traffic corresponding to a UL subframe boundary. However, when a certain interval is set, it may be preferable to consider the switching time from DL to UL.

[0203] Fig.23 An example of a user equipment transmitting a data channel to a base station according to another embodiment of the present invention is shown.

[0204] Reference Fig.23 , when UL transmission is scheduled after a DL subframe in the same carrier, the user equipment may start UL transmission according to a channel access procedure not based on a backoff procedure. Specifically, the user equipment may perform type 2 channel access and start UL transmission based on whether the channel is idle during a single sensing interval.

[0205] Specifically, the user equipment senses whether the channel is idle during a single sensing interval. If the channel is idle, the user equipment can start UL transmission through the corresponding channel. At this time, the single sensing interval can represent the minimum time interval of the idle time interval required for the user equipment to access the channel. At this time, the user equipment can determine whether the corresponding channel is idle through an idle channel assessment (CCA) operation. In addition, the user equipment can start UL transmission at the subframe boundary. At this time, the user equipment can sense whether the channel corresponding to the UL transmission is idle during a single sensing interval (e.g., a 25us interval), and can start UL transmission when the corresponding channel is idle. At this time, the specific operation of the user equipment can be the same as the method for transmitting UL by performing the above-mentioned type 2 channel access.

[0206] Fig.24 The configuration of the user equipment and the base station according to an embodiment of the present invention is illustrated. In an embodiment of the present invention, the user equipment can be implemented by various types of wireless communication devices or computing devices that are guaranteed to be portable and have mobility. The user equipment may be referred to as a station (STA), a mobile subscriber (MS), etc. In an embodiment of the present invention, the base station may control and manage a cell (e.g., a macro cell, a femto cell, a micro cell, etc.) corresponding to a service area, and perform functions such as transmitting signals, specifying channels, monitoring channels, self-diagnosis, and relaying. The base station may be referred to as an evolved Node B (eNB), an access point (AP), etc.

[0207] Reference Fig.24 , the user equipment 100 may include a processor 110 , a communication module 120 , a memory 130 , a user interface unit 140 , and a display unit 150 .

[0208] The processor 110 may execute various commands or programs according to the present invention and process data in the user equipment 100. Further, the processor 100 may control all operations of the corresponding units of the user equipment 100 and control data transmission / reception between these units. For example, the processor 110 may receive a DL signal in an LTE-U cell in an LAA environment, and may send a HARQ-ACK response for the DL signal to a base station.

[0209] The communication module 120 may be an integrated module for performing mobile communication by using a mobile communication network and performing wireless LAN access by using a wireless LAN. To this end, the communication module 120 may include a plurality of network interface cards, such as cellular communication interface cards 121 and 122 and an internal or external type wireless LAN interface card 123. Fig.24 In the figure, the communication module 120 is shown as an integrated module, but it can be configured according to the circuit or different Fig.24 The corresponding network interface card is set independently according to the purpose.

[0210] The cellular communication interface card 121 sends / receives a radio signal to / from at least one of the base station 200, the external device, and the server by using a mobile communication network, and provides a cellular communication service at a first frequency band based on a command of the processor 110. The cellular communication interface card 121 may include at least one NIC module using an LTE licensed frequency band. The cellular communication interface card 122 sends / receives a radio signal to / from at least one of the base station 200, the external device, and the server by using a mobile communication network, and provides a cellular communication service at a second frequency band based on a command of the processor 110. The cellular communication interface card 122 may include at least one NIC module using an LTE unlicensed frequency band. For example, the LTE unlicensed frequency band may be a band of 2.4 GHz or 5 GHz.

[0211] The wireless LAN interface card 123 transmits / receives a radio signal to / from at least one of the base station 200, an external device, and a server through a wireless LAN access, and provides a wireless LAN service at a second frequency band based on a command of the processor 110. The wireless LAN interface card 123 may include at least one NIC module using a wireless LAN frequency band. For example, the wireless LAN frequency band may be an unlicensed radio band, such as a 2.4 GHz or 5 GHz band.

[0212] The memory 130 stores a control program and various result data used in the user equipment 100. The control program may include a program required for the user equipment 100 to perform wireless communication with at least one of the base station 200, the external device, and the server. The user interface 140 includes various types of input / output devices provided in the user equipment 100. The display unit 150 outputs various images on a display screen.

[0213] Further, the base station 200 according to the exemplary embodiment of the present invention may include a processor 210 , a communication module 220 , and a memory 230 .

[0214] The processor 210 may execute various commands or programs according to the present invention and process data in the base station 200. Further, the processor 210 may control all operations of the corresponding units of the base station 200 and control data transmission / reception between these units. For example, the processor 210 may perform downlink transmission. Specifically, the processor 210 may perform downlink transmission, HARQ-ACK feedback set check, and CWS adjustment, etc., according to situations 1, 2-1, and 2-2.

[0215] The communication module 220 may be an integrated module for performing mobile communication by using a mobile communication network and performing wireless LAN access by using a wireless LAN, such as the communication module 120 of the user device 100. To this end, the communication module 120 may include a plurality of network interface cards, such as cellular communication interface cards 221 and 222 and an internal or external type wireless LAN interface card 223. Fig.18 In the embodiment, the communication module 220 is shown as an integrated module, but may be configured according to a circuit or different Fig.18 The corresponding network interface card is set independently according to its purpose.

[0216] The cellular communication interface card 221 sends / receives a radio signal to / from at least one of the user equipment 100, the external device, and the server by using a mobile communication network, and provides a cellular communication service at a first frequency band based on a command of the processor 210. The cellular communication interface card 221 may include at least one NIC module using an LTE licensed frequency band. The cellular communication interface card 222 sends / receives a radio signal to / from at least one of the user equipment 100, the external device, and the server by using a mobile communication network, and provides a cellular communication service at a second frequency band based on a command of the processor 210. The cellular communication interface card 222 may include at least one NIC module using an LTE unlicensed frequency band. The LTE unlicensed frequency band may be a band of 2.4 GHz or 5 GHz.

[0217] The wireless LAN interface card 223 sends / receives a radio signal to / from at least one of the user equipment 100, an external device, and a server through a wireless LAN access, and provides a wireless LAN service at a second frequency band based on a command of the processor 210. The wireless LAN interface card 223 may include at least one NIC module using a wireless LAN frequency band. For example, the wireless LAN frequency band may be an unlicensed radio band, such as a 2.4 GHz or 5 GHz band.

[0218] exist Fig.24 In the figure, the blocks of the user equipment and the base station are logically divided and the elements of the device are illustrated. Depending on the design of the device, the elements of the device can be installed as one chip or multiple chips. Further, some components of the user equipment 100 (that is, the user interface 140 and the display unit 150) can be selectively set in the user equipment 100. Further, some components of the base station 200 (that is, the wireless LAN interface 223, etc.) can be selectively set in the base station 200. If necessary, the user interface 140 and the display unit 150 can also be set in the base station 200.

[0219] The method and system of the present invention are described in conjunction with specific embodiments, but some or all of the components and operations of the present invention may be implemented by using a computer system with a general hardware architecture.

[0220] The description of the present invention is used for illustration, and those skilled in the art will appreciate that the present invention can be easily modified into other detailed forms without changing the technical spirit or essential features of the present invention. Therefore, the aforementioned exemplary embodiments are illustrative in all respects, rather than restrictive. For example, each component described as a single type can be implemented as a distributed component, and similarly, the components described as distributed components can also be implemented in a combined form.

[0221] The scope of the present invention is indicated by the claims to be described below rather than the detailed description, but the scope of the present invention should be interpreted as the meaning and scope of the claims and all changes or modifications from equivalents thereof are within the scope of the present invention.

[0222] Industrial Applicability

[0223] The present invention is applicable to various communication devices used in a wireless communication system (for example, a station using unlicensed band communication, a station using cellular communication, a base station, etc.).

Claims

1. A method for performing uplink transmission by a user equipment to a base station through an unlicensed cell in a wireless communication system, the method comprising: receiving, from the base station, an uplink grant scheduling the uplink transmission in at least one subframe; as well as performing the uplink transmission in the at least one subframe using at least one of a first type of channel access or a second type of channel access, wherein the first type of channel access is based on channel sensing with a random backoff using a contention window CW of a variable size before data transmission, wherein a maximum value of the CW and a minimum value of the CW are determined according to a channel access priority level of the uplink transmission, and wherein the second type of channel access is based on channel sensing with a single interval before data transmission, Wherein, when all of the uplink transmissions in the at least one subframe are included in a predetermined interval determined based on downlink transmissions from the base station through the unlicensed cell, the uplink transmission is performed using the second type of channel access.

2. The method according to claim 1, wherein: The uplink grant indicates a channel access type to be used in the uplink transmission among the first type of channel access or the second type of channel access.

3. The method according to claim 1, wherein: When the uplink transmission in the at least one subframe is not included in the predetermined interval or only a portion of the uplink transmission in the at least one subframe is included in the predetermined interval, the uplink transmission is performed using a channel access type indicated in the uplink grant.

4. The method according to claim 1, wherein: The predetermined interval is determined based on a maximum channel occupancy time set by the downlink transmission.

5. The method according to claim 1, wherein: Information on whether the at least one subframe is a last subframe for the uplink transmission is received through a common control channel.

6. The method according to claim 1, wherein: When the uplink transmission is performed in a next subframe of the downlink transmission through the unlicensed cell, the uplink transmission is performed using the second type of channel access.

7. A user equipment in a wireless communication system, the user equipment comprising: Wireless communication module; and a processor, the processor being configured to, through the wireless communication module, receive an uplink grant for scheduling uplink transmission in at least one subframe from a base station, and to perform the uplink transmission in the at least one subframe using at least one of a first type of channel access or a second type of channel access through the wireless communication module, wherein the first type of channel access is based on channel sensing with random backoff using a contention window CW of a variable size before data transmission, wherein a maximum value of the CW and a minimum value of the CW are determined according to a channel access priority level of the uplink transmission, wherein the second type of channel access is based on channel sensing with a single interval before data transmission, Wherein, when all of the uplink transmissions in the at least one subframe are included in a predetermined interval determined based on downlink transmissions from the base station through an unlicensed cell, the processor performs the uplink transmission using the second type channel access.

8. The user equipment according to claim 7, wherein: The uplink grant indicates a channel access type to be used in the uplink transmission among the first type of channel access or the second type of channel access.

9. The user equipment according to claim 7, wherein: When the uplink transmission in the at least one subframe is not included in the predetermined interval or only a portion of the uplink transmission in the at least one subframe is included in the predetermined interval, the processor is configured to perform the uplink transmission using the channel access type indicated in the uplink grant.

10. The user equipment according to claim 7, wherein: The predetermined interval is determined based on a maximum channel occupancy time set by the downlink transmission.

11. The user equipment according to claim 7, wherein: Information on whether the at least one subframe is a last subframe for the uplink transmission is received through a common control channel.

12. The user equipment according to claim 7, wherein: When the uplink transmission is performed in a next subframe of the downlink transmission through the unlicensed cell, the processor is configured to perform the uplink transmission using the second type of channel access.

13. A method for a base station to receive uplink transmission from a user equipment through an unlicensed cell in a wireless communication system, the method comprising: sending an uplink grant to the user equipment, the uplink grant scheduling transmission of the uplink transmission in at least one subframe and indicating a channel access type to be used when the user equipment transmits the uplink transmission in a first type of channel access or a second type of channel access, wherein the first type of channel access is based on channel sensing with random backoff using a contention window CW of a variable size before data transmission, wherein a maximum value of the CW and a minimum value of the CW are determined according to a channel access priority level, wherein the second type of channel access is based on channel sensing with a single interval before data transmission; and receiving the uplink transmission in the at least one subframe, The method further includes: when all of the uplink transmissions in the at least one subframe are included in a predetermined interval determined based on the downlink transmission through the unauthorized cell, sending common downlink control information indicating that the second type of channel access is performed in the uplink transmission.

14. The method according to claim 13, wherein: The uplink grant indicates the first type channel access when the uplink transmission in the at least one subframe is not included in the predetermined interval or only a portion of the uplink transmission of the at least one subframe is included in the predetermined interval.

15. The method according to claim 13, wherein: The predetermined interval is determined based on a maximum channel occupancy time set by the downlink transmission.

16. The method according to claim 13, wherein: The common downlink control information includes information on whether the at least one subframe is a last subframe for the uplink transmission.

17. A base station in a wireless communication system, the base station comprising: Wireless communication module; and a processor configured to send, through the wireless communication module, to a user equipment, an uplink grant for scheduling uplink transmission through an unlicensed cell in at least one subframe and indicating a channel access type to be used when the user equipment sends the uplink transmission in a first type of channel access or a second type of channel access, wherein the first type of channel access is based on channel sensing with random backoff using a contention window CW of a variable size before data transmission, wherein a maximum value of the CW and a minimum value of the CW are determined according to a channel access priority level, wherein the second type of channel access is based on channel sensing with a single interval before data transmission, and receive, through the wireless communication module, the uplink transmission from the user equipment in the at least one subframe, Wherein, when all of the uplink transmissions in the at least one subframe are included in a predetermined interval determined based on the downlink transmission through the unlicensed cell, the processor is configured to send common downlink control information indicating that the second type of channel access is performed in the uplink transmission.

18. The base station according to claim 17, wherein: The uplink grant indicates the first type channel access when the uplink transmission in the at least one subframe is not included in the predetermined interval or only a portion of the uplink transmission of the at least one subframe is included in the predetermined interval.

19. The base station according to claim 17, wherein: The predetermined interval is determined based on a maximum channel occupancy time set by the downlink transmission.

20. The base station according to claim 17, wherein: The common downlink control information includes information on whether the at least one subframe is a last subframe for the uplink transmission.

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