Method for operating user equipment in a communication network

Abstract

Disclosed is an operation method of a user equipment (UE) in a communication network, comprising: receiving a plurality of physical downlink shared channels (PDSCHs) from a base station in consecutive subframes of an unlicensed frequency band; transmitting a plurality of hybrid automatic repeat request (HARQ) responses to the plurality of PDSCHs to the base station; and receiving information indicating the size of a contention window (CW) from the base station, wherein the size of the contention window (CW) is determined based on one or more HARQ responses in the plurality of HARQ responses. Therefore, the performance of the communication network can be improved.

Description

[0001] This application is a divisional application of the invention patent application with the application date of August 5, 2016, application number 201680029717.6, and invention name "Operation method of communication nodes in a network supporting licensed frequency bands and unlicensed frequency bands". Technical Field

[0002] The present invention relates to a communication technology supporting licensed bands and unlicensed bands, and more particularly, to a channel access technology for a communication node supporting License Assisted Access (LAA). Background Art

[0003] Various wireless communication technologies are being continuously developed with the advancement of information and communication technologies. Generally speaking, wireless communication technologies can be categorized based on the frequency bands they utilize into technologies that use licensed bands and technologies that use unlicensed bands (e.g., the Industrial-Scientific-Medical (ISM) band). Because licensed bands are used exclusively by specific operators, technologies that use licensed bands can offer better reliability and communication quality than technologies that use unlicensed bands.

[0004] Representative cellular communication technologies using licensed frequency bands include Long Term Evolution (LTE) and LTE-Advanced (LTE-A), standardized by the Third Generation Partnership Project (3GPP). Thus, base stations or user equipment (UE) supporting LTE or LTE-A can transmit or receive signals using the licensed frequency bands. Furthermore, representative wireless communication technologies using unlicensed frequency bands include wireless local area networks (WLANs) defined in IEEE 802.11. Thus, access points or stations supporting WLANs can transmit or receive signals using the unlicensed frequency bands.

[0005] At the same time, the explosive growth of mobile traffic requires more licensed spectrum bands to handle the increased mobile traffic flowing through them. However, licensed spectrum bands are a limited resource. Because licensed spectrum bands are typically acquired through auctions between operators, acquiring more licensed spectrum bands can require significant investment. To address this issue, providing LTE or LTE-A services through unlicensed spectrum bands can be considered.

[0006] When providing LTE (or LTE-A) services via an unlicensed band, coexistence with communication nodes (e.g., access points, stations, etc.) supporting WLAN is required. For coexistence in the unlicensed band, communication nodes (e.g., base stations, UEs, etc.) supporting LTE (or LTE-A) can occupy the unlicensed band based on an LBT (Listen Before Talk) scheme. For example, the communication nodes supporting LTE (or LTE-A) can determine a contention window by performing a random backoff operation, randomly select a backoff value within the determined contention window, and occupy the unlicensed band when the unlicensed band is idle for a period of time corresponding to the selected backoff value.

[0007] Here, the size of the contention window can be changed statically or dynamically. However, the procedure for changing the contention window size in an unlicensed band in which LTE (or LTE-A) services are provided is not clearly defined. In addition, there is also the problem of changing the size of the contention window without considering the unlicensed band conditions.

[0008] At the same time, in order to understand the background of the present disclosure, this specification is given with respect to the related art. Therefore, information related to conventional technologies known to those skilled in the art in addition to the technology of the present disclosure may be included in this specification. Summary of the Invention

[0009] Technical issues

[0010] In order to solve the above problems, the present invention aims to provide a method for changing the size of the contention window in an unlicensed frequency band.

[0011] Technical Solution

[0012] To achieve the above objectives, one aspect of the present invention may provide a method for operating a base station in a communication network. The method includes transmitting a physical downlink shared channel (PDSCH) to a user equipment (UE) via an unlicensed frequency band; receiving a hybrid automatic repeat request (HARQ) response to the PDSCH from the UE; and determining a contention window (CW) size based on a negative acknowledgement (NACK) ratio of the HARQ response.

[0013] Here, the base station may transmit the PDSCH in consecutive subframes, and when the size of the first subframe is 1 millisecond, the size of the CW may be determined according to the HARQ response to the PDSCH transmitted through the first subframe among the consecutive subframes.

[0014] Here, the base station can transmit PDSCH in consecutive subframes. When the size of the first subframe (subframe #n) is less than 1 millisecond, the size of CW can be determined based on the HARQ response to the PDSCH transmitted by the first subframe (subframe #n) and the second subframe (subframe (#n+1)) in the consecutive subframes, where n is an integer equal to or greater than 0.

[0015] Here, when the PDSCH includes two codewords, the HARQ response may include HARQ responses for the two corresponding codewords.

[0016] Here, the HARQ response may be a bundled HARQ response for a plurality of subframes in consecutive subframes.

[0017] Here, when the NACK ratio is equal to or greater than a predetermined threshold, the size of the CW may be increased.

[0018] Here, when the NACK ratio is less than a predetermined threshold, the size of the CW may be reduced.

[0019] Here, the size of the CW may be determined according to a NACK ratio which is a ratio of the sum of NACK, discontinuous transmission (DTX), and ANY.

[0020] Here, the operating method may further include transmitting a PDSCH to the UE through an unlicensed frequency band according to the changed size of the CW.

[0021] To achieve the above objectives, one aspect of the present invention provides a base station supporting an unlicensed frequency band. The base station includes a processor and a memory storing at least one instruction executed by the processor, wherein the at least one instruction is configured to: transmit a physical downlink shared channel (PDSCH) to a user equipment (UE) via the unlicensed frequency band; receive a hybrid automatic repeat request (HARQ) response to the PDSCH from the UE; and determine the size of a contention window (CW) based on a negative acknowledgement (NACK) ratio of the HARQ response.

[0022] Here, the PDSCH may be transmitted through consecutive subframes, and when the size of the first subframe is 1 millisecond, the size of the CW may be determined according to a HARQ response to the PDSCH transmitted through the first subframe among the consecutive subframes.

[0023] Here, PDSCH can be transmitted through consecutive subframes. When the size of the first subframe (subframe #n) is less than 1 millisecond, the size of CW can be determined based on the HARQ response to the PDSCH transmitted through the first subframe (subframe #n) and the second subframe (subframe (#n+1)) in the consecutive subframes, where n is an integer equal to or greater than 0.

[0024] Here, when the PDSCH includes two codewords, the HARQ response may include HARQ responses for the two corresponding codewords.

[0025] Here, the HARQ response may be a bundled HARQ response for a plurality of subframes in consecutive subframes.

[0026] Here, when the NACK ratio is equal to or greater than a predetermined threshold, the size of the CW may be increased.

[0027] Here, when the NACK ratio is less than a predetermined threshold, the size of the CW may be reduced.

[0028] Here, the size of the CW may be determined according to a NACK ratio which is a ratio of the sum of NACK, discontinuous transmission (DTX), and ANY.

[0029] Here, the at least one instruction may be further configured to transmit the PDSCH to the UE through the unlicensed frequency band according to the changed size of the CW.

[0030] In order to achieve the above-mentioned purpose, one aspect of the present invention may provide an operating method of a user equipment UE in a communication network, including: receiving multiple physical downlink shared channels PDSCH from a base station in consecutive subframes of an unlicensed frequency band; transmitting multiple hybrid automatic repeat request HARQ responses to the multiple PDSCHs to the base station; and receiving information indicating the size of a contention window CW from the base station, wherein the size of the contention window CW is determined based on one or more HARQ responses among the multiple HARQ responses.

[0031] advantage

[0032] According to the present invention, the contention window (e.g., the size of the contention window) can be changed according to the occupancy state of the unlicensed band. In addition, the contention window can also be changed according to the hybrid automatic repeat request (HARQ) response to the data transmitted by the unlicensed band. In this case, due to the use of the HARQ response to the first subframe in multiple subframes included in the unlicensed band burst (burst) or the HARQ response to the first subframe and the multiple subframes connected to the first subframe, the impact caused by the transmission delay of the HARQ response can be minimized. Moreover, the contention window can also be changed according to the collision-aware information of the data transmitted by the unlicensed band. The communication node can use the changed contention window in the unlicensed band to perform communication. Therefore, the performance of the communication network can be improved.

[0033] Description of the drawings

[0034] Figure 1 is a conceptual diagram illustrating a first exemplary embodiment of a wireless communication network.

[0035] Figure 2 is a conceptual diagram illustrating a second exemplary embodiment of a wireless communication network.

[0036] Figure 3 is a conceptual diagram illustrating a third exemplary embodiment of a wireless communication network.

[0037] Figure 4 is a conceptual diagram illustrating a fourth exemplary embodiment of a wireless communication network.

[0038] Figure 5 is a block diagram illustrating one embodiment of communication nodes that constitute a wireless communication network.

[0039] Figure 6 is a conceptual diagram illustrating an exemplary embodiment of a Type 1 frame.

[0040] Figure 7 is a conceptual diagram illustrating an exemplary embodiment of a Type 2 frame.

[0041] Figure 8 is a conceptual diagram illustrating an exemplary embodiment of a resource grid including slots in a subframe.

[0042] Figure 9 is a timing diagram illustrating an exemplary embodiment of an unlicensed band burst.

[0043] Figure 10 is a sequence diagram illustrating a first exemplary embodiment of a method for activating or deactivating an unlicensed band cell.

[0044] Figure 11 is a flow chart illustrating a first exemplary embodiment of a method of changing a contention window size according to a channel occupancy status.

[0045] Figure 12 is a sequence diagram illustrating a second exemplary embodiment of a method of changing a contention window size according to a channel occupancy status.

[0046] Figure 13 is a timing diagram illustrating a first embodiment of a collision situation in an unlicensed frequency band.

[0047] Figure 14 is a sequence diagram illustrating an exemplary embodiment of a method for changing a contention window size according to a HARQ response.

[0048] Figure 15 is a timing diagram illustrating HARQ responses for determining contention window size.

[0049] Figure 16is a sequence diagram illustrating an exemplary embodiment of a method for changing a contention window size according to collision awareness information.

[0050] Figure 17 is a timing diagram illustrating a first exemplary embodiment of a method for transmitting collision perception information.

[0051] Figure 18 is a timing diagram illustrating a second exemplary embodiment of a method for transmitting collision perception information.

[0052] Figure 19 is a sequence diagram illustrating another exemplary embodiment of a method for changing a contention window size according to collision awareness information.

[0053] Figure 20 is a timing diagram illustrating a third exemplary embodiment of a method for transmitting collision perception information.

[0054] Figure 21 is a timing diagram illustrating a fourth exemplary embodiment of a method for transmitting collision perception information.

[0055] Figure 22 is a sequence diagram illustrating a third exemplary embodiment of a method for changing a contention window size according to collision awareness information.

[0056] Figure 23 is a timing diagram illustrating the channel occupancy status of the unlicensed band. Specific embodiments

[0057] Embodiments of the present disclosure are disclosed herein. However, for the purpose of describing the embodiments of the present disclosure, the specific structural and functional details disclosed herein are merely representative. However, the embodiments of the present disclosure may be embodied in many alternative forms, and the embodiments of the present disclosure should not be considered limited to those described herein.

[0058] Therefore, although the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are described herein by way of example only in the accompanying drawings, and these embodiments will be described in detail herein. However, it should be understood that this disclosure is not intended to be limited to the specific forms disclosed, but rather, the disclosure is intended to cover all modifications, equivalents, and alternative forms falling within the spirit and scope of the disclosure. Throughout the description of the drawings, like numerals refer to like elements.

[0059] It should be appreciated that although the terms "first," "second," etc. may be used herein to describe different elements, these terms do not limit the elements. These terms are used solely to distinguish elements from one another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element without departing from the scope of this disclosure. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0060] It should be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. Conversely, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements. Other words used to describe the relationship between two elements should be interpreted in a similar manner (i.e., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).

[0061] The terms used herein are intended only to describe specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be appreciated that when used herein, the terms "comprise," "contain," "include," and / or "include" indicate the presence of stated features, integers, steps, operations, elements, and / or parts, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or combinations thereof.

[0062] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It should also be understood that such terms as defined in commonly used dictionaries should be interpreted as having the same meaning as in the context of the relevant technical field, and will not be interpreted in an idealized or extra-formal sense unless expressly defined as such herein.

[0063] Hereinafter, embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. In the description of the present disclosure, in order to facilitate overall understanding, the same reference numerals are used to represent the same components in the drawings, and their repeated descriptions will be omitted.

[0064] The following describes a wireless communication network to which the exemplary embodiments of the present disclosure are applied. However, the wireless communication network to which the exemplary embodiments of the present disclosure are applied is not limited to the wireless communication network described below. That is, the exemplary embodiments of the present disclosure can be applied to various wireless communication networks.

[0065] Figure 1 is a conceptual diagram illustrating a first exemplary embodiment of a wireless communication network.

[0066] Reference Figure 1 , the first base station 110 can support cellular communications standardized in the Third Generation Partnership Project (3GDP) (e.g., Long Term Evolution (LTE), Advanced LTE (LTE-A), Licensed Assisted Access (LAA), etc.). The first base station 110 can support technologies such as Multiple Input Multiple Output (MIMO) (e.g., Single User (SU)-MIMO, Multi-User (MU)-MIMO, Massive MIMO, etc.), Coordinated Multipoint Transmission / Reception (CoMP), Carrier Aggregation (CA), etc. The first base station 110 can operate in a licensed frequency band (F1) and form a macro cell. The first base station 110 can be connected to other base stations (e.g., the second base station 120, the third base station 130, etc.) through an ideal backhaul link or a non-ideal backhaul link.

[0067] The second base station 120 can be located within the coverage area of ​​the first base station 110. In addition, the second base station 120 can operate in the unlicensed frequency band F3 and form a small cell. The third base station 130 can also be located within the coverage area of ​​the first base station 110. The third base station 130 can operate in the unlicensed frequency band F3 and form a small cell. Both the second base station 120 and the third base station 130 can support wireless local area networks (WLANs) standardized in the Institute of Electrical and Electronics Engineers (IEEE) 802.11. Each user equipment (UE) connected to the first base station 110 can use the licensed frequency band F1 and the unlicensed frequency band F3 to transmit and receive signals through CA.

[0068] Figure 2 is a conceptual diagram illustrating a second exemplary embodiment of a wireless communication network.

[0069] Reference Figure 2 , both the first base station 210 and the second base station 220 can support cellular communications (e.g., LTE, LTE-A, LAA, etc.). Both the first base station 210 and the second base station 220 can support MIMO (e.g., SU-MIMO, MU-MIMO, massive MIMO, etc.), CoMP, CA, etc. In addition, both the base stations 210 and 220 can operate in the licensed frequency band F1 and each form a small cell. Both the base stations 210 and 220 can be located within the coverage range of the base station forming the macro cell. The first base station 210 can be connected to the third base station 230 via an ideal backhaul link or a non-ideal backhaul link. Furthermore, the second base station 220 can be connected to the fourth base station 240 via an ideal backhaul link or a non-ideal backhaul link.

[0070] The third base station 230 may be located within the coverage area of ​​the first base station 210. The third base station 230 may operate in the unlicensed frequency band F3 and form a small cell. The fourth base station 240 may be located within the coverage area of ​​the second base station 220. The fourth base station 240 may operate in the unlicensed frequency band F3 and form a small cell. Both base stations 230 and 240 may support WLAN standardized in IEEE 802.11. The first base station 210, a UE connected to the first base station 210, the second base station 220, and the UE connected to the second base station 220 may all use the licensed frequency band F1 and the unlicensed frequency band F3 to transmit and receive signals through carrier aggregation.

[0071] Figure 3 is a conceptual diagram illustrating a third exemplary embodiment of a wireless communication network.

[0072] Reference Figure 3 , the first base station 310, the second base station 320, and the third base station 330 can all support cellular communications (for example, LTE, LTE-A, LAA, etc.). The first base station 310, the second base station 320, and the third base station 330 can all support MIMO (for example, SU-MIMO, MU-MIMO, massive MIMO, etc.), CoMP, CA, etc. The first base station 310 can operate in the authorized frequency band F1 and form a macro cell. The first base station 310 can be connected to other base stations (for example, the second base station 320, the third base station 330, etc.) through an ideal backhaul link or a non-ideal backhaul link. The second base station 320 can be located within the coverage area of ​​the first base station 310. The second base station 320 can operate in the authorized frequency band F1 and form a small cell. The third base station 330 can be located within the coverage area of ​​the first base station 310. The third base station 330 can operate in the authorized frequency band F1 and form a small cell.

[0073] The second base station 320 can be connected to the fourth base station 340 via an ideal backhaul link or a non-ideal backhaul link. The fourth base station 340 can be located within the coverage area of ​​the second base station 320. The fourth base station 340 can operate in the unlicensed frequency band F3 and form a small cell. The third base station 330 can be connected to the fifth base station 350 via an ideal backhaul link or a non-ideal backhaul link. The fifth base station 350 can be located within the coverage area of ​​the third base station 330. The fifth base station 350 can operate in the unlicensed frequency band F3 and form a small cell. Both base stations 340 and 350 can support WLAN standardized in IEEE 802.11.

[0074] The first base station 310, the UE (not shown) connected to the first base station 310, the second base station 320, the UE (not shown) connected to the second base station 320, the third base station 330, and the UE (not shown) connected to the third base station 330 can all use the licensed frequency band F1 and the unlicensed frequency band F3 to transmit and receive signals through CA.

[0075] Figure 4 is a conceptual diagram illustrating a fourth exemplary embodiment of a wireless communication network.

[0076] Reference Figure 4 , the first base station 410, the second base station 420, and the third base station 430 can all support cellular communications (e.g., LTE, LTE-A, LAA, etc.). The first base station 410, the second base station 420, and the third base station 430 can all support MIMO (e.g., SU-MIMO, MU-MIMO, massive MIMO, etc.), CoMP, CA, etc. The first base station 410 can operate in the authorized frequency band F1 and form a macro cell. The first base station 410 can be connected to other base stations (e.g., the second base station 420, the third base station 430, etc.) through an ideal backhaul link or a non-ideal backhaul link. The second base station 420 can be located within the coverage area of ​​the first base station 410. The second base station 420 can operate in the authorized frequency band F2 and form a small cell. The third base station 430 can be located within the coverage area of ​​the first base station 410. The third base station 430 can operate in the authorized frequency band F2 and form a small cell. The second base station 420 and the third base station 430 may each operate in an authorized frequency band F2 that is different from the authorized frequency band F1 in which the first base station 410 operates.

[0077] The second base station 420 can be connected to the fourth base station 440 via an ideal backhaul link or a non-ideal backhaul link. The fourth base station 440 can be located within the coverage area of ​​the second base station 420. The fourth base station 440 can operate in the unlicensed frequency band F3 and form a small cell. The third base station 430 can be connected to the fifth base station 450 via an ideal backhaul link or a non-ideal backhaul link. The fifth base station 450 can be located within the coverage area of ​​the third base station 430. The fifth base station 450 can operate in the unlicensed frequency band F3 and form a small cell. Both base stations 440 and 450 can support WLAN standardized in IEEE 802.11.

[0078] The first base station 410 and a UE (not shown) connected to the first base station 410 can both use the licensed frequency band F1 and the unlicensed frequency band F3 to transmit and receive signals through CA. The second base station 420 and a UE (not shown) connected to the second base station 420, as well as the third base station 430 and a UE (not shown) connected to the third base station 430, can both use the licensed frequency band F2 and the unlicensed frequency band F3 to transmit and receive signals through CA.

[0079] The communication nodes (e.g., base stations, UEs, etc.) constituting the wireless communication network described above can transmit signals in an unlicensed frequency band according to a listen-before-talk (LBT) protocol. That is, the communication node can determine whether the unlicensed frequency band is occupied by performing an energy detection operation. When it is determined that the unlicensed frequency band is in an idle state, the communication node can transmit a signal. In this case, during a contention window according to a random backoff operation, when the unlicensed frequency band is maintained in an idle state, the communication node can transmit a signal. On the contrary, when it is determined that the unlicensed frequency band is in a busy state, the communication node cannot transmit a signal.

[0080] Alternatively, the communication entity may transmit signals according to a carrier sense adaptive transmission (CSAT) operation. That is, the communication node may transmit signals according to a preconfigured duty cycle. When the current duty cycle is the duty cycle assigned to a communication node supporting cellular communication, the communication node may transmit signals. Conversely, when the current duty cycle is the duty cycle assigned to a communication node supporting communications other than cellular communication (e.g., WLAN, etc.), the communication node may not transmit signals. The duty cycle may be adaptively determined based on the number of communication nodes existing in the unlicensed band that support WLAN, the usage status of the unlicensed band, and the like.

[0081] Communication node can carry out discontinuous transmission in unlicensed frequency band.For example, if for unlicensed frequency band configuration maximum transmission duration or maximum channel occupancy time, then during maximum transmission duration or maximum channel occupancy time, communication node can transmit signal.When communication node can not transmit whole signal during current maximum transmission duration (or maximum channel occupancy time), communication node can transmit remaining signal in next maximum transmission duration.In addition, communication node can also select the carrier wave with relatively less interference in unlicensed frequency band, and can operate in selected carrier wave.And, when communication node transmits signal in unlicensed frequency band, can control transmission power, to reduce interference to other communication nodes.

[0082] On the other hand, the communication nodes can support communication protocols based on code division multiple access (CDMA), wideband CDMA (WCDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), single carrier FDMA (SC-FDMA), orthogonal frequency division multiplexing (OFDM), orthogonal frequency division multiple access (OFDMA).

[0083] A base station in a communication node may be referred to as a Node-B (NB), an evolved Node-B (eNB), a base transceiver station (BTS), a radio base station, a radio transceiver, an access point (AP), or an access node. Furthermore, a user equipment (UE) in a communication node may be referred to as a terminal, an access terminal, a mobile terminal, a station, a user station, a portable user station, a mobile station, a node, or a device. A communication node may have a structure as described below.

[0084] Figure 5 is a block diagram illustrating one embodiment of communication nodes that constitute a wireless communication network.

[0085] Reference Figure 5 , the communication node 500 may include at least one processor 510, a memory 520, and a transceiver 530 connected to a network and performing communication. In addition, the communication node 500 may also include an input interface unit 540, an output interface unit 550, and a storage 560. The various components included in the communication node 500 may be connected via a bus 570 to communicate with each other.

[0086] The processor 510 may execute program commands stored in the memory 520 and / or storage 560. The processor 510 may be a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor in which the method according to the embodiment of the present disclosure is executed. The memory 520 and the storage 560 may include volatile storage media and / or non-volatile storage media. For example, the memory 520 may include a read-only memory (ROM) and / or a random access memory (RAM).

[0087] The following describes the operation methods of communication nodes in a wireless communication network. Although the methods performed by a first communication node (e.g., signal transmission or reception) will be described, a second communication node corresponding thereto may also perform methods (e.g., signal reception or transmission) corresponding to the methods performed by the first communication node. That is, when describing the operation of a UE, the corresponding base station may also perform operations corresponding to the operation of the UE. Conversely, when describing the operation of a base station, the UE may also perform operations corresponding to the operation of the base station.

[0088] At the same time, carrier aggregation can be applied to at least one unlicensed band cell and at least one licensed band cell. The configuration, addition, modification, or release of an unlicensed band cell can be performed through radio resource control (RRC) signaling (e.g., the transmission and reception of an 'RRCConnectionReconfiguration' message (hereinafter referred to as an 'RRC message')). The RRC message can be transmitted to the UE via the licensed band cell and may include information required for the management and operation of the unlicensed band cell.

[0089] Unlike licensed band cells, the period during which signals can be continuously transmitted in unlicensed band cells can be limited to a maximum transmission duration. Furthermore, when transmitting a signal in accordance with LBT, the signal can be transmitted when another communication node's transmission has completed. When providing LTE (or LTE-A) services in an unlicensed band cell, the transmissions of communication nodes supporting LTE (or LTE-A) can include aperiodic, discontinuous, and opportunistic characteristics. Based on these characteristics, the continuous transmission of signals for a certain period of time in the unlicensed band by communication nodes supporting LTE (or LTE-A) can be referred to as an 'unlicensed band burst.'

[0090] Alternatively, a continuous set of subframes consisting of a combination of at least one of the channels defined in the licensed band (e.g., the Physical Control Format Indicator Channel (PCFICH), the Physical Hybrid Automatic Repeat Request (ARQ) Indicator Channel (PHICH), the Physical Downlink Control Channel (PDCCH), the Physical Multicast Channel (PMCH), the Physical Uplink Control Channel (PUCCH), and the Physical Uplink Shared Channel (PUSCH)) and signals (e.g., synchronization signals and reference signals) may be transmitted in the unlicensed band. In this case, the transmission of these subframes may be referred to as 'unlicensed band transmission'.

[0091] Frames used for transmission in an unlicensed band can be categorized as downlink (DL) unlicensed band burst frames, uplink (UL) unlicensed band burst frames, and UL / DL unlicensed band burst frames. A DL unlicensed band burst frame can include subframes to which unlicensed band transmission can be applied, and can also include an 'unlicensed band signal.' In a DL unlicensed band burst frame, the unlicensed band signal can precede the subframe to which unlicensed band transmission is applied. The unlicensed band signal can be configured to match the timing of the subframe to which unlicensed band transmission is applied (or the timing of OFDM symbols) with the timing of the subframe in the licensed band (e.g., the timing of OFDM symbols). Furthermore, the unlicensed band signal can be used for automatic gain control (AGC), synchronization acquisition, channel estimation, and the like required for receiving data transmitted over the unlicensed band.

[0092] The subframes to which unlicensed band transmission is to be applied can be configured within a maximum transmission duration (or maximum channel occupancy time). That is, the number of subframes to which unlicensed band transmission is to be applied can be determined based on the maximum transmission duration (or maximum channel occupancy time). Here, the number of subframes to which unlicensed band transmission is to be applied can be determined taking into account the unlicensed band signal. In the unlicensed case, the maximum transmission duration (or maximum channel occupancy time) can be notified through RRC signaling. The UE can identify the starting point of the unlicensed band burst by detecting the PDCCH (or EPDCCH) or the unlicensed band signal. The actual occupancy time of the subframe to which the unlicensed band burst or unlicensed band transmission is to be applied can be known through the unlicensed band signal or the PHICH.

[0093] The unlicensed band signal may include information (or a sequence) indicating the number (or time) of subframes used for unlicensed band bursts or unlicensed band transmissions. Alternatively, the information (or a sequence) indicating the number (or time) of subframes used for unlicensed band bursts or unlicensed band transmissions may also be transmitted via the PHICH.

[0094] In the unlicensed band, HARQ-related information for the UL is transmitted asynchronously, unlike in the licensed band. Therefore, the RV and HARQ process number can be transmitted on the PDCCH (or EPDCCH) rather than the PHICH. In this case, the PHICH can be used to transmit other information. For example, information (or a sequence) indicating the number (or time) of subframes used for unlicensed band bursts or unlicensed band transmissions can be transmitted via the PHICH.

[0095] Meanwhile, a cellular communication network (eg, an LTE network) may support frequency division duplex (FDD) or time division duplex (TDD). A frame based on FDD may be defined as a type 1 frame, and a frame based on TDD may be defined as a type 2 frame.

[0096] Figure 6 is a conceptual diagram illustrating an exemplary embodiment of a Type 1 frame.

[0097] Reference Figure 6 , the radio frame 600 may include 10 subframes, and each subframe may include 2 time slots. Thus, the radio frame 600 may include 20 time slots (e.g., time slot #0, time slot #1, time slot #2, time slot #3, ..., time slot #18, and time slot #19). The length of the radio frame 600 (T f ) can be 10 milliseconds (ms). In addition, the length of each subframe can be 1 ms. Moreover, the length of each time slot (T slot) may be 0.5 ms. Here, Ts may be 1 / 30,720,000 seconds.

[0098] Each time slot may include multiple OFDM symbols in the time domain and multiple resource blocks (RBs) in the frequency domain. Each resource block may include multiple subcarriers in the frequency domain. The number of OFDM symbols constituting each time slot may be determined based on the configuration of the cyclic prefix (CP). CPs may be classified into normal CPs and extended CPs. If a normal CP is used, each time slot may include 7 OFDM symbols, and each subframe may include 14 OFDM symbols. If an extended CP is used, each time slot may include 6 OFDM symbols, and each subframe may include 12 OFDM symbols.

[0099] For example, when each subframe consists of 14 OFDM symbols, the OFDM symbols constituting each subframe can be respectively referred to as OFDM symbol #0, OFDM symbol #1, OFDM symbol #2, OFDM symbol #3, OFDM symbol #4, OFDM symbol #5, OFDM symbol #6, OFDM symbol #7, OFDM symbol #8, OFDM symbol #9, OFDM symbol #10, OFDM symbol #11, OFDM symbol #12, and OFDM symbol #13.

[0100] Figure 7 is a conceptual diagram illustrating an exemplary embodiment of a Type 2 frame.

[0101] Reference Figure 7 , the radio frame 700 may include 2 half frames, and each half frame may include 5 subframes. Therefore, the radio frame 700 may include 10 subframes. The length of the radio frame 700 (T f ) can be 10 milliseconds (ms), and the length of each half frame can be 5 ms. The length of each subframe can be 1 ms. Here, T s It can be 1 / 30,720,000 seconds.

[0102] Radio frame 700 may include at least one downlink subframe, at least one uplink subframe, and at least one special subframe. Each downlink subframe and uplink subframe may include two time slots. The length of each time slot (Tslot) may be 0.5 ms. Among the subframes comprising radio frame 700, subframe #1 and subframe #6 may both be special subframes. Each special subframe may include a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS).

[0103] The DwPTS can be considered to be included in the downlink period and is used by the UE for cell search and time and frequency synchronization acquisition. The GP can be used to mitigate interference with uplink data transmission that may occur due to delays in downlink data reception. Furthermore, the GP can also include the time required to transition from downlink data reception to uplink data transmission. The UpPTS can be used by the UE for uplink channel estimation and time and frequency synchronization acquisition.

[0104] The lengths of the DwPTS, GP, and UpPTS may be variably controlled when necessary. In addition, the number and positions of downlink subframes, uplink subframes, and special subframes included in the radio frame 700 may also be changed when necessary.

[0105] Figure 8 is a conceptual diagram illustrating an exemplary embodiment of a resource grid including slots in a subframe.

[0106] Reference Figure 8 When a normal CP is used, each resource block (RB) included in a time slot in a downlink subframe or uplink subframe may include 7 OFDM symbols in the time domain and 12 subcarriers in the frequency domain. In this case, a resource defined by a single OFDM symbol in the time domain and a single subcarrier in the frequency domain may be referred to as a resource element (RE).

[0107] In downlink transmission of a cellular communication network (eg, an LTE network), allocation of resources to a UE may be performed in RB units, and mapping of reference signals and synchronization signals may be performed in RE units.

[0108] The control channel can be allocated to the first three OFDM symbols (e.g., OFDM symbols #0 to #2) or four OFDM symbols (e.g., OFDM symbols #0 to #3) located in the first time slot of the subframe. The control channel may include the PDCCH, PCFICH, PHICH, and others. The data channel (e.g., PDSCH) for data transmission can be allocated to the remaining region (e.g., OFDM symbols #4 to #13) in the subframe excluding the region where the control channel is configured. In addition, the EPDCCH can be configured in a certain RB (or RE) in the remaining region.

[0109] Information indicating the number of OFDM symbols used for control channels may be transmitted via the PCFICH. The PCFICH may be configured in OFDM symbol #0 of a subframe. Responses (eg, HARQ responses, etc.) to uplink transmissions (eg, PUSCH, etc.) may be transmitted via the PHICH.

[0110] Downlink control information (DCI) may be transmitted via at least one of the PDCCH and the EPDCCH. Furthermore, the DCI may include at least one of resource allocation information and resource control information for a UE or a specific UE group. For example, the DCI may include downlink scheduling information, uplink scheduling information, uplink transmission power control commands, and the like. Here, the specific UE group may include at least one UE.

[0111] DCI can have various formats according to the type, number, and size of the information field (for example, the number of bits that make up the information field). DCI formats 0, 3, 3A, 4, etc. can be used for uplink, while DCI formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, etc. can be used for downlink. The information included in the DCI can be changed according to the format of the DCI. For example, at least one of the carrier indication field (CIF), resource block allocation information, modulation and coding scheme (MCS) information, redundancy version (RV) information, new data indication (NDI) information, transmission power control (TPC) information, HARQ process number information, precoding matrix indication (PMI) information (or PMI confirmation information), jump flag information, flag field information, etc. can be selectively included in the DCI according to the format of the DCI. Thus, the size of the control information can change with the format of the DCI. In addition, the DCI format can be used to transmit two or more types of control information. In this case, the control information can be classified according to the flag field included in the DCI. According to each DCI format, control information included in the DCI can be explained as shown in Table 1 below.

[0112] [Table 1]

[0113]

[0114]

[0115] The PDCCH can be allocated to a set of one or more consecutive control channel elements (CCEs), and the EPDCCH can be allocated to a set of one or more consecutive enhanced CCEs (ECCEs). A CCE or ECCE can be a logical allocation unit and contains multiple resource element groups (REGs). The size of the bits transmitted via the PDCCH (or EPDCCH) can be determined based on the number of CCEs or ECCEs, the coding rate, and other factors.

[0116] Figure 9 is a timing diagram illustrating an exemplary embodiment of an unlicensed band burst.

[0117] Reference Figure 9, the timing of the subframes (or, time slots or OFDM symbols) in the licensed band can be the same as the timing of the subframes (or, time slots or OFDM symbols) in the unlicensed band. Herein, the licensed band can be referred to as a 'licensed band cell' or a 'primary cell (PCell)'. The unlicensed band can be referred to as an 'unlicensed band cell', a 'secondary cell (SCell)', or a 'LAA cell'. In the licensed band, signals can be transmitted continuously. That is, burst transmissions in the licensed band can occur continuously.

[0118] In contrast, burst transmissions in an unlicensed band may occur discontinuously. For example, an unlicensed band burst may occur in units of 4 subframes. The starting subframe in the subframes constituting the unlicensed band burst may have a size of less than 1 millisecond (ms). The starting subframe having a size of less than 1ms may be referred to as a "starting partial subframe". In addition, the ending subframe in the subframes constituting the unlicensed band burst may also have a size of less than 1ms. The ending subframe having a size of less than 1ms may be referred to as an "ending partial subframe". The sum of the lengths of the starting partial subframe and the ending partial subframe may be configured to be 1ms. For example, the starting partial subframe may include OFDM symbol #4 of the first time slot to OFDM symbol #6 of the second time slot. In this case, the ending partial subframe may include OFDM symbols #0 to #3 of the first time slot.

[0119] The starting point of the unlicensed band burst (or the starting part of the subframe) can be configured in a set of predetermined OFDM symbols. For example, the starting point of the unlicensed band burst can be configured as OFDM symbol #0 of the first time slot or OFDM symbol #0 of the second time slot. Alternatively, the starting point of the unlicensed band burst can also be configured as an OFDM symbol that is shifted from OFDM symbol #0 of the first time slot by a predetermined shift amount in a TDD-based network. Here, the predetermined shift amount can be a value corresponding to the duration of 'GP+UpPTS'. For example, the starting point of the unlicensed band burst in a TDD-based network can be OFDM symbol #0, #2, #3, or #5 of the first time slot in a subframe, or OFDM symbol #1 of the second time slot.

[0120] Alternatively, the start point of the unlicensed band burst can be configured as the start point or end point of the PDCCH, or the transmission point of a reference signal (e.g., a cell-specific reference signal (CRS)). For example, the start point of the unlicensed band burst can be OFDM symbol #0 or #4 in the first time slot of a subframe. However, the start point of the unlicensed band burst is not limited to the examples described above and can be configured as any OFDM symbol in the subframe.

[0121] At the same time, a cyclic redundancy check (CRC) for error detection may be attached to the control information transmitted via the PDCCH (or EPDCCH) according to the DCI format. The CRC may be masked (e.g., scrambled) according to the radio network temporary identifier (RNTI) of the communication node (e.g., UE, station, etc.) that will receive the PDCCH (or EPDCCH). Alternatively, the CRC may be masked (e.g., scrambled) according to a specific RNTI configured for various purposes. Various RNTIs and corresponding values ​​are described in Table 2 below.

[0122] [Table 2]

[0123]

[0124] Each RNTI may have its specific purpose, as described in Table 3.

[0125] [Table 3]

[0126]

[0127] An identifier associated with an unlicensed band cell may be referred to as an unlicensed band cell RNTI (U-RNTI), and may be named differently depending on the information of the unlicensed band cell. The U-RNTI may be transmitted to the UE via RRC signaling.

[0128] A PDCCH (or EPDCCH) containing a CRC masked (e.g., scrambled) using a U-RNTI may be transmitted via a common search space or a UE-specific search space. The location of the PDCCH (or EPDCCH) in the common search space or the UE-specific search space may be determined based on the CCE (or ECCE) aggregation level, the CCE (or ECCE) index calculated based on the U-RNTI, or other factors. The location of the candidate CCE (or ECCE) to be monitored in the common search space or the UE-specific search space may be determined according to the following equation 1: The UE may monitor the candidate CCEs (or ECCEs) to obtain the PDCCH (or EPDCCH).

[0129] [Equation 1]

[0130]

[0131] L may indicate an aggregation level. For example, L may be 1, 2, 4, or 8. The aggregation level of CCEs (or ECCEs) in a PDCCH (or EPDCCH) transmitted in a subframe of an unlicensed band (i.e., a subframe with a length of less than 1 ms) may be greater than 8 (e.g., 16, 32, etc.). In the common search space, Y may bek Set to 0. In addition, Y can be determined according to RNTI (e.g., U-RNTI in unlicensed bands) k , m′ can be a positive integer less than the total number (M(L)-1) of candidate PDCCHs (or candidate EPDCCHs, candidate CCEs, candidate ECCEs) to be monitored in the common search space (or the search space specifically for UE). N CCE,k The total number of CCEs (or ECCEs) included in subframe k may be indicated.

[0132] At the same time, the U-RNTI can be configured as a value specific to the UE, a value common to the base station, a value common to unlicensed band cells, an initial value, or other values. A U-RNTI with a value specific to the UE can be referred to as a "UE-specific U-RNTI." A U-RNTI with a value common to the base station can be referred to as a "base station-common U-RNTI." A U-RNTI with a value common to unlicensed band cells can be referred to as an "unlicensed band cell-common U-RNTI."

[0133] A U-RNTI specifically for the UE may be transmitted via RRC signaling with information related to the configuration, addition, etc. of an unlicensed band cell. The base station common U-RNTI may be used to transmit the configuration, system information, etc. of an unlicensed band cell that has been configured by the base station. The base station common U-RNTI may be preset to be equal to or approximately the SI-RNTI, or obtained via RRC signaling. The unlicensed band cell common U-RNTI may have a different value for each unlicensed band cell and may be obtained via RRC signaling. For example, in a procedure in which an unlicensed band cell is newly configured as an SCell, the unlicensed band cell common U-RNTI may be included in an RRC message (e.g., an RRCConnectionReconfiguration message).

[0134] U-RNTI can be used to transmit information related to unlicensed bands supported by the base station (for example, configuration / addition / modification / release of unlicensed band cells, system information, etc.). In addition, U-RNTI can be used to transmit control information of different unlicensed band cells. U-RNTI can also be used to transmit dynamic activation or deactivation request messages of unlicensed band cells. Here, the U-RNTI can be configured differently according to its purpose of use or the PDCCH (or EPDCCH) receiving target. For example, a U-RNTI for the transmission of activation or deactivation messages for public unlicensed band cells, or a U-RNTI for the transmission of activation or deactivation messages for unlicensed band cells specifically for UEs can be configured.

[0135] In addition, U-RNTI can also be used to schedule UL resources for transmitting specific information of unlicensed band cells. In this case, the UE can collect such additional information by detecting the scheduling information of UL resources and U-RNTI. For example, the UE can receive a PDCCH (or EPDCCH) containing a U-RNTI-masked (e.g., scrambled) CRC in a subframe using an authorized band. When a collision occurs between signals in a subframe of an unlicensed band corresponding to a subframe of an authorized band through which the PDCCH (or EPDCCH) is transmitted, the UE can transmit information indicating that a collision has been identified to the base station (hereinafter referred to as "collision perception information"). Here, the collision perception information can be transmitted via the UL resources indicated by the scheduling information included in the PDCCH (or EPDCCH).

[0136] Hereinafter, methods for activating and deactivating licensed frequency band cells will be described.

[0137] Activation and deactivation of a secondary cell in the licensed band can be performed based on an activation / deactivation MAC control element (CE). The secondary cell index in the licensed band (set to '0' in the activation / deactivation MAC CE) can indicate that the secondary cell in the licensed band is operating in an inactive state. On the other hand, the secondary cell index in the licensed band (set to '1' in the activation / deactivation MAC CE) can indicate that the secondary cell in the licensed band is operating in an active state.

[0138] In addition, activation and deactivation of the secondary cell in the authorized band may also be performed according to the time indicated by the SCell deactivation time field included in the RRC message. The SCell deactivation time field may indicate 20ms, 40ms, 80ms, 160ms, 320ms, 640ms, 1280ms, or others. For example, if the time indicated by the SCell deactivation time field has passed, the state of the secondary cell in the authorized band may be converted from an active state to an inactive state. The case where the SCell deactivation time field is not set may mean that the SCell deactivation time field indicates an uncertain time. The time indicated by the SCell deactivation time field may be applied to all secondary cells in the authorized band.

[0139] For example, if an activation / deactivation MAC CE indicating activation of a secondary cell is received in subframe #n of the licensed band, the UE may activate the secondary cell in the licensed band and activate (or reactivate) the timer according to the time indicated by the SCell deactivation time field from subframe #(n+8). Then, when the UE receives a PDCCH (or EPDCCH) for UL or DL ​​scheduling (e.g., self-carrier scheduling or cross-carrier scheduling) for the activated secondary cell in the licensed band, the timer may be reactivated according to the time indicated by the SCell deactivation time field. If an activation / deactivation MAC CE indicating deactivation of the secondary cell in the licensed band is received or the time indicated by the SCell deactivation time field has passed, the UE may deactivate the secondary cell in the licensed band. In this case, the UE may deactivate the secondary cell in the licensed band even before subframe #(n+8).

[0140] At the same time, activation and deactivation of unlicensed cells can also be performed based on the activation / deactivation MAC CE and SCell deactivation time fields. When another communication node occupies the unlicensed band, the UE cannot receive the PDCCH (or EPDCCH) until the time indicated by the SCell deactivation time field has passed (for example, until the state of the unlicensed band cell changes from active to inactive). In this case, reactivation of the unlicensed band may be required. To address this issue, activation and deactivation of the unlicensed band cell can be performed as follows.

[0141] Activation / deactivation based on minimum deactivation time

[0142] The 'minimum deactivation time' can be set independently of the time indicated by the SCell deactivation time field included in the RRC message. The minimum deactivation time can be pre-set by the base station and the UE. Alternatively, the minimum deactivation time can also be transmitted to the UE via the RRC message. The UE can obtain the SCell deactivation time field and the minimum deactivation time, and compare the time indicated by the SCell deactivation time field with the minimum deactivation time. If the time indicated by the SCell deactivation time field is greater than the minimum deactivation time, the UE can activate a timer for the time indicated by the SCell deactivation time field, and if the timer expires, deactivate the unlicensed band cell. On the other hand, if the time indicated by the SCell deactivation time field is less than the minimum deactivation time, the UE can activate a timer for the minimum deactivation time, and if the timer expires, deactivate the unlicensed band cell. Here, the minimum deactivation time can indicate an indeterminate time. In this case, the UE can activate the timer for the minimum deactivation time regardless of the SCell deactivation time field.

[0143] Activation / deactivation based on the time indicated by the SCell Deactivation Time field

[0144] The UE can calculate the changed time by multiplying the time indicated by the SCell Deactivation Time field by a predetermined integer. The UE can activate a timer for the changed time and, when the timer expires, deactivate the unlicensed band cell. The predetermined integer can be predetermined by the base station and the UE. Alternatively, the predetermined integer can be transmitted to the UE via an RRC message.

[0145] Based on the time indicated by the unlicensed band SCell deactivation time field defined for the unlicensed band cell Activation / deactivation between

[0146] The UE can obtain the Unlicensed Band SCell Deactivation Time field via RRC signaling in the licensed band or the unlicensed band. The Unlicensed Band SCell Deactivation Time field can be used by communication nodes operating in the unlicensed band. The UE can activate a timer for the time indicated by the Unlicensed Band SCell Deactivation Time field and deactivate the unlicensed band cell when the timer expires.

[0147] Activation / deactivation based on the SCell deactivation time field indicating an uncertain time

[0148] When the SCell deactivation time field indicates an uncertain time, the UE may activate or deactivate the unlicensed band cell according to the activation / deactivation MAC CE.

[0149] On the other hand, unlike the activation and deactivation of licensed band cells, the activation and deactivation of unlicensed band cells can be performed based on PDCCH (or EPDCCH) rather than MAC CE. The method of activating or deactivating unlicensed band cells based on PDCCH (or EPDCCH) is described below.

[0150] Figure 10 is a sequence diagram illustrating a first exemplary embodiment of a method for activating or deactivating an unlicensed band cell.

[0151] Reference Figure 10 , the base station and UE can form a reference Figures 1 to 4 The wireless communication network described herein can support both licensed and unlicensed frequency bands. The base station can support carrier aggregation. The base station and the UE can be configured to communicate with the reference Figure 5 The communication node 500 is the same as or similar to the described communication node 500. The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band may be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band.

[0152] The base station may transmit a PDCCH (or EPDCCH) including information requesting activation of an unlicensed band cell to the UE via subframe #n of the licensed band or another activated unlicensed band (S1000). To request activation of an unlicensed band cell, a PDCCH (or EPDCCH) including a CRC masked (e.g., scrambled) using a C-RNTI or a PDCCH (or EPDCCH) including a CRC masked (e.g., scrambled) using an activation U-RNTI may be used. The activation U-RNTI may be used to request activation of an unlicensed band cell.

[0153] When a PDCCH (or EPDCCH) including a CRC masked (e.g., scrambled) according to a C-RNTI is used, the DCI included in the PDCCH (or EPDCCH) may include information (e.g., CIF) indicating that the unlicensed band cell is deactivated. Alternatively, the DCI included in the PDCCH (or EPDCCH) may further include a newly defined activation / deactivation field. The size of the activation / deactivation field may be 1 bit. An activation / deactivation field set to '0' may indicate activation of an unlicensed band cell, while an activation / deactivation field set to '1' may indicate deactivation of an unlicensed band cell. Conversely, an activation / deactivation field set to '0' may indicate deactivation of an unlicensed band cell, while an activation / deactivation field set to '1' may indicate activation of an unlicensed band cell.

[0154] The UE may receive a PDCCH (or EPDCCH) including information requesting activation of an unlicensed band cell from a base station through subframe #n of a licensed band or another activated unlicensed band. If a PDCCH (or EPDCCH) including a CRC masked (e.g., scrambled) according to a C-RNTI is used, the UE may identify a CIF or activation / deactivation field included in the DCI of the PDCCH (or EPDCCH) and may determine that activation has been requested (S1010). Alternatively, if a PDCCH (or EPDCCH) including a CRC masked (e.g., scrambled) according to an activation U-RNTI is used, the UE may determine that activation of an unlicensed band cell has been requested (S1010) by identifying that the CRC included in the PDCCH (or EPDCCH) is masked (e.g., scrambled) according to the activation U-RNTI.

[0155] In addition, the UE can also calculate the subframe number (n+N act ) Determine whether the unlicensed frequency band cell is activated. N act It can be an integer of 1 or greater than 1. For example, N actIt can be 2, 4, 8, or other numbers. N can be pre-determined in the base station and the UE. act Alternatively, N can also be sent via RRC signaling. act Transmitted to UE. If DCI contains the newly defined act The transmitted field can be transmitted via DCI act If N is determined based on the UE's receiving / demodulation capabilities act , then N can be reported through the reporting procedure for UE capability information act Transmitted to UE.

[0156] At the same time, since the subframe # (n+N act ) activates the unlicensed band cell, so the UE cannot receive the PDCCH of subframe #n scheduled by the PDCCH (or EPDCCH) of subframe #n. Therefore, the UE may transmit a HARQ response (e.g., NACK, DTX) indicating that the PDCCH of subframe #n was not received to the base station via the UL resources of subframe #(n+4) (S1020). Here, if the unlicensed band cell is activated, the HARQ response may indicate that the UE has confirmed the request. Therefore, when the base station receives the HARQ response from the UE, the base station may determine that the UE has confirmed the request to activate the unlicensed band cell.

[0157] On the other hand, if no HARQ response is received from the UE, the base station may determine that the UE has not confirmed the request to activate the unlicensed band cell. Since the activation procedure of the unlicensed band cell is not performed normally, the base station may request the UE to activate the unlicensed band cell again by using the activation procedure of the unlicensed band cell described above (e.g., the activation procedure based on the activation / deactivation MAC CE).

[0158] At the same time, in the subframes #n to #(n+(N act -1)), the base station may schedule UL resources or DL ​​resources of the unlicensed band cell according to a predefined operation policy.

[0159] Here, when the CRC included in the PDCCH (or EPDCCH) received at the UE is masked (or scrambled) according to the C-RNTI, step S1020 may be performed. That is, if the CRC included in the PDCCH (or EPDCCH) received at the UE is masked (e.g., scrambled) according to the activated U-RNTI, step S1020 may not be performed.

[0160] UE can calculate the subframe number (n+N act) activates the unlicensed band cell (S1030). Therefore, the UE can receive the subframe #(n+N) of the unlicensed band cell from act ) receives the PDCCH (or EPDCCH), receives the PDCCH through the DL resources indicated by the scheduling information included in the PDCCH (or EPDCCH), and can transmit the PUSCH through the UL resources indicated by the scheduling information included in the PDCCH (or EPDCCH).

[0161] Meanwhile, if the CRC included in the PDCCH (or EPDCCH) received by the UE in step S1000 is masked (eg, scrambled) according to the activated U-RNTI, the UE may receive the subframe #(n+N act The subframe #(N+N) of the unlicensed band cell indicated by the scheduling information in the PDCCH (or EPDCCH) act ) in the PDSCH of the unlicensed band. In this case, the UE can act +4) will indicate that the pair is included in subframe #(n+N act ) in the PDSCH is transmitted to the base station. Here, the HARQ response may indicate that the unlicensed band cell is activated. Therefore, when the base station receives the HARQ response from the UE, the base station may determine that the unlicensed band cell is activated. On the other hand, if the base station fails to successfully receive the HARQ response from the UE, the base station may determine that the unlicensed band cell is not activated. Since the activation procedure of the unlicensed band cell is not performed normally, the base station may use the activation procedure of the unlicensed band cell described above (e.g., the activation procedure based on the activation / deactivation MAC CE) to request the UE to activate the unlicensed band cell again.

[0162] When PDCCH (or EPDCCH) is transmitted via the common search space, the above-described procedure for confirming activation of the unlicensed band cell based on the HARQ response may not be performed. In this case, the base station may use subframe # (n+N act ) schedules the UE using the C-RNTI of the unlicensed band cell and receives from the UE a HARQ response to the PDSCH transmitted according to the schedule. When the HARQ response is received from the UE, the base station can determine that the unlicensed band cell is activated. On the other hand, if the base station fails to successfully receive the HARQ response from the UE, the base station can determine that the unlicensed band cell is not activated. Since the activation procedure for the unlicensed band cell is not performed normally, the base station can request the UE to activate the unlicensed band cell again by using the activation procedure for the unlicensed band cell described above (for example, the activation procedure based on the activation / deactivation MAC CE).

[0163] At the same time, the base station may transmit a PDCCH (or EPDCCH) including information requesting deactivation of an unlicensed band cell to the UE via the unlicensed band (or the licensed band) (S1040). The information requesting deactivation of the unlicensed band cell may be the activation / deactivation field described above. Alternatively, the information requesting deactivation of the unlicensed band cell may be information included in the DCI that does not indicate any specific meaning (for example, RB information set to all 0s).

[0164] The UE may receive a PDCCH (or EPDCCH) from a base station via an unlicensed band (or a licensed band). The UE may confirm that deactivation of the unlicensed band cell has been requested by identifying information (e.g., an activation / deactivation field) requesting deactivation of the unlicensed band cell included in the PDCCH (or EPDCCH). The UE may receive a PDCCH (or EPDCCH) from a base station via a subframe in which the information requesting deactivation of the unlicensed band cell is transmitted. Dact After N subframes, the unlicensed band cell is activated (S1060). Dact It can be an integer of 1 or greater than 1. For example, N Dact It can be 2, 4, 8, or other numbers. N can be pre-determined in the base station and the UE. Dact Alternatively, N can also be sent via RRC signaling. Dact Transmitted to UE. If DCI contains the newly defined Dact The transmitted field can be transmitted via DCI Dact If N is set according to the UE's reception / demodulation capabilities Dact , then N can be reported through the reporting procedure for UE capability information Dact Transmitted to UE.

[0165] Next, a method for scheduling unlicensed band cells will be described.

[0166] When the self-carrier scheduling scheme is used, scheduling information for the PDSCH included in subframe #n of the unlicensed band cell may be transmitted via the PDCCH (or EPDCCH) included in subframe #n of the unlicensed band cell. When the cross-carrier scheduling scheme is used, scheduling information for the PDSCH included in subframe #n of the unlicensed band cell may be transmitted via the PDCCH (or EPDCCH) included in subframe #n of the licensed band cell corresponding to subframe #n of the unlicensed band cell.

[0167] Scheduling information (e.g., grant) for a PUSCH included in subframe #(n+4) of an unlicensed band cell may be transmitted via a PDCCH (or EPDCCH) included in subframe #n of a licensed band cell or an unlicensed band cell. Scheduling information for a PUSCH included in subframe #(n+4) of an unlicensed band cell may be included in a DCI (e.g., a DCI having format 0). In this case, the UE may transmit the PUSCH via UL resources included in subframe #(n+4) of the unlicensed band cell indicated by the scheduling information. However, if subframe #(n+4) of the unlicensed band cell is occupied by another communication node, the UE may transmit the PUSCH as follows.

[0168] As a first method, when another communication node occupies subframe #(n+4) of an unlicensed band cell, the UE may abandon the transmission of the PUSCH in subframe #(n+4) of the unlicensed band cell. In this case, the UE may monitor the licensed band cell or the unlicensed band cell to receive a PDCCH (or EPDCCH) containing DCI (e.g., DCI with format 0) containing new scheduling information for the PUSCH. Upon receiving a PDCCH (or EPDCCH) containing DCI (e.g., DCI with format 0) containing new scheduling information for the PUSCH, the UE may transmit the PUSCH using the resources of the unlicensed band cell indicated by the new scheduling information.

[0169] As a second method, the UE may check subframes #(n+4) to #(n+4+N UL_Window ) in the channel condition, if the channel condition becomes idle, the UE can transmit PUSCH through the UL resources of the unlicensed band cell. In this case, the UE can transmit PUSCH according to the scheduling information received through the subframe #n of the licensed band cell or the unlicensed band cell. Here, N can be predetermined in the base station and the UE. UL_Window Alternatively, N may also be transmitted to the UE via an RRC message (eg, an RRC message newly defined for an unlicensed band cell). UL_Window . You can use N UL_Window Set to be equal to or less than the maximum transmission duration or the maximum channel occupancy time. UL_Window Can be an integer greater than or equal to 0. For example, in N UL_WindowWhen the number of subframes is 0, if another communication node occupies subframe #(n+4) of the unlicensed band cell, the UE may abandon the transmission of the PUSCH in subframe #(n+4) of the unlicensed band cell. In this case, the UE may monitor the licensed band cell or the unlicensed band cell to receive the PDCCH (or EPDCCH) including the DCI (e.g., the DCI with format 0) containing new scheduling information for the PUSCH.

[0170] At the same time, the communication node can perform an LBT operation to use the unlicensed band. For example, the communication node can check the channel conditions of the unlicensed band through energy measurement (or signal detection) and use the unlicensed band when the channel conditions are idle. The LBT operation may include a clear channel estimation (CCA) operation and a random access operation. The CCA operation can be performed to identify the channel conditions of the unlicensed band. The CCA operation can basically be performed on a time slot basis.

[0171] When performing a CCA operation, the communication node may identify the channel condition of the unlicensed frequency band within a predetermined period of time (e.g., a period of time corresponding to a predetermined number of time slots). Here, the predetermined period of time may be a distributed coordination function (DCF) interframe space (DIFS) defined in the WLAN standard. When it is determined that the channel condition of the unlicensed frequency band is idle within the predetermined period of time, the communication node may perform a random access operation.

[0172] When performing a random access operation, a communication node may randomly select a backoff value within the contention window and check the channel conditions of the unlicensed frequency band for a period of time corresponding to the backoff value. When the channel conditions of the unlicensed frequency band are idle for a predetermined period of time, the communication node may use the unlicensed frequency band. The size of the contention window may be fixed or variable. The size of the contention window may be varied based on channel occupancy (e.g., the time during which one or more signals having a predetermined threshold strength are detected, the ratio (or occupancy rate) of signals having a predetermined threshold strength, a histogram of signals having a predetermined threshold strength, etc.), the number of communication nodes using the same unlicensed frequency band (or the same channel in the unlicensed frequency band), HARQ responses (ACK, NACK, DTX, ANY), collision detection information, information detected by other communication nodes, and other factors.

[0173] The size of the contention window can be changed in a semi-static or dynamic manner. In the case of the semi-static mode, at least one of the information such as the number of communication nodes using the same unlicensed frequency band (or the same channel in the unlicensed frequency band), HARQ responses (ACK, NACK, DTX, ANY), collision perception information, and the information detected by other communication nodes can be obtained within a predetermined time, and the size of the contention window can be changed at predetermined intervals by using the statistical results based on the obtained information. In the case of the dynamic mode, at least one of the information such as the number of communication nodes using the same unlicensed frequency band (or the same channel in the unlicensed frequency band), HARQ responses (ACK, NACK, DTX, ANY), collision perception information, and the information detected by other communication nodes can be obtained within a predetermined time, and the size of the contention window can be directly changed according to the information obtained.

[0174] The method of changing the size of the contention window according to the channel occupancy status may be performed as follows: Furthermore, the method of changing the size of the contention window according to the channel occupancy status may be performed in a semi-static or dynamic manner.

[0175] Figure 11 is a flow chart illustrating a first exemplary embodiment of a method of changing a contention window size according to a channel occupancy status.

[0176] Reference Figure 11 , the base station and UE can form a reference Figures 1 to 4 The wireless communication network described herein can support both licensed and unlicensed frequency bands. The base station can support carrier aggregation. The base station and the UE can be configured to communicate with the reference Figure 5 The communication node 500 is the same as or similar to the described communication node 500. The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band may be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band.

[0177] The base station may measure the channel occupancy status of the unlicensed frequency band within a predetermined period of time (S1100). For example, the base station may compare the strength of the signal received through the unlicensed frequency band within a predetermined period of time with a predetermined threshold value (e.g., a predetermined signal strength), and measure the channel occupancy status based on the comparison result. Here, the signal received through the unlicensed frequency band within the predetermined period of time may not include the signal scheduled by the base station. That is, the signal received through the unlicensed frequency band within the predetermined period of time may be an interference signal generated by another communication node. The time scheduled by the base station may not be included in the predetermined period of time. Here, the measurement of the channel occupancy status may be performed at each predetermined period.

[0178] For example, the base station may measure the channel occupancy status (eg, channel occupancy rate) according to Equation 2 below.

[0179] [Equation 2]

[0180]

[0181] The base station may change the size of the contention window according to the channel occupancy status (S1110). Here, the size of the contention window may be changed every predetermined period. If the channel occupancy rate indicated by the channel occupancy status is equal to or greater than a predetermined occupancy threshold, the base station may increase the size of the contention window. On the other hand, if the channel occupancy rate indicated by the channel occupancy status is less than a predetermined occupancy threshold, the base station may maintain, reduce, or initialize the size of the contention window.

[0182] The base station may perform an LBT operation based on the changed contention window size (S1120). For example, the base station may select a backoff value in the changed contention window and check the channel condition within a time corresponding to the selected backoff value. If the channel condition is idle, the base station may transmit a signal in the unlicensed band. In addition, the base station may also transmit information indicating the changed contention window size to the UE via an RRC message or DCI.

[0183] Figure 12 is a sequence diagram illustrating a second exemplary embodiment of a method of changing a contention window size according to a channel occupancy status.

[0184] Reference Figure 12 , the base station and UE can form a reference Figures 1 to 4 The wireless communication network described herein can support both licensed and unlicensed frequency bands. The base station can support carrier aggregation. The base station and the UE can be configured to communicate with the reference Figure 5 The communication node 500 is the same as or similar to the described communication node 500. The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band may be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band.

[0185] The base station may transmit measurement-related information to the UE (S1200). The measurement-related information may include an algorithm for measuring channel occupancy status, a predetermined threshold (e.g., a predetermined signal strength), a measurement period, a measurement time, a reporting condition, and other information. The measurement-related information may be transmitted to the UE via an RRC message. The RRC message may be masked (e.g., scrambled) based on the C-RNTI or the U-RNTI. Alternatively, the measurement-related information may also be configured in the base station and the UE. In this case, since the UE already knows the measurement-related information, step S1200 may be omitted.

[0186] If the unlicensed band cell for which the channel occupancy status measurement is performed is in an active state, the RRC message may be transmitted to the UE via the licensed band cell or the activated unlicensed band cell. On the other hand, if the unlicensed band cell for which the channel occupancy status measurement is performed is in an inactive state, the RRC message may be transmitted to the UE via the licensed band cell or another unlicensed band cell. At the same time, the UE may receive the RRC message from the base station and may obtain information related to the measurement from the received RRC message.

[0187] If the unlicensed band cell for which the channel occupancy status measurement is performed is in an inactive state, the UE may measure the channel occupancy status in the inactive unlicensed band cell. Alternatively, if the unlicensed band cell for which the channel occupancy status measurement is performed is in an inactive state, the UE may also measure the channel occupancy status in the inactive unlicensed band cell after performing the unlicensed band cell activation procedure. The unlicensed band cell activation procedure may be as follows.

[0188] The base station may transmit an RRC message requesting the addition of an unlicensed band cell to the UE (S1201). The RRC message requesting the addition of an unlicensed band cell may be transmitted to the UE via the licensed band cell or another unlicensed band cell in an active state. The UE may receive the RRC message requesting the addition of an unlicensed band cell from the base station and may add the unlicensed band cell in response to the addition request of the unlicensed band cell. If the unlicensed band cell is added, the UE may transmit a response indicating the completion of the addition of the unlicensed band cell (e.g., a response to the RRC message) to the base station (S1202). If a response indicating the completion of the addition of the unlicensed band cell is received from the UE, the base station may determine that the unlicensed band cell has been added. The base station may then transmit information requesting activation of the added unlicensed band cell (e.g., an activation / deactivation MAC CE included in the DCI) to the UE (S1203). If information requesting activation of the added unlicensed band cell is received from the base station, the UE may activate the added unlicensed band cell.

[0189] When the added unlicensed band cell is activated, the base station may transmit a message requesting measurement of the channel occupancy status of the unlicensed band (i.e., the activated added unlicensed band cell) to the UE (or all UEs belonging to the unlicensed band cell) (S1024). The message requesting measurement of the channel occupancy status of the unlicensed band may be an RRC message, and may be transmitted to the UE via the licensed band or the unlicensed band. The RRC message may be masked (e.g., scrambled) according to the C-RNTI or the U-RNTI. Upon receiving the message requesting measurement of the channel occupancy status of the unlicensed band, the UE may measure the channel occupancy status of the unlicensed band (S1205). Alternatively, the UE may also measure the channel occupancy status of the unlicensed band without a request from the base station. In this case, step S1204 may be omitted.

[0190] The UE may measure the channel occupancy status of the unlicensed band according to the measurement period included in the information related to the measurement. For example, the UE may measure the strength of the signal received over a predetermined period of time via the unlicensed band, compare the measured strength with a predetermined threshold (the predetermined threshold included in the information related to the measurement), and identify a signal having a strength equal to or higher than the predetermined threshold. The signal received over the unlicensed band over the predetermined period of time may not include a signal scheduled by the base station. That is, the signal received over the unlicensed band over the predetermined period of time may be an interference signal generated by another communication node. The predetermined period of time may not include time scheduled by the base station. The UE may measure the channel occupancy status (e.g., channel occupancy rate) according to an algorithm (e.g., Equation 2) included in the information related to the measurement.

[0191] The UE may transmit (or report) information indicating the measured channel occupancy status to the base station according to the reporting conditions included in the measurement-related information. For example, the UE may transmit information indicating the channel occupancy status to the base station according to the periodicity defined in the reporting conditions. If the change between the channel occupancy status measured in the current period and the channel occupancy status measured in the previous period is equal to or greater than a predetermined threshold (i.e., if the channel occupancy status has changed), the UE may transmit information indicating the channel occupancy status to the base station. The UE may transmit information indicating the channel occupancy status to the base station as follows.

[0192] The UE may transmit information indicating the channel occupancy status to the base station in response to the RRC message. Alternatively, the UE may also transmit information indicating the channel occupancy status to the base station through the UL resources allocated by the base station. For example, the UE may request the base station to schedule UL resources for transmitting information indicating the channel occupancy status (S1206). If a scheduling request for UL resources is received, the base station may allocate UL resources to the UE. For example, the base station may transmit a UL grant to the UE (S1207). Here, the UL resources allocated to the UE may be UL resources of a licensed band or UL resources of an unlicensed band. The UE may transmit information indicating the channel occupancy status to the base station through the UL resources allocated by the base station (S1208).

[0193] The base station receives information indicating the channel occupancy status from the UE. The base station may change the size of the contention window according to the channel occupancy status (S1209). Here, the size of the contention window may be changed every predetermined period. If the channel occupancy rate indicated by the channel occupancy status is equal to or greater than a predetermined threshold, the base station may increase the size of the contention window. If the channel occupancy rate indicated by the channel occupancy status is less than the predetermined occupancy limit, the base station may maintain, reduce, or initialize the size of the contention window.

[0194] The base station may perform an LBT operation based on the changed contention window size (S1210). For example, the base station may select a backoff value within the changed contention window and check channel conditions within a time corresponding to the selected backoff value. If the channel condition is idle, the base station may transmit signals via the unlicensed band. The base station may also notify the UE of the changed contention window size.

[0195] Next, a method for dynamically changing the size of the contention window will be described. In addition, the method for changing the size of the contention window described below can be performed either semi-statically or dynamically.

[0196] If a dynamic solution is used, the size of the contention window can be changed based on at least one of a HARQ response (ACK, NACK, DTX, ANY), collision detection information, data loss information, and information detected by other communication nodes. Here, the size of the contention window can be increased or decreased exponentially. Alternatively, the size of the contention window can be initialized. The size of the contention window can be set in a predetermined set of contention windows or in a set of contention windows obtained via an RRC message.

[0197] Meanwhile, collisions between signals in unlicensed bands may occur as follows.

[0198] Figure 13is a timing diagram illustrating a first embodiment of a collision situation in an unlicensed frequency band.

[0199] Reference Figure 13 , the timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band can be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band. The base station and the UE can support the licensed band and the unlicensed band. The base station can support carrier aggregation in the licensed band and the unlicensed band. The licensed band cell can be a primary cell (i.e., PCell) or a primary SCell (i.e., PSCell). The licensed band cell can be used for UL transmission and DL transmission. The unlicensed band cell can be used for DL ​​transmission between the base station and the UE, and can be used for communication between communication nodes supporting WLAN (hereinafter referred to as 'WLAN communication nodes').

[0200] The base station may transmit unlicensed band burst #1 in subframe #(n+1) and subframe #(n+2) in the unlicensed band. Unlicensed band burst #1 may collide with WLAN signals generated by the WLAN communication node in subframe #(n+1) and subframe #(n+2) of the unlicensed band.

[0201] The base station may transmit unlicensed band burst #2 in subframes #(n+5) to #(n+8) of the unlicensed band. Unlicensed band burst #2 may collide with the WLAN signal generated by the WLAN communication node in subframes #(n+5) to #(n+7) of the unlicensed band.

[0202] The base station may transmit unlicensed band burst #3 in subframes #(n+11) to #(n+16) of the unlicensed band. Since WLAN signals generated by WLAN communication nodes are transmitted in subframes #(n+11), #(n+12), #(n+13), #(n+15), and #(n+16), unlicensed band burst #3 may collide with the WLAN signals.

[0203] In unlicensed bands, collisions can be categorized into Type 1 and Type 2 collisions. If the transmission timing of a signal transmitted by a base station using LBT coincides with the transmission timing of a signal transmitted by a WLAN communication node using LBT, a collision between the signals may occur. This type of collision is defined as a Type 1 collision.

[0204] Even when a base station transmits signals in an unlicensed band according to LBT operation, WLAN communication nodes may not be able to detect the signals transmitted from the base station due to hidden node issues or other reasons. In this case, the WLAN communication node can determine that the channel conditions in the unlicensed band are idle and may transmit signals in the unlicensed band. As a result, the signal transmitted by the base station may collide with the signal transmitted by the WLAN communication node. This type of collision is defined as a Type 2 collision. The collision problem according to Type 2 collision can be resolved through the procedures for exchanging Request-to-Send (RTS) frames and Clear-to-Send (CTS) frames specified in the WLAN standard. In addition, to avoid collisions caused by Type 2 collisions, the base station can change the unlicensed band cell or configure a new unlicensed band cell.

[0205] Meanwhile, can carry out LBT operation according to the hypothesis that can detect the signal of the other party's communication node according to communication node.So, with regard to the size that changes the contention window, can not consider because of the collision (for example, type 2 collision) that causes of the signal that fails to detect the other party's communication node successfully.

[0206] Hereinafter, a method of changing the size of the contention window according to the HARQ response will be described.

[0207] Figure 14 is a sequence diagram illustrating an exemplary embodiment of a method for changing a contention window size according to a HARQ response.

[0208] Reference Figure 14 , the base station and UE can form a reference Figures 1 to 4 The wireless communication network described herein can support both licensed and unlicensed frequency bands. The base station can support carrier aggregation in both licensed and unlicensed frequency bands. The base station and the UE can be configured to communicate with the reference Figure 5 The communication node 500 described above is the same as or similar to the one described above. The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band can be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band. The configuration of the unlicensed band burst can be the same as that of the referenced subframes (or time slots, OFDM symbols, etc.). Figure 9 The configuration of the unlicensed band burst is the same or similar as described. The unlicensed band burst may be scheduled according to a cross-carrier scheduling scheme or a self-carrier scheduling scheme.

[0209] The base station may transmit an unlicensed band burst #1 to the UE via the unlicensed band (S1400). The unlicensed band burst #1 may include multiple subframes. The start subframe (or end subframe) of the multiple subframes included in the unlicensed band burst #1 may be smaller than 1 millisecond. Each of the multiple subframes included in the unlicensed band burst #1 may include a PDSCH.

[0210] The UE may receive an unlicensed band burst #1 from the base station via the unlicensed band. The UE may transmit a HARQ response to a PDSCH included in each of the multiple subframes included in the unlicensed band burst #1 to the base station (S1410). For example, the UE may transmit a HARQ response to a PDSCH included in subframe #n of the unlicensed band to the base station via subframe #(n+4) of the licensed band. If subframe #n in the unlicensed band is a partial subframe, the UE may transmit a HARQ response to a PDSCH included in subframe #n of the unlicensed band to the base station via subframe #(n+5) of the licensed band.

[0211] The HARQ response may include ACK, NACK, DTX, ANY, etc. When the PDSCH included in subframe #n of the unlicensed band is normally received, the UE may transmit an ACK to the base station in the HARQ response. When the PDSCH included in subframe #n of the unlicensed band is not normally received, the UE may transmit a NACK to the base station in the HARQ response. When an interference signal generated by another communication node is detected during reception of the PDSCH included in subframe #n of the unlicensed band, the UE may transmit a DTX to the base station in the HARQ response. Here, DTX and ANY may be considered NACK.

[0212] The base station may receive a HARQ response to an unlicensed band burst from the UE and change the size of the contention window according to the HARQ response (S1420). Here, the HARQ response used to change the size of the contention window may be a HARQ response to a PDSCH scheduled by the base station. The base station may change the size of the contention window using a HARQ response to a PDSCH of a starting subframe (i.e., a first subframe) among the plurality of subframes included in the unlicensed band burst in the HARQ response.

[0213] For example, if the size of the starting subframe of the unlicensed band burst is 1 ms, the base station can change the size of the contention window using only the HARQ response to the PDSCH of the starting subframe of the unlicensed band burst. If the size of the starting subframe of the unlicensed band burst is less than 1 ms (i.e., the starting subframe is a partial subframe), the base station can change the size of the contention window by using the HARQ response to the PDSCH of the starting subframe (i.e., subframe #n) and the PDSCH of the second subframe (e.g., subframe #(n+1)). Here, the size of the second subframe of the unlicensed band burst can be 1 ms.

[0214] Alternatively, the base station may also change the size of the contention window using HARQ responses to PDSCHs of all subframes included in the unlicensed band burst.

[0215] Alternatively, the base station may also change the size of the contention window by using the HARQ response to the start subframe (i.e., the first subframe) and the HARQ responses to x subframes consecutive to the start subframe among the multiple subframes included in the unlicensed band burst. Here, x may be an integer of 1 or greater, and may be predetermined in the base station and the UE. Alternatively, x may be transmitted to the UE via an RRC message. Alternatively, x may be set differently for each base station (or manufacturer).

[0216] For example, if the starting subframe of the unlicensed band burst is a partial subframe, x may be 1. Therefore, the base station may change the size of the contention window using the HARQ response to the PDSCH of the starting subframe of the unlicensed band burst (e.g., subframe #n) and the PDSCH of the second subframe (e.g., subframe #(n+1)). Here, the size of the second subframe of the unlicensed band burst is 1 ms.

[0217] Figure 15 is a timing diagram illustrating HARQ responses for determining contention window size.

[0218] Reference Figure 15 The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band can be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band. The base station and the UE can support the licensed band and the unlicensed band. The base station can support carrier aggregation in the licensed band and the unlicensed band. The licensed band cell can be a primary cell (i.e., PCell) or a primary SCell (i.e., PSCell). The licensed band cell can be used for UL transmission and DL transmission. The unlicensed band cell can be used for DL ​​transmission between the base station and the UE, and can be used for communication between WLAN communication nodes.

[0219] The base station may transmit unlicensed band burst #1 to the UE in subframes #(n+1) to #(n+5) of the unlicensed band. The WLAN communication node may transmit WLAN signals in subframes #n to #(n+3) of the unlicensed band. Therefore, a collision between unlicensed band burst #1 and the WLAN signal may occur in subframes #(n+1) to #(n+3) of the unlicensed band. That is, the UE cannot receive unlicensed band burst #1 in subframes #(n+1) to #(n+3) of the unlicensed band. On the other hand, the UE can receive unlicensed band burst #1 in subframes #(n+4) and #(n+5) of the unlicensed band because no WLAN signal is detected.

[0220] In this case, the UE may transmit a HARQ response (i.e., NACK, DTX, or ANY) to the PPDU included in subframe #(n+1) of the unlicensed band to the base station through subframe #(n+5) of the licensed band. The UE may transmit a HARQ response (i.e., NACK, DTX, or ANY) to the PPDU included in subframe #(n+2) of the unlicensed band to the base station through subframe #(n+6) of the licensed band. The UE may transmit a HARQ response (i.e., NACK, DTX, or ANY) to the PPDU included in subframe #(n+3) of the unlicensed band to the base station through subframe #(n+7) of the licensed band. The UE may transmit a HARQ response (i.e., NACK, DTX, or ANY) to the PPDU included in subframe #(n+4) of the unlicensed band to the base station through subframe #(n+8) of the licensed band. The UE may transmit a HARQ response (ie, NACK, DTX, or ANY) to the PPDU included in subframe #(n+5) of the unlicensed band to the base station through subframe #(n+9) of the licensed band.

[0221] The base station may change the size of the contention window using the HARQ response to the PPDU included in the first subframe of the unlicensed band burst (i.e., subframe #(n+1)). Alternatively, the base station may change the size of the contention window using the HARQ response to the PPDU included in all subframes (i.e., subframes #(n+1) to #(n+5) included in the unlicensed band burst). Alternatively, the base station may change the size of the contention window using the HARQ response to the PPDU included in the first subframe of the unlicensed band burst (i.e., subframe #(n+1)) and the HARQ response to the PPDU included in x subframes consecutive to the first subframe.

[0222] Refer again Figure 14 , the HARQ responses to two codewords transmitted on a single PDSCH in a subframe can be considered as two independent HARQ responses. In addition, the bundled HARQ responses for y subframes can be considered as y HARQ responses. Here, y can be an integer of 2 or greater.

[0223] When the base station receives at least one NACK (or DTX, ANY) from the UE, the base station may increase the size of the contention window. On the other hand, when the base station fails to successfully receive a NACK (or DTX, ANY) from the UE, the base station may maintain, reduce, or initialize the size of the contention window.

[0224] Alternatively, the base station may also determine NACK ratio and percentage, DTX ratio and percentage, ANY ratio and percentage, 'NACK+DTX' ratio and percentage, 'NACK+ANY' ratio and percentage, 'DTX+ANY' ratio and percentage, and 'NACK+DTX+ANY' ratio and percentage.

[0225] [Equation 3]

[0226]

[0227]

[0228]

[0229]

[0230]

[0231]

[0232]

[0233]

[0234]

[0235]

[0236]

[0237]

[0238]

[0239]

[0240] If the ratio (or percentage) calculated according to Equation 3 is equal to or greater than a preset threshold, the base station may increase the size of the contention window. On the other hand, when the ratio (or percentage) calculated according to Equation 3 is less than a preset threshold, the base station may maintain, reduce, or initialize the size of the contention window. In addition, the base station and the UE may initialize (or minimize) the size of the contention window in the following cases.

[0241] For example, when a predetermined period of time T CWS-Init When no unlicensed band burst is generated during the period, the base station may initialize (or minimize) the size of the contention window. CWS-InitIt can be combined with the predetermined time T for DL ​​unlicensed band burst CWS-Init The same or different. T for UL unlicensed band bursts can be pre-determined in the base station and the UE. CWS-Init Alternatively, the T for UL unlicensed band burst may be sent to CWS-Init Transmitted to UE. If at a predetermined time T CWS-Init If no scheduling information for the UL unlicensed band burst is generated during this period, the UE may initialize (or minimize) the size of the contention window.

[0242] Here, T CWS-Init It can be the same as the Discovery Reference Signal (DRS) period. In this case, the UE can identify T based on the DRS period included in the RRC message. CWS-Init Alternatively, T CWS-Init Set to x times the DRS period. Here, x can be a natural number equal to or greater than 0. If the DRS period is 40ms and x is 2, T can be set to CWS-Init Set to 80ms. x can be predetermined in the base station and the UE. Alternatively, x can also be transmitted to the UE via an RRC message.

[0243] In addition, if the unlicensed band cell is in an inactive state, the size of the contention window may be initialized (or minimized). For example, if the state of the unlicensed band cell transitions from an inactive state to an active state, the size of the contention window may be initialized (or minimized).

[0244] At the same time, if the size of the contention window is changed according to the method described above, the base station may transmit the next unlicensed band burst (i.e., unlicensed band burst #2) using the contention window having the changed size (S1430). If the HARQ response to unlicensed band burst #1 is not successfully recognized (or demodulated) by the transmission time of unlicensed band burst #2, the base station may transmit unlicensed band burst #2 according to the contention window used for transmission of unlicensed band burst #1.

[0245] For example, when unlicensed band burst #1, unlicensed band burst #2, and unlicensed band burst #3 are sequentially transmitted, unlicensed band burst #3 may be transmitted using a contention window determined based on the HARQ responses to unlicensed band burst #1 and unlicensed band burst #2. Alternatively, unlicensed band burst #3 may be transmitted using a contention window determined based on the HARQ response to unlicensed band burst #2.

[0246] Next, an embodiment of a method for changing the size of a contention window according to collision perception information will be described. Here, the method for changing the size of a contention window can be performed in a dynamic manner.

[0247] Figure 16 is a sequence diagram illustrating an exemplary embodiment of a method for changing a contention window size according to collision awareness information.

[0248] Reference Figure 16 , the base station and UE can form a reference Figures 1 to 4 The wireless communication network described herein can support both licensed and unlicensed frequency bands. The base station can support carrier aggregation in both licensed and unlicensed frequency bands. The base station and the UE can be configured to communicate with the reference Figure 5 The communication node 500 described above is the same as or similar to the one described above. The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band can be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band. The configuration of the unlicensed band burst can be the same as that of the referenced subframes (or time slots, OFDM symbols, etc.). Figure 9 The configuration of the unlicensed band burst is the same or similar as described. The unlicensed band burst can be scheduled in a cross-carrier scheduling manner or a self-carrier scheduling manner.

[0249] The base station may transmit scheduling information (e.g., uplink grant) indicating UL resources for transmission of collision sensing information to the UE (S1600). The scheduling information indicating UL resources for transmission of collision sensing information may be referred to as 'collision scheduling information'. The collision scheduling information may be transmitted to the UE in an authorized band (e.g., a PDCCH (or EPDCCH) of an authorized band) or an unlicensed band. The base station may transmit an unlicensed band burst to the UE in an unlicensed band (S1610). Here, the collision scheduling information and the unlicensed band burst may be transmitted based on carrier aggregation.

[0250] When the starting subframe is subframe #n among the multiple subframes in the unlicensed band burst, the collision scheduling information may be transmitted to the UE via the PDCCH (or EPDCCH) of subframe #(n-1) or subframe #n of the licensed band. The PDCCH (or EPDCCH) containing the collision scheduling information may be masked (e.g., scrambled) based on the C-RNTI, the cell-common U-RNTI, or the UE-specific U-RNTI. The PDCCH (or EPDCCH) containing the collision scheduling information may be transmitted via the common search space or the UE-specific search space.

[0251] The UE may receive collision scheduling information from the base station and identify the UL resource indicated by the received collision scheduling information. In addition, the UE may also receive an unlicensed band burst from the base station. The UE may transmit collision perception information (e.g., PDSCH of the colliding subframe) about at least one colliding subframe among a plurality of subframes included in the unlicensed band burst to the base station (S1620). That is, the collision perception information may be transmitted to the base station instead of the HARQ response. The collision perception information may be transmitted via the UL resource indicated by the collision scheduling information. For example, due to Figure 15 In subframes #(n+1) to #(n+3), the unlicensed band burst #1 collides with the WLAN signal, so the UE can transmit collision perception information about subframes #(n+1) to #(n+3) of the unlicensed band burst #1.

[0252] The UE may transmit only collision perception information about the first subframe among multiple subframes included in the unlicensed band burst to the base station. Alternatively, the UE may also transmit collision perception information about the first subframe among multiple subframes included in the unlicensed band burst and x subframes consecutive to the first subframe to the base station. Here, x may be an integer 1 or greater than 1, and x may be predetermined in the base station and the UE. Alternatively, x may also be transmitted to the UE via an RRC message. The UE may transmit collision perception information about all subframes included in the unlicensed band burst to the base station. Alternatively, even if there are colliding subframes, the UE does not transmit collision perception information about the colliding subframes to the base station.

[0253] At the same time, a specific bit, a specific second sequence signal, or other information may be used as collision perception information. When a PDCCH (or EPDCCH) containing collision scheduling information is masked (e.g., scrambled) according to a UE-specific U-RNTI, the UE indicated by the UE-specific U-RNTI may transmit the collision perception information. Alternatively, when a PDCCH (or EPDCCH) containing collision scheduling information is masked (e.g., scrambled) according to a cell-common U-RNTI, the UE indicated by the cell-common U-RNTI may transmit the collision perception information.

[0254] Meanwhile, when the base station does not transmit collision scheduling information, the UE may transmit collision sensing information through a subframe of the licensed band corresponding to a first subframe (or a second subframe) of a plurality of subframes included in the unlicensed band.

[0255] Figure 17 is a timing diagram illustrating a first exemplary embodiment of a method for transmitting collision perception information.

[0256] Reference Figure 17The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band can be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band. The base station and the UE can support the licensed band and the unlicensed band. The base station can support carrier aggregation in the licensed band and the unlicensed band. The licensed band cell can be a primary cell (i.e., PCell) or a primary SCell (i.e., PSCell). The licensed band cell can be used for UL transmission and DL transmission. The unlicensed band cell can be used for DL ​​transmission between the base station and the UE, and can be used for communication between WLAN communication nodes.

[0257] The base station may transmit an unlicensed band burst to the UE in subframes #(n+1) to #(n+5) of the unlicensed band. In addition, the base station may also transmit collision scheduling information for the unlicensed band burst to the UE in subframe (n+1) of the licensed band. The collision scheduling information may be transmitted via a PDCCH (or EPDCCH) masked (e.g., scrambled) by the cell-common U-RNTI. The PDCCH (or EPDCCH) may be transmitted via a common search space or a search space specifically for the UE. The UE indicated by the cell-common U-RNTI may identify the collision scheduling information by receiving the PDCCH (or EPDCCH). The collision scheduling information may indicate the UL resources included in subframe #(n+4) of the licensed band. The collision between the unlicensed band burst and the WLAN signal occurs in subframes #(n+1) and #(n+2) of the unlicensed band, so the UE may transmit collision perception information about the unlicensed band to the base station via subframe #(n+4) of the licensed band.

[0258] Figure 18 is a timing diagram illustrating a second exemplary embodiment of a method for transmitting collision perception information.

[0259] Reference Figure 18 The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band can be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band. The base station and the UE can support the licensed band and the unlicensed band. The base station can support carrier aggregation in the licensed band and the unlicensed band. The licensed band cell can be a primary cell (i.e., PCell) or a primary SCell (i.e., PSCell). The licensed band cell can be used for UL transmission and DL transmission. The unlicensed band cell can be used for DL ​​transmission between the base station and the UE, and can be used for communication between WLAN communication nodes.

[0260] The base station may transmit unlicensed band burst #1 to the UE in subframes #(n+1) to #(n+5) of the unlicensed band. In addition, the base station may also transmit collision scheduling information for unlicensed band burst #1 to the UE in subframe (n+1) of the licensed band. The collision scheduling information may be transmitted via a PDCCH (or EPDCCH) masked (e.g., scrambled) with a U-RNTI specifically for the UE. The PDCCH (or EPDCCH) may be transmitted via a search space specifically for the UE. The UE indicated by the U-RNTI specifically for the UE may identify the collision scheduling information by receiving the PDCCH (or EPDCCH). The collision scheduling information may indicate the UL resources included in subframe #(n+4) of the licensed band. The collision between the unlicensed band burst and the WLAN signal occurs in subframes #(n+1) to #(n+3) of the unlicensed band, and thus, the UE may transmit collision perception information about the unlicensed band #1 to the base station via subframe #(n+4) of the licensed band.

[0261] The base station may transmit the unlicensed band burst #2 to the UE in subframes #(n+8) and #(n+9) of the unlicensed band. In addition, the base station may also transmit collision scheduling information for the unlicensed band burst #2 to the UE in subframe #(n+7) of the licensed band (i.e., a subframe preceding the first subframe in the multiple subframes included in the unlicensed band burst #2). The collision scheduling information may be transmitted via a PDCCH (or EPDCCH) masked (e.g., scrambled) with a U-RNTI specifically for the UE. The PDCCH (or EPDCCH) may be transmitted via a search space specifically for the UE. The UE indicated by the U-RNTI specifically for the UE may identify the collision scheduling information by receiving the PDCCH (or EPDCCH). The collision scheduling information may indicate the UL resources included in subframe #(n+10) of the licensed band. The collision between the unlicensed band burst #2 and the WLAN signal occurs in subframes #(n+8) and #(n+9) of the unlicensed band. Therefore, the UE can transmit the collision perception information about the unlicensed band burst #2 to the base station through subframe #(n+10) of the licensed band.

[0262] The base station may transmit unlicensed band burst #3 to the UE in subframes #(n+14) and #(n+15) of the unlicensed band. In addition, the base station may also transmit collision scheduling information for unlicensed band burst #3 to the UE in subframes #(n+12) and #(n+13) of the licensed band. The collision scheduling information may be transmitted via a PDCCH (or EPDCCH) masked (e.g., scrambled) with a U-RNTI specifically for the UE. The PDCCH (or EPDCCH) may be transmitted via a search space specifically for the UE. The UE indicated by the U-RNTI specifically for the UE may identify the collision scheduling information by receiving the PDCCH (or EPDCCH). The collision scheduling information transmitted via subframe #(n+12) may indicate the UL resources included in subframe #(n+15) of the licensed band. The collision scheduling information transmitted via subframe #(n+13) may indicate the UL resources included in subframe #(n+16) of the licensed band. The collision between the unlicensed band burst #3 and the WLAN signal occurs in subframes #(n+14) and #(n+15) of the unlicensed band. Therefore, the UE can transmit the collision perception information about the unlicensed band burst #3 to the base station through the subframe #(n+16) indicated by the collision scheduling information included in the previous subframe of the first subframe among the multiple subframes in the unlicensed band burst #3 (i.e., subframe #(n+13)).

[0263] Refer again Figure 16 , the base station may receive collision perception information from the UE using the UL resources indicated by the collision scheduling information. The base station may change the size of the contention window based on the collision perception information (S1630). For example, if at least one collision perception information is received, the base station may increase the size of the contention window. On the other hand, if no collision perception information is received, the base station may maintain, reduce, or initialize the size of the contention window. Here, the base station may change the size of the contention window while considering only the collision perception information for the first subframe among the multiple subframes included in the unlicensed band burst. Alternatively, the base station may determine the size of the contention window while considering the collision perception information for the first subframe among the multiple subframes included in the unlicensed band burst and the collision perception information for x subframes consecutive to the first subframe. Here, x may be an integer of 1 or greater, and may be predetermined in the base station and the UE. Alternatively, x may be transmitted to the UE via an RRC message. Alternatively, the base station may change the size of the contention window while considering the collision perception information for all subframes included in the unlicensed band burst.

[0264] The base station may perform an LBT operation based on the changed contention window (S1640). For example, the base station may select a backoff value in the contention window and check the channel condition within a time corresponding to the selected backoff value. If the channel condition is idle, the base station may transmit a signal on the unlicensed band (e.g., an unlicensed band burst). The base station may also notify the UE of the changed size of the contention window.

[0265] Next, another embodiment of a method for changing the size of a contention window according to collision perception information will be described. Here, the method for changing the size of a contention window may be performed in a semi-static manner.

[0266] Figure 19 is a sequence diagram illustrating another exemplary embodiment of a method for changing a contention window size according to collision awareness information.

[0267] Reference Figure 19 , the base station and UE can form a reference Figures 1 to 4 The wireless communication network described herein can support both licensed and unlicensed frequency bands. The base station can support carrier aggregation in both licensed and unlicensed frequency bands. The base station and the UE can be configured to communicate with the reference Figure 5 The communication node 500 described above is the same as or similar to the one described above. The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band can be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band. The configuration of the unlicensed band burst can be the same as that of the referenced subframes (or time slots, OFDM symbols, etc.). Figure 9 The configuration of the unlicensed band burst is the same or similar as described. The unlicensed band burst can be scheduled in a cross-carrier scheduling manner or a self-carrier scheduling manner.

[0268] The base station may transmit an RRC message including collision scheduling information to the UE (S1900). The RRC message may be transmitted to the UE via an authorized band or an unauthorized band. The collision scheduling information may indicate the PUCCH of the authorized band. Collision perception information for unauthorized band bursts may be transmitted to the base station via the PUCCH indicated by the collision scheduling information (hereinafter referred to as 'collision PUCCH'). In addition, the HARQ response to the unauthorized band burst may also be transmitted to the base station via the collision PUCCH. The collision PUCCH may be configured in all subframes of the authorized band. Alternatively, the collision PUCCH may also be configured according to a predetermined period. The predetermined period for the collision PUCCH may be transmitted to the UE via an RRC message.

[0269] Collision PUCCH can be configured for each UE on different UL resources. In this case, the UL resources can be set based on the UE's radio resource management (RRM) and other related capabilities and information. Alternatively, collision PUCCH can be configured for each unlicensed band cell on different UL resources. Alternatively, collision PUCCH can be configured in a predetermined UL resource.

[0270] The UE may receive an RRC message from a base station and identify a collision PUCCH indicated by collision scheduling information included in the RRC message. The base station may transmit an unlicensed band burst to the UE in an unlicensed band (S1910). The UE may receive an unlicensed band burst from the base station and may identify at least one colliding subframe among a plurality of subframes included in the unlicensed band burst. The UE may transmit collision perception information for at least one colliding subframe to the base station via the collision PUCCH (S1920). Here, a HARQ response (e.g., NACK, DTX, ANY) may be transmitted to the base station via the collision PUCCH instead of the collision perception information.

[0271] The UE may transmit collision perception information only for the first subframe of multiple subframes included in the unlicensed band burst to the base station through the collision PUCCH. Alternatively, the UE may also transmit collision perception information for the first subframe of multiple subframes included in the unlicensed band burst and collision perception information for x subframes consecutive to the first subframe. Here, x may be an integer 1 or greater than 1, and x may be preset in the base station and the UE. Alternatively, x may also be transmitted to the UE via an RRC message. Alternatively, the UE may also transmit collision perception information for all subframes included in the unlicensed band burst to the base station through the collision PUCCH.

[0272] At the same time, when the collision PUCCH is configured in different UL resources for each UE, information (e.g., bits, sequences, etc.) for distinguishing the unlicensed band cells in which the colliding subframes are located can be pre-configured. Alternatively, the information for distinguishing the unlicensed band cells in which the colliding subframes are located can also be transmitted to the UE via an RRC message or DCI (e.g., CIF). In this case, the UE can transmit collision perception information to the base station through the collision PUCCH based on the information for distinguishing the unlicensed band cells in which the colliding subframes are located.

[0273] When a collision PUCCH is configured in different UL resources for each unlicensed band cell (or when a collision PUCCH is configured in a predetermined UL resource), information (e.g., bits, sequences, etc.) for distinguishing UEs transmitting collision awareness information may be preconfigured. Alternatively, information for distinguishing UEs transmitting collision awareness information may be transmitted via an RRC message or DCI (e.g., CIF). In this case, the UE may transmit the collision awareness information to the base station via the collision PUCCH based on the information for distinguishing UEs transmitting collision awareness information.

[0274] Figure 20 is a timing diagram illustrating a third exemplary embodiment of a method for transmitting collision perception information.

[0275] Reference Figure 20 The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band can be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band. The base station and the UE can support the licensed band and the unlicensed band. The base station can support carrier aggregation in the licensed band and the unlicensed band. The licensed band cell can be a primary cell (i.e., PCell) or a primary SCell (i.e., PSCell). The licensed band cell can be used for UL transmission and DL transmission. The unlicensed band cell can be used for DL ​​transmission between the base station and the UE, and can be used for communication between WLAN communication nodes.

[0276] In the licensed band, a collision PUCCH can be configured every 4 subframes. For example, the collision PUCCH can be divided into subframe #n, subframe #(n+4), subframe #(n+8), subframe #(n+12), subframe #(n+16), and others. The base station can transmit the unlicensed band burst #1 to the UE in subframes #(n+1) and #(n+2) of the unlicensed band. In subframes #(n+1) and #(n+2) of the unlicensed band, the unlicensed band burst #1 may collide with the WLAN signal. Therefore, the UE can transmit collision perception information for the unlicensed band burst #1 to the base station via the collision PUCCH included in subframe #(n+4) of the licensed band. In this case, the UE can transmit collision perception information for only the first subframe (i.e., subframe #(n+1)) of the multiple subframes included in the unlicensed band burst #1 to the base station through the collision PUCCH included in subframe #(n+4) of the licensed band.

[0277] The base station may transmit unlicensed band burst #2 to the UE in subframes #(n+5) to #(n+8) of the unlicensed band. In subframes #(n+5) to #(n+7) of the unlicensed band, unlicensed band burst #2 may collide with the WLAN signal. Therefore, the UE may transmit collision perception information for unlicensed band burst #2 to the base station via the collision PUCCH included in subframe #(n+8) of the licensed band. In this case, the UE may transmit collision perception information only for the first subframe (i.e., subframe #(n+5)) of the multiple subframes included in the unlicensed band burst #2 to the base station via the collision PUCCH included in subframe #(n+8) of the licensed band.

[0278] The base station may transmit unlicensed band burst #3 to the UE in subframes #(n+11) to #(n+16) of the unlicensed band. In subframes #(n+11) to #(n+13) of the unlicensed band, unlicensed band burst #3 may collide with the WLAN signal. Therefore, the UE may transmit collision perception information for unlicensed band burst #3 to the base station via the collision PUCCH included in subframe #(n+16) of the licensed band. In this case, the UE may transmit collision perception information only for the first subframe (i.e., subframe #(n+11)) of the multiple subframes included in the unlicensed band burst #3 to the base station via the collision PUCCH included in subframe #(n+16) of the licensed band.

[0279] Figure 21 is a timing diagram illustrating a fourth exemplary embodiment of a method for transmitting collision perception information.

[0280] Reference Figure 21 The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band can be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band. The base station and the UE can support the licensed band and the unlicensed band. The base station can support carrier aggregation in the licensed band and the unlicensed band. The licensed band cell can be a primary cell (i.e., PCell) or a primary SCell (i.e., PSCell). The licensed band cell can be used for UL transmission and DL transmission. The unlicensed band cell can be used for DL ​​transmission between the base station and the UE, and can be used for communication between WLAN communication nodes.

[0281] In the licensed band, a collision PUCCH can be configured every 3 subframes. For example, the collision PUCCH can be divided into subframe #(n+2), subframe #(n+5), subframe #(n+8), subframe #(n+11), subframe #(n+14), and others. The base station can transmit the unlicensed band burst #1 to the UE in subframes #(n+1) and #(n+2) of the unlicensed band. In subframes #(n+1) and #(n+2) of the unlicensed band, the unlicensed band burst #1 may collide with the WLAN signal. Therefore, the UE can transmit collision perception information for each of the collided subframe #(n+1) and the collided subframe #(n+2) in multiple subframes included in the unlicensed band burst #1 to the base station through the collision PUCCH included in subframe #(n+5) of the licensed band.

[0282] The base station may transmit unlicensed band burst #2 to the UE in subframes #(n+5) to #(n+8) of the unlicensed band. In subframes #(n+6) and #(n+7) of the unlicensed band, unlicensed band burst #2 may collide with the WLAN signal. Therefore, the UE may transmit collision perception information regarding subframe #(n+6) that collides among multiple subframes included in unlicensed band burst #2 to the base station via a collision PUCCH included in subframe #(n+8) of the licensed band. In addition, the UE may transmit collision perception information regarding subframe #(n+7) that collides among multiple subframes included in unlicensed band burst #2 to the base station via a collision PUCCH included in subframe #(n+11) of the licensed band.

[0283] The base station may transmit unlicensed band burst #3 to the UE in subframes #(n+11) to #(n+16) of the unlicensed band. Unlicensed band burst #3 may collide with the WLAN signal in subframes #(n+11) and #(n+12) of the unlicensed band. Therefore, the UE may transmit collision awareness information for each of the collided subframes #(n+11) and #(n+12) among the multiple subframes included in unlicensed band burst #3 to the base station via a collision PUCCH included in subframe #(n+14) of the licensed band.

[0284] Refer again Figure 19, the base station can receive collision perception information for the UE through the collision PUCCH. In the case where the collision PUCCH is configured in different UL resources for each UE, the base station can identify the unlicensed band cell in which the colliding subframe is located by using information for distinguishing the unlicensed band cell in which the colliding subframe is located. Alternatively, when the collision PUCCH is configured in different UL resources for each unlicensed band cell (or in the case where the collision PUCCH is configured in a predetermined UL resource), the base station can identify the UE that transmits the collision perception information by using information for distinguishing the UE that transmits the collision perception information.

[0285] The base station may change the size of the contention window based on the collision perception information (S1930). For example, if at least one collision perception information is received, the base station may increase the size of the contention window. On the other hand, if no collision perception information is received, the base station may maintain, reduce, or initialize the size of the contention window. Here, the base station may change the size of the contention window while considering only the collision perception information for the first subframe of multiple subframes included in the unlicensed band burst. Alternatively, the base station may determine the size of the contention window while considering the collision perception information for the first subframe of multiple subframes included in the unlicensed band burst and the collision perception information for x subframes consecutive to the first subframe. Here, x may be an integer of 1 or greater, and x may be pre-set in the base station and the UE. Alternatively, x may also be transmitted to the UE via an RRC message. Alternatively, the base station may also change the size of the contention window while considering the collision perception information for all subframes included in the unlicensed band burst.

[0286] The base station may perform an LBT operation based on the changed contention window (S1940). For example, the base station may select a backoff value in the changed contention window and check the channel condition within a time corresponding to the selected backoff value. If the channel condition is idle, the base station may transmit a signal on the unlicensed band (e.g., an unlicensed band burst). The base station may also notify the UE of the changed size of the contention window.

[0287] Next, a method of changing the size of the contention window according to the channel occupancy status in a dynamic manner will be described.

[0288] Figure 22 is a sequence diagram illustrating a third exemplary embodiment of a method for changing a contention window size according to collision awareness information.

[0289] Reference Figure 22 , the base station and UE can form a reference Figures 1 to 4The wireless communication network described herein can support both licensed and unlicensed frequency bands. The base station can support carrier aggregation in both licensed and unlicensed frequency bands. The base station and the UE can be configured to communicate with the reference Figure 5 The communication node 500 described above is the same as or similar to the one described above. The timing of the subframes (or time slots, OFDM symbols, etc.) of the licensed band can be the same as the timing of the subframes (or time slots, OFDM symbols, etc.) of the unlicensed band. The configuration of the unlicensed band burst can be the same as that of the referenced subframes (or time slots, OFDM symbols, etc.). Figure 9 The configuration of the unlicensed band burst is the same or similar as described. The unlicensed band burst can be scheduled in a cross-carrier scheduling manner or a self-carrier scheduling manner.

[0290] The base station may measure the channel occupancy status for a predetermined period of time (S2200). The predetermined period of time may include the time between consecutive unlicensed band bursts (e.g., the time from the end of unlicensed band burst #n to the start of unlicensed band burst #(n+1)), the time from when the backoff value is selected to when the backoff value becomes 0, the time from when the backoff value is selected to when transmission of the unlicensed band burst begins, etc. The channel occupancy status may indicate the number of occupied channels, the number of occupied time slots, and the like.

[0291] Figure 23 is a timing diagram illustrating the channel occupancy status of the unlicensed band.

[0292] Reference Figure 23 The predetermined period of time may be the time from the end time t0 of unlicensed band burst #n to the start time t1 of unlicensed band burst #(n+1). That is, the predetermined period of time may be a time corresponding to 15 time slots. The number of channels occupied during the predetermined period of time may be 3. The number of time slots occupied during the predetermined period of time may be 10.

[0293] Refer again Figure 22 , the base station may change the size of the contention window according to the channel occupancy status (S2210). For example, when the number of occupied channels is greater than or equal to a predetermined threshold, the base station may increase the size of the contention window, and when the number of occupied channels is less than the predetermined threshold, the base station may maintain, reduce, or initialize the size of the contention window. Alternatively, when the number (or ratio) of occupied time slots is greater than or equal to a predetermined threshold, the base station may increase the size of the contention window, and when the number (or ratio) of occupied time slots is less than the predetermined threshold, the base station may maintain, reduce, or initialize the size of the contention window.

[0294] Alternatively, the base station may also change the size of the contention window based on the amount of change between the current channel occupancy state (e.g., the number of occupied channels, the number of occupied time slots, the occupied time slot ratio) and the previous occupancy state (e.g., the number of occupied channels, the number of occupied time slots, the occupied time slot ratio). When unlicensed band burst #(n-1), unlicensed band burst #n, and unlicensed band burst #(n+1) are sequentially transmitted, the previous channel occupancy state may be measured during the time between the end of unlicensed band burst #(n-1) and the start of unlicensed band burst #n. The current channel occupancy state may be measured during the time between the end of unlicensed band burst #n and the start of unlicensed band burst #(n+1). The amount of change between the current channel occupancy state and the previous channel occupancy state may be calculated according to the following equation 4.

[0295] [Equation 4]

[0296] ΔCU,.i=CU i -CU i-1

[0297] Here, ΔCU,.i may indicate the amount of change, CU i Can indicate the current channel occupancy status, CU i-1 The previous channel occupancy status may be indicated. If ΔCU,.i is equal to or greater than a preset threshold, the base station may increase the size of the contention window. If ΔCU,.i is less than the preset threshold, the base station may maintain, reduce, or initialize the size of the contention window. Alternatively, the size of the contention window corresponding to the channel occupancy status may also be preset, as shown in Table 4 below.

[0298] [Table 4]

[0299]

[0300]

[0301] TH may indicate a predetermined threshold. TH0 may indicate the minimum threshold among the predetermined thresholds. TH4 may indicate the maximum threshold among the predetermined thresholds. That is, the predetermined thresholds may be increased in the order of TH0, TH1, TH2, TH3, and TH4. CWS may indicate the size of the contention window. CWS0 may indicate the size of the minimum contention window, while CWS3 may indicate the size of the maximum contention window. That is, the size of the contention window may be increased in the order of CWS0, CWS1, CWS2, and CWS3. The correspondence between the channel occupancy status and the contention window is not limited to that described in Table 4 and may be set differently.

[0302] The base station can change the size of the contention window according to Table 4. For example, if the channel occupancy state corresponds to 'TH1 < CU ≤ TH2', the base station can change the size of the contention window to CWS1. Alternatively, if the channel occupancy state corresponds to 'TH3 < CU ≤ TH4', the base station can change the size of the contention window to CWS3.

[0303] Meanwhile, the base station can determine the size of the contention window for uplink transmission and the size of the contention window for downlink transmission according to the channel occupancy state. The size of the contention window for uplink transmission can be smaller than the size of the contention window for downlink transmission. The size of the contention window for uplink transmission can be indicated as a ratio of the size of the contention window for downlink transmission.

[0304] The base station can transmit information related to the contention window (S2220) to the UE. Information related to the contention window (e.g., information related to the contention window for uplink transmission) can include the size of the contention window, the selected backoff value in the contention window, and others. The information related to the contention window can be transmitted to the UE via an RRC message or DCI.

[0305] Transmission of information related to contention window based on RRC message

[0306] The base station can transmit an RRC message including information indicating the size of the contention window to the UE. For example, the information indicating the size of the contention window can be transmitted in a broadcast manner by a PDCCH (or EPDCCH) masked (e.g., scrambled) according to the U-RNTI or SI-RNTI. Additionally, the base station can generate a DCI including the selected backoff value in the contention window, uplink grant, and others, and can transmit the generated DCI to the UE. Here, the UE can receive information about the contention window, backoff value, uplink grant, etc. from the base station. The UE can identify the uplink resources indicated by the uplink grant, and can transmit signals through the uplink resources by performing an LBT operation according to the contention window and the backoff value.

[0307] DCI-based transmission of information related to the contention window

[0308] The base station can generate a DCI including information indicating the size of the contention window, backoff value, uplink grant, and others, and can transmit the generated DCI to the UE. Here, the UE can receive information about the contention window, backoff value, uplink grant, etc. from the base station. The UE can identify the uplink resources indicated by the uplink grant, and can transmit signals through the uplink resources by performing an LBT operation according to the contention window and the backoff value.

[0309] At the same time, the base station can perform LBT operations based on the changed contention window. For example, the base station can select a backoff value within the changed contention window and check the channel status within a time corresponding to the selected backoff value. If the channel status is idle, the base station can transmit signals via the unlicensed band.

[0310] Hereinafter, an embodiment of a method of changing the size of a contention window when carrier aggregation is applied in an unlicensed band (eg, when carrier #1, carrier #2, and carrier #3 are aggregated in an unlicensed band) will be described.

[0311] The communication node may perform an LBT operation on carrier #1. Alternatively, the communication node may also perform a CCA operation on carriers #2 and #3 for a predetermined period of time before the signal transmission time (e.g., the time when the backoff value becomes 0 due to the LBT operation on carrier #1). Here, when the received signal strength on carrier #1 is equal to or greater than a preset threshold, the communication node performing the LBT operation may determine that carrier #1 is in a busy state. When the received signal strength on carrier #1 is less than a preset threshold, the communication node performing the LBT operation may determine that carrier #1 is in an idle state.

[0312] When the received signal strength in carrier #2 (or carrier #3) is equal to or greater than a preset threshold, the communication node performing the CCA operation can determine that carrier #2 (or carrier #3) is in a busy state. When the received signal strength in carrier #2 (or carrier #3) is less than a preset threshold, the communication node performing the CCA operation can determine that carrier #2 (or carrier #3) is in an idle state. Here, the preset threshold for LBT operation can be the same as or different from the preset threshold for CCA operation. The preset threshold can be transmitted to the communication node via an RRC message. If the CCA operation determines that the state of carrier #2 is busy, unlicensed band bursts cannot be transmitted through carrier #2. In this case, the communication node can transmit unlicensed band bursts through carrier #1 and carrier #3.

[0313] Meanwhile, when the LBT operation determines that the state of carrier #1 is busy, the communication node can stop the transmission attempt in all carriers (e.g., carrier #1, carrier #2, and carrier #3). In this case, the communication node can freeze the backoff value according to the LBT operation and freeze the backoff value according to the CCA operation.

[0314] Alternatively, when it is determined that carrier #1 is busy due to an LBT operation, the communication node may determine the status of a different carrier (e.g., carrier #3) based on the backoff value corresponding to the LBT operation on carrier #1. Here, a different carrier may be selected from the multiple carriers comprising the unlicensed band based on received signal strength (e.g., received signal strength indication (RSSI)), channel occupancy status, channel state information, or other factors. Alternatively, different carriers may be set based on a predetermined priority of the carriers. The predetermined priority of the carriers may be transmitted to the communication node via an RRC message. If the status of the different carrier is idle, the communication node may transmit the unlicensed band burst on the different carrier. That is, the unlicensed band burst may be transmitted on a different carrier (e.g., carrier #2, carrier #3) instead of carrier #1.

[0315] At the same time, the communication node can transmit an unlicensed band burst based on carrier aggregation of carrier #1 determined to be idle by the LBT operation and carrier #2 (or carrier #3) determined to be idle by the CCA operation. If it is determined that a collision between an unlicensed band burst and another signal has occurred, the communication node can change the size of the contention window for the next unlicensed band burst transmission. For example, the communication node can change the size of the contention window based on the HARQ response (or collision perception information) to the first subframe (or the HARQ response to the first subframe in multiple subframes included in the unlicensed band burst and the x subframes consecutive to the first subframe, where x is an integer of 1 or greater than 1). Here, the HARQ response for changing the size of the contention window can be at least one of NACK, DTX, and ANY.

[0316] That is, the communication nodes can refer to Figure 14 The method of changing the size of the contention window described, referring to Figure 16 The method of changing the size of the contention window described, or referring to Figure 19 The described method of changing the size of the contention window changes the size of the contention window.

[0317] Hereinafter, another embodiment of a method of changing the size of a contention window when carrier aggregation is applied in an unlicensed band (eg, when carrier #1, carrier #2, and carrier #3 are aggregated in an unlicensed band) will be described.

[0318] A communication node may perform LBT operations in each of a plurality of carriers (e.g., carrier #1, carrier #2) in an unlicensed band. The backoff value for the LBT operation in carrier #1 may be different from the backoff value for the LBT operation in carrier #2. In this case, the transmission time in carrier #1 may be different from the transmission time in carrier #2. For example, if the transmission time in carrier #1 is earlier than the transmission time in carrier #2, the transmission time in carrier #1 may be delayed so that the transmission time in carrier #1 becomes equal to the transmission time in carrier #2. On the other hand, when carrier #1 is far away from carrier #2 in the frequency domain, carrier #1 may be operated independently of carrier #2. In this case, no delay in transmission time may be applied. Therefore, an unlicensed band burst may be transmitted at the transmission time of carrier #1, and an unlicensed band burst may be transmitted at the transmission time of carrier #2 regardless of the transmission in carrier #1.

[0319] At the same time, a collision between an unlicensed band burst transmitted from the plurality of carriers and another signal may occur. If a collision between an unlicensed band burst and another signal is determined to have occurred, the communication node may change the size of a contention window for the next transmission of the unlicensed band burst. The size of the contention window may be changed independently for each carrier or equally for each carrier.

[0320] Method for independently changing the size of the contention window for each carrier

[0321] The communication node may change the size of the contention window based on a HARQ response (or collision awareness information) to a first subframe (or the first subframe and x subframes consecutive to the first subframe, where x is an integer equal to or greater than 1) among the multiple subframes included in the unlicensed band burst transmitted from carrier #1. Furthermore, the communication node may also change the size of the contention window based on a HARQ response (or collision awareness information) to a first subframe (or the first subframe and x subframes consecutive to the first subframe, where x is an integer equal to or greater than 1) among the multiple subframes included in the unlicensed band burst transmitted from carrier #2.

[0322] Here, the size of the contention window for carrier #1 may be changed independently of the size of the contention window for carrier #2. Thus, the size of the contention window for carrier #1 may be different from the size of the contention window for carrier #2. The HARQ response for adjusting the contention window size may be at least one of NACK, DTX, and ANY. The communication node may be configured to adjust the contention window size according to the reference Figure 14 The method of changing the size of the contention window described, referring to Figure 16 The method of changing the size of the contention window described, or referring to Figure 19The described method of changing the size of the contention window changes the size of the contention window.

[0323] Method for changing the size of contention window equally for all carriers

[0324] The communication node may change the size of the contention window based on a HARQ response (or collision awareness information) to a first subframe (or the first subframe and x subframes consecutive to the first subframe, where x is an integer equal to or greater than 1) of a plurality of subframes included in an unlicensed band burst transmitted from at least one carrier. The changed contention window may be applied to all carriers in the unlicensed band (e.g., carrier #1, carrier #2, and carrier #3). Here, the HARQ response for changing the contention window size may be at least one of NACK, DTX, and ANY. The communication node may be configured to change the size of the contention window based on a reference signal. Figure 14 The method of changing the size of the contention window described, referring to Figure 16 The method of changing the size of the contention window described, or referring to Figure 19 The described method of changing the size of the contention window changes the size of the contention window.

[0325] Next, a method of changing the size of the contention window according to the priority level of data will be described.

[0326] The CCA operation can be classified into an initial CCA (hereinafter referred to as 'I_CCA') operation and an extended CCA (hereinafter referred to as 'E_CCA') operation. A communication node can transmit an unlicensed band burst according to the I_CCA operation and the E_CCA operation. The I_CCA operation can be performed when the first unlicensed band burst is transmitted. For example, when the channel condition of the unlicensed band is idle for 25 μs, the communication node can transmit the unlicensed band burst. 25 μs can be the sum of the length of the short interframe space (SIFS) defined in the WLAN standard (i.e., 16 μs) and the length of one time slot (i.e., 9 μs).

[0327] If the channel condition of the unlicensed band is determined to be busy by the I_CCA operation, the communication node can identify the channel condition of the unlicensed band according to the E_CCA operation for the unlicensed band burst transmission. In addition, when the first unlicensed band burst is transmitted, the communication node can identify the channel condition of the unlicensed band according to the E_CCA operation for the next unlicensed band burst transmission. The time during which the E_CCA operation is performed can be called a delay period (DP). The DP can be the sum of 16 μs and the length of k time slots (where k is an integer greater than 1). k can be determined based on the priority level of the data shown in Table 5 below.

[0328] [Table 5]

[0329]

[0330] Priority level 1 may indicate data having the highest priority among data. On the other hand, priority level 4 may indicate data having the lowest priority among data. Here, priority level 3 may indicate data to be transmitted in a best-effort manner.

[0331] Data with different priority levels (e.g., data to be transmitted in a best-effort manner, Voice over Internet Protocol (VoIP) data, etc.) can be transmitted via one unlicensed band burst. The maximum occupied length of the unlicensed band burst can be determined based on the priority level of the data included in the unlicensed band burst. For example, if the unlicensed band burst includes data with a priority level of 1 and data with a priority level of 4, the maximum occupied length of the unlicensed band burst can be determined based on the priority level of 1 (e.g., a relatively high priority level). Alternatively, if the unlicensed band burst includes data with a priority level of 1 and data with a priority level of 4, the maximum occupied length of the unlicensed band burst can also be determined based on the priority level of 4 (e.g., a relatively low priority level).

[0332] In addition, the contention window for transmitting an unlicensed band burst may also be determined based on the priority level of the data contained in the unlicensed band burst. For example, if the unlicensed band burst includes data with a priority level of 1 and data with a priority level of 4, the contention window for transmitting the unlicensed band burst may be determined based on the priority level of 1 (e.g., a relatively high priority level). Alternatively, if the unlicensed band burst includes data with a priority level of 1 and data with a priority level of 4, the contention window for transmitting the unlicensed band burst may also be determined based on the priority level of 4 (e.g., a relatively low priority level).

[0333] At the same time, according to the reference Figure 14 The described method, reference Figure 16 The method described, or reference Figure 19 When the described method changes the size of the contention window, the size of the contention window may be changed based on the priority level of data included in the unlicensed band burst. For example, the size of the contention window may be changed for priority level 1 (or 2, 3, or 4) based on a HARQ response (or collision awareness information) to an unlicensed band burst containing data with priority level 1 (or 2, 3, or 4).

[0334] Alternatively, when the contention window size is changed based on the HARQ response (or collision awareness information) to the unlicensed band burst, the changed contention window size can be used for all priority levels regardless of the priority level of the data included in the unlicensed band burst. In this case, since the maximum size of the contention window is different for each priority level, the contention window size can be changed while taking the maximum size of the contention window into consideration.

[0335] For example, if the size of the contention window changed according to the HARQ response (or collision awareness information) is less than or equal to the maximum size of the contention window, the contention window changed according to the HARQ response (or collision awareness information) can be used. If the size of the contention window changed according to the HARQ response (or collision awareness information) is equal to or greater than the maximum size of the contention window, the maximum size of the contention window can be used. In this case, if the maximum size of the contention window is used within a predetermined period of time, the minimum size of the contention window can be used for the transmission of the next unlicensed band burst. Here, the predetermined period of time can be transmitted to the communication node via an RRC message.

[0336] The embodiments of the present disclosure can be implemented as program instructions that can be executed by various computers and can be recorded on computer-readable media. The computer-readable media can include program instructions, data files, data structures, or combinations thereof. The program instructions recorded on the computer-readable media can be designed and configured specifically for the present disclosure, or these program instructions recorded on the computer-readable media can be commonly known and commonly available to those skilled in the art of computer software.

[0337] Examples of computer-readable media may include hardware devices such as ROM, RAM, and flash memory, which are specifically configured to store and execute program instructions. Examples of program instructions include machine code (e.g., machine code generated by a compiler) and high-level language code that can be executed by a computer using an interpreter. The above exemplary hardware devices can be configured to operate as at least one software module to perform embodiments of the present disclosure, and vice versa.

[0338] Although the embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the scope of the disclosure.

Claims

1. A method for operating a user equipment UE in a communication network, comprising: receiving a plurality of physical downlink shared channels (PDSCHs) from a base station in consecutive subframes of an unlicensed frequency band; Transmitting multiple hybrid automatic repeat request HARQ responses to multiple PDSCHs to the base station; as well as receiving information indicating a size of a contention window CW from the base station, wherein the size of the contention window CW is determined based on one or more HARQ responses of a plurality of HARQ responses, The number of one or more HARQ responses used to determine the size of the contention window CW is determined based on the size of the first subframe belonging to the consecutive subframes, When the size of the first subframe is 1 millisecond, the number of the one or more HARQ responses is 1, and When the size of the first subframe is less than 1 millisecond, the number of the one or more HARQ responses is 2.

2. The operating method according to claim 1, wherein: When the size of the first subframe is 1 millisecond, the size of the contention window CW is determined using a first HARQ response among the multiple HARQ responses, and the first HARQ response is a HARQ response to a first PDSCH that has been transmitted in the first subframe.

3. The operating method according to claim 1, wherein: When the size of the first subframe is less than 1 millisecond, the size of the contention window CW is determined using a first HARQ response and a second HARQ response among the multiple HARQ responses, wherein the first HARQ response is a HARQ response for a first PDSCH that has been transmitted in the first subframe, and the second HARQ response is a HARQ response for a second PDSCH that has been transmitted in a second subframe belonging to the continuous subframes.

4. The operating method according to claim 1, wherein: When each of the plurality of PDSCHs includes two codewords, two HARQ responses for the two codewords are used.

5. The operating method according to claim 1, wherein: Each of the plurality of HARQ responses is a bundled HARQ response for a plurality of subframes in the consecutive subframes.

6. The operating method according to claim 1, wherein: When a negative acknowledgement (NACK) ratio of the one or more HARQ responses is equal to or greater than a predetermined threshold, the size of the contention window (CW) is increased.

7. The operating method according to claim 1, wherein: When a negative acknowledgement (NACK) ratio of the one or more HARQ responses is less than a predetermined threshold, the size of the contention window (CW) is reduced.

8. The operating method according to claim 1, wherein: The size of the contention window CW is determined based on a negative acknowledgement (NACK) ratio which is a ratio of a sum of a negative acknowledgement (NACK) and a discontinuous transmission (DTX).

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