KR20170111643A - Method and apparatus for uplink transmission supporting unlicensed band - Google Patents

Abstract

A method and apparatus for performing uplink transmission on a license-exempt band in a wireless communication system.
A method for performing uplink transmission in a license-exempt band in a wireless communication system includes determining whether to perform an uplink LBT or an uplink CCA before performing uplink transmission, A configuration for adjusting window size, processing signaling information for uplink transmission, and applying an uplink LBT parameter adaptively according to an uplink LBT channel access priority class.

Description

Technical Field [0001] The present invention relates to a method and apparatus for supporting a license-

The present invention relates to a wireless communication system, and more particularly, to a recording medium storing a method, apparatus, software, or software for performing uplink transmission in a wireless communication system supporting a license-unlicensed band phase.

It is required to support uplink transmission of LAA base stations and terminals operating on a license-unlicensed carrier or frequency (unlicensed carrier or frequency) such as a License Assisted Access (LAA) serving cell.

Uplink transmission is basically performed by one or more UEs transmitting data and / or control signals to the BS, and uplink transmission is required based on a UL-LBT scheme by a plurality of UEs .

However, concrete measures for this have not yet been established.

The present invention provides a method and apparatus for optimizing UL transmission.

The present invention provides a channel occupancy method and apparatus of a terminal for performing UL transmission by applying an LBT scheme.

The present invention provides a method and apparatus for performing UL LBT considering fairness of channel occupancy with other transmission nodes.

The present invention provides a method and apparatus for performing UL LBT to optimize the performance of an LAA system.

The present invention provides an SRS transmission method and apparatus for optimizing the performance of a LAA system.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

According to an aspect of the present invention, there is provided a method for performing uplink transmission in a license-exempt band in a wireless communication system, the method comprising: determining whether to perform uplink LBT or uplink CCA before performing uplink transmission; Adjusting the contention window size for the LBT or the uplink CCA, processing the signaling information for the uplink transmission, and adaptively applying the uplink LBT parameter according to the uplink LBT channel access priority class .

The features briefly summarized above for the present invention are only illustrative aspects of the detailed description of the invention which are described below and do not limit the scope of the invention.

According to the present invention, a UL LBT scheme and an SRS transmission scheme for efficiently occupying a channel of a UE, maintaining fairness with a heterogeneous network, and optimizing performance of an LAA system can be provided.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention, illustrate various embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 to 4 are diagrams for explaining a conditional UL CCA skip method according to an example of the present invention.
FIGS. 5 to 8 are diagrams for explaining a method of adjusting (or adaptively determining) a contention window size value for UL LBT according to an exemplary embodiment of the present invention.
9 is a diagram illustrating a configuration of a wireless device according to an exemplary embodiment of the present invention.
10 is a diagram illustrating an SRS transmission operation according to an exemplary embodiment of the present invention.
11 is a flowchart illustrating an operation of transmitting SRS according to another exemplary embodiment of the present invention.
12 is a flowchart illustrating an operation of a terminal for transmitting SRS according to an exemplary embodiment of the present invention.
13 is a flowchart illustrating an operation of a base station receiving SRS according to an exemplary embodiment of the present invention.

Hereinafter, the contents related to the present invention will be described in detail with reference to exemplary drawings and embodiments. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

In addition, the present invention will be described with respect to a wireless communication network. Operations performed in the wireless communication network may be performed in a process of controlling a network and transmitting or receiving a signal from a system (e.g., a base station) And may be performed in a process of transmitting or receiving a signal from a terminal coupled to the wireless network.

That is, it is apparent that various operations performed for communication with a terminal in a network composed of a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A 'base station (BS)' may be replaced by a term such as a fixed station, a Node B, an eNode B (eNB), an access point (AP) In addition, 'terminal' may be replaced with terms such as User Equipment (UE), Mobile Station (MS), Mobile Subscriber Station (MSS), Subscriber Station (SS) .

The terms used to describe the embodiments of the present invention may be described by 3GPP LTE or LTE-Advanced (LTE-Advanced) standards documents, except where explicitly stated to be used in different meanings. It should be noted, however, that this is only for economy and clarity of explanation, and that the embodiments of the present invention are not limited to apply only to systems conforming to 3GPP LTE or LTE-A or subsequent standards.

Table 1 contains a description of the LBT process.

The following UL LBT Candidate Procedure can be applied for self-carrier scheduling.

As a first example, it is possible to define a Clear Channel Assessment (CCA) duration of 25 microseconds (US) before UL burst transmission to sense the channel during the CCA duration. Here, the duration in which the sensing is performed may be equal to or less than the CCA duration.

As a second example, the maximum contention window size can be selected from {3, 4, 5, 6, 7} while applying a defer period of 25us. That is, if the UE senses a channel for a period of 25us delay during the UL CCA and determines that the channel is in an idle state, the number of CCA slots corresponding to the contention window size (i.e., contention window size * CCA slot duration) to perform UL transmission if N = 0 (see DL LBT in Table 1). For example, one CCA slot duration may be 9us.

In the self-scheduling scheduling, there may be UL burst transmission immediately after a DL burst transmission with a predefined time gap. Here, the time gap may include a maximum of 16 us.

Meanwhile, the following UL LBT candidate procedure can be applied for cross-carrier scheduling.

As a first example, you can define a CCA duration of 25us before UL burst transmission to sense the channel during the CCA duration. Here, the duration in which the sensing is performed may be equal to or less than the CCA duration.

As a second example, a delay interval and an additional channel sensing interval may be applied before the UL burst transmission. The size of the delay interval may be less than 25us, and the size of the contention window determining the additional channel sensing interval, such as self- contention window size) may be less than or equal to that applied in the case of DL LBT.

Hereinafter, the UL LBT scheme according to the present invention will be described in detail.

In order to transmit uplink data through a Physical Uplink Shared Channel (PUSCH), a mobile station is required to receive an uplink grant from a base station. Here, the uplink grant may correspond to a Downlink Control Information (DCI) Downlink Control Information Format 0 or 4. The uplink grant includes scheduling information and control information for uplink data transmission and may be provided to the UE through a Physical Downlink Control Channel (PDCCH) or an Enhanced PDCCH (EPDCCH) channel.

In order to transmit such an uplink grant in the license-exempt zone, the base station may perform CCA (or LBT) to occupy the corresponding license-exempt band (or license-exempt channel). If the CCA result channel is in the idle state, it can transmit the uplink grant on the PDCCH or EPDCCH to the UE on the unlicensed band. In one example of the present invention, two modes are provided as a signaling method for instructing scheduling.

In the present invention, when a physical uplink shared channel (PUSCH) transmission associated with an uplink grant is performed in the same serving cell (or carrier, band, etc.) as described above, self- scheduling - carrier scheduling).

In other words, when the PUSCH transmission associated with the uplink grant is performed in another serving cell (or carrier, band, etc.), it is referred to as cross-carrier scheduling.

The cross-carrier scheduling is set for the UE through RRC (Radio Resource Control) signaling. If there is no such setting, the base station performs uplink scheduling based on self-scheduling and the UE can perform uplink data transmission have.

(CCA) for data scheduling (uplink grant transmission) in the case of uplink data transmission, unlike the case where a clear channel assessment (CCA) is required for downlink scheduling by a base station and data clearance in a license- And a UE (hereinafter referred to as UE) for uplink data transmission (PUSCH transmission) may be further required.

Here, the CCA performed by the UE to which the present invention is applied can consider the fairness with other wireless systems coexisting in the license-exempt band. For example, unlike the LTE (hereinafter referred to as LAA) system, a Wi-Fi system is a system in which data by the scheduling of a specific central node (for example, an access point (AP) corresponding to an eNB of the LAA system) (E.g., a non-AP station (STA) corresponding to the UE of the LAA system) always occupies the channel through the CCA and transmits the radio signal on the license-exempted band occupying the radio signal Transmission can be performed.

In this way, it may be difficult to maintain the fairness of license-exempt channel occupancy due to the different allocation of wireless resources between the LAA and the Wi-Fi system. That is, in order for the LAA UE to transmit data in the uplink, the DL LBT success of the LAA eNB and the LA LBT success of the LAA UE must be concurrently performed. Therefore, Will be placed in an adverse channel occupancy environment (or condition) as compared to -Fi AP or STA. To solve this problem, the CCA performed by the UE can be simplified much more than the CCA performed for the uplink grant transmission of the base station.

Hereinafter, the CCA performed by the UE will be referred to as UL Listed before Talk (UL LBT) or UL CCA. On the other hand, the CCA performance by the base station is referred to as DL LBT or DL CCA. The DL LBT operation of the base station may be required for PDSCH or DRS transmission.

On the other hand, if cross-carrier scheduling by a licensed carrier (e.g., a primary cell (PCell)) is performed for an uplink transmission on an LAA serving cell (e.g., a license-exempt carrier or a secondary cell If it is set for scheduling, the DL LBT of the base station for uplink grant transmission may not be required to the UE.

Hereinafter, an example of a channel access procedure (i.e., UL LBT) for uplink transmission (e.g., PUSCH transmission, SRS transmission, PUCCH transmission, or PRACH transmission) in the license- Specific examples of the invention will be described.

1 to 4 are diagrams for explaining a conditional UL CCA skip method according to an example of the present invention.

According to the conditional UL CCA skip method according to an exemplary embodiment of the present invention, the UE skips or omits the UL CCA (or the UL LBT) according to a predetermined condition in the LAA serving cell in which the BS acquires the channel occupation time through the DL LBT And perform UL transmission immediately. Whether the terminal skips the UL CCA (or a change in the CCA operation mode of the terminal) may be signaled to the terminal (s) by the base station or may be determined by the terminal (s) themselves. Also, the change of the CCA operation mode may be applied as a long term or a short term, and a predetermined condition may be a channel occupancy measurement value, a received signal strength, a regulation, a UL transmission channel type, Can be determined. Hereinafter, a long-term is an integer multiple of 10 ms (10 * n ms) (where n is greater than or equal to 2) than a unit corresponding to a UL burst / subframe (Where n is a natural number greater than or equal to 2)) of 40 ms, 80 ms, 160 ms (for example, 40 ms, 80 ms, or 160 ms) . On the other hand, a short-term can be defined as an interval corresponding to a UL burst / subframe (e.g., ~ 10 ms).

1 illustrates an exemplary DL burst and UL burst structure in which a UL CCA is not required according to an example of the present invention. 1 shows an example in which only the DL LBT by the eNB is performed. Accordingly, the UE may perform the UL transmission immediately after the minimum time gap without performing the CCA before the UL transmission.

In order to perform UL transmission (at least data transmission) by the terminal in the LAA serving cell, it must first receive an UL grant (transmitted via (E) PDCCH) transmitted by the base station. Also, one or more UEs may be instructed by the base station to perform UL transmission in the same subframe. In this case, a plurality of terminals can perform the CCA for UL transmission in the same subframe.

In this case, the UEs perform CCA in the same time interval (e.g., UL CCA DURATION in FIG. 1) to check whether the channel is idle, and perform UL transmission if the UE determines that the channel is idle . Unlike the DL LBT (i.e., CCA by eNB only), a plurality of UEs perform CCA within the same CCA duration for UL transmission in the same subframe. Therefore, during a CCA of UEs, it is possible to minimize the error that prevents other terminal (s) from accessing the channel.

A terminal whose UL transmission is scheduled or indicated by the base station may be required to perform the CCA before performing UL transmission as mentioned above. However, requiring the UE to always perform the CCA before UL transmission may cause unnecessary overhead. The UL CCA may be skipped if the interference power of the terminal is not large or the influence of the interference can be appropriately controlled so as to not disturb the interference or the channel occupancy fairness. Therefore, the UEs scheduled by the base station (within the Maximum Channel Occupancy Time (MCOT) ( T _{mcot, p} in Table 2 below) within the maximum occupied time of the channel occupied by the base station through the DL LBT, Can lead to performance improvement of the LAA system.

Table 2 below shows a channel access priority class for DL LBT (for PDSCH) for DL LBT applicable in case of PDSCH transmission.

In Table 2, m _p , CW _{min, p} , CW _{max, p} , T _{mcot, p} and CW _p denote the number of CCA slots corresponding to channel access priority class p, Occupancy time, and allowed competition window sizes.

Therefore, in one embodiment of the present invention, a method of performing UL CCA selectively or conditionally by a terminal without always requesting UL CCA (UL LBT) is proposed. However, if the UE skips the UL CCA, the UEs that need to perform UL transmission should transmit the DL burst by the base station (i.e., the UE receiving the DL burst transmission from the base station must perform UL transmission without UL CCA) Can be performed). Therefore, within the maximum channel occupation time occupied by the DL LBT of the base station ( T _{mcot, p} in Table 2), UEs can perform UL transmission without performing UL CCA.

In the example of FIG. 1, if the proposed method is applied to an LAA serving cell including all DL-UL bursts, the DL burst ends and a minimum time gap (for example, 9us, 16us, 25us, 36us ...), the UE can perform the UL transmission immediately without performing the CCA. Also, the definition of the interval for performing the CCA may be arranged in front of one subframe or in the rear as shown in FIG. In the present invention, the minimum time gap for UL transmission in the DL can be defined as a switching gap for UL transmission in the DL. The switching gap may have a value less than 9 [micro] s. Alternatively, the switching gap (or time gap) may be defined as an integer multiple of the CCA slot length (9 μs) (9 μs * 1, 9 μs * 2, ... 9 μs * N). Also, the switching gap may be defined as a value of a UE specific (or UE dependent value) defined according to the specification of the UE.

In addition, the present invention proposes an operation for selectively determining whether or not the CCA for UL LBT is performed by the type of signal to be transmitted by the terminal, frequency and measurement value of the license-exempt channel, regulation of license- do. By newly defining such an operation, it is possible to reduce the disadvantage of channel access that a scheduling-based system (e.g., LAA system) inevitably has (e.g., non-scheduling basis such as Wi-Fi (no centralized scheduler) system), which can lead to higher performance because the LAA terminals can perform UL transmission with higher probability. Also, DL burst and UL bursts can be used more effectively if there is no hidden node problem around the terminal.

Hereinafter, it is assumed that the DL LBT by the base station must be performed in order to conditionally perform UL CCA in order to transmit the DL burst in the same LAA serving cell immediately before the UL burst. Therefore, the DL burst transmission and the UL burst transmission can be sequentially performed within the maximum channel occupation time in the LAA serving cell occupied by the DL LBT of the base station. In that case, for UL burst, data, or signal transmission, the terminal may not (ie, skip) UL CCA performance according to the proposed specific conditions.

In the present invention, the UL CCA skip method is applied assuming that a DL burst for transmitting a PDSCH is occupied by a DL LBT by an eNB. As another example of the present invention, the UL CCA skip method may not be applied to DL LBT (without PDSCH) for LAA DRS (Discovery Reference Signal) transmission. Examples of the present invention for the UL CCA skip method are described below. The following examples may be applied individually or in combination of two or more.

In Example 1-1, a UL CCA operation method of a UE is performed based on channel occupancy measurement (CO) and RSSI (Received Signal Strength Indicator) values measured by both a base station and a terminal in a long-term (Or operation mode) can be changed.

FIG. 2 is a diagram for explaining channel occupancy and RSSI measurement and reporting operations of a terminal according to an exemplary embodiment of the present invention. Referring to FIG.

In the example of FIG. 2, channel occupancy and RSSI measurement and reporting may be performed for the LAA serving cell. It is also assumed that L1 (i.e., physical (PHY) layer) averaging duration corresponds to one OFDM symbol length and L1 measurement duration corresponds to 70 OFDM symbol length.

The LAA UE (terminal) measures the occupancy frequency measurement value of the license-exempt channel (i.e., how many transfer nodes the one license-issuing channel is being used by) and the RSSI value, as in the example of FIG. 2, Report to the base station based on the period.

In the LAA system, the period value for the RSSI and the channel occupancy timing configuration (hereinafter, referred to as RMTC) for one license-exempt serving cell can be set by the base station through higher layer signaling to the UE. Therefore, the cycle in which the RSSI measurement duration (L1 measurement duration) appears is determined according to the period setting of the RMTC. The period values may be {40, 80, 160, 320, 640} milliseconds.

Also, as shown in the example of FIG. 2, the L1 averaging duration value is always one OFDM symbol and the RSSI measurement duration is set by the base station to one of {1, 14, 28, 42, 70} . The RSSI measurement duration value indicates the number of consecutive OFDM symbols. In FIG. 2, the RSSI measurement duration is 70 and the number of the 70 OFDM symbols is 5 ms.

As shown in FIG. 2, an L1 RSSI sample value is averaged through L3 (for example, RRC layer) filtering to determine RSSI value and channel occupancy (hereinafter referred to as " CO) values may be reported together by the UE to the base station. Here, the CO value is measured by comparing the RSSI threshold value (for example, the value of the channelOccupancyThreshold parameter) set by the base station with all the L1 RSSI samples in the L3 averaging window, and the ratio of RSSI samples larger than the RSSI threshold value. Therefore, the CO value has a ratio value of 0 to 100. In FIG. 2, 210 RSSI samples are normalized in one L3 averaging window to derive one UE reported RSSI value, and CO also compares RSSI threshold values with 210 L1 RSSI samples to determine the ratio (i.e., CO ) With the UE reported RSSI value to the base station.

The UE to which the example 1-1 applies measures the CO value and transmits the measured value along with the measured RSSI value according to the report period set in the base station. The base station may consider the RSSI value and the CO value measured by the base station in addition to the RSSI value and the CO value reported by the UE through the above process. Finally, the UE determines whether to perform the CCA before UL transmission of the UEs in the cell, and signals the determined value to the UEs.

Here, the CO value and the RSSI value measured by at least the base station and / or the terminal are compared with the newly defined channel occupancy ratio threshold value, and when the measured value is larger, Or may provide signaling for UL CCA skip to at least one or more terminals corresponding to a particular group.

At this time, since the value of the Channel Occupancy Ratio Threshold ( C _Thresh ) proposed in Example 1-1 is used in the base station, it may not be signaled or set to the UE. Accordingly, the UE can receive the signaling on whether to perform the CCA indicated by the BS, and determine whether to perform the CCA before UL transmission according to the signaling. If the CCA is not performed by the UE, a PUSCH, a Physical Uplink (PUCCH), or a PUCCH (Physical Uplink) may be performed immediately after a predetermined time gap (e.g., 34us, 25us, 20us, 16us, 9us, Control Channel), Physical Random Access Channel (PRACH), or SRS (see the example of FIG. 1).

FIG. 3 is a view for explaining a base station operation for determining whether to perform UL CCA according to an exemplary embodiment of the present invention. Referring to FIG.

In the example of FIG. 3, the following parameters may be used by the base station to determine whether to perform the CCA of the terminal.

C _{m, i} : Channel Occupancy Measurement measured at the measurement reporting period corresponding to index i by the UE on one LAA carrier. This value is [0 ... 100]. ≪ / RTI > The index i is the index value for the channel occupancy measured within the L3 measurement window (measurement reporting period) at a particular point in time. Basically, the range of i may be at least one or more than one set number (M).

C _Thresh : Threshold value for CO value on one LAA serving cell with Channel Occupancy Ratio Threshold. This value is [0 ... 100]. ≪ / RTI > When the CO value measured in the L3 measurement window is greater than the specific threshold value C _Thresh , the BS indicates signaling to the LAA terminals in the cell to perform UL CCA. In this case, the base station must perform signaling that the UL CCA needs to be performed.

C _{m, i} < C _Thresh (i = 0 ... M -1) is X% or more, or avg [ C _{m, i} ] C _Thresh (i.e., C _m, when the average value of _i is less than the threshold value C _Thresh) for, since by the signaling of the base station the terminal end of the DL burst transmitted without performing the CCA in the Channel Access procedure, a predetermined time gap ( PUSCH, PRACH, or SRS, for example, up to 34us, 25us, 20us, 16us, 9us, or 10us) (see FIG. Where the value of M is the total number of samples of the CO value and can have M measurement reporting periods. It can also be called the length of the observation section. The value can be a value of 1 or more including 1, and can be set and indicated by higher layer signaling.

K _{RSSI, i} : L3 RSSI value measured based on L1 RSSI sample values in the L3 averaging window. This value can be considered in determining whether to perform UL CCA in addition to the above procedure for comparing CO values. For example, if the ratio of C _{m, i} < C _Thresh (i = 0 ... M -1) is more than X%, but the K _{RSSI, i} values are measured or reported below a certain RSSI power level, You can skip.

The M value may be fixed to any value (e.g., 1), or one value may be selected and used by the base station in any set (e.g., {1, 2, 3 ... 9}).

As shown in FIG. 3, in order to determine whether the UL CCA skip occurs, the BS can determine whether UL CCA skip by comparing the total M = 3 CO and the RSSI report value with the threshold value C _Thresh . Where C _{m, i = 0} = 70, C _{m, i = 1} = 50, C _{m, i = 2} = 60, the average value of C _{m, i} values (i.e., C _{m, avg} or avg [ C _{m, i} ]) is 60. C _{m, avg} Since the value is less than C _Thresh = 70, the base station determines that it is a UL CCA skip. Thus, the base station may instruct the LAA terminals to skip the UL CCA via cell-specific common signaling (e.g., a system information block (SIB) or LAA common DCI signaling) And immediately after the UL burst, or UL CCA skip before transmission within the subframe, and immediately perform UL transmission.

In the case of M = 3 as in the above example, the following average value is calculated as C _{m, i = 1} = 50, C _{m, i = 2} = 60, C _{m, i = 3} = 40, the average value of the C _{m, i} values (i.e., C _{m, avg} or avg [ C _{m, i} ]) is 50. In this way, the average value can be measured by reflecting the latest measurement result to a new measurement result for each measurement reporting interval. Also, the averaging window (averaging samples) can be moved (cumulative average) and measured as an average value.

Although the above method shows that the UE skips the UL CCA under a certain condition based on the signaling of the base station, the present invention is not limited to this, and the terminal or the terminal group can individually (or by itself) It is also possible to determine whether to skip UL CCA.

Next, according to the example 1-2 of the present invention, it is possible to change the CCA operation method only when the absence of another RAT (Radio Access Technology) system is guaranteed as the long-term.

Example 1-2 shows that if the absent of RAT other than the LAA on the unlicensed carrier is assured by the level of regulation, the base station transmits a CCA (UL (E.g., SIB) or dedicated signaling (e.g., RRC reconfiguration) via a licensed carrier (e.g., PCell) so as not to perform a CCA And instructions are available. This is because the base station performs the DL LBT for the (E) PDCCH transmission including at least the UL grant, and then _calculates the maximum occupied time T _{mcot, p} Section corresponding to The terminal may transmit one or more of PUSCH, PUCCH, PRACH, or SRS without performing UL CCA.

Further, in Example 1-2, if an absent RAT other than the LAA is guaranteed on the corresponding unlicensed carrier at the regulation level, the base station can transmit the next UL If the UE determines in the burst or subframe not to perform the UL CCA, the base station may request broadcasting information (e.g., SIB) or Higher layer signaling (e.g., UL CCA) to prevent the UE from performing UL CCA , RRC signaling).

Also, in the case where the absence of RAT other than the LAA is assured on the unlicensed carrier according to the regional regulation without signaling by the base station, the UE always uses the maximum channel occupation time occupied by the base station It is possible to skip the CCA operation before the UL transmission.

Therefore, if the CCA is not performed by the UE according to the above method, after a predetermined time gap (for example, maximum 34 us, 25 us, 20 us, 16 us, 9 us, or 10 us) (E.g., transmission of one or more of PUSCH, PUCCH, PRACH, or SRS) (see FIG. 1).

According to exemplary embodiment 2-1 of the present invention, the CCA operation method can be changed by a short-circuit, and the CCA operation method can be changed according to UL transmission channel or signal information type.

Unlike the example 1-1 or the example 1-2, in the example 2-1, whether the CCA is performed by the UE before the UL transmission can be determined according to the UL transmission channel type or UL signal type in the corresponding UL burst or UL subframe. The UL transmission channel or the type of signal may be classified into PUSCH, PUCCH, PRACH, and SRS. The UL signal type can be classified into data, Hybrid Automatic Repeat reQuest (HARQ) -ACK, Scheduling Request (SR), Channel State Information (CSI) feedback, BSR (Buffer Status Report)

The UL physical channel or the signal type may be divided individually into two or more groups. The CCA skip for all combinations of type classification can be defined in advance, and the base station can instruct the UE (s) requiring the UL transmission to use the dynamic signaling method such as (E) PDCCH in advance to skip the CCA. Therefore, the UL CCA skip of each possible UL transmission combination in the next UL burst can be defined in advance, and the base station can determine whether the UL CCA skip is based on the UL CCA skip, and signal the result to the UEs.

For example, through (E) PDCCH signaling with UL grant (DCI format 0 or 4) or LAA common DCI (DCI format 1C scrambled by CC-RNTI), the base station transmits a UL burst or UL You can indicate before the subframe. For example, the BS may preliminarily determine UL CCA skip according to UL channel or signal type as shown in Table 3 below, and transmit the corresponding UL burst or UL burst according to the type of the channel or signal to be transmitted by the UEs in the corresponding UL burst or UL subframe. UL subframe to indicate whether the UE is skipping the CCA. Thus, dynamic signaling such as (E) PDCCH signaling with UL grant or LAA common DCI may be used to indicate UL CCA skip for each UL channel or signal type.

Herein, the operation indicating whether to skip the UL CCA is effective after the DL burst is transmitted to the UEs through the DL LBT by the base station. If the DL LBT is not required (for example, the PDSCH is included The UL burst or the UL subframe must be transmitted by performing the UL LBT without DL burst transmission). However, this may not apply in the case of operation for the CCA skip.

Table 3 exemplifies whether or not to perform the CCA according to the type of the channel or signaling that can be transmitted in the UL LAA serving cell, but the present invention is not limited thereto. The items marked with "-" in Table 3 indicate that the actual combination is not possible (eg, when transmitting UE's data information via PRACH or PUCCH).

For example, if the type of channel and signaling information for UL transmission in the UL burst or UL subframe transmission immediately after the DL burst is PUCCH and HARQ-ACK or SR, then the terminal sends a UL CCA for transmission on the LAA UL serving cell it is possible to transmit the HARQ-ACK or SR directly on the PUCCH after skip and a predetermined time (for example, 16 us). Here, the switching gap for UL transmission in the DL is 9us, 16us, 25us, 36us ... (9 mu s * 1, 9 mu s * 2, ... 9 mu S * N) of the CCA slot length (9 mu s), or different values depending on the specifications of the terminal.

As a further example, if data (or PUSCH) transmissions within an upcoming UL burst or UL subframe transmission are scheduled at least once or more (or if present), the terminal will always have UL CCA Can be performed. Otherwise, if the data (or PUSCH) transmission is not scheduled (or does not exist) in the upcoming UL burst or UL subframe transmission, skip the UL CCA according to the signal type or use some signaling information type (e.g., PUCCH with HARQ-ACK > PUSCH with CSI) or a combination of some channel and signaling information types (e.g., PUCCH with HARQ-ACK> UL CCA can be skipped only for UL transmission and the remaining signal types can be UL CCA.

4 is a diagram for explaining an example of changing the CCA operation method according to the UL transport channel or the signal information type.

In the example of FIG. 4, the BS can secure the channel occupation time through the DL LBT and signal the UL grant for UL transmission while transmitting the DL burst to the UE. In order to transmit UL burst after DL burst is terminated, the UE may perform DL-UL switching for a predetermined time gap and determine whether to perform UL CCA for UL burst or UL subframe. Whether UL CCA is performed may be indicated by the base station or may be determined by the terminal itself.

In the example of FIG. 4, UE 1 performs UL CCA because it includes at least one PUSCH transmission since data transmission over PUSCH is scheduled in UL subframe # 0 (UL SF # 0), UL SF # 1 and UL SF # . UE2 does not include PUSCH transmission because it transmits HARQ-ACK in UL SF # 0 and UL SF # 1 over PUCCH and transmits SR or CSI in PUCCH in UL SF # 3, so it is determined to skip UL CCA . UE3 may transmit a PRACH in UL SF # 0 and may decide to perform UL CCA because it includes at least one PUSCH transmission since the DATA transmission on the PUSCH in UL SF # 2 and UL SF # 3 is scheduled.

As a further example, it is assumed that each terminal has a UL channel (for example, PUSCH, PUCCH, PRACH, or SRS) to be transmitted in UL subframes in the upcoming UL burst and a specific type of signaling information type is Y It is also possible to skip the UL CCA only when it is transmitted, and to perform the UL CCA otherwise.

However, in the example 2-1, only the OFDM symbols in the sub-frame performing the UL CCA, i.e., the last partial subframe of the DL burst (i.e., some OFDM symbols within one subframe, such as the DwPTS of the DL burst, UL scheduling information (for example, UL grant by DCI format 0 or 4) of the (E) PDCCH transmitted in the subframe used for UL CCA may not be considered in determining whether to perform the UL CCA. This is because the UL data transmission beyond the maximum channel occupation time occupied by the DL LBT is out of the time occupied by the DL LBT, so that a new UL only LBT is performed and UL data transmission must be performed.

Hereinafter, a base station dynamic signaling method for performing UL CCA will be described.

The CCA performed by the UE before the transmission of a specific UL burst (or UL subframe) by the base station may be performed by a UL grant (DCI format 0 or 4) or a 1-bit size field (for example, CCA a field indicating skip on / off), and the base station can dynamically instruct the terminal in advance. In particular, DCI format 1C with CC-RNTI is an LAA common control signal transmitted on a common search space, which is one of the PDCCH transmission resources defined for each LAA DL serving cell. The signaling basically repeats the same information in the last subframe n of the DL burst and in the subframe n-1 immediately before the last subframe. Through the signaling, the number of OFDM symbols used for DL transmission in the last partial subframe of the DL burst is signaled to the UE, and utilized for accurate data or control signal decoding and CSI measurement of the UE.

An exemplary embodiment of the present invention may signal the UEs by adding a CCA skip on / off indicator (1 bit) field to DCI format 0 or 4 or DCI format 1C with CC-RNTI. Considering signaling overhead and DCI size increase of DCI format 0 or 4, signaling may be performed to a plurality of LAA terminals at once using DCI format 1C with CC-RNTI instead of individually signaling to each of LAA terminals. Or scrambling (scrambling) the DCI format 1C to indicate the CCA skip on / off value in the 16-bit CRC in the CC-RNTI. In this case, it is possible to prevent 1-bit increase of DCI format.

According to exemplary embodiment 2-2 of the present invention, if the absent of RAT other than the LAA is ensured on the unlicensed carrier in the LAA serving as a regulatory level, CCA You can change the way you operate.

Example 2-2 shows an example 2-1 (i.e., in an environment where the absent of another RAT other than LAA is guaranteed on the LAA serving cell at the regulatory level) Change of short-circuit CCA operation method) operation is applied. Example 2-2 demonstrates that ULA serving cells can be equitably utilized and coordinated with each other, because at least other RAT members are guaranteed by regulation in the LAA serving cell, it is possible to minimize the interference problem that may occur in skip.

According to the example 2-3 of the present invention, if the CCA operation method is changed according to the UL transmission channel or the signal information type as a short-term with the determination through example 1-1 in a specific measurement period.

Examples 2-3 determine whether a CCA skip is to be performed in the long-term through the above-described example 1-1 (that is, a method of determining whether CCA is performed based on a long-term statistic (for example, CO, RSSI, And a method of determining whether UL CCA skip is performed for each UL burst or subframe through an operation of Example 2-1 (that is, change of CCA operation method).

Since the example 2-3 is based on the license-exempt channel environment information of the UE measured in the long-term, and additionally the example 2-1 is applied thereto, the UL CCA skip It is possible to decide whether to skip UL CCA based on more reliable information.

Example 3 of the present invention corresponds to a method of applying CCA skip to UEs in a cell by applying one of Examples 2-1 to 2-3 in addition to applying the above-described Example 1-2. In some UEs, since there are many transmission nodes in the vicinity, the channel may be busy. Therefore, only those terminals can judge whether CCA skip is based on CO or RSSI value.

For example, when the BS occupies the scheduling and the channel so that the UL burst comes immediately after a predetermined time interval (for example, 16 us) next to the DL burst, the BS determines the UL burst according to the UL channel in the next UL burst or subframe, Refer to Examples 2-1 to 2-3.) It is possible to instruct UEs whether UL CCA is skipped. Meanwhile, each terminal compares the channel occupancy measurement value (CO) and the RSSI value of the neighboring LAA serving cell with an arbitrary threshold value, so that terminals having channel measurement values of a threshold value or more may not skip UL CCA for UL transmission (E.g., performs the operation of the terminal according to example 1-1).

Also, in the present invention, an operation of a method of transmitting an SRS (Sounding Reference Signal) in a situation where the UE performs the UL CCA skip will be described.

The SRS is a reference signal transmitted in an uplink, and the base station is used to acquire uplink channel information and path attenuation value between each UE and a base station, and time / frequency resources to be used by each UE for SRS are all transmitted to the base station . The SRS is divided into parameters commonly used in the cell by the base station and parameters used separately for each UE, so that the UEs in the cell are configured. The parameters are provided via system information block (SIB) and radio resource control (RRC) signaling, which are layer 3 signaling.

More specifically, the SRS is operated by the base station according to the following settings.

Table 4 shows the frame structure type 1 sounding reference signal subframe configuration.

Table 5 shows the frame structure type 2 sounding reference signal subframe configuration.

The cycle or offset value for the cell specific SRS subframe setting is set using values of the above table in accordance with each of FDD (frame structure type 1) and TDD (frame structure type 2) through upper layer signaling. Based on the information on the SRS subframe in the cell, the UEs connected to the cell can confirm information on the cell-specific SRS subframe considered in the current cell.

In addition to the cell specific SRS subframe setting, each of the UEs is additionally set such that the subframe capable of SRS transmission by the base station is a subset of the cell specific SRS subframe above. In the following description, a UE specific SRS subframe setting method corresponding to the type 0/1 SRS subframe and a condition for the SRS transmission subframe are shown.

와 오프셋

아래 테이블에서 FDD와 TDD를 위해 각각 정의한다. 타입 0 SRS 전송은 TDD 서빙셀(

)와 FDD 서빙셀에서는

를 만족하는 서브프레임에서 수행된다. 여기서 FDD인 경우

를 사용하고 TDD인 경우에서는 표 6을 이용한다. 즉, 표 6은 TDD를 위한

을 나타낸 것이다.Type 0 SRS setting cycle

And offset

Define for FDD and TDD respectively in the table below. Type 0 SRS transmission is performed in the TDD serving cell (

) And the FDD serving cell

Lt; / RTI &gt; Here, in the case of FDD

And in Table 6 for TDD cases. That is, Table 6 shows the

Lt; / RTI &gt;

and Subframe Offset Configuration

을 나타낸 것이다.Table 7 shows the UE Specific SRS Periodicity for trigger type 0 (periodic SRS) in FDD

and Subframe Offset Configuration

Lt; / RTI &gt;

and Subframe Offset Configuration

을 나타낸 것이다.Table 8 shows the UE Specific SRS Periodicity for trigger type 0 (periodic SRS) in TDD.

and Subframe Offset Configuration

Lt; / RTI &gt;

와 오프셋

를 이용하여 정의하고 그 값은 아래 표 9 내지 10을 보듯이 FDD와 TDD 서빙셀을 위해 각각 정의하고 있다. On the other hand, Type 1 SRS sub-

And offset

And the values are defined for FDD and TDD serving cells, respectively, as shown in Tables 9 to 10 below.

and Subframe Offset Configuration

을 나타낸 것이다.Table 9 shows the UE Specific SRS Periodicity (SFR) for trigger type 1 (aperiodic SRS) in FDD.

and Subframe Offset Configuration

Lt; / RTI &gt;

and Subframe Offset Configuration

를 나타낸 것이다.Table 10 shows the UE Specific SRS Periodicity for trigger type 1 (aperiodic SRS) in TDD

and Subframe Offset Configuration

.

와

(

를 가지는 TDD 서빙셀과 FDD 서빙셀인 경우)이고

(

를 가지는 TDD 서빙셀인 경우) 이다. 여기서 FDD 서빙셀인 경우에는

이고 TDD 서빙셀인 경우에서는

위의 TDD를 위한

값을 이용한다.If a Type 1 SRS transmission is received in a serving cell in a subframe n, then the Type 1 SRS transmission shall be transmitted in a subframe satisfying the following conditions. The conditions

Wow

(

Lt; / RTI &gt; serving cell and an FDD serving cell)

(

Lt; / RTI &gt; serving cell). In the case of the FDD serving cell

And in the case of the TDD serving cell

Above TDD

Value.

10 is a diagram illustrating an SRS transmission operation according to an exemplary embodiment of the present invention.

Referring to FIG. 10, SRS 1030 may be transmitted in the same subframe as PUSCH 1020 and SRS may be transmitted in the same subframe. Here, when an arbitrary terminal desires to transmit only the SRS through the unlicensed band in a single subframe, it is confirmed that the SRS transmission is possible through the LBT process. In addition, the SRS should be transmitted in the fastest OFDM symbol after the LBT interval is terminated such that the license-exempt band is not occupied by other UEs and devices.

Therefore, according to the present invention, when the UL CCA skip condition is satisfied, a UE that desires to transmit only SRS can transmit SRS at a time when UL transmission is possible without CCA.

11 is a flowchart illustrating an operation of transmitting SRS according to another exemplary embodiment of the present invention.

As shown in FIG. 11, in the same LAA serving cell, the DL burst 1110 exists before the UL burst and the DL LBT by the base station is necessarily performed in order to transmit the DL burst 1110. Therefore, only the SRS 1130 If the UE recognizes that the UL CCA skip is possible, there is a UE in which the PUSCH 1120 proceeds immediately without the CCA in the UL transmission interval, and UEs and other RAT (radio access technology) devices controlled by other base stations It can be determined that the PUSCH transmission occupies 80% or more of the LAA serving cell band by the PUSCH 1120 transmission of the other UEs so that the LAA serving cell band is not occupied.

Therefore, the UE transmitting only the SRS 1130 may set the transmission time of the SRS 1130 to the last OFDM symbol of the UL subframe in which the PUSCH 1120 is transmitted. If information on a time point of a subframe in which transmission of an UL burst is completed is included in control information including an indicator for indicating the UL CCA skip, the terminal transmitting only the SRS starts the UL burst And transmits the SRS 1130 in the last OFDM symbol of the UL subframe to which the SRS is to be transmitted for the SRS transmitted during the termination of at least one or more subframes.

12 is a flowchart illustrating an operation of a terminal for transmitting SRS according to an exemplary embodiment of the present invention.

Referring to FIG. 12, a UE to which only the SRS is to be transmitted in a specific LAA serving cell is checked based on the conditional UL CCA skip method proposed in the present invention. 1 through 4, the determination as to whether to skip the UL CCA by the terminal (or the change of the CCA operation mode of the terminal) may be performed by the base station by the terminal (s) , Or the terminal (s) may determine 1210 itself.

Also, the change of the CCA operation mode may be applied as a long term or a short term, and a predetermined condition for changing the CCA operation mode may be a channel occupancy measurement value, a received signal strength, a regulation, UL transport channel type or signal type, and the like.

If it is determined that the UL CCA skip is possible, the OFDM symbol in the UL subframe to which the SRS is to be transmitted is confirmed (1220). If the UL subframe is a partial UL subframe including a part of the DL data transmission period, the position of the OFDM symbol in the UL subframe in which the SRS is to be transmitted may be the beginning of the UL data transmission period after the OFDM symbol in which the DL data transmission period ends, Lt; RTI ID = 0.0 &gt; OFDM &lt; / RTI &gt; Or may be fixedly defined as the last OFDM symbol of the partial UL subframe. Or may be indicated by the base station in either the first OFDM symbol or the last OFDM symbol. In this case, the BS may provide the indication information in the SIB or RRC reconfiguration message to the UE by including the indication information as a cell-specific parameter for the indication.

The UE may transmit the SRS on the confirmed SRS transmission symbol (1230).

13 is a flowchart illustrating an operation of a base station receiving SRS according to an exemplary embodiment of the present invention.

In step 1310, the BS confirms that data to be scheduled in downlink has a traffic pattern of a DL burst type and that there is data to be currently scheduled, to some of the UEs that are established in the RRC connection with the current BS. At the same time, based on buffer status report (BSR) information received from some UEs of the RRC connection established with the base station, it is confirmed that the UEs currently transmit data to be transmitted through the uplink, It is confirmed that a traffic pattern of a radio bearer (RB) having a one-to-one correspondence with an existing logical channel (LC) is a UL burst type traffic pattern.

Herein, the BSR is a report on the amount of data stored in the buffer in the current terminal among the data to be transmitted to the base station by the terminal. In addition, the RB is logically connected between the P-GW (Packet Gateway), which is a point of contact with the external network of the mobile communication system, and the Bearer defined between the BS and the UE among the elements constituting the EPS bearer supporting a single QoS do.

Here, some UEs scheduling the DL burst data and some UEs scheduling the UL burst data may be identical to each other, but some may be different from each other. That is, some UEs may only need to schedule DL burst data, and some UEs may only need UL burst data scheduling. If it is determined that the DL burst data and the UL burst data need to be continuously scheduled through the above-described confirmation procedure, the base station determines the UL CCA skip indication for the scheduling (1320).

Based on the determination, the BS transmits UL CCA skip related information including indication information for the UL CCA skip indication to all MSs in the LAA serving cell, if necessary. The UL CCA skip related information may include information on a time point of a subframe in which UL burst transmission is ended. If there is an UL subframe in which the base station can point to the SRS transmission OFDM symbol position, it may transmit the relevant indication information to each terminal.

The BS receives the UL data and / or the SRS according to the information scheduled for each UE in the cell (1330).

FIGS. 5 to 8 are diagrams for explaining a method of adjusting (or adaptively determining) a contention window size value for UL LBT according to an exemplary embodiment of the present invention.

According to the adaptive contention window size setting method for UL LBT of the present invention, it is possible to determine a reference subframe and / or a reference UE, and to adaptively determine a contention window size based on the determined reference subframe and / or reference UE. The determination of the reference subframe and / or the reference UE for this may be made by determining the most recent UL burst as a reference subframe (regardless of the UE to which the UL transmission will be scheduled, or the UE to which the UL transmission is to be scheduled, individually or wholly) The UE (s) scheduled in the reference subframe may be determined as the reference UE (s). In addition, the CWS value can be increased when the NACK rate for the reference UE (s) in the reference subframe is individually or entirely considered, and is equal to or greater than a predetermined threshold value. Otherwise, the CWS value may be maintained or reduced. Specific examples of the present invention will be described below with reference to the drawings.

If UL LBT is performed based on short DL LBT and shortened DL LBT with random back-off, then there is a need to define how to properly adjust the contention window size (CWS) for UL LBT have.

In the DL LBT to which the present invention is applied, the CWS value is incremented for each priority class based on the HARQ-ACK information corresponding to the first subframe available in the DL burst (i.e., the reference subframe for DL LBT) Or initialize it. This is because the HARQ-ACK information corresponding to the first subframe in the DL burst can be used to adjust the CWS size more adaptively to the license-exempt channel environment in the next DL burst. In general, One of them is the frequent collision with transmission nodes.

On the other hand, the reference subframe determination method for CWS adjustment for each priority class of the UL LBT according to the present invention must be performed in a manner different from the reference subframe determination for CWS adjustment of the DL LBT.

Unlike DL LBT (or DL CCA), a device that performs UL LBT (or UL CCA) is at least one or more UEs. That is, considering that DL LBT (DL CCA) performs only one base station, it is sufficient to consider one and the same channel environment, but consider different channel environments to which a plurality of UEs performing UL LBT (UL CCA) belong.

Unlike the DL LBT, the UL LBT operation and related parameter values (e.g., Defer period, CWS max, CWS min, and maximum channel occupancy time) of the UE depend on whether the UE is self-scheduling or cross- ED (Energy Detection) threshold value, etc.) may be different, the reference subframe determination method for the associated CWS adjustment should also be different from DL LBT.

The DL burst transmission is capable of transmitting consecutive DL bursts when the channel is idle for at least 24us (or 36us) times through the CCA during consecutive DL burst transmissions (for example, Japan) It is necessary to consider HARQ-ACK only for the first subframe (reference subframe) since a time of X ms (for example, 4 ms, HARQ-ACK timing between UL grant and PUSCH) Is not high. In particular, during self-scheduling, more time is required between UL bursts for DL LBT performance.

(SF # k, SF # k + 1, SF # k + 2) from a plurality of UEs (UE # 0, UE # 1, UE # 2, UE # 3) ) May be used for CWS determination in the upcoming UL burst.

Based on the above considerations, the present invention proposes the following methods for determining a reference subframe and / or a reference UE for a UL LBT (UL CCA).

5 is a diagram for explaining a reference subframe and a reference UE determination method for CWS determination to be utilized in a next (upcoming) UL burst according to the present invention.

The base station may perform PUSCH transmission on the LAA SCell to at least one or more UEs. Here, the BS considers the setting of the scheduling method of each MS. That is, it is determined whether self-scheduling or cross-carrier scheduling is performed for each UE.

The base station transmits the (E) PDCCH including the UL grant (i.e., DCI format 0 or 4) in the same serving cell as the LAA SCELL in which the PUSCH transmission is performed to the UE with self-scheduling, while cross-carrier scheduling is set The UE performs (E) PDCCH transmission including UL grant in a serving cell other than the LAA SCell in which the PUSCH transmission is performed (for example, PCell or another SCell on the license carrier). A UE with cross-carrier scheduling may perform UL LBT (e.g., another LBT parameter-based operation) different from the case where self-scheduling is set.

The base station may require a reference subframe and / or reference UE to determine a common CWS value of the UL LBT (UL CCA) of the UEs for upcoming UL bursts or UL transmissions in the subframe. The CWS value for the DL LBT is determined based on the HARQ-ACK information for the PDSCHs transmitted in the first subframe of the latest DL burst in which the HARQ-ACK is available. The base station receiving the HARQ-ACK information for the PDSCH transmitted from the reference subframe of the LAA SCELL increases the CWS value if at least the HARQ-ACK information corresponding to the reference subframe has a NACK rate of 80% or more.

On the other hand, a method for acquiring or deriving the CWS value of the UL LBT proposed by the present invention is as follows.

The first possible way is for the UL CWS value to be applied for the next UL burst or UL LBT on the UL subframe to indicate the determined CWS value to at least one or more UEs scheduled for that UL burst by signaling the base station to the UE. Each terminal can attempt to occupy a channel for UL transmission by performing UL LBT based on the common CWS value indicated by the base station.

The second possible method is that the UL CWS value can be derived by each terminal individually (or by itself) on a constant basis. And performs UL LBT based on the determined value to attempt to occupy the channel for UL transmission.

Among the above two possible methods, a method of determining a reference subframe and / or a reference UE for adjusting a specific UL CWS value, assuming that the first method (i.e., the base station determines the CWS and signals the UE) I suggest. One or more of the schemes described below may also be applied to the second method (i.e., the method by which the terminals individually determine the CWS). Referring to FIG. 6, for upcoming UL bursts or UL transmissions on UL subframes The reference subframe and / or the reference UE in the UL CWS adjustment may be configured such that at least one or more UL subframes in the UL burst or subframe received most recently from the base station become reference subframes and are scheduled to be at least One or more UEs become reference UEs.

Also, regardless of the previous PUSCH transmissions of UEs scheduled in the upcoming UL burst, ACK or NACK information corresponding to the PUSCH received on all UL subframes corresponding to the UL burst received most recently from the base station The CWS value for all UEs scheduled for the next UL burst can be increased to the next larger allowed CWS if the ratio of the NACKs of all UEs is at least Z% (for example, 50 or 80%). However, if the current CWS values of the terminals are not the same, the base station increases the next largest CWS value based on the current CWS value corresponding to the largest, smallest, or intermediate (average) of them. The modified CWS value may then be signaled to the UEs by the base station and used for UL LBT operation of UEs scheduled for the next UL burst.

Referring to FIG. 7, a reference subframe and / or a reference UE for UL CWS coordination for an upcoming UL burst or UL transmission on a UL subframe may include at least one UL subframe in the UL burst or subframe received from the base station, Are reference subframes and at least one or more UEs that have been scheduled in the at least one or more UL subframes become reference UEs on a per UE or UE group basis.

6 differs from the example of FIG. 6 in that the difference of the NACKs for each UE or group of UEs (e.g., the UE group can be composed of UEs scheduled for UL subframes in the UL burst received most recently in the base station view) Calculates a ratio and selects UEs with the highest, lowest, or median NACK ratios calculated, and if the ratio of NACKs of the selected UE is at least Z% (e.g., 50 or 80%), the CWS value for all UEs scheduled for the next UL burst can be increased to the next larger allowed CWS. However, if the current CWS values of the terminals are not the same, the base station increases the next largest CWS value based on the current CWS value corresponding to the largest, smallest, or intermediate (average) of them. The modified CWS value may then be signaled to the UEs by the base station and used for UL LBT operation of UEs scheduled for the next UL burst.

In the example of FIG. 6, the NACK ratios of all the UL subframes and the scheduled UEs in the UL burst received most recently in the base station view are calculated on the basis of all the UEs, but in the example of FIG. 7, the NACK ratios of all UL subframes in the burst and the scheduled UEs are individually calculated for each UE, and it is more than Z% based on the UE having the highest NACK ratio (for example, UE1 with a NACK rate of 100%) It can then be increased to a larger allowed CWS value. However, if the current CWS values of the terminals are not the same, the base station increases the next largest CWS value based on the current CWS value corresponding to the largest, smallest, or intermediate (average) of them. The increased CWS value is the UL LBT parameter for the next UL transmission, and the next UL burst or transmission within the subframe may be indicated by the base station to the terminal that is scheduled or indicated.

Referring to FIG. 8, a reference subframe and / or a reference UE for UL CWS coordination for upcoming UL bursts or UL transmissions on a UL subframe may be allocated to at least one or more UL subframes in the upcoming UL burst or subframe, One or a plurality of subframes in a UL burst or a subframe (viewpoint of each UE) of a UE to be scheduled becomes a reference subframe and the UEs scheduled to be scheduled become a reference UE.

The difference from the example of FIG. 6 and FIG. 7 is that in the example of FIG. 8, a statistic value of the NACK for the UL burst of the latest UL burst or the UL burst of the terminals to which UL transmission is instructed or instructed on the UL subframe is used Is the point. Therefore, according to the scheduling performed by the base station in the previous UL burst, the UE can adjust the NACK rate for the PUSCH transmission performed in the previous UL burst, not the latest UL burst in the base station view, to CWS control for the upcoming UL burst transmission It can be used as a corresponding statistical value.

In addition, in the present invention, not only a recently scheduled UL burst or a subframe but also a UL burst or a subframe scheduled before the UL burst or a subframe can be considered as a reference subframe. In addition, if there is a large time difference (for example, K bursts, a subframe or a frame difference) with respect to UL burst or subframe transmission in which the most recent UL burst or subframe scheduled in the UE-side is scheduled, the NACK rate of the corresponding UE is . Where K may be any value greater than one.

The method of selecting the statistic value may be performed by calculating a NACK (or NACK%) of UEs having the highest (lowest, lowest, or median NACK%) as shown in FIG. 7, As shown in FIG. If the percentage of NACKs determined by this scheme is at least Z% (e.g., 50 or 80%), the CWS value for all UEs scheduled for the next UL burst can be increased to the next larger allowed CWS. However, if the current CWS values of the terminals are not the same, the base station increases the next largest CWS value based on the current CWS value corresponding to the largest, smallest, or intermediate (average) of them. The modified CWS value may be signaled to the UEs by the base station and used for UL LBT operation of UEs scheduled for the next UL burst.

In addition to the measured NACK ratio value based on at least one of the above proposed methods, the base station may have additional considerations for adjusting the CWS value. It will be the CO value and / or the RSSI value measured by the base station. Therefore, the base station may determine the CWS value to be used for the upcoming UL burst based on the NACK ratio measurements of the previously performed UEs (based on the proposed method above) and the channel measurements of the base station (eg CO or RSSI values) eg whether the CO value or RSSI value is above a certain threshold) and finally decide whether to change the CWS.

The example shown in FIG. 8 may be effective in considering the previous channel environment of the UEs involved in scheduling in the upcoming UL burst, but if the latest scheduling time point differs from the present time point in view of the UE, And there is a need for a scheduling constraint to predict UL scheduling for an upcoming UL burst or subframe in advance. Therefore, this method can be effectively applied in indoor environments where the license-exempt channel environment is not changed much or when there are few contiguous competing nodes.

In addition, as another example of the present invention, the above-described examples of Figs. 6 to 8 may be applied in combination.

For example, a CWS to be used for upcoming UL bursts or channel occupancy in a subframe may be one or more subframes in the most recent burst or subframe in terms of a base station, and the scheduled UEs become reference UEs . In addition, as in the example of FIG. 8, the UL burst or the ratio of the NACK received in the subframe can be considered from the viewpoint of the UEs scheduled in the upcoming UL burst. By determining the CWS size in consideration of the number of samples of the NACK, a more stable CWS value can be selected than the above methods.

In the case of deriving the CWS value alone without the above-mentioned base station signaling, the NACK ratio of the terminal performing the UL LBT, except for considering the signaling by the base station and the NACK ratio of a plurality of terminals, Can be applied in the same manner. Therefore, each UE can independently apply the CWS value to the upcoming UL LBT by adjusting the NACK rate value of each UE.

Hereinafter, a common signaling scheme for UL LAA will be described.

You can use DCI format 1C with CC-RNTI in the LAA common DCI format. The LAA common DCI may include subframe configuration for LAA (4 bits) information, and the subframe configuration for LAA information may include information on the last subframe of the DL burst (i.e., a partial subframe that performs DL transmission only on some OFDM symbols) And the common signaling is a common signaling signal from the base station to the terminals. The LAA common DCI may be scrambled with the DCI format 1C with CC-RNTI, and the LAA serving cell or scheduling cell in which UL burst or subframe transmission scheduled by the LAA common DCI is performed (e.g., cross-carrier scheduling is set Terminal) or the common search space of the PC, and the terminal performs PDCCH monitoring based on the mapped information.

Signaling information that may additionally be included in the LAA common DCI to further support UL burst transmissions may include an UL burst length indicator, a CWS adaptation indicator for UL LBT, or a UL CCA And a UL CCA skip indicator.

The UL burst length indicator is the total number of UL subframes within the UL burst and can be defined in SF (subframe) or ms. If a UL subframe in which a reservation signal is transmitted for a channel occupation purpose of a UE can be excluded from the UL burst length value. The range of values that this signaling information can have is 1, 2, ... , 9, 10 SF (or ms).

The CWS adaptation indicator for the UL LBT may be used to indicate to the terminal the CWS value determined by the base station as described in the examples of FIGS. 5-8. That is, the CWS value determined by the base station can be indicated to the UEs through the LAA common DCI. The range of values that this signaling information may have is 3, 4, 5, 6, 7.

The UL CCA skip indicator may be used to indicate whether the UL CCA skip is determined by the base station as described in the example of FIGS. 1-4. For example, the signaling information may be included in the DCI as a field indicating a 1-bit CCA skip on / off.

Hereinafter, an adaptive UL LBT parameter setting method corresponding to the UL LBT channel access priority class will be described.

The DL LBT by the base station can be performed based on the parameter values as described with reference to Table 2 above. The base station can perform channel occupancy on the LAA serving cell according to DL traffic based on different LBT parameter values for each channel access priority class.

In addition to the DL LBTs thus carried out by the base station for at least UL grant transmission purposes, examples of the present invention for UL LBT parameter settings utilized for UL LBT purposes are described below.

The CWS adjustment scheme for UL LBT described with reference to FIGS. 5 to 8 may be performed for each channel access priority class (p). Also, as mentioned above, if the CWS should be increased, the value to be increased to a certain CWS value can be determined based on the allowed CWS value as shown in Tables 11 to 16 below. However, the UE may have different channel access parameters depending on whether the UE is configured as self-scheduling, cross-carrier scheduling, or at least PDSCH transmission.

In the present invention, a method of selectively or adaptively applying different UL Channel access parameters (hereinafter referred to as UCAP) according to different settings and DL LBT operation conditions is proposed. However, each of the proposed methods can be applied to different cases.

Case 1 is set to self-scheduling or cross-carrier scheduling (at least including PDSCH transmission on the LAA serving cell), and the maximum channel occupancy time (MCOT) by DL LBT (DL LBT for at least (E) PDCCH transmission) Is shared between the BS and the UE for DL and UL transmissions. The UCAP values of UL LBT that can be utilized in this case can be defined as shown in Table 11 or Table 12 below. Here, the maximum channel occupation time value T _{mcot, p} can refer to the value of the DL LBT. Case 1 deals with the UCAP value for performing UL LBT when DL LBT for PDSCH transmission is performed regardless of the scheduling scheme.

In the present invention, in order to perform the reduced UL LBT, m _p indicated for each Channel Access Priority Class is always 1. m _p is one value that constitutes the Defer period to be considered in performing UL LBT. Defer period is calculated through the 16us 9us + m * _p.

CW _{min, p} and CW _{max, p} represent the minimum and maximum values of the CWS, respectively, and represent the range of the changeable CWS considered in the examples of FIGS. 5 to 8, and the size of the allowed CW _p is allowed within the range Gt; CWS &lt; / RTI &gt;

Case 2 is set to self-scheduling, and the MCOT values of DL LBT and UL LBT are selected independently (or individually). The UCAPs of the UL LBT for this case can be selected independently of (or separately from) the parameters of the DL LBT based on the values shown in Table 13 or Table 14 below.

Case 3 is set to cross-carrier scheduling, and UCAPs of only UL LBT without DL LBT (or without PDSCH) can be selected based on values such as Table 15 or Table 16 below. Or the LBT parameter values (i.e., Table 2) utilized for PDSCH transmission. In the case of cross-carrier scheduling, there is no UL grant transmission failure probability due to the DL LBT. However, in order to have a competitive advantage compared to a grant-less transmission system (for example, Wi-Fi system) Shorter LBT parameters can be used.

For example, in Japan, the DL burst maximum transmission time at the regulation level is limited to 4ms. When the DL burst transmission is continuously performed, the channel sensing time (CCA) between the DL bursts is 34us, and the sum of the sensing time and the DL burst transmission time is smaller than the time value of us unit calculated according to the following equation It should not be big.

In Equation (1), T _mcot is the maximum channel occupation time. T _j is 4us and T _js is 34us.

In contrast, in the UL burst transmission considered in the present invention, in the case where the UL burst transmission is permitted after the DL burst transmission performed on the channel occupied through the DL LBT, the UL burst transmission is performed during the channel sensing time CCA of 34 UL burst transmission may be possible depending on idle or busy compared with ED threshold. In this case, the sum of the channel sensing time and the DL-UL burst transmission time should not be larger than the result of Equation (1).

Although the above-described exemplary methods are represented by a series of acts for clarity of explanation, they are not intended to limit the order in which the steps are performed, and if necessary, each step may be performed simultaneously or in a different order. In addition, not all illustrated steps are necessary to implement the method according to the present invention.

The foregoing embodiments include examples of various aspects of the present invention. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

The scope of the present invention includes an apparatus (e.g., a wireless device and its components described with reference to FIG. 9) that processes or implements an operation in accordance with various embodiments of the present invention.

9 is a diagram for explaining a configuration of a wireless device according to the present invention.

FIG. 9 illustrates a terminal apparatus 100 corresponding to an example of a downlink receiving apparatus or an uplink transmitting apparatus, and a base station apparatus 200 corresponding to an example of a downlink transmitting apparatus or an uplink receiving apparatus.

The terminal device 100 may include a processor 110, an antenna unit 120, a transceiver 130, and a memory 140. [

The processor 110 performs baseband-related signal processing and may include an upper layer processing unit 111 and a physical layer processing unit 112. The upper layer processing unit 111 may process an operation of a MAC (Medium Access Control) layer, an RRC (Radio Resource Control) layer, or higher layers. The physical layer processing unit 112 can process the operation of the physical (PHY) layer (e.g., uplink transmission signal processing, downlink reception signal processing). The processor 110 may control the overall operation of the terminal device 100, in addition to performing baseband-related signal processing. In addition, the processor 110 checks whether the UL CCA skip is enabled according to an exemplary embodiment of the present invention. For this purpose, the processor 110 confirms the signaling transmitted to the base station, or the terminal itself measures the channel occupancy measurement value, regulation, UL transmission channel type, or signal type. In addition, when the processor 110 determines that the UL CCA skip is possible, the processor 110 identifies an OFDM symbol in the UL subframe to which the SRS is to be transmitted. Therefore, after checking the SRS transmission availability and the SRS transmission time, the SRS transmission is controlled. The processor 110 may check signaling information that may be additionally included in the LAA common DCI to further support UL burst transmission. (UL Burst Length Indicator), a CWS Adaptation Indicator for UL LBT, or a UL CCA Skip Indicator (UL CCA Skip Indicator) from the risk LAA common DCI The location of the SRS transmission symbol can be confirmed.

The antenna unit 120 may include one or more physical antennas, and may support MIMO transmission / reception when the antenna unit 120 includes a plurality of antennas. The transceiver 130 may include a radio frequency (RF) transmitter and an RF receiver. The memory 140 may store information processed by the processor 110, software related to the operation of the terminal device 100, an operating system, applications, and the like, and may include components such as buffers.

The base station apparatus 200 may include a processor 210, an antenna unit 220, a transceiver 230, and a memory 240.

The processor 210 performs baseband-related signal processing, and may include an upper layer processing unit 211 and a physical layer processing unit 212. The upper layer processing unit 211 may process the operations of the MAC layer, the RRC layer, or higher layers. The physical layer processing unit 212 can process the operation of the PHY layer (e.g., downlink transmission signal processing, uplink reception signal processing). In addition to performing baseband related signal processing, the processor 210 may also control operation of the entire base station apparatus 200. [ In accordance with one example of the present invention, the processor 210 may indicate UL CCA skip capability or provide relevant information for the terminal to determine. For example, the processor may determine UL CCA skip indication in consideration of scheduling of DL burst data and UL burst data, and control the signaling for the UL CCA skip indication to be transmitted to the UE. Here, the indication information for indicating the UL CCA skip may be controlled to be delivered to all UEs in the LAA serving cell, and may include information about a time point of a subframe in which UL burst transmission is terminated. In addition, the processor 210 receives the UL data and / or the SRS according to the scheduling information for each UE in the cell, acquires uplink channel information and path attenuation values between the UE and the BS, .

The antenna unit 220 may include one or more physical antennas, and may support MIMO transmission / reception when the antenna unit 220 includes a plurality of antennas. The transceiver 230 may include an RF transmitter and an RF receiver. The memory 240 may store information processed by the processor 210, software related to the operation of the base station 200, an operating system, applications, and the like, and may include components such as buffers.

(For example, received signal strength, etc.) for UL CCA operation described in various examples of the present invention is generated by the physical layer processing unit 112 of the processor 110 of the terminal 100 And may be transmitted to the upper layer processing unit 111. In addition, the physical layer processing unit 112 can receive DCI information and the like from the base station and transmit the DCI information and the like to the upper layer processing unit 111. The upper layer processing unit 111 may process the conditional UL CCA skip operation, adjustment of the contention window size value, LAA signaling information, UL LBT parameter, etc., described in various examples of the present invention.

More specifically, the processor 110 receives the transmitted DCI and confirms information indicating a skip or a hold for the CCA operation for uplink transmission, adjusts a contention window size for the uplink CCA, Adaptively applies uplink LBT parameters according to the link LBT channel access priority class to determine skipping or maintenance for UL CCA operation. Also, the processor 110 may control to determine a skip or hold for the UL CCA operation using the maximum channel occupancy time occupied by the DL LBT of the channel access priority class for the DL LBT. Also, the processor 110 may determine skipping or maintaining the UL CCA operation based on channel occupancy measurement (CO) and RSSI (Received Signal Strength Indicator) values measured by the terminal . The processor 110 may also determine a Skip or Hold for the UL CCA operation by checking the System Information Block (SIB) or LAA common DCI signaling. In addition, the processor 110 may determine skipping or maintenance of the UL CCA operation based on a scheduled UL burst, a subframe, or a reference subframe. Herein, the operation of checking the DCI by the processor 110 includes confirming the DCA format 1C with CC-RNTI by checking the LAA common DCI format. The processor 110 may also include one or more of an UL burst length indicator, a CWS adaptation indicator for a UL LBT, or a UL CCA skip indicator. Can be confirmed.

The physical layer processing unit 212 of the processor 210 of the base station 200 may transmit DCI information and the like for UL transmission described in various examples of the present invention to the terminal 100. The upper layer processing unit 211 may process the conditional UL CCA skip operation, adjustment of the contention window size value, LAA signaling information, UL LBT parameters, and the like, which are described in various examples of the present invention.

More specifically, the processor 210 controls the DCI to be transmitted and transmits the DCI to the terminal. In order to allow the terminal to skip or maintain the CCA for uplink transmission, Or adjusts the contention window size for the uplink CCA or adaptively applies the uplink LBT parameter according to the uplink LBT channel access priority class so as to determine skipping or maintenance for the UL CCA operation.

In addition, the processor 110 may skip or maintain the UL CCA operation for the UE based on channel occupancy measurement (CO) and RSSI (Received Signal Strength Indicator) values measured by the base station You can decide. In addition, the processor 110 may configure a system information block (SIB) or LAA common DCI signaling to determine a skip or hold for the UL CCA operation of the terminal. In addition, the processor 110 may determine skipping or maintenance of the UL CCA operation based on a UL burst, a subframe, or a reference subframe scheduled for the UE. Here, the operation of configuring the DCI by the processor 210 includes configuring DCI format 1C with CC-RNTI by configuring LAA common DCI format. The processor 210 may also include one or more of an UL burst length indicator, a CWS adaptation indicator for a UL LBT, or a UL CCA skip indicator. The DCI format may be configured to include the DCI format.

The operation of the processor 110 of the terminal 100 or the processor 210 of the base station 200 described above may be implemented by software processing or hardware processing or may be implemented by software and hardware processing.

The scope of the present invention includes software (or an operating system, application, firmware, program, etc.) that enables an operation according to various embodiments of the present invention to be performed on a device or computer, It includes a possible medium.

While various embodiments of the present invention have been described with reference to 3GPP LTE or LTE-A systems, they may be applied to various mobile communication systems.

Claims (7)

A method for performing uplink transmission in a license-exempt band in a wireless communication system,
Adjusting a contention window size for the uplink LBT or the uplink CCA;
Processing signaling information for uplink transmission and adaptively applying an uplink LBT parameter according to an uplink LBT channel access priority class;
And determining whether to perform an uplink LBT or an uplink CCA considering at least one of the adjusted window size, the signaling information, and the LBT parameter. An apparatus for performing uplink transmission in a license-exempt band in a wireless communication system,
An RF module for receiving a downlink signal from a base station or transmitting an uplink signal to the base station,
And a processor for controlling the operation of the RF module, wherein the processor receives a DCI transmitted to the base station and confirms information indicating a skip or a hold for a CCA operation for uplink transmission, Or adaptively applies uplink LBT parameters according to the uplink LBT channel access priority class to determine skipping or maintaining for UL CCA operation,
And a memory coupled to the processor for storing information and parameters indicated by the base station. 3. The apparatus of claim 2, wherein the processor
Wherein a skip or hold for the UL CCA operation is determined using the maximum channel occupation time occupied by the DL LBT of the channel access priority class for the DL LBT. 3. The apparatus of claim 2, wherein the processor
(UL) CCA operation based on channel occupancy measurement (CO) values and RSSI (Received Signal Strength Indicator) values measured by the BS or the UL transmission apparatus. And transmitting the uplink data. 3. The apparatus of claim 2, wherein the processor
And determines a skip or a hold for the UL CCA operation by checking a system information block (SIB) or LAA common DCI signaling. 3. The apparatus of claim 2, wherein the processor
Wherein the UL CCA operation is skipped or maintained based on a scheduled UL burst, a subframe or a reference subframe. 3. The apparatus of claim 2, wherein the processor
Considering the scheduling of DL burst data and UL burst data, UL CCA skip is determined,
Wherein the control unit checks the symbol for SRS transmission considering the transmission of the UL burst data and controls the SRS transmission.

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