KR102443134B1 - Method and apparatus for uplink transmission supporting unlicensed band - Google Patents

Abstract

A method and apparatus for performing uplink transmission on an unlicensed band in a wireless communication system are provided.
A method of performing uplink transmission in an unlicensed band in a wireless communication system determines whether to perform uplink LBT or uplink CCA before performing uplink transmission, which is contention for uplink LBT or uplink CCA It may include at least one operation of adjusting the window size, processing signaling information for uplink transmission, and adaptively applying uplink LBT parameters according to an uplink LBT channel access priority class.

Description

Unlicensed band support uplink transmission method and apparatus {METHOD AND APPARATUS FOR UPLINK TRANSMISSION SUPPORTING UNLICENSED BAND}

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

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

Uplink transmission basically means that one or more terminals transmit data and/or control signals to the base station. Uplink transmission is required based on a listen-before-talk (UL LBT) scheme by a plurality of terminals. can

However, a specific method for this has not yet been determined.

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

The present invention provides a method and apparatus for occupying a channel of a terminal in performing UL transmission by applying the LBT method.

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

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

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

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. will be able

According to an aspect of the present invention, in a method for performing uplink transmission in an unlicensed band in a wireless communication system, it is determined whether to perform uplink LBT or uplink CCA before performing uplink transmission, and uplink It may include adjusting the contention window size for LBT or uplink CCA, processing signaling information for uplink transmission, and adaptively applying uplink LBT parameters according to the uplink LBT channel access priority class. .

The features briefly summarized above with respect to the invention are merely exemplary aspects of the detailed description of the invention that follows, and do not limit the scope of the invention.

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

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art from the following description. will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are intended to provide an understanding of the present invention, and represent various embodiments of the present invention, and together with the description of the specification, serve to explain the principles of the present invention.
1 to 4 are diagrams for explaining a conditional UL CCA skip method according to an example of the present invention.
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 example of the present invention.
9 is a diagram for explaining the configuration of a wireless device according to an example of the present invention.
10 is a diagram illustrating an SRS transmission operation according to an example of the present invention.
11 is a flowchart of an operation of transmitting an SRS according to another example of the present invention.
12 is a flowchart of an operation of a terminal transmitting an SRS according to an example of the present invention.
13 is a flowchart of an operation of a base station receiving an SRS according to an example of the present invention.

Hereinafter, content related to the present invention will be described in detail with reference to exemplary drawings and embodiments. In adding reference numerals to components in each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated in different drawings. In addition, in describing the embodiments of the present specification, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

In addition, this specification describes a wireless communication network, and an operation performed in the wireless communication network is performed in the process of controlling the network and transmitting or receiving a signal in a system (eg, a base station) having jurisdiction over the wireless communication network, This can be done in the process of transmitting or receiving a signal from a terminal coupled to the corresponding wireless network.

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

Terms used to describe embodiments of the present invention may be described by 3GPP LTE or LTE-Advanced (LTE-Advanced) standard documents, except when specified to be used in a different meaning. However, it should be noted that this is only for economical efficiency and clarity of explanation, and embodiments of the present invention are not limited to being applied only to a system conforming to 3GPP LTE or LTE-A or a subsequent standard.

Table 1 contains a description of the LBT process.

For self-carrier scheduling, the following UL LBT candidate procedure may be applied.

As a first example, before uplink burst transmission (UL burst transmission), by defining a CCA (Clear Channel Assessment) duration of 25 microseconds (us), the channel may be sensed during the CCA duration. Here, the duration for which sensing is performed may be less than or equal to the CCA duration.

As a second example, one of {3, 4, 5, 6, 7} may be selected as the maximum contention window size while applying a defer period of 25 us. That is, at the time of performing UL CCA, the UE senses the channel for a delay period of 25us, and if the sensing result determines that the channel is in an idle state, the number of CCA slots corresponding to the contention window size (that is, the contention window size * If N=0 (refer to DL LBT in Table 1) by performing additional channel sensing by CCA slot duration, UL transmission may be performed. For example, one CCA slot duration may be 9 us.

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

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

As a first example, before UL burst transmission, a CCA duration of 25 us may be defined, and a channel may be sensed during the CCA duration. Here, the duration for which sensing is performed may be less than or equal to the CCA duration.

As a second example, a delay period and an additional channel sensing period may be applied before UL burst transmission. The size of the delay period may be 25 us or less, and the contention window size ( 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), the UE is required to receive an uplink grant from the base station. Here, the uplink grant may correspond to 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 the above uplink grant in the unlicensed band, the base station may perform CCA (or LBT) to occupy the unlicensed band (or unlicensed channel). If the CCA result channel is in the idle state, the uplink grant may be transmitted to the UE through the PDCCH or EPDCCH on the corresponding unlicensed band. An example of the present invention provides two modes as a signaling method for instructing scheduling.

First, as described above, in the present invention, in a case in which Physical Uplink Shared Channel (PUSCH) transmission associated with an uplink grant is performed in the same serving cell (or carrier, band, etc.), self-scheduling (or self-scheduling) -carrier scheduling).

Otherwise, that is, when PUSCH transmission associated with an uplink grant is performed in another serving cell (or carrier, band, etc.), it is called cross-carrier scheduling.

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

Unlike the one-time CCA (Clear Channel Assessment) for downlink scheduling and data transmission required by the base station in the unlicensed band, in the case of uplink data transmission, the base station performs CCA for data scheduling (uplink grant transmission) and CCA performance of a UE (hereinafter referred to as UE) for uplink data transmission (PUSCH transmission) may be additionally required.

Here, the CCA performance by the UE to which the present invention is applied may consider equity with other wireless systems coexisting in the unlicensed band. For example, the Wi-Fi (Wi-Fi) system is different from the LTE (hereinafter, LAA) system, data by scheduling of a specific central node (eg, an access point (AP) corresponding to the eNB of the LAA system). Since it does not perform transmission, a node requiring transmission (eg, a non-AP station (STA) corresponding to a UE in the LAA system) always occupies a channel through performing CCA and is on the unlicensed band occupying the radio signal. transfer can be performed.

As described above, it may be difficult to maintain fairness in occupying unlicensed channels due to different radio resource allocation methods between LAA and Wi-Fi systems. That is, in order for the LAA UE to transmit data in the uplink, the success of the DL LBT of the LAA eNB and the success of the UL LBT of the LAA UE must be simultaneously accompanied. -Fi will be placed in a channel occupancy environment (or condition) that is unfavorable compared to the AP or STA. In order to solve this problem, the CCA performance by the UE can be much more simplified than the CCA performance for the uplink grant transmission of the base station.

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

On the other hand, cross-carrier scheduling by a licensed carrier (eg, a primary cell (PCell)) for uplink transmission on an LAA serving cell (eg, an unlicensed carrier or a secondary cell (SCell)) When configured for scheduling, the DL LBT of the base station for uplink grant transmission may not be required for the terminal.

Hereinafter, a channel access procedure (ie, UL LBT) for uplink transmission (eg, PUSCH transmission, sounding reference signal (SRS) transmission, PUCCH transmission, or one or more of PRACH transmission) in the unlicensed band. 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 embodiment of the present invention, the UE skips or omits the UL CCA (or UL LBT) according to a predetermined condition in the LAA serving cell in which the base station secures the channel occupancy time through the DL LBT. and UL transmission can be performed immediately. Whether the terminal skips the UL CCA (or the change of the CCA operation mode of the terminal) may be signaled to the terminal(s) by the base station, or the terminal(s) may determine by itself. In addition, the change of the CCA operation mode may be applied in a long term or a short term, and a predetermined condition is a channel occupancy measurement value, received signal strength, regulation, UL transmission channel type or signal type, etc. can be determined based on Hereinafter, as an example of the present invention, long-term is a time longer than the unit (e.g. ~ 10ms) corresponding to UL burst/subframe, and is an integer multiple of 10ms (10*n ms) (where n is greater than ≥2) large natural number), and for example 40ms, 80ms, 160ms (integer multiple of one of the values of 40ms, 80ms, and 160ms (here, n is a natural number greater than ≥2))) It can be defined as a section. . On the other hand, a short-term may be defined as a section corresponding to a UL burst/subframe (e.g. ~ 10ms).

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

In order to perform UL transmission (at least data transmission) by the UE in the LAA serving cell, the UL grant (transmitted through (E)PDCCH) transmitted by the base station must be received. Also, one or more terminals may be instructed by the base station to perform UL transmission in the same subframe. In this case, a plurality of terminals may perform CCA for UL transmission within the same subframe.

In this case, all the terminals check whether the channel is idle by performing CCA in the same time interval (eg, UL CCA DURATION of FIG. 1 ), and if it is determined that the channel is idle, UL transmission can be performed. . Unlike DL LBT (ie, CCA only by eNB), a plurality of UEs perform CCA within the same CCA duration for UL transmission in the same subframe. It is possible to minimize the error blocking the channel access of other terminal(s) by entering the (busy) state.

As mentioned above, the UE for which UL transmission is scheduled or indicated by the base station may be required to perform CCA before performing UL transmission. However, requesting the UE to always perform CCA before UL transmission may cause unnecessary overhead. UL CCA may be skipped if the interference signal power from the terminal is not large to the nodes surrounding the terminal, or the influence of interference can be appropriately controlled so that interference or channel occupation fairness is not broken. Therefore, within the Maximum Channel Occupancy Time (MCOT) ( T _mcot,p in Table 2 below) occupied by the base station through the DL LBT, the terminals scheduled by the base station directly transmit UL without performing additional CCA. This can lead to performance improvement of the LAA system.

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

In Table 2, m _p , CW _min,p , CW _max,p , T _mcot,p , and CW _p are the number of CCA slots corresponding to channel access priority class p, respectively, contention window minimum value, contention window maximum value, maximum channel The occupancy time corresponds to the allowed contention window sizes.

Therefore, an example of the present invention proposes a method of selectively or conditionally performing UL CCA by the UE without always requiring UL CCA (UL LBT) from the UE. However, if the UE skips the UL CCA, the UEs that need to perform UL transmission must be premised on DL burst transmission by the eNB (that is, the UE receiving the DL burst transmission from the eNB performs UL transmission without performing UL CCA). can be done). Therefore, within the maximum channel occupation time ( T _mcot,p in Table 2) occupied by the DL LBT of the base station, the UEs may perform UL transmission without performing UL CCA.

In the example of FIG. 1 , if the proposed method is applied to the LAA serving cell including both DL-UL bursts, the DL burst ends and the minimum time gap for DL to UL transmission (eg, 9us, 16us, 25us, 36us...), the UE may directly perform UL transmission without performing CCA. In addition, the definition of a section for performing CCA may be disposed in front of one subframe or disposed at the back as shown in FIG. 1 . Here, in the present invention, the minimum time gap for DL-to-UL transmission may be defined as a switching gap for DL-to-UL transmission. The switching gap may have a value smaller than 9 μs. 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). In addition, 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.

Additionally, in the present invention, an operation that can selectively determine whether to perform CCA for UL LBT by the type of signal to be transmitted by the terminal, the occupancy frequency and measurement value of the unlicensed channel, regulation on unlicensed channel access, etc. is proposed. do. By newly defining this operation, the disadvantage of channel access that a scheduling-based system (eg, LAA system) inevitably has (eg, a non-scheduling-based system such as Wi-Fi (ie, without a central scheduler) (no centralized scheduler)) It is possible to overcome the disadvantage of channel access relative to the system) to some extent, and through it, it can lead to performance improvement because LAA terminals can perform UL transmission with a higher probability. In addition, if it can be ensured that there is no hidden node problem around the UE, the DL burst and the UL burst can be more effectively utilized.

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

In the present invention, the proposed UL CCA skip method is applied, for example, assuming that the channel is occupied through the DL LBT by the eNB in the DL burst for transmitting the PDSCH. 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 will be described below. The following examples may be applied individually or may be applied in combination of two or more.

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

2 is a diagram for explaining a channel occupation and RSSI measurement and reporting operation of a terminal according to an embodiment of the present invention.

In the example of FIG. 2 , channel occupancy and RSSI measurement and reporting may be performed for an LAA serving cell. In addition, it is assumed that the L1 (ie, physical (PHY) layer) average duration corresponds to 1 OFDM symbol length, and the L1 measurement duration corresponds to 70 OFDM symbol lengths.

The LAA UE (terminal) reports the occupancy frequency of the unlicensed channel (that is, a value measured by how many transmission nodes one unlicensed channel is used) and the RSSI value as in the example of FIG. 2 . Report to the base station based on the period.

The period value for RSSI and channel occupancy timing configuration (hereinafter, RSSI Measurement Timing Configuration, RMTC) for one unlicensed serving cell in the LAA system can be set by the base station to the terminal through higher layer signaling. Therefore, the period in which the RSSI measurement duration (L1 measurement duration) appears is determined according to the period setting of the RMTC. As the period values, {40, 80, 160, 320, 640} millisecond (msec) values may be used.

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

As in FIG. 2 , the L1 RSSI sample value is averaged through L3 (eg, RRC layer) filtering, and the RSSI value and the channel occupancy (hereinafter, CO) value may be reported to the base station by the UE together. Here, the CO value compares the RSSI threshold (eg, the value of the channelOccupancyThreshold parameter) set by the base station with all L1 RSSI samples in the L3 averaging window, and measures the ratio of RSSI samples greater 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 within one L3 averaging window to derive one UE reported RSSI value, and CO is similarly compared with 210 L1 RSSI samples and RSSI Threshold value and the ratio (that is, CO ) may be reported to the base station together with the UE reported RSSI value.

The terminal to which Example 1-1 is applied measures the CO value and transmits the value along with the measured RSSI value to the base station according to the set reporting period. The base station may additionally 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, it is determined whether or not to perform CCA before UL transmission of the UEs in the cell, and the determined value is signaled to the UEs.

Here, the CO value and RSSI value measured by at least the base station and/or the terminal are compared with the newly defined Channel Occupancy Ratio Threshold value. Alternatively, signaling on whether to skip UL CCA may be provided to at least one or more UEs corresponding to a specific group.

In this case, since the Channel Occupancy Ratio Threshold ( C _Thresh ) value proposed in Example 1-1 is a value used in the base station, it may not be signaled or configured to the UE. Accordingly, the terminal may receive the signaling on whether to perform CCA indicated by the base station and determine whether to perform CCA before UL transmission according to it. If CCA is not performed by the UE, PUSCH and PUCCH (Physical Uplink) immediately after a predetermined time gap (eg, up to 34us, 25us, 20us, 16us, 9us, or 10us) has elapsed after DL burst transmission is finished. Control Channel), PRACH (Physical Random Access Channel), or SRS may be transmitted (refer to the example of FIG. 1 ).

3 is a diagram for explaining an operation of a base station for determining whether to perform UL CCA according to an example of the present invention.

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

C _m,i : A channel occupancy value measured in a measurement reporting period corresponding to index i by a UE on one LAA carrier (Channel Occupancy Measurement). This value is [0 … 100]. The index i is an index value for a channel occupancy value measured within an L3 measurement window (measurement reporting period) of a specific time point. Basically, the range of i may be at least one, or may be one or more set numbers (M).

C _Thresh : As Channel Occupancy Ratio Threshold, the threshold value for the CO value on one LAA serving cell. This value is [0 … 100]. When the CO value measured within the L3 measurement window is greater than a specific threshold C _Thresh , the base station instructs the LAA terminals in the cell whether to perform UL CCA through signaling. In this case, UL CCA should be performed, and signaling should be performed by the base station.

If the proportion of C _m,i < C _Thresh (i=0 ... M -1) is greater than or equal to X %, then avg[ C _m,i ] < At C _Thresh (that is, when the average value of C _m,i values is smaller than the threshold C _Thresh ), the UE does not perform CCA during the channel access procedure by signaling of the base station, and a predetermined time gap ( For example, after a maximum of 34us, 25us, 20us, 16us, 9us, or 10us) passes, one or more of PUSCH, PUCCH, PRACH, or SRS may be transmitted (see FIG. 1 ). Here, the value of M is the total number of samples of CO values and may have as many as M measurement reporting periods. It can also be called the length of the observation section. The value can be 1 or more including 1, and can be set and indicated through higher layer signaling.

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

The M value may be fixed to one arbitrary value (eg, 1), or one value may be selected and used by the base station from an arbitrary set (eg, {1, 2, 3 ... 9}).

3 , in order for the base station to determine whether to skip UL CCA, it is possible to determine whether to skip UL CCA by comparing a total of M=3 COs and RSSI report values with a threshold C _Thresh . where C _{m,i =0} = 70, C _{m,i =1} = 50 and C _{m,i =2} = 60, the average value of the C _m,i values (ie, C _m,avg or avg[ C _m,i ]) is 60. C _{m, avg} Since the value is smaller than C _Thresh = 70, the base station determines that it is UL CCA skip. Accordingly, the base station may instruct the LAA terminals to skip the UL CCA through cell-specific common signaling (eg, system information block (SIB) or LAA common DCI signaling), and the terminals receiving it then receive the DL burst and skip UL CCA before transmission in the next UL burst or subframe and perform UL transmission immediately.

Also, as in the above example, when M=3, the following average value is measured, C _{m,i =1} = 50, C _{m,i =2} = 60 and C _{m,i =3} = 40, the average value of C _m,i values (ie, C _m,avg or avg[ C _m,i ]) is 50. In this way, the average value can be measured by reflecting the recent measurement result in the new measurement result for each measurement reporting section. Also, the average value can be measured by moving the averaging window (averaging samples) (cumulative average).

The above method shows as an example that the terminal skips UL CCA under a specific condition based on the signaling of the base station, but it is not limited thereto and the terminal or terminal group individually (or by themselves) without base station signaling based on the above method It is also possible to determine whether to skip the UL CCA.

Next, according to Example 1-2 of the present invention, the CCA operation method can be changed only when the absence of another RAT (Radio Access Technology) system for a long term is guaranteed.

In Example 1-2, if the absence (absent) of another RAT other than LAA is guaranteed on the corresponding LAA serving cell (unlicensed carrier) by level of regulation, the base station provides the UE with CCA for UL transmission (UL Broadcasting information (eg, SIB) or dedicated signaling (eg, RRC reconfiguration) through a licensed carrier (eg, PCell) not to perform CCA) and instructions are possible. This is the maximum occupancy time T _mcot,p after the base station performs DL LBT for (E)PDCCH transmission including at least a UL grant, and occupies the corresponding channel section corresponding to UE may transmit one or more of PUSCH, PUCCH, PRACH, and SRS without performing UL CCA.

Furthermore, in Example 1-2, if the absence of RAT other than LAA is guaranteed on the corresponding LAA serving cell (unlicensed carrier) at the regulatory level, in addition, by the method as in Example 1-1, the base station performs the next UL If it is determined that the UE does not perform UL CCA in a burst or subframe, broadcasting information (eg, SIB) or higher layer signaling (eg, SIB) so that the base station does not perform CCA for UL transmission (UL CCA) to the UE , RRC signaling) can be preset and indicated.

In addition, when the absence of an RAT other than LAA is guaranteed on the corresponding LAA serving cell (unlicensed carrier) according to regional regulation without signaling by the base station, the UE always determines the maximum channel occupancy time occupied by the base station. It is possible to skip performing CCA before the UL transmission.

Therefore, according to the above method, if CCA is not performed by the UE, the UL immediately after a predetermined time gap (eg, up to 34us, 25us, 20us, 16us, 9us or 10us) has elapsed after the DL burst transmission is finished. Transmission (eg, transmission of one or more of PUSCH, PUCCH, PRACH, or SRS) may be performed (see FIG. 1 ).

According to Example 2-1 of the present invention, the CCA operation method may be changed in short term, and the CCA operation method may be changed according to a UL transport channel or signal information type.

Unlike Example 1-1 or 1-2, in Example 2-1, whether the UE performs CCA before UL transmission may be determined according to a UL transmission channel type or UL signal type in a corresponding UL burst or UL subframe. The types of UL transport channels or signals may be divided into PUSCH, PUCCH, PRACH, and SRS. In addition, the UL signal type may be divided into data, Hybrid Automatic Repeat request (HARQ)-ACK, Scheduling Request (SR), Channel State Information (CSI) feedback, Buffer Status Report (BSR), random access, and the like.

These UL physical channels or signal types may be individually distinguished one by one, or may be divided into two or more group units. Whether to skip CCA for all combinations of types can be defined in advance, and the base station can instruct UE(s) requiring UL transmission whether to skip CCA in advance using a dynamic signaling method such as (E)PDCCH. Accordingly, whether or not to skip UL CCA for each of all possible UL transmission combinations within the next UL burst is defined in advance, and the base station determines whether to skip UL CCA based on it, and the result can be signaled to the UEs.

For example, through (E)PDCCH signaling with a UL grant (DCI format 0 or 4) or LAA common DCI (DCI format 1C scrambled by CC-RNTI), the base station informs the terminals of whether to skip CCA every UL burst or UL It can be indicated before the subframe. For example, the base station determines in advance whether to skip UL CCA for each UL channel or signal type as shown in Table 3 below, and selects the corresponding UL burst or signal according to the type of channel or signal to be transmitted by UEs in the corresponding UL burst or UL subframe. Whether to skip CCA by the UE may be indicated in the UL subframe. As such, in order to indicate whether to skip UL CCA for each UL channel or signal type, dynamic signaling such as (E)PDCCH signaling with a UL grant or LAA common DCI may be used.

Here, the operation of indicating whether to skip the UL CCA is always effective after the DL burst is transmitted to the terminals through the DL LBT by the base station, and if the DL LBT is not required (eg, including the PDSCH When it is necessary to transmit UL burst or UL subframe by performing UL LBT without DL burst transmission), the CCA skip operation may not be applied.

Table 3 exemplarily shows whether CCA is performed according to the type of channel or signaling that can be transmitted in the UL LAA serving cell, but is not limited thereto. In Table 3, items marked with “-” mean that actual combination is impossible (eg, when data information of the UE is transmitted through PRACH or PUCCH, etc.).

For example, when the type of channel and signaling information for UL transmission within the UL burst or UL subframe transmission immediately following the DL burst is PUCCH and HARQ-ACK or SR, the UE uses UL CCA for transmission on the LAA UL serving cell. HARQ-ACK or SR may be transmitted through PUCCH immediately after skipping and after a certain period of time (eg, 16us). Here, the switching gap for UL transmission in the DL is 9us, 16us, 25us, 36us... Alternatively, it may be defined as an integer multiple (9μs*1, 9μs*2,…9μs*N) of the CCA slot length (9μs), or a different value according to the specification of the terminal.

As an additional example, if data (or PUSCH) transmission is scheduled (or exists) at least once or more within an upcoming UL burst or UL subframe transmission, the UE always UL CCA regardless of the existence of other channels or signaling information types. can be performed. Otherwise, when data (or PUSCH) transmission is not scheduled (or does not exist) within the upcoming UL burst or UL subframe transmission, UL CCA is skipped or some signaling information type (eg, SR) depending on the signal type. >(or =) may be defined as HARQ-ACK > CSI) or a combination of some channels and signaling information types (eg, PUCCH with HARQ-ACK > PUSCH with HARQ-ACK > PUSCH with CSI) It is also possible to skip UL CCA only for UL transmission and perform UL CCA for the remaining signal types.

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

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

In the example of FIG. 4, UE1 includes at least one PUSCH transmission because DATA transmission through PUSCH is scheduled in UL subframe #0 (UL SF#0), UL SF#1, and UL SF#2. it can be decided that UE2 transmits HARQ-ACK through PUCCH in UL SF#0 and UL SF#1 and transmits SR or CSI through PUCCH in UL SF#3. can UE3 transmits PRACH in UL SF#0, and DATA transmission through PUSCH is scheduled in UL SF#2 and UL SF#3.

As an additional example, a specific type among the UL channel (eg, PUSCH, PUCCH, PRACH, or SRS) and signaling information types that each UE should transmit in UL subframes within the upcoming UL burst exceeds a certain percentage (Y%). A method of skipping UL CCA only when transmitted, and performing UL CCA otherwise is also applicable.

However, in Example 2-1 above, only some OFDM symbols are DL transmitted in a subframe in which UL CCA is performed, that is, a last partial subframe of a DL burst (ie, in one subframe like DwPTS of a DL burst). UL scheduling information (eg, UL grant by DCI format 0 or 4) of the (E)PDCCH transmitted in the subframe used for . This is because, since the UL data transmission exceeding the maximum channel occupation time occupied through the DL LBT is out of the time occupied by the DL LBT, a new UL only LBT is performed and UL data transmission must be performed.

Hereinafter, a base station dynamic signaling method for whether UL CCA is performed will be described.

Whether or not CCA is performed by the UE before transmission of a specific UL burst (or UL subframe) by the base station is determined by a 1-bit field in the UL grant (DCI format 0 or 4) or DCI format 1C with CC-RNTI (eg, CCA). By adding a field indicating skip on/off) value, the base station can dynamically instruct the terminal in advance. In particular, the above DCI format 1C with CC-RNTI is an LAA common control signal transmitted on a common search space, which is one of PDCCH transmission resources defined for each LAA DL serving cell. In the signaling, the same information is repeatedly transmitted in the last subframe (subframe n) of the DL burst and the subframe immediately before the last subframe (subframe n-1). Through the signaling, the number of OFDM symbols used for DL transmission is signaled to the UE in the last partial subframe of the DL burst, and used for accurate data or control signal decoding and CSI measurement of the UE.

An example of the present invention may signal to 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 the signaling overhead and the increase in the DCI size of DCI format 0 or 4, instead of individually signaling to each of the LAA terminals, DCI format 1C with CC-RNTI may be utilized to signal to a plurality of LAA terminals at once. Alternatively, in DCI format 1C with CC-RNTI, masking (scrambling) for indicating a CCA skip on/off value in 16bit-CRC may be performed to instruct the UE. In this case, 1 bit increase in DCI format can be prevented.

According to Example 2-2 of the present invention, if the absence of RAT other than LAA is guaranteed on the corresponding LAA serving cell (unlicensed carrier) at the regulatory level, CCA according to the UL transport channel or signal information type in short term You can also change the way it works.

Example 2-2 is the same as Example 1-2 described above (that is, if the absence of RAT other than LAA on the corresponding LAA serving cell at the regulatory level is guaranteed), Example 2-1 (ie, Short-term CCA operation method change) operation may be applied. In Example 2-2, at least because the absence of another RAT is guaranteed by the regulation in the corresponding LAA serving cell, it may be easier to use the LAA serving cell fairly and to coordinate the interference between each other, so that the UL CCA It has the advantage of minimizing the interference problem that may occur in skipping.

According to Example 2-3 of the present invention, the CCA operation method may be changed according to the UL transport channel or signal information type in a short term along with the determination in Example 1-1 within a specific measurement period.

Example 2-3 is a method of determining whether to skip CCA in a long term through Example 1-1 (that is, a method of determining whether to perform CCA based on long-term statistics (eg, CO, RSSI, etc.)) described above In addition, it corresponds to a method of determining whether to skip the final UL CCA for each UL burst or subframe through the operation of Example 2-1 (ie, changing the CCA operation method).

Example 2-3 is based on the terminal's unlicensed channel environment information measured in the long term, and since Example 2-1 is additionally applied to this, whether to skip UL CCA in consideration of more channel usage status information and transmission signal or channel type This is a method that can determine whether to skip UL CCA based on more reliable information.

Example 3 of the present invention corresponds to a method in which the base station instructs terminals in a cell whether to skip CCA by applying one of Examples 2-1 to 2-3 while applying Example 1-2 described above. In the case of some terminals, since there may be many cases where the channel is busy because there are many neighboring transmission nodes, only such terminals can determine whether to skip CCA again based on the CO or RSSI value.

For example, the base station schedules and occupies a channel so that the UL burst comes immediately after a certain time interval (eg, 16us) after the DL burst. According to the UL channel and information type in the next UL burst or subframe (eg, See Examples 2-1 to 2-3) Whether to skip UL CCA may be indicated to UEs. On the other hand, each terminal compares the channel occupancy measurement value (CO) and RSSI value of the neighboring LAA serving cell with an arbitrary threshold value, and terminals having a channel measurement value greater than or equal to the threshold value may not skip the UL CCA for UL transmission. There is (eg, performing the operation of the terminal according to Example 1-1).

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

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

In more detail, 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 period or offset value for the cell-specific SRS subframe setting is set using the values in the above table according to each of FDD (frame structure type 1) and TDD (frame structure type 2) through higher layer signaling. Based on the information on the SRS subframe in the cell through the above configuration, UEs connected to the cell can check information on the cell-specific SRS subframe being considered in the current cell.

In addition to the cell-specific SRS subframe configuration, each UE is additionally configured by the base station so that a subframe capable of SRS transmission becomes a subset of the above cell-specific SRS subframe. In the following description, a UE-specific SRS subframe configuration method corresponding to a type 0/1 SRS subframe and conditions for an 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 is period

with offset

Each is defined for FDD and TDD in the table below. Type 0 SRS transmission is a TDD serving cell (

) and in the FDD serving cell

It is performed in a subframe that satisfies where FDD

, and in the case of TDD, use Table 6. That is, Table 6 is for TDD.

is shown.

and Subframe Offset Configuration

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

and Subframe Offset Configuration

is shown.

and Subframe Offset Configuration

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

and Subframe Offset Configuration

is shown.

와 오프셋

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

with offset

is defined using , and its value is 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 UE Specific SRS Periodicity for Trigger Type 1 (Aperiodic SRS) in FDD

and Subframe Offset Configuration

is shown.

and Subframe Offset Configuration

를 나타낸 것이다.Table 10 shows UE Specific SRS Periodicity for Trigger Type 1 (Aperiodic SRS) in TDD

and Subframe Offset Configuration

is shown.

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 type 1 SRS transmission is received in subframe n in one serving cell, the type 1 SRS transmission should be transmitted in a subframe that satisfies the following condition. those conditions

Wow

(

In the case of a TDD serving cell and an FDD serving cell having

(

In the case of a TDD serving cell having Here, in the case of an FDD serving cell,

and in the case of a TDD serving cell

for the above TDD

use the value

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

Referring to FIG. 10 , there may be a case in which the SRS 1030 is transmitted together with the PUSCH 1020 and a case in which only the SRS is transmitted within the same subframe. Here, when an arbitrary terminal intends to transmit only SRS through the unlicensed band within a single subframe, it should be confirmed that SRS transmission is possible through the LBT process. In addition, the SRS should be transmitted in the earliest OFDM symbol after the LBT period ends so that the unlicensed band is not occupied by other UEs and devices.

Therefore, in the present invention, when the UL CCA skip condition is satisfied, a UE desiring to transmit only the SRS may transmit the SRS at a point in time when UL transmission is possible without CCA.

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

11, since the DL burst 1110 exists before the UL burst in the same LAA serving cell and DL LBT is always performed by the base station to transmit the DL burst 1110, only the SRS 1130 is used. When the transmitting terminal recognizes that UL CCA skip is possible, there are terminals that proceed directly to PUSCH 1120 without CCA in the UL transmission interval, and there are UEs controlled by other base stations and other radio access technology (RAT) devices. Thus, it may be determined that the PUSCH transmission occupies 80% or more of the LAA serving cell band by transmission of the PUSCH 1120 of the other terminals so that the LAA serving cell band is not occupied by the UE.

Accordingly, the UE transmitting only the SRS 1130 may set the SRS 1130 transmission time point to the last OFDM symbol of the UL subframe in which the PUSCH 1120 transmission is performed and transmit the same. If the information on the time of the subframe at which the UL burst transmission ends is included in the control information including the indicator for indicating the UL CCA skip and is provided, the terminal transmitting only the SRS starts the UL burst and With respect to the SRS transmitted during at least one or more subframe periods that are terminated, the SRS 1130 is transmitted in the last OFDM symbol of the UL subframe in which the SRS is to be transmitted.

12 is a flowchart of an operation of a terminal transmitting an SRS according to an example of the present invention.

Referring to FIG. 12 , a terminal that wants to transmit only the SRS in a specific LAA serving cell checks whether it is possible based on the conditional UL CCA skip method proposed in the present invention. As an example, as suggested through the description of FIGS. 1 to 4 of the present invention, the determination of whether to skip UL CCA by the terminal (or change of the CCA operation mode of the terminal) is determined by the base station by the base station (s) may be signaled to, or the terminal(s) may determine by itself ( 1210 ).

In addition, the change of the CCA operation mode may be applied in a long term or a short term, and a predetermined condition for the change of the CCA operation mode is a channel occupancy measurement value, received signal strength, regulation, It may be determined based on a UL transport channel type or a signal type.

If it is determined that UL CCA skip is possible through the confirmation procedure, an OFDM symbol in a UL subframe to transmit SRS is checked ( 1220 ). The position of the OFDM symbol in the UL subframe for transmitting the SRS is a partial UL subframe including a part of the DL data transmission period, the UL data transmission period starts after the OFDM symbol at which the DL data transmission period ends. It can be fixedly defined as the first OFDM symbol. Alternatively, it may be fixedly defined as the last OFDM symbol of the partial UL subframe. Alternatively, one of the first OFDM symbol or the last OFDM symbol may be indicated by the base station. In this case, the base station may provide the indication information to each terminal by including the indication information as a cell-specific parameter in the SIB or RRC reconfiguration message for the indication.

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

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

The base station confirms that data to be scheduled in downlink has a DL burst type traffic pattern to some of the terminals currently in RRC connection with the base station and that data to be scheduled currently exist ( 1310 ). At the same time, based on buffer status report (BSR) information received from some of the UEs that have been RRC-connected with the base station, it is confirmed that there is data that the UEs want to transmit through the uplink, and the data is It is confirmed that a traffic pattern of a radio bearer (RB) that forms a one-to-one correspondence with an existing logical channel (LC) is a UL burst type traffic pattern.

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

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

Based on the determination, if necessary, the base station transmits UL CCA skip related information including indication information for the UL CCA skip indication to all terminals in the LAA serving cell. The UL CCA skip related information may include information on the timing of a subframe at which UL burst transmission ends. If there is a UL subframe capable of indicating the position of the SRS transmission OFDM symbol, the base station may transmit related indication information to each terminal.

The base station receives UL data and/or SRS according to information scheduled to each terminal in the cell (1330).

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 example of the present invention.

According to the method for setting the adaptive contention window size for UL LBT of the present invention, a reference subframe and/or a reference UE may be determined, and the contention window size may be adaptively determined based on this. Determining the reference subframe and/or the reference UE for this purpose determines the most recent UL burst (regardless of the UE in which the UL transmission is to be scheduled, or individually or as a whole for the UE in which the UL transmission is scheduled) as the reference subframe, UE(s) scheduled in the corresponding reference subframe may be determined as reference UE(s). In addition, by considering the NACK ratio for the reference UE(s) in the reference subframe individually or as a whole, the CWS value may be increased when it is equal to or greater than a predetermined threshold. Otherwise, the CWS value may be kept 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 random back-off, it is necessary to define a method for appropriately adjusting the contention window size (hereinafter, CWS) for UL LBT. have.

In DL LBT to which the present invention is applied, the CWS value is increased for each priority class based on HARQ-ACK information corresponding to the first subframe (ie, reference subframe for DL LBT) available in the DL burst. can be reset or reset. The reason for this is that the CWS size can be more adaptively adjusted to the unlicensed channel environment in the immediately following DL burst by referring to HARQ-ACK information corresponding to the first subframe in the DL burst. One of the reasons may be the frequent collisions with transmission nodes.

On the other hand, the method of determining the reference subframe for CWS adjustment for each priority class of the UL LBT according to the present invention must be performed in a different way from the determination of the reference subframe for CWS adjustment of the DL LBT, and the reason is as follows.

Unlike DL LBT (or DL CCA), an apparatus for performing UL LBT (or UL CCA) is at least one or more or a plurality of UEs. That is, since only the base station performs DL LBT (DL CCA), it is sufficient to consider one same channel environment, but different channel environments to which a plurality of UEs performing UL LBT (UL CCA) belong must be considered.

In addition, unlike DL LBT, in UL LBT, UL LBT operation of the UE and related parameter values (eg, Defer period, CWS max, CWS min, maximum channel occupancy time, Since the ED (Energy Detection) Threshold value, etc.) may be different, the reference subframe determination method for CWS adjustment related thereto must also be different from the DL LBT.

In DL burst transmission, continuous DL burst transmission is possible when the channel is idle for at least 24us (or 36us) by performing CCA between consecutive DL burst transmissions (eg Japan), but UL burst is at least Since a time of X ms (eg, 4 ms, HARQ-ACK timing between UL grant and PUSCH) is required between consecutive UL burst transmissions, it is necessary to consider only the first subframe (reference subframe) corresponding to available HARQ-ACK this is not high In particular, during self-scheduling, more time for performing DL LBT is required between UL bursts.

As shown in FIG. 5 , a plurality of UL subframes (SF#k, SF#k+1, SF#k+2) from a plurality of UEs (UE#0, UE#1, UE#2, UE#3) ), the HARQ-ACK for the PUSCH transmitted 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 UL LBT (UL CCA).

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

The base station may schedule PUSCH transmission to at least one or more terminals on the LAA SCell. Here, the base station considers the configuration of the scheduling method of each terminal. That is, whether self-scheduling or cross-carrier scheduling is determined for each UE.

The base station transmits the (E)PDCCH including the UL grant (ie, DCI format 0 or 4) to the terminal in which the self-scheduling is configured in the same serving cell as the LAA SCell in which PUSCH transmission is performed, while the cross-carrier scheduling is configured. The UE performs (E)PDCCH transmission including the UL grant in a serving cell other than the LAA SCell on which PUSCH transmission is performed (eg, PCell or other SCell on a licensed carrier). A terminal in which cross-carrier scheduling is configured may perform a different UL LBT (eg, an operation based on a different LBT parameter) from a case in which self-scheduling is configured.

The base station may need a reference subframe and/or a reference UE to determine a common CWS value of UL LBT (UL CCA) of UEs for UL transmission in an upcoming UL burst or subframe. The CWS value for the DL LBT is determined with HARQ-ACK information for PDSCHs transmitted in the first subframe of the most recent DL burst for which HARQ-ACK is available. The base station receiving the HARQ-ACK information for the PDSCH transmitted in the corresponding reference subframe of the LAA SCell from the terminal increases the CWS value if the HARQ-ACK information corresponding to at least the reference subframe has a NACK ratio of at least 80% or more.

On the other hand, the method for the UE to obtain or derive the CWS value of the UL LBT proposed by the present invention is as follows.

The first possible method is that the UL CWS value to be applied for the UL LBT on the next UL burst or UL subframe is signaled by the base station to the UE to indicate the determined CWS value to at least one or more UEs scheduled for the UL burst. Each terminal may 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 each UE can derive the UL CWS value individually (or by itself) according to a certain criterion. An attempt is made to occupy a channel for UL transmission by performing UL LBT based on the determined value.

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 the first method (that is, a method in which the base station determines the CWS and signals the terminal) suggest One or more of the methods described below may also be applied to the second method (ie, a method for the UE to individually determine the CWS). Referring to FIG. 6 , for UL transmission on an upcoming UL burst or UL subframe, The reference subframe and/or the reference UE of UL CWS coordination is at least one or more UL subframes in the most recently received UL burst or subframe from the base station's point of view become the reference subframe and at least those that were scheduled in the at least one or more UL subframes One or more UEs become the reference UE.

Also, according to the present invention, ACK or NACK information corresponding to a PUSCH received on all UL subframes corresponding to the most recently received UL burst from the viewpoint of a base station, regardless of previous PUSCH transmissions of UEs scheduled for an upcoming UL burst Based on the base, if the ratio of NACKs of all UEs is at least Z% (eg, 50 or 80%) or more, the CWS values for all UEs scheduled for the next UL burst may be increased to the next large allowed CWS. However, if the current CWS values of the terminals are not the same, the base station increases the allowed CWS value to the next largest value based on the current CWS value corresponding to the largest, smallest, or middle (average) among them. Then, the CWS value thus changed is signaled to the UEs by the base station to be 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 of UL CWS coordination for UL transmission on an upcoming UL burst or UL subframe is at least one or more UL subframes within the most recently received UL burst or subframe from the viewpoint of a base station. are the reference subframes, and at least one or more UEs scheduled in the at least one or more UL subframes become reference UEs in units of individual UEs or UE groups.

The difference from the example of FIG. 6 is that each UE or UE group (eg, the UE group may be composed of UEs scheduled for each UL subframe within the most recently received UL burst from the base station perspective) is the NACK value for each UE. Calculate the ratio, select the UE corresponding to the calculated NACK ratio is the highest (highest), the lowest (lowest), or the middle (median), the ratio of the NACK 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 may be increased to the next large allowed CWS. However, if the current CWS values of the terminals are not the same, the base station increases the allowed CWS value to the next largest value based on the current CWS value corresponding to the largest, smallest, or middle (average) among them. Then, the changed CWS value is signaled to the UEs by the base station and can be used for UL LBT operation of UEs scheduled for the next UL burst.

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

Referring to FIG. 8 , a reference subframe and/or a reference UE of UL CWS coordination for UL transmission on an upcoming UL burst or UL subframe is scheduled in at least one or more UL subframes within an upcoming UL burst or subframe from the viewpoint of a base station. One or a plurality of subframes within the most recent UL burst or subframe (from the viewpoint of each UE) of the UEs to be scheduled become the reference subframe, and the UEs scheduled to be scheduled become the reference UEs.

Here, the difference from the examples of FIGS. 6 and 7 is that, in the example of FIG. 8 , a statistical value of NACK for the most recent UL burst of terminals to which UL transmission is indicated or to be indicated on an upcoming UL burst or UL subframe is used. is the point. Therefore, according to the scheduling performed by the base station on the previous UL burst, a specific terminal sets the NACK ratio for the PUSCH transmission performed in the previous UL burst rather than the most recent UL burst from the base station's point of view to adjust the CWS for the upcoming UL burst transmission. It can be used as a corresponding statistical value.

Also, in the present invention, from the viewpoint of each UE, not only the recently scheduled UL burst or subframe but also the previously scheduled UL burst or subframe may be considered as a reference subframe. Additionally, if the most recent UL burst or subframe scheduled from the UE's point of view has a large time difference from the upcoming UL burst or subframe transmission (eg, K bursts, subframes, or frames difference), the NACK rate of the corresponding UE is the total statistics of the base station. may not be taken into account. where K can be any value greater than one.

The method of selecting the statistical value is the average NACK ratio (or NACK%) of all terminals as in the example of FIG. 6 or the NACK% of the UE selected as in the example of FIG. 7 (having the highest, lowest, or median NACK%) can be decided based on If the ratio of NACK determined by this method is at least Z% (eg, 50 or 80%) or more, CWS values for all terminals scheduled for the next UL burst may be increased to the next large allowed CWS. However, if the current CWS values of the terminals are not the same, the base station increases the allowed CWS value to the next largest value based on the current CWS value corresponding to the largest, smallest, or middle (average) among them. The changed CWS value is signaled to the UEs by the base station and may be used for UL LBT operation of UEs scheduled for the next UL burst.

Additionally, in addition to the NACK ratio value measured 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 that the base station measures. Therefore, the base station determines the CWS value to be used for the upcoming UL burst based on the previously performed NACK rate measurement value (based on the above proposed method) and the channel measurement value of the base station (e.g. CO value or RSSI value) ( e.g. whether the CO value or the RSSI value is above a specific threshold) Finally, it is possible to determine whether or not the CWS is changed.

The example shown in FIG. 8 can be effective in that the previous channel environment of UEs involved in scheduling for the upcoming UL burst is considered, but from the UE's point of view, if the most recent scheduling time is different from the current time, the current channel environment is not properly reflected. There is a possibility that it is not possible, and a scheduling constraint is required to predict in advance UL scheduling for an upcoming UL burst or subframe. Therefore, this method can be effectively applied in an indoor environment where the unlicensed channel environment does not change much or when there are few adjacent competing nodes.

Additionally, as another example of the present invention, the above-described examples of FIGS. 6 to 8 may be combined and applied.

For example, in the CWS to be used for channel occupancy in an upcoming UL burst or subframe, one or more subframes in the most recent burst or subframe from the base station's point of view become the reference subframe, and the scheduled terminals become the reference UE. . In addition to this, as in the example of FIG. 8 , the ratio of NACKs received in the most recent UL burst or subframe may be considered from the viewpoint of UEs scheduled in an upcoming UL burst. In this way, a more stable CWS value can be selected than the above methods by determining the CWS size in consideration of the larger number of NACK samples.

In addition, in the case of deriving the CWS value alone without the above-mentioned base station signaling, among the above proposed methods, the NACK ratio of the terminal performing UL LBT except for considering the signaling by the base station and the NACK ratio of a plurality of terminals The method of measuring can be applied in the same way. Therefore, each terminal can independently adjust the CWS value based on the NACK ratio value of each terminal and apply it for the upcoming UL LBT.

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

DCI format 1C with CC-RNTI may be used as 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 includes several OFDM symbols in the last subframe of a DL burst (that is, a partial subframe in which DL transmission is performed only on some OFDM symbols). It corresponds to common signaling in which the base station indicates to the terminals whether it is composed of . Such LAA common DCI may be scrambled in DCI format 1C with CC-RNTI, and an LAA serving cell or scheduling cell in which UL burst or subframe transmission scheduled by LAA common DCI is performed (eg, cross-carrier scheduling is set). UE) or the transmission may be mapped on the common search space of the PCell, and the UE detects it by performing PDCCH monitoring based on it.

Signaling information that may be additionally included in the LAA common DCI to additionally support UL burst transmission is a UL burst length indicator, a CWS adaptation indicator for UL LBT, or a UL CCA. It may include one or more of a skip indicator (UL CCA skip indicator).

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

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

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

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

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

As such, in addition to the DL LBT performed for at least the UL grant transmission purpose by the base station, examples of the present invention for the UL LBT parameter setting used for the UL LBT purpose will be described below.

The CWS coordination 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 needs to be increased, the value to be increased to a certain CWS value may be determined based on the allowed CWS values as shown in Tables 11 to 16 below. However, the corresponding terminal may have different channel access parameters depending on whether the terminal is configured for self-scheduling, cross-carrier scheduling, or at least whether or not there is PDSCH transmission.

The present invention proposes a method of selectively or adaptively applying different UL Channel access parameters (hereinafter, UCAP) according to different settings and DL LBT operation conditions. However, each of the proposed methods is applicable to different cases.

Case 1 is set to self-scheduling or cross-carrier scheduling (including at least PDSCH transmission on the LAA serving cell), and maximum channel occupancy time (MCOT) by DL LBT (at least DL LBT for (E)PDCCH transmission purpose) corresponds to the case where the base station and the terminal share for DL and UL transmission. In this case, the UCAP value of the UL LBT that can be utilized may be defined as shown in Table 11 or Table 12 below. Here, the maximum channel occupancy time value T _mcot,p may refer to the value of the DL LBT. Case 1 deals with a UCAP value for performing UL LBT when DL LBT for PDSCH transmission is performed regardless of a scheduling method.

In the present invention, in order to perform the abbreviated UL LBT , _mp indicated for each Channel Access Priority Class below always has a value of 1. mp is one value constituting the _Defer period to be considered for performing UL LBT. Defer period is calculated through 16us+9us* m _p .

CW _min,p and CW _max,p correspond to the minimum and maximum values of CWS, respectively, and indicate the range of changeable CWS considered in the examples of FIGS. 5 to 8, and the size of allowed CW _p is allowed within the range Shows the CWS values.

Case 2 corresponds to a case where self-scheduling is set, and the MCOT values of DL LBT and UL LBT are independently (or individually) selected. UCAPs of the UL LBT for this case may be selected based on values such as Table 13 or Table 14 below independently (or separately) from the parameters of the DL LBT.

Case 3 is configured for cross-carrier scheduling, and UCAPs of only UL LBT without DL LBT (or without PDSCH) may be selected based on the values shown in Table 15 or Table 16 below. Alternatively, LBT parameter values used for PDSCH transmission (ie, Table 2) may be used. In the case of cross-carrier scheduling, there is no UL grant transmission failure probability due to DL LBT, but if the channel occupancy probability is to be competitive compared to the grant-less transmission system (eg, Wi-Fi system), in other cases In comparison, shorter LBT parameters can be used.

For example, in Japan, the maximum DL burst transmission time is limited to 4 ms at the regulatory level. When DL burst transmission is performed continuously, the channel sensing time (CCA) between DL bursts is 34 us, and the sum of the sensing time and DL burst transmission time is greater than the time value in us calculated according to Equation 1 below. should not be large.

In Equation 1, T _mcot is the maximum channel occupancy time. T _j is defined as 4 us and T _js is defined as 34 us.

On the other hand, in the UL burst transmission considered in the present invention, after DL burst transmission performed in a channel occupied through DL LBT, when UL burst transmission is allowed, during the channel sensing time (CCA) of 34 (or 24) us. Compared to the ED threshold, UL burst transmission may be possible depending on whether it is idle or busy. Also, in this case, the sum of the channel sensing time and the DL-UL burst transmission time should not be greater than the result of Equation 1 above.

Although the above-described exemplary methods are expressed as a series of operations for the sake of brevity of description, this is 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 necessarily required for implementing the method according to the present invention.

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

The scope of the present invention includes an apparatus for processing or implementing an operation according to various embodiments of the present invention (eg, a wireless device and components thereof described with reference to FIG. 9 ).

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

9 illustrates a terminal device 100 corresponding to an example of a downlink reception device or an uplink transmission device, and a base station device 200 corresponding to an example of a downlink transmission device or an uplink reception device.

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 medium access control (MAC) layer, a radio resource control (RRC) layer, or a higher layer. The physical layer processing unit 112 may process operations (eg, uplink transmission signal processing, downlink reception signal processing) of the physical (PHY) layer. The processor 110 may control the overall operation of the terminal device 100 in addition to performing baseband-related signal processing. In addition, according to an example of the present invention, the processor 110 checks whether UL CCA skip is possible. For this purpose, it checks the signaling transmitted to the base station, or the terminal itself measures the channel occupancy value, received signal strength, regulation ( regulation), a UL transport channel type or a signal type is taken into consideration to control the CCA operation. In addition, when determining that the UL CCA skip is possible, the processor 110 checks the OFDM symbol in the UL subframe to transmit the SRS. Therefore, after checking whether the SRS transmission is possible 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 additionally support UL burst transmission. For the above, from the LAA common DCI, check one or more of a UL burst length indicator, a CWS adaptation indicator for UL LBT, or a UL CCA skip indicator. In this way, the location of the SRS transmission symbol, etc. can be confirmed.

The antenna unit 120 may include one or more physical antennas, and when it includes a plurality of antennas, it may support MIMO transmission/reception. 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, an application, and the like, and may include components such as a buffer.

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 higher layer processing unit 211 may process an operation of the MAC layer, the RRC layer, or higher layers. The physical layer processing unit 212 may process PHY layer operations (eg, downlink transmission signal processing, uplink reception signal processing). The processor 210 may control the overall operation of the base station apparatus 200 in addition to performing baseband-related signal processing. According to an example of the present invention, the processor 210 provides related information to indicate that the UL CCA skip is possible or to allow the terminal to determine it. For example, the processor may determine a UL CCA skip indication in consideration of scheduling of DL burst data and UL burst data, and may control signaling for this to be transmitted to the UE. Here, the indication information for the UL CCA skip indication may be controlled to be delivered to all UEs in the LAA serving cell, and information on a time point of a subframe at which UL burst transmission ends may be included. In addition, the processor 210 receives UL data and/or SRS according to information scheduled to each UE in the cell, and obtains uplink channel information and a path attenuation value between each UE and the base station for efficient scheduling. to promote

The antenna unit 220 may include one or more physical antennas, and when it includes a plurality of antennas, it may support MIMO transmission/reception. 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 apparatus 200 , an operating system, an application, and the like, and may include components such as a buffer.

Basic information (eg, received signal strength, etc.) of the channel state determination for the 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 . Also, the physical layer processing unit 112 may receive DCI information from the base station and transmit it to the higher layer processing unit 111 . The upper layer processing unit 111 may process the conditional UL CCA skip operation described in various examples of the present invention, adjustment of the contention window size value, LAA signaling information, UL LBT parameters, and the like.

More specifically, the processor 110 receives the transmitted DCI and confirms information indicating skip or maintenance for the CCA operation for uplink transmission, adjusts the contention window size for the uplink CCA, or uplink By adaptively applying the uplink LBT parameter according to the link LBT channel access priority class, skip or maintain for the UL CCA operation is determined. In addition, the processor 110 may control to determine skip or maintain 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. In addition, the processor 110 may determine to skip or maintain the UL CCA operation based on a channel occupancy measurement (CO) and a received signal strength indicator (RSSI) value measured by the terminal. . Also, the processor 110 may determine to skip or maintain the UL CCA operation by checking the system information block (SIB) or the LAA common DCI signaling. Also, the processor 110 may determine to skip or maintain the UL CCA operation based on the scheduled UL burst, subframe, or reference subframe. Here, the operation of checking the DCI by the processor 110 is checking the LAA common DCI format and includes checking the DCI format 1C with CC-RNTI. In addition, the processor 110 displays one or more of a UL burst length indicator, a CWS adaptation indicator for UL LBT, or a UL CCA skip indicator. can be checked

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

More specifically, the processor 210 comprises configuring the transmitted DCI to be transmitted to the terminal, and controlling to include information instructing skip or maintenance of the CCA operation for uplink transmission by the terminal. Or, by adjusting the contention window size for the uplink CCA, or by adaptively applying the uplink LBT parameter according to the uplink LBT channel access priority class, control to determine skip or maintain for the UL CCA operation.

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

The operation of the processor 110 of the terminal 100 or the processor 210 of the base station 200 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 operating system, application, firmware, program, etc.) that causes the operations according to various embodiments of the present invention to be executed on a device or computer, and stores such software and executes on the device or computer. Including possible medium.

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

Claims (7)

delete An apparatus for performing uplink transmission in an unlicensed band in a wireless communication system, comprising:
a radio frequency (RF) module for receiving a downlink signal from a base station or transmitting an uplink signal to the base station;
Including a processor for controlling the operation of the radio frequency module, the processor receives downlink control information (DCI) transmitted to the base station to the uplink available channel assessment (clear channel assessment, CCA) operation Check information indicating skip or maintenance for the UL, adjust the contention window size for the uplink available channel evaluation operation, or adaptively according to the uplink listen before talk (LBT) channel access priority class By applying the uplink listen before talk parameter,
Uplink burst, subframe or reference subframe scheduled by checking system information block (SIB) or license assisted access (LAA) common downlink control information signaling Determining skip or maintenance of uplink channel availability evaluation operation based on (reference subframe),
and a memory connected to the processor for storing information and parameters indicated by the base station. delete delete delete delete delete

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