阅读说明：本技术 发送信号的方法 (Method for transmitting signal ) 是由 严重善 郑润 朴承根 柳星珍 于 2016-12-28 设计创作，主要内容包括：本发明提供一种由终端发送探测参考信号(SRS)的方法。该包括：通过无线资源控制RRC消息和下行链路控制信息DCI消息中的至少一个,从基站接收用于SRS传输的定时提前TA信息；以及通过使用被配置用于SRS传输的SRS子帧和扩展的上行链路导频时隙UpPTS中的至少一个,在基于TA信息的定时发送SRS,其中,扩展的UpPTS与具有下行链路导频时隙DwPTS长度的下行链路部分子帧相隔预定的间隔。(The present invention provides a method for transmitting a Sounding Reference Signal (SRS) by a terminal. The method comprises the following steps: receiving Timing Advance (TA) information for SRS transmission from a base station through at least one of a Radio Resource Control (RRC) message and a Downlink Control Information (DCI) message; and transmitting the SRS at a timing based on the TA information by using at least one of an SRS subframe configured for SRS transmission and an extended uplink Pilot time Slot UpPTS, wherein the extended UpPTS is separated from a downlink part subframe having a Downlink Pilot time Slot DwPTS length by a predetermined interval.)

1. A method for transmitting Sounding Reference Signals (SRS) by a terminal includes:

receiving Timing Advance (TA) information for SRS transmission from a base station through at least one of a Radio Resource Control (RRC) message and a Downlink Control Information (DCI) message; and

transmitting the SRS at a timing based on the TA information by using at least one of an SRS subframe configured for SRS transmission and an extended uplink Pilot time Slot UpPTS,

wherein the extended UpPTS is spaced apart from a downlink part subframe having a length of a downlink pilot time slot DwPTS by a predetermined interval.

2. The method of claim 1, wherein,

the downlink partial subframe has a length corresponding to one of three time domain symbols, six time domain symbols, nine time domain symbols, ten time domain symbols, eleven time domain symbols, and twelve time domain symbols, and

the predetermined interval is equal to or greater than a length corresponding to one time domain symbol.

3. The method of claim 1, wherein,

the last time domain symbol of the subframe including the extended UpPTS is used to evaluate CCA for a clear channel of an unlicensed band channel.

4. The method of claim 1, wherein,

some time domain symbols existing at the front among the time domain symbols of the SRS subframe or some time domain symbols existing at the rear among the time domain symbols of the SRS subframe may be used for SRS transmission.

5. The method of claim 1, wherein,

one time domain symbol existing at the front among the time domain symbols of the SRS subframe or one time domain symbol existing at the rear among the time domain symbols of the SRS subframe may be used to evaluate CCA for a clear channel of the unlicensed band channel.

6. The method of claim 1, wherein,

even-numbered time domain symbols among time domain symbols of the SRS subframe can be used for SRS transmission, an

Odd-numbered time domain symbols among the time domain symbols of the SRS subframe may be used to assess CCA for a clear channel of the unlicensed band channel.

7. The method of claim 1, wherein,

a second slot among a first slot and a second slot subsequent to the first slot included in the SRS subframe may be used for SRS transmission.

Technical Field

The present invention relates to a method and apparatus for transmitting a sounding reference signal in a wireless communication system of an unlicensed band (unlicensed band).

Furthermore, the present invention relates to a method and apparatus for configuring and allocating resources for sounding reference signal transmission.

Background

With the development of information communication technology, various wireless communication technologies have been developed. Depending on the frequency band used, wireless communication technologies may be mainly classified into a wireless communication technology using a licensed frequency band, a wireless communication technology using an unlicensed frequency band (e.g., an Industrial Scientific Medical (ISM) frequency band), and the like. The usage right of the licensed band is exclusively allocated to one operator, and thus the wireless communication technology using the licensed band can provide more excellent reliability, communication quality, and the like than the wireless communication technology using the licensed band.

Examples of representative wireless communication technologies using licensed frequency bands may include Long Term Evolution (LTE) defined in the 3rd generation partnership project (3 GPP) standard, and the like. A base station (node B, NB) and a terminal (user equipment, UE) supporting LTE may transmit and receive signals through a licensed frequency band.

Examples of representative wireless communication technologies using unlicensed frequency bands may include a Wireless Local Area Network (WLAN) defined in the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, and the like. Each WLAN-capable Access Point (AP) and Station (STA) may transmit and receive signals over an unlicensed frequency band.

Meanwhile, mobile traffic has increased explosively in recent years. Therefore, additional licensed bands are required to handle mobile traffic passing through the licensed bands. However, the licensed band is limited, and the licensed band can be obtained by band auction between operators or the like in general. Thus, the operator may spend a significant amount of money to obtain the additional licensed bands. To solve this problem, a method of providing an LTE service through an unlicensed band may be considered.

Unlicensed band cells have different characteristics than cells in existing licensed bands. The unlicensed band cell opportunistically occupies the channel and thus may not continuously occupy the channel for a predetermined time. For this reason, resources capable of transmitting a Sounding Reference Signal (SRS) in a wireless communication system of an unlicensed frequency band may not be guaranteed. Therefore, unlike the licensed band, a method for configuring and allocating resources for transmitting the sounding reference signal in the unlicensed band needs to be defined.

Disclosure of Invention

Technical problem

The present invention is directed to a method and apparatus for transmitting a sounding reference signal in a wireless communication system of an unlicensed frequency band.

Further, the present invention is directed to a method and apparatus for configuring and allocating resources for sounding reference signal transmission.

In addition, the present invention is directed to a method and apparatus for configuring resources for sounding reference signal transmission in an unlicensed frequency band and allocating the resources to a user equipment.

Technical scheme

An exemplary embodiment of the present invention provides a method of transmitting a Sounding Reference Signal (SRS) by a terminal. The method for transmitting the SRS by the terminal includes: receiving a grant for a plurality of subframes for an uplink from a base station; determining a first subframe for SRS transmission of a terminal among a plurality of subframes in an uplink based on SRS transmission position information received from a base station; and transmitting the SRS in the first subframe.

The number of bits included in the SRS transmission position information may be determined based on a first value that is a maximum number of subframes included in the uplink plurality of subframes and a second value that is a maximum number of subframes that can be configured for SRS transmission among the uplink plurality of subframes.

The determining may include: receiving 2 bits of SRS transmission position information from the base station when the first value is 4 and the second value is 4; and receiving 1 bit of SRS transmission position information from the base station when the first value is 4 and the second value is 2.

The determining may include: a first time domain symbol for SRS transmission of the terminal among the time domain symbols of the first subframe is determined based on the SRS symbol position information. The SRS symbol position information may be included in UE-specific SRS configuration parameters signaled by higher layers.

The SRS symbol position information may be included in Downlink Control Information (DCI) for triggering SRS transmission.

Another exemplary embodiment of the present invention provides a method of triggering Sounding Reference Signal (SRS) transmission by a base station. The method for triggering SRS transmission by a base station includes: granting a first uplink plurality of subframes including a plurality of SRS subframes in which SRS transmission is possible to a first terminal; for a first terminal, triggering SRS transmission in a first SRS subframe among a plurality of SRS subframes; granting a first SRS subframe to a second terminal; and for the second terminal, triggering SRS transmission in the first SRS subframe.

For the first terminal, triggering SRS transmission may include: for a first terminal, SRS transmission is triggered in a first SRS subframe and remaining SRS subframes among a plurality of SRS subframes through an SRS request field included in first Downlink Control Information (DCI) for granting a first uplink plurality of subframes.

For the first terminal, triggering SRS transmission may include: for a first terminal, SRS transmission is triggered in a first, foremost SRS subframe among a plurality of SRS subframes through an SRS request field included in first Downlink Control Information (DCI) for granting a first uplink plurality of subframes.

In remaining SRS subframes other than the first SRS subframe among the plurality of SRS subframes, SRS transmission may not be triggered.

A Physical Uplink Shared Channel (PUSCH) may be configured in the last time domain symbol of the remaining SRS subframes. For the first terminal, triggering SRS transmission may include: for a first terminal, SRS transmission is triggered in a first SRS subframe that is a last subframe among a plurality of SRS subframes through an SRS request field included in first Downlink Control Information (DCI) for granting a first uplink plurality of subframes.

In remaining SRS subframes other than the first SRS subframe among the plurality of SRS subframes, SRS transmission may not be triggered. The licensing to the second terminal may comprise: a second uplink plurality of subframes different from the first uplink plurality of subframes and including the first SRS subframe are granted to the second terminal.

For the first terminal, triggering SRS transmission may include: for a first terminal, SRS transmission is triggered in a first SRS subframe by an SRS request field included in first Downlink Control Information (DCI) for granting a first uplink plurality of subframes. For the second terminal, triggering SRS transmission may include: for the second terminal, SRS transmission is triggered in the first SRS subframe by an SRS request field included in second Downlink Control Information (DCI) for granting a second uplink plurality of subframes.

The SRS may not be transmitted in remaining subframes other than the first SRS subframe among the first uplink plurality of subframes.

The SRS may not be transmitted in remaining subframes other than the first SRS subframe among the second uplink plurality of subframes.

Yet another exemplary embodiment of the present invention provides a method of transmitting a Sounding Reference Signal (SRS) by a terminal. The method for transmitting the SRS by the terminal includes: receiving Timing Advance (TA) information for SRS transmission from a base station through at least one of a Radio Resource Control (RRC) message and a Downlink Control Information (DCI) message; and transmitting the SRS at a timing based on the TA information by using at least one of an SRS subframe configured for SRS transmission and an extended uplink pilot time slot (UpPTS).

The extended UpPTS may be spaced apart from a downlink part subframe having a downlink pilot time slot (DwPTS) length by a predetermined interval.

The downlink partial subframe may have a length corresponding to one of three time domain symbols, six time domain symbols, nine time domain symbols, ten time domain symbols, eleven time domain symbols, and twelve time domain symbols.

The predetermined interval may be equal to or greater than a length corresponding to one time domain symbol.

The last time domain symbol of the subframe including the extended UpPTS is used for Clear Channel Assessment (CCA) for the unlicensed band channel.

Some time domain symbols existing at the front among the time domain symbols of the SRS subframe or some time domain symbols existing at the rear among the time domain symbols of the SRS subframe may be used for SRS transmission.

One time domain symbol existing at the front among the time domain symbols of the SRS subframe or one time domain symbol existing at the rear among the time domain symbols of the SRS subframe may be used for Clear Channel Assessment (CCA) for the unlicensed band channel.

Even-numbered time domain symbols among the time domain symbols of the SRS subframe may be used for SRS transmission.

Odd-numbered time domain symbols among the time domain symbols of the SRS subframe may be used for Clear Channel Assessment (CCA) for the unlicensed band channel.

A second slot among a first slot and a second slot subsequent to the first slot included in the SRS subframe may be used for SRS transmission.

Advantageous effects

According to the embodiments of the present invention, a sounding reference signal can be efficiently transmitted in consideration of an opportunistic discontinuous channel characteristic of an unlicensed frequency band.

Drawings

Fig. 1,2,3, and 4 are diagrams illustrating examples of a wireless communication network.

Fig. 5 is a diagram illustrating a communication node configuring a wireless communication network.

Fig. 6 is a diagram illustrating an SRS symbol set configured after a last partial subframe included in a downlink transmission burst (downlink transmission burst) according to an exemplary embodiment of the present invention.

Fig. 7 is a diagram illustrating an SRS symbol set configured at the end of a subframe according to an exemplary embodiment of the present invention.

Fig. 8 is a diagram illustrating a subframe configured of only an SRS symbol set corresponding to one time domain symbol according to an exemplary embodiment of the present invention.

Fig. 9 is a diagram illustrating an SRS symbol set configured by time-division of a Physical Uplink Shared Channel (PUSCH) and an SRS according to an exemplary embodiment of the present invention.

Fig. 10 is a diagram illustrating a case where an SRS symbol set is configured in a last time domain symbol of a subframe including a Discovery Reference Signal (DRS) of an unlicensed band cell according to an exemplary embodiment of the present invention.

Fig. 11 is a diagram illustrating a case where an 'SRS-subframe config' parameter and a maximum configurable number of SRS symbols per subframe are transmitted through different fields of a Radio Resource Control (RRC) message according to an exemplary embodiment of the present invention.

FIG. 12 is a diagram illustrating an exemplary embodiment of the present invention'srs-SubframeConfig'The parameters specified by the parameters include the maximum configurable number of SRS symbols, and thus the 'SRS-subframe config' parameter and the maximum configurable number of SRS symbols per subframe are illustrated in a diagram for the case where they are transmitted through one field of an RRC message.

Fig. 13 is a diagram illustrating a method of configuring and transmitting an SRS for frame structure type 2 according to an exemplary embodiment of the present invention.

Fig. 14 is a diagram illustrating a method of configuring and transmitting an SRS for frame structure type 3 or a dropped SRS configuration according to an exemplary embodiment of the present invention.

Fig. 15 is a diagram illustrating a method of transmitting an SRS in all subframes corresponding to an SRS subframe configuration when a grant for a plurality of subframes in an uplink and SRS transmission are triggered according to an exemplary embodiment of the present invention.

Fig. 16 is a diagram illustrating a method of transmitting an SRS only in the most advanced subframe among SRS subframes corresponding to an SRS subframe configuration when permission for a plurality of subframes in an uplink and SRS transmission are triggered according to an exemplary embodiment of the present invention.

Fig. 17 is a diagram illustrating a method of transmitting an SRS only in the last subframe among SRS subframes corresponding to an SRS subframe configuration when a grant for a plurality of subframes in an uplink and SRS transmission are triggered according to an exemplary embodiment of the present invention.

Fig. 18 is a diagram illustrating that an SRS transmission position is designated by Downlink Control Information (DCI) granting a plurality of subframes according to an exemplary embodiment of the present invention.

Fig. 19 is a diagram illustrating a method of transmitting only an SRS according to an exemplary embodiment of the present invention.

Fig. 20 is a diagram illustrating a method of transmitting an SRS when the maximum configurable number of SRS symbols is 2, according to an exemplary embodiment of the present invention.

Fig. 21 is a diagram illustrating a method of non-periodically transmitting an SRS after a downlink partial subframe according to an exemplary embodiment of the present invention.

Fig. 22 is a diagram illustrating an extended uplink pilot time slot (UpPTS) composed of 10 time domain symbols according to an exemplary embodiment of the present invention.

Fig. 23 is a diagram illustrating a timing at which a base station receives an SRS when the extended UpPTS of fig. 22 is used according to an exemplary embodiment of the present invention.

Fig. 24 is a diagram illustrating that the extended UpPTS does not include the last time domain symbol according to an exemplary embodiment of the present invention.

Fig. 25 is a diagram illustrating an SRS transmission subframe in which the first 9 time domain symbols are configured for SRS transmission according to an exemplary embodiment of the present invention.

Fig. 26 is a diagram illustrating an SRS transmission subframe in which the last 8 time domain symbols are configured for SRS transmission according to an exemplary embodiment of the present invention.

Fig. 27 is a diagram illustrating an SRS transmission subframe in which neither a first time domain symbol nor a last time domain symbol is configured for SRS transmission according to an exemplary embodiment of the present invention.

Fig. 28 is a diagram illustrating an SRS transmission subframe in which the first time domain symbol and the last three time domain symbols are not configured for SRS transmission according to an exemplary embodiment of the present invention.

Fig. 29 is a diagram illustrating a case where an SRS is configured in a time domain symbol satisfying (time domain symbol index mod2) ═ 1 according to an exemplary embodiment of the present invention.

Fig. 30 is a diagram illustrating a case in which a second slot of a subframe is configured for SRS transmission according to an exemplary embodiment of the present invention.

Detailed Description

In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. Like reference numerals refer to like elements throughout the specification.

In this specification, a repetitive description of the same components will be omitted.

Further, in the present specification, it will be understood that when a component is referred to as being "connected to" or "coupled to" another element, it can be directly connected to or directly coupled to the other element or be connected to or coupled to the other element in a manner that another element is interposed therebetween. On the other hand, in the present specification, it should be understood that when one element is referred to as being "directly connected to" or "directly coupled to" another element, it may be connected to or coupled to the other element without the other element intervening therebetween.

Furthermore, the terminology used in the description is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting of the invention.

Furthermore, in this specification, the singular forms may be intended to include the plural forms unless the context clearly dictates otherwise.

Furthermore, in the present specification, it will be further understood that the terms "comprises" or "comprising," when used in this specification, specify the presence of stated features, amounts, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, amounts, steps, operations, components, parts, or combinations thereof.

Further, in this specification, the term "and/or" includes a combination of a plurality of related items or any of a plurality of related items. In the present specification, 'a or B' may include 'a', 'B', or 'a and B'.

Further, in this specification, a terminal may refer to a mobile terminal, a station, a mobile station, an advanced mobile station, a high reliability mobile station, a subscriber station, a portable subscriber station, an access terminal, a User Equipment (UE), a node, a device, etc., and may also include all or some of the functions of a terminal, a mobile terminal, a station, a mobile station, an advanced mobile station, a high reliability mobile station, a subscriber station, a portable subscriber station, an access terminal, a user equipment, a node, a device, etc.

Further, in this specification, a Base Station (BS) may refer to an advanced base station, a high reliability base station, a node B (nb), an evolved node B (eNodeB, eNB), a wireless base station, a wireless transceiver, an access point, an access node, a wireless access station, a base station transceiver, a mobile multi-hop relay (MMR) -BS, a relay station serving as a base station, a high reliability relay station serving as a base station, a repeater (repeater), a macro base station, a small base station, and the like, and may further include all or part of functions of the base station, the advanced base station, the high reliability base station, the node B, eNodeB, the wireless base station, the wireless transceiver, the access point, the access node, the wireless access station, the base station transceiver, the MMR-BS, the relay station, the high reliability relay station, the repeater, the macro base station, the small base station, and the like.

Fig. 1,2,3, and 4 are diagrams illustrating examples of a wireless communication network.

In detail, fig. 1 to 4 illustrate a wireless communication network to which a method and apparatus according to an exemplary embodiment of the present invention are applied. However, this is merely an example, and a wireless communication network to which the method and apparatus according to the exemplary embodiments of the present invention are applied is not limited to the wireless communication network described herein. The method and apparatus according to the exemplary embodiments of the present invention may be applied to various wireless communication networks.

Fig. 1 is an example illustrating a wireless communication network.

In the wireless communication network shown in fig. 1, the first base station 110 may support cellular communication (e.g., LTE-advanced (LTE-a), LTE-unlicensed (LTE-U), etc., as defined in the 3GPP standard). The first base station 110 may support Multiple Input Multiple Output (MIMO) (e.g., Single User (SU) -MIMO, multi-user (MU) -MIMO, massive MIMO, etc.), coordinated multipoint (CoMP), Carrier Aggregation (CA), etc.). The first base station 110 may operate in the licensed frequency band F1 and may form a macro cell. The first base station 110 may be connected to other base stations (e.g., the second base station 120, the third base station 130, etc.) through an ideal backhaul or a non-ideal backhaul.

The second base station 120 may be located within the coverage of the first base station 110. The second base station 120 may operate in the unlicensed frequency band F3 and may form a small cell.

The third base station 130 may be located within the coverage of the first base station 110. The third base station 130 may operate in the unlicensed frequency band F3 and may form a small cell.

The second base station 12 and the third base station 130 may each support a WLAN as defined in the IEEE 802.11 standard.

The first base station 110 and a terminal (e.g., UE) connected to the first base station 110 may each transmit/receive signals through CA between the licensed frequency band F1 and the unlicensed frequency band F3.

Fig. 2 is another example of a wireless communication network.

In the wireless communication network shown in fig. 2, both the first base station 210 and the second base station 220 may support cellular communication (e.g., LTE-A, LTE-U, etc., as defined in the 3GPP standards). The first base station 210 and the second base station 220 may each support MIMO (e.g., SU-MIMO, MU-MIMO, massive MIMO, etc.), CoMP, CA, etc. The first base station 210 and the second base station 220 may each operate in a licensed frequency band F1 and may form a small cell. The first base station 210 and the second base station 220 may both be located within the coverage area of the base stations forming the macro cell. The first base station 210 may be connected to the third base station 230 through an ideal backhaul or a non-ideal backhaul. The second base station 220 may be connected to the fourth base station 240 through an ideal backhaul or a non-ideal backhaul.

The third base station 230 may be located within the coverage of the first base station 210. The third base station 230 may operate in the unlicensed frequency band F3 and may form a small cell.

The fourth base station 240 may be located within the coverage of the second base station 220. The fourth base station 240 may operate in the unlicensed frequency band F3 and may form a small cell.

The third base station 230 and the fourth base station 240 may each support a WLAN as defined in the IEEE 802.11 standard.

The first base station 210, the terminal connected to the first base station 210, the second base station 220, and the terminal connected to the second base station 220 may each transmit/receive signals through CA between the licensed frequency band F1 and the unlicensed frequency band F3.

Fig. 3 is yet another example of a wireless communication network.

In the wireless communication network shown in fig. 3, the first base station 310, the second base station 320, and the third base station 330 may each support cellular communication (e.g., LTE-A, LTE-U, etc., as defined in the 3GPP standards). The first base station 310, the second base station 320, and the third base station 330 may each support MIMO (e.g., SU-MIMO, MU-MIMO, massive MIMO, etc.), CoMP, CA, etc.

The first base station 310 may operate in the licensed frequency band F1 and may form a macro cell. The first base station 310 may be connected to other base stations (e.g., the second base station 320, the third base station 330, etc.) through an ideal backhaul or a non-ideal backhaul.

The second base station 320 may be located within the coverage of the first base station 310. The second base station 320 may operate in the licensed frequency band F1 and may form a small cell.

The third base station 330 may be located within the coverage of the first base station 310. The third base station 330 may operate in the licensed frequency band F1 and may form a small cell.

The second base station 320 may be connected to the fourth base station 340 through an ideal backhaul or a non-ideal backhaul. The fourth base station 340 may be located within the coverage of the second base station 320. The fourth base station 340 may operate in the unlicensed frequency band F3 and may form a small cell.

The third base station 330 may be connected to the fifth base station 350 through an ideal backhaul or a non-ideal backhaul. The fifth base station 350 may be located within the coverage of the third base station 330. The fifth base station 350 may operate in the unlicensed frequency band F3 and may form a small cell.

The fourth base station 340 and the fifth base station 350 may each support a WLAN as defined in the IEEE 802.11 standard.

The first base station 310, the terminal connected to the first base station 310, the second base station 320, the terminal connected to the second base station 320, the third base station 330, and the terminal connected to the third base station 330 may each transmit/receive signals through CA between the licensed frequency band F1 and the unlicensed frequency band F3.

Fig. 4 is a diagram illustrating yet another example of a wireless communication network.

In the wireless communication network shown in fig. 4, the first base station 410, the second base station 420, and the third base station 430 may each support cellular communication (e.g., LTE-A, LTE-U, etc., as defined in the 3GPP standards). The first base station 410, the second base station 420, and the third base station 430 may each support MIMO (e.g., SU-MIMO, MU-MIMO, massive MIMO, etc.), CoMP, CA, etc.

The first base station 410 may operate in the licensed frequency band F1 and may form a macro cell. The first base station 410 may be connected to other base stations (e.g., the second base station 420, the third base station 430, etc.) through an ideal backhaul or a non-ideal backhaul.

The second base station 420 may be located within the coverage of the first base station 410. The second base station 420 may operate in the licensed frequency band F2 and may form a small cell.

The third base station 430 may be located within the coverage of the first base station 410. The third base station 430 may operate in the licensed frequency band F2 and may form a small cell.

The second base station 420 and the third base station 430 may each operate in a licensed frequency band F2 that is different from the licensed frequency band F1 in which the first base station 410 operates.

The second base station 420 may be connected to the fourth base station 440 through an ideal backhaul or a non-ideal backhaul. The fourth base station 440 may be located within the coverage of the second base station 420. The fourth base station 440 may operate in the unlicensed frequency band F3 and may form a small cell.

The third base station 430 may be connected to the fifth base station 450 through an ideal backhaul or a non-ideal backhaul. The fifth base station 450 may be located within the coverage of the third base station 430. The fifth base station 450 may operate in the unlicensed frequency band F3 and may form a small cell.

The fourth base station 440 and the fifth base station 450 may each support a WLAN as defined in the IEEE 802.11 standard.

The first base station 410 and a terminal (e.g., UE) connected to the first base station 410 may each transmit/receive signals through CA between the licensed frequency band F1 and the unlicensed frequency band F3. The second base station 420, the terminal connected to the second base station 420, the third base station 430, and the terminal connected to the third base station 430 may each transmit/receive signals through CA of F3 between the licensed frequency band F2 and the unlicensed frequency band.

Meanwhile, a communication node (e.g., a base station, a terminal, etc.) configuring a wireless communication network may transmit a signal in an unlicensed frequency band based on a Listen Before Talk (LBT) procedure. That is, the communication node may perform an energy detection operation to determine an occupancy state of the unlicensed frequency band. The communication node may transmit a signal when it is determined that the unlicensed frequency band is in an idle state. In this case, the communication node may transmit a signal while the unlicensed band is in an idle state during a contention window (contention window) according to a random backoff operation (random backoff operation). On the other hand, when it is determined that the state of the unlicensed band is in a busy state, the communication node may not transmit a signal.

Alternatively, the communication node may transmit the signal based on a Carrier Sensing Adaptive Transmission (CSAT) procedure. That is, the communication node may transmit a signal based on a preset duty cycle. The communication node may transmit a signal when the current duty cycle is a duty cycle allocated for the communication node supporting cellular communication. On the other hand, when the current duty cycle is a duty cycle allocated for a communication node supporting communication other than cellular communication (e.g., WLAN, etc.), the communication node may not transmit a signal. The duty cycle may be adaptively determined based on the number of communication nodes existing in the unlicensed band and supporting the WLAN, the use state of the unlicensed band, and the like.

The communication node may perform discontinuous transmission in the unlicensed frequency band. For example, when a maximum transmission duration or a maximum Channel Occupancy Time (COT) is set in the unlicensed band, the communication node may transmit a signal for the maximum transmission duration. If the communication node fails to transmit all signals within the current maximum transmission duration, the remaining signals may be transmitted within the next maximum transmission duration. Further, the communication node may select a carrier having relatively less interference within the unlicensed frequency band and may operate in the selected carrier. Further, when transmitting signals in the unlicensed frequency band, the communication node may control transmission power to reduce interference with other communication nodes.

Meanwhile, the communication node may support a communication protocol based on Code Division Multiple Access (CDMA), a communication protocol based on Wideband CDMA (WCDMA), a communication protocol based on Time Division Multiple Access (TDMA), a communication protocol based on Frequency Division Multiple Access (FDMA), a communication protocol based on Single Carrier (SC) -FDMA, a communication protocol based on Orthogonal Frequency Division Multiplexing (OFDM), a communication protocol based on Orthogonal Frequency Division Multiple Access (OFDMA), and the like.

Fig. 5 is a diagram illustrating a communication node configuring a wireless communication network. The communication node 500 may be a base station, a terminal, etc. as described in the present invention.

In the exemplary embodiment of fig. 5, the communication node 500 may include at least one processor 510, a transmission/reception device 520 connected to a network to perform communication, and a memory 530. Further, the communication node 500 may also comprise a storage 540, an input interface 540, an output interface 560, etc. Each of the components included in the communication node 500 may be connected to each other through a bus 570 to communicate with each other.

Processor 510 may execute program commands stored in at least one of memory 530 and storage 540. The processor 510 may mean a Central Processing Unit (CPU), a Graphic Processing Unit (GPU), or a dedicated process performing a method according to an exemplary embodiment of the present invention. The processor 510 may be configured to implement the processes, functions, and methods described with reference to the exemplary embodiments of the present invention. Processor 510 may control each of the components of communication node 500.

Memory TN130 and storage 540 may each store various information associated with the operation of processor 510. The memory 530 and the storage 540 may each be configured of at least one of a volatile memory medium and a non-volatile memory medium. For example, the memory 530 may be configured by at least one of a Read Only Memory (ROM) and a Random Access Memory (RAM).

The transmitting/receiving device 520 may transmit or receive a wired signal or a wireless signal. Further, the communication node 500 may have a single antenna or multiple antennas.

Meanwhile, a communication node in a wireless communication network may operate as follows. Even when a method (e.g., transmission or reception of a signal) performed by a first communication node among the communication nodes is described, a second communication node corresponding to the first communication node may perform a method (e.g., reception or transmission of a signal) corresponding to the method performed by the first communication node. That is, when describing the operation of the terminal, the base station corresponding to the terminal may perform the operation corresponding to the operation of the terminal. Conversely, when describing the operation of the base station, the terminal corresponding to the base station may perform the operation corresponding to the operation of the base station.

Hereinafter, a method of configuring a Sounding Reference Signal (SRS) using two or more time domain symbols (e.g., SC-FDMA symbols) within a Transmission Time Interval (TTI) of 1ms will be described. Further, hereinafter, a method of transmitting the SRS in a plurality of SC-FDMA symbol intervals or a method of transmitting the SRS according to a period and symbol position information configured (set) in the terminal in a TTI except for a downlink pilot time slot (DwPTS) will be described.

Further, hereinafter, a method of configuring (setting) the SRS in the terminal according to the SC-FDMA symbol index will be described.

Also, hereinafter, a method of transmitting the SRS according to trigger information of Downlink Control Information (DCI) will be described. When DCI is used, the DCI may be DCI of a UE-specific Physical Downlink Control Channel (PDCCH) or DCI of a common PDCCH for an unlicensed band cell. In this specification, the time domain symbol may be an OFDM symbol, an OFDMA symbol, an SC-FDMA symbol, or the like according to a multiple access scheme. For example, in the present specification, when an OFDM symbol is used, the OFDM symbol may be replaced with an SC-FDMA symbol, and vice versa.

1. Configuration of unlicensed band cells

The unlicensed band cell operates through Carrier Aggregation (CA) with the licensed band cell. The configuration, addition, modification, or release of the unlicensed band cell is performed through RRC signaling (e.g., RRCConnectionReconfiguration message). The associated RRC message is sent from the licensed band cell to the terminal. The RRC message may include information required for maintenance and operation of the unlicensed band.

2. Structure of downlink control channel

In Downlink (DL), one subframe is composed of 2 slots. Each slot is composed of 7 or 6 time domain symbols (e.g., OFDM symbols). A maximum of 3 or 4 OFDM symbols configured in the foremost part of the subframe include a control channel. The downlink control channel of the licensed band cell may include, for example, a Physical Control Format Indicator Channel (PCFICH), a Physical Downlink Control Channel (PDCCH), a physical hybrid automatic repeat request indicator channel (PHICH), and the like. A Physical Downlink Shared Channel (PDSCH), which is a data channel for data transmission, is basically allocated to the remaining part of the subframe, and an Enhanced Physical Downlink Control Channel (EPDCCH) may be allocated to some Resource Blocks (RBs).

The first OFDM symbol in the subframe includes a PCFICH for transmitting information on the number of OFDM symbols used for transmission of the control channel. In addition, the control channel region may include a PHICH that transmits a hybrid automatic repeat request (HARQ) acknowledgement/negative acknowledgement (ACK/NACK) signal as response information for uplink transmission. The control information DCI is transmitted through PDCCH and ePDCCH. The DCI may include resource allocation information or resource control information for a terminal and a plurality of terminal groups. For example, the DCI may include uplink scheduling information, downlink scheduling information, an uplink transmission power control command, and the like.

DCI, which is control information transmitted through PDCCH or ePDCCH, has different formats according to the kind and number of information fields, the number of bits per information field, and the like. DCI formats 0, 3, and 3A are defined for the uplink. DCI formats 1, 1A, 1B, 1C, 1D, 2A, 2B, 2C, etc. are defined for the downlink. Each DCI format selectively includes information of a Carrier Indicator Field (CIF), RB allocation, Modulation Coding Scheme (MCS), Redundancy Version (RV), New Data Indicator (NDI), Transmit Power Control (TPC), HARQ process number (process number), Precoding Matrix Indicator (PMI) acknowledgement, a hopping flag, a flag field, and the like, according to the format. Accordingly, the size of control information suitable for the DCI format may be changed. In addition, the same DCI format may be used to transmit at least two kinds of control information. In this case, the control information is separated by a DCI format flag field. Table 1 below summarizes some of the information contained in each DCI format.

(Table 1)

The PDCCH (or ePDCCH) is transmitted through an aggregation of one or more consecutive control channel elements (or enhanced cces (ecces)). In this specification, PDCCH or ePDCCH is referred to as (e) PDCCH, and CCE or eCCE is referred to as (e) CCE.

(e) The CCE is a logical allocation unit and is configured of a plurality of Resource Element Groups (REGs). Determining the number of bits to transmit through the (e) PDCCH based on a relationship between the number of the (e) CCEs and a code rate provided by the (e) CCEs.

Control information transmitted through (e) the PDCCH according to the DCI format is attached with a Cyclic Redundancy Check (CRC) for error detection. The CRC is masked with a Radio Network Temporary Identifier (RNTI) according to (e) a PDCCH reception target (e.g., a terminal, etc.) or (e) a PDCCH reception purpose. Specifically, a scrambled CRC based on RNTI is attached to control information transmitted through (e) PDCCH.

Table 2 below summarizes the kind and value of RNTI.

(Table 2)

Table 3 below shows the usage (usage) of each RNTI

(Table 3)

3. Uplink link

A plurality of terminals simultaneously access the uplink through the SCFDMA scheme. According to a Cyclic Prefix (CP), a slot of 0.5ms is composed of SC-FDMA symbols of 6 SC-FDMA symbols (e.g., when an extended CP is used) or 7 SC-FDMA symbols (when a normal CP is used). Two slots configure one subframe.

The uplink subframe may be composed of a Physical Random Access Channel (PRACH) for initial access (e.g., random access), a Physical Uplink Shared Channel (PUSCH) for data transmission, a Physical Uplink Control Channel (PUCCH) for uplink control information transmission, a demodulation reference signal (DMRS), and a Sounding Reference Signal (SRS).

The DRMS and SRS, which are uplink Reference Signals (RSs) of LTE, are composed of Zadoff-Chu sequences. According to application to the basic sequenceCyclic shift of alpha, sequence of two uplink reference signalsIs defined as equation 1 below.

(equation 1)

In the above-described equation 1, the,is composed ofAnd represents a multiple (m) of a set of subcarriers of each Resource Block (RB). The value m may range from 1 to the number of RBs allocated to the uplink. Several reference signals can be generated based on a applied to one base sequence.

Basic sequence signalAre divided into a total of 30 groups and the group number is defined as u e {0,1, 2.

According to andcorresponding length (defined as the value v), each group having one or two base sequences. Here, v is 0 or (v is 0, 1). In particular, ifIs thatWhere m ranges from 1 to 5, a base sequence signal is defined, and ifIs thatWhere m is equal to or greater than 6, two base sequence signals are defined.

The values of u and v change in the time domain. Based on 17 different group hopping patterns f_gh(n_s) And 30 different sequence shift patterns f defined for each slot_ssU is defined as the following equation 2.

(equation 2)

U＝(f_gh(n_s)+f_ss)mod3O

The Group hopping pattern may determine whether to use Group hopping throughout the cell according to a "Group-hopping-enabled" parameter provided by a higher layer. However, even if group hopping is used for the entire cell, a specific terminal may not perform hopping according to a higher layer parameter called "disable-sequence-group-hopping".

The group hopping pattern may be defined differently for a reference signal for PUSCH, a reference signal for PUCCH, and SRS. If frequency hopping is not used, f_gh(n_s) Is zero. When frequency hopping is used, the frequency hopping pattern is defined as the following equation 3.

(equation 3)

In equation 3, n_sRepresenting the slot number (index). In equation 3 above, c (i) is a pseudorandom sequence, and is generated by equation 4 below applied to a gold sequence of length 31.

(equation 4)

c(n)＝(x₁(n+N_C)+x₂(n+N_C))mod2

x₁(n+31)＝(x₁(n+3)+x₁(n))mod2

x₂(n+31)＝(x₂(n+3)+x₂(n+2)+x₂(n+1)+x₂(n))mod2

In the above equation (4), the initial value of the primary m-sequence is defined as x₁0 ═ 1 and x₁(n) 0(n 1, 2.., 30). In equation 4, the secondary m permutation (m-permutation) is defined as c considered for permutation generation (permutation generation)_initCorresponding toIs started. In equation 4 above, N_C＝1600。

An initial value generated by a pseudo-random noise (PN) permutation for group frequency hopping may be defined asAnd is initialized every time a radio frame starts. Here, the first and second liquid crystal display panels are,using values specified by higher layers (e.g., values associated with PUSCH)Or associated with PUCCH). If no value specified by higher layers is defined orIn the case of the SRS, the SRS is,here, the first and second liquid crystal display panels are,meaning the physical cell ID.

Only atUnder the condition of (2) performing sequence hopping. When in useWhen v is 0. In thatUnder the condition (1), v is defined as the following equation 5.

(equation 5)

An initial value generated by pseudorandom noise permutation associated with PUSCH may be defined asAnd is initialized every time a radio frame starts. Here, the first and second liquid crystal display panels are,is defined asΔss∈{0，1，2，...，29}。

An initial value generated by a pseudorandom noise permutation associated with an SRS can be defined asAnd is initialized every time a radio frame starts.

According to the following equation 6Defining SRS permutations

(equation 6)

In the above equation 6, according to the 'cyclic shift' parameter and the 'cyclic shift-ap' parameter as higher layer parameters, will beSeparately into a periodic SRS or an aperiodic SRS. In equation 6 above, N_apIndicating the number of antenna ports used for SRS transmission.

Taking into account beta_SRSAs a crest factor (amplitude factor), SRS permutation is transmitted when being allocated to RE (k, I) which is a frequency and time resource, as in the following equation (7) with respect to the antenna port p. RE (k, I) denotes a Resource Element (RE) corresponding to a frequency index k and a time index I.

(equation 7)

In the above equation 7, in the above equation,indicating the frequency domain starting position of the SRS. In equation 7 above, B ═ B_SRS. In the above equation 7, in the above equation,denotes the length of the SRS permutation and is defined as the following equation 8.

(equation 8)

In equation 8 above, the uplink bandwidth is based onm_SRS,bCan be seen from the following Table 4Table 5 belowTable 6 below showsAnd table 7 belowThe defined value is obtained.

(Table 4)

(Table 5)

(Table 6)

(Table 7)

C_SRSE {0,1,2,3,4,5,6,7} is the cell-specific parameter 'srs-BandwidthhConfig' value, and B_SRSE {0,1,2,3} are the UE specific parameter 'srs-BandwidthConfig' values, all given by higher layers.

The SRS is transmitted when being allocated to an even index or an odd index (or every two REs), and 1/2 elements are included in equation (8).

In case of UpPTS, resources for PRACH channel need to be considered. In UpPTS, when a cell specific parameter 'srsmaxiuppts' is enabled by a higher layer, M_SRS,0Is defined asThat is, the SRS bandwidth may be defined as the overall resource in the uplinkExcept according to PRACH format 4 (N)_RA) Number of resources 6N_RAThe largest possible size among the remaining resources.

When the cell specific parameter 'srsMaxUpPTS' is not enabled by the higher layer, according to the defined value c,

in the frequency domain, the starting position of the SRSDepending on equation 9 below.

(equation 9)

In the above equation 9, in case of a normal uplink subframe,depends on the following equation 10, and in case of UpPTS, depends on the following equation 11. In the above equation 9, n_bIndicating a frequency position index.

(equation 10)

(equation 11)

In the above equation 10 or equation 11,is defined as the following equation 12. In the above equation 11, n_fIndicates the number of system frames, and N_SPIndicating a frequency change (e.g., 1 or 2) from downlink to uplink (or vice versa) during a predetermined number (e.g., 10) of subframes. In equation 11 above, when UpPTS is located in subframes numbered 0 to 4, n_hfIs 0, when the UpPTS is located in the subframes numbered 5 to 9, n is_hfHas a value of 1.

In the above equation 12, in the above equation,a value defined by higher layers as 0 or 1.

(equation 12)

Frequency hopping (frequency hopping) of SRS follows 'SRS-hoppingBandwidth' parameter b defined by higher layers_hopE.g. {0,1,2,3 }. For reference, aperiodic SRS transmission does not support frequency hopping.

If frequency hopping is not used, thenHere, N_bMay have one of values 1,2,3,4, and 5, and is in accordance with SRS bandwidth B_SRSAnd an 'SRS bandwidth configuration' value, defined in the standard specification as a Table (Table). n is_RRCAre higher parameters of 'freqDomainPosition' and 'freqDomainPosition-ap' given according to periodic transmission or aperiodic transmission.

If frequency hopping is supported, n_bThe following equation 13 is followed.

(equation 13)

In the above equation 13, b_hopMay have one of the values 0,1,2 and 3 and may be defined by the higher parameter 'srs-HoppingBandwidth'. In the above equation 13, F_b(n_SRS) The following equation 14 is followed.

(equation 14)

In equation 14 above, no matter N_bIn what way the user can, however,both have a value of 1. In equation 14 above, n_SRSFollow the followingThe following equation 15.

(equation 15)

In the above equation 15, T_SRSDenotes the UE-specific SRS Transmission period (Transmisson period), T_offsetDenotes SRS subframe offset, T_{offset_max}Indicating the SRS subframe maximum offset.

In a normal subframe (normal subframe), UpPTS is transmitted in the last time domain symbol of the subframe.

The cell specific subframe for SRS transmission is according to a period T_SFCAnd an offset delta_SFCTo be defined. According to the value of the higher layer 'srs-subframe config' parameter, T_SFCAnd Δ_SFCIs defined as shown in table 8 or table 9 below.

(Table 8)

Table 8 above shows frame structure type 1

(watch 9)

Table 9 above shows the frame structure type 2. In frame structure type 2, the SRS may be configured to be transmitted only in uplink or UpPTS.

Methods of triggering SRS transmission are divided into two. One is a higher layer signaling based method (trigger type 0) and the other is a DCI based method (trigger type 1). DCI formats 0, 4, or 1A for the DCI-based method (trigger type 1) may be used in frequency division multiplexing (FDD) and time division multiplexing (TDD), and DCI formats 2B, 2C, or 2D for the DCI-based method (trigger type 1) are applicable only to TDD.

Meanwhile, for the licensed band cell, the LTE-based wireless communication system may form an uplink and a downlink based on a frame structure type 1 (or a frame type 1) and a frame structure type 2 (or a frame type 2). For unlicensed band cells, the wireless communication system may configure the uplink and downlink based on frame structure type 3.

Frame structure type 3 (or frame type 3) includes a normal downlink subframe, a start downlink part subframe composed of only the second slot, an end downlink part subframe composed of only the DwPTS, and an uplink subframe. A contiguous set of downlink subframes (e.g., a starting downlink partial subframe + a normal downlink subframe + an ending downlink partial subframe) is referred to herein as a downlink transmission burst. A contiguous set of uplink subframes is referred to herein as an uplink transmission burst.

In frame structure type 3, the base station or the terminal may perform a procedure for confirming a channel occupancy state (e.g., Clear Channel Assessment (CCA)) before signal transmission.

SRS resource

In frame structure type 3, the uplink transmission may be a normal uplink subframe transmission, a normal UpPTS transmission, or an SRS transmission having a length corresponding to one or more SC-FDMA symbols. In the specification, a set including at least one SC-FDMA symbol for SRS transmission is referred to as an "SRS symbol set". The SRS symbol set may include PRACH.

The resources for the SRS symbol set may be subframes consisting of only SRS symbol sets. Alternatively, the resources for the SRS symbol set may be configured at the last SC-FDMA symbol interval after the uplink PUSCH. Alternatively, the resource for the SRS symbol set may be a time domain symbol set configured at the end of a subframe after a partial subframe in the last subframe of the downlink transmission burst.

Alternatively, the resource for the SRS symbol set may be a last time domain symbol of a subframe in which only a Discovery Reference Signal (DRS) for an unlicensed band cell is transmitted.

Referring to fig. 6 to 10, examples of SRS symbol sets are described. In fig. 6 to 10, N may be 1 or a constant greater than 1.

Fig. 6 is a diagram illustrating an SRS symbol set configured after a last partial subframe included in a downlink transmission burst according to an exemplary embodiment of the present invention. Specifically, fig. 6 shows a case where an SRS symbol set is configured at the end of a subframe after a partial subframe in the last subframe of a downlink transmission burst.

The subframe shown in fig. 6 includes a partial subframe and an SRS symbol set.

An SRS symbol set including N (N ═ 1,2, 3.) time domain symbols may be disposed at the end of a subframe after a partial subframe within a subframe (1 ms). Here, the partial subframe is included at the end of the downlink transmission burst and has the length of DwPTS.

Fig. 7 is a diagram illustrating an SRS symbol set configured at the end of a subframe according to an exemplary embodiment of the present invention.

Specifically, the subframe (1ms) described in fig. 7 includes only the SRS symbol set.

An SRS symbol set including N (N ═ 1,2, 3.) time domain symbols may be set at the end of a subframe.

Fig. 8 is a diagram illustrating a subframe configured of only an SRS symbol set corresponding to one time domain symbol according to an exemplary embodiment of the present invention.

Specifically, the subframe (1ms) shown in fig. 8 includes only the SRS symbol set.

A SRS symbol set including only one time domain symbol may be set at the end of the subframe.

Fig. 9 is a diagram illustrating SRS symbol sets configured by time division of a Physical Uplink Shared Channel (PUSCH) and an SRS according to an exemplary embodiment of the present invention.

Specifically, the subframe (1ms) shown in fig. 9 includes PUSCH and SRS symbol sets.

An SRS symbol set including N (e.g., N ═ 1) time domain symbols may be set after an interval for PUSCH within a subframe. For example, the SRS symbol set may be set at the end of the subframe.

In this case, the PUSCH and SRS are transmitted in one subframe by a time division manner.

Fig. 10 is a diagram illustrating a case where an SRS symbol set is configured in a last time domain symbol of a subframe including a Discovery Reference Signal (DRS) of an unlicensed band cell according to an exemplary embodiment of the present invention.

When the DRS is transmitted without multiplexing with a PDCCH, EPDCCH, or PDSCH in an unlicensed band cell (or unlicensed cell), downlink transmission is not performed in the last two time domain symbols of the subframe.

In this case, the last two time domain symbols of the subframe may be used for SRS transmission.

Fig. 10 shows that the last of two unused time domain symbols of a subframe is used for SRS transmission.

In other words, one subframe (1ms) includes an SRS symbol set including an interval (e.g., corresponding to 12 time domain symbols) of DRSs for an unlicensed band cell and N (e.g., N ═ 1) time domain symbols.

The SRS symbol set may be set after an interval for DRSs in a subframe. For example, the SRS symbol set may be set at the end of the subframe.

Meanwhile, resources having a length shorter than that of a time domain symbol (e.g., SC-FDMA symbol) within a subframe including the PUSCH may be configured (set) for SRS transmission. In this specification, an SRS having a length shorter than that of one time domain symbol is referred to as a "shortened SRS" (short SRS).

The shortened SRS may not be an SRS composed of two RE intervals, but may be an SRS composed of two or more Resource Element (RE) intervals. For example, when the SRS is configured at four RE intervals, a repetition pattern occurs in a time domain for a time domain symbol (e.g., SC-FDMA symbol), and the shortened SRS transmits only 1,2, or 3 repetition patterns among the four repetition patterns. In addition, the remaining intervals (e.g., the remaining repetition pattern) may be used for CCA. At least one subframe including the CCA and the shortened SRS may be included in an uplink transmission burst.

5.'srs-subframe config' parameter

In frame structure type 3, a downlink subframe and an uplink subframe may be dynamically configured. In addition, the length of the uplink subframe may also be dynamically configured. Accordingly, the 'srs-SubframeConfig' parameter of the frame structure type 1 and the 'srs-SubframeConfig' parameter of the frame structure type 2 can be configured in the frame structure type 3. The 'srs-subframe config' parameter is cell specific information sent from higher layers and all terminals can know the corresponding information. The 16 'srs-subframe config' parameters, which are composed of a total of 4 bits, are defined in frame structure type 1 and frame structure type 2. Each 'SRS-subframe config' parameter is defined as a subframe period T configured for SRS transmission_SFCAnd a transmission offset delta_SFC。

Unlike the licensed band, in the case of the unlicensed band, the uplink is not continuously configured but opportunistically configured. Therefore, the 'srs-subframe config' parameter defined at different offsets of the same period may be invalid, since there may be cases where no transmission opportunity is available.

Therefore, the higher layer informs an arbitrary offset value or defines the offset value fixedly in the standard. For example, the offset value may be defined as a value of at least 1 by considering DRS transmission and Primary Synchronization Signal (PSS) transmission and Secondary Synchronization Signal (SSS) transmission of an unlicensed band in 0 th and 5 th subframes.

In case of the frame structure type 1, the SRS transmission period may be defined as 1,2, 5 and 10, and in case of the frame structure type 2, the SRS transmission period may be defined as 5 and 10. However, in case of frame structure type 3 of the unlicensed band, there is a limitation on a maximum channel occupying time and the like, and thus if the SRS is configured every 10 subframe periods, the probability that the SRS will be actually transmitted is low. In contrast, the SRS transmission period needs to be defined as 3 or 4. Thus, the table defining the 'SRS-subframe config' parameter for frame structure type 3 may include an SRS transmission period of 3 or 4, and the like. Furthermore, the length of the SRS symbol set may be different, and thus the maximum configurable number of time domain symbols may be defined by higher layers.

Thus, the 'srs-subframe config' parameter signaled in higher layers may consist of three or four bits of information. At this time, the 'srs-subframe config' parameter may not include a transmission offset (Δ)_SFC) And (4) information. The 'SRS-subframe config' parameter may include a value of 3 or 4 as the SRS subframe configuration period. Here, the SRS subframe or the SRS transmission subframe indicates a subframe in which SRS transmission is possible. Accordingly, the SRS transmission period for the frame structure type 3 may be composed of at least one of values of 1,2,3,4,5, and 10.

In frame structure type 3, if the SRS subframe configuration period (transmission period) is long, the opportunity to transmit the SRS in the unlicensed band may be low. In this case, the plurality of terminals may transmit only the SRS without transmitting the PUSCH, and the at least one time domain symbol may be configured to increase the SRS transmission capacity.

Configurable number of SRS Transmission symbols or maximum configurable number N of time Domain symbols in one subframe_SFCMay be included in the table defining the 'srs-subframe config' parameter ('srs-subframe config' signaling table), or may be signaled separately by higher layers.

As another method for the case where the SRS subframe configuration period (transmission period) is long, there is a method for specifying a plurality of subframe offset values.

In the case where a plurality of subframe offsets or a transmission period is short in order to increase SRS transmission opportunities, the PUSCH time length for data transmission is reduced due to resource configuration for SRS transmission, and thus spectral efficiency may be reduced.

Therefore, in frame structure type 3, a method of transmitting PUSCH or PUCCH without transmitting SRS in a subframe corresponding to SRS subframe configuration (subframe defined as SRS subframe configuration) by a combination (one or more combinations) of scheduling or triggering may be used. An exemplary embodiment of the present invention associated with SRS configuration dropping (e.g., srsconfigugdiscard) will be described below.

Fig. 11 is a diagram illustrating a case where an 'SRS-subframe config' parameter and a maximum configurable number of SRS symbols per subframe are transmitted through different fields of a Radio Resource Control (RRC) message according to an exemplary embodiment of the present invention.

The RRC message may correspond to a message of layer 3 among layer 1, layer 2, and layer 3.

As shown in fig. 11, the base station may transmit the 'srs-subframe config' parameter (e.g., T) to the terminal through a field of the RRC message_SFC，Δ_SFC). In addition, the base station may transmit the maximum number of time domain symbols (e.g., N) that can be used for SRS transmission among the time domain symbols of the subframe to the terminal through another field of the RRC message_SFC). An SRS symbol means a time domain symbol that may be (configured to be) used for SRS transmission.

FIG. 12 is a diagram illustrating an exemplary embodiment of the present invention'srs-SubframeConfig'The parameters specified by the parameters include the maximum configurable number of SRS symbols, and thus the 'SRS-subframe config' parameter and the maximum configurable number of SRS symbols per subframe are illustrated in a diagram for the case where they are transmitted through one field of an RRC message.

The RRC message may correspond to a message of layer 3 among layer 1, layer 2, and layer 3.

As shown in fig. 12, the base station may transmit a subframe period T corresponding to the 'srs-subframe config' parameter to the terminal through one field of the RRC message_SFCAnd a transmission offset Δ_SFCAnd a maximum configurable number of SRS symbols per subframe (e.g., N)_SFC)。

Hereinafter, tables (table 10, table 11, table 12, table 13, and table 14) defining a parameter designated (or indicated) by the 'srs-subframe config' parameter signaled by a higher layer and a value of the parameter will be described.

Subframe indices 0 and 5 may be excluded from SRS transmission. This is because it is possible that the DRS may be transmitted in subframes numbered 0 and 5, and it is possible that a downlink subframe including the PSS and the SSS may be transmitted.

Table 10 below shows the transmission offset Δ as defined in the standard or signaled by higher layers_SFCA case of being fixed to a value equal to 1 or more. In particular, the following tableFig. 10 shows a case where the maximum number of SRS symbols transmitted in a subframe is defined to be fixed to 1 or an expected value signaled by a higher layer. The following table 10 shows a table indicating an SRS subframe configuration period (or transmission period) T_SFCIs 3. For example, the SRS subframe configuration period T_SFCMay represent one of 1,2,3,4,5 and 10.

(watch 10)

Table 11 below shows the transmission offset Δ defined in the standard or signaled by higher layers_SFCA case of being fixed to a value of 1 or more.

Specifically, table 11 below shows the maximum number N of SRS symbols transmitted in a subframe_SFCIncluded in the 'srs-subframe config' parameter. Table 11 below shows a table indicating the SRS subframe configuration period T_SFCAnd a maximum number N of SRS symbols_SFCIs 3. For example, the SRS subframe configuration period (or transmission period) T_SFCMay represent one of 1,2,3,4,5 and 10. For example, the maximum number of SRS symbols N_SFCOne of 1,2,3, and 4 may be indicated.

(watch 11)

Table 12 below illustrates defining the transmission period T_SFCA transmission offset delta_SFCAnd a maximum configurable number N of SRS symbols per subframe_SFCThe case (1). The following table 12 shows a configuration period T of the SRS subframe_SFCA transmission offset delta_SFCAnd a maximum number N of SRS symbols_SFCIs 4. For example, the SRS subframe configuration period T_SFCMay represent one of 1,2,3,4,5 and 10. For example, the transmission offset Δ_SFCOne of {0}, {1}, {9}, and { a combination of 0 to 9} may be represented. For example, the maximum number of SRS symbolsN_SFCOne of 1,2,3, and 4 may be indicated.

(watch 12)

Table 13 below configuring the 'SRS-subframe config' parameter indicates the SRS subframe configuration period (transmission period) T_SFCFixed to 10 and the actual SRS subframes are transmitted with an offset Δ from each subframe_SFCIs configured. Table 13 below shows a configuration period T of SRS subframe_SFCAnd a transmission offset delta_SFCIs 4. For example, the SRS subframe may be configured with a period T_SFCIs fixed at 10. For example, the transmission offset Δ_SFCOne of {0}, {1}, {9}, and { a combination of 0 to 9} may be represented.

(watch 13)

The following table 14, in which the 'SRS-subframe config' parameter is configured, indicates an SRS subframe configuration period (transmission period) T_SFCFixed to 10 and the actual SRS subframes are transmitted with an offset Δ according to each subframe_SFCIs configured. The following table 14 shows a configuration period T representing an SRS subframe_SFCTransmission offset delta_SFCAnd a maximum number N of SRS symbols_SFCIs 4. For example, the SRS subframe may be configured with a period T_SFCIs fixed at 10. For example, the transmission offset Δ_SFCOne of {0}, {1}, {9}, and { a combination of 0 to 9} may be represented. For example, the maximum number of SRS symbols N_SFCOne of 1,2,3 and 4 may be indicated.

(watch 14)

When periodic transmission based on trigger type 0 may be performed in frame structure type 3, each terminal may perform SRS transmission according to the SRS subframe configuration and the UE-specific 'SRSconfixIndex' parameter.

For aperiodic SRS transmission such as trigger type 1 in frame structure type 3 or a new trigger type considering an unlicensed band, an SRS transmission method to be described below may be defined.

The SRS transmission method to be described below includes SRS configuration dropping (e.g., srsconfigugdiscard). Here, SRS configuration discard (e.g., srsconfigugsiscard) indicates that the terminal may transmit PUSCH or PUCCH in a subframe (corresponding to the SRS subframe configuration) included in the SRS subframe configuration or in a time domain symbol used for SRS transmission.

In frame structure type 1 and frame structure type 2, when a terminal that intends to transmit data through a PUSCH in a subframe corresponding to an SRS transmission subframe does not receive an SRS transmission trigger request, the last time domain symbol of the subframe is null (empty) for SRS transmission of other terminals.

The SRS configuration and SRS transmission for frame structure type 2 will be described with reference to fig. 13.

Fig. 13 is a diagram illustrating a method of configuring and transmitting an SRS for frame structure type 2 according to an exemplary embodiment of the present invention.

In detail, fig. 13 shows an SRS subframe configuration period T_SFCCase 2. That is, the intervals between the SRS subframes SFSRS1a, SFSRS1b, and SFSRS1c may correspond to two subframes 2x1 ms.

As shown in fig. 13, when SRS transmission is not triggered in a subframe included in the SRS subframe configuration, a time domain symbol for SRS transmission may be empty without any signal transmission. For example, a time domain symbol for SRS transmission among time domain symbols of the SRS subframe SFSRS1a is empty without SRS transmission.

Meanwhile, in frame structure type 3, signaling to the terminal may be performed so as to leave the last time domain symbol without signal transmission for Listen Before Talk (LBT). Therefore, if the terminal receives a grant (scheduling) for PUSCH transmission in a subframe configured for SRS transmission, but an aperiodic SRS transmission trigger is not requested, the terminal may transmit PUSCH until an SRS transmission period.

That is, unlike frame structure type 1 and frame structure type 2, in frame structure type 3, even if a subframe in which aperiodic SRS transmission is not triggered corresponds to an SRS subframe configuration, a terminal can transmit PUSCH or PUCCH without leaving a time domain symbol (e.g., srsconfigugdiscard) of the corresponding subframe. This is because when a time domain symbol for SRS transmission is unoccupied, another system may occupy a corresponding channel in the unlicensed band. In particular, this may be more effective when the transmission period of the SRS subframe configuration is configured to be smaller in order to increase the transmission probability of the SRS in the unlicensed band based on opportunistic channel access and opportunistic signal transmission. This will be described with reference to fig. 14.

Fig. 14 is a diagram illustrating a method of configuring and transmitting an SRS or dropped SRS configuration for frame structure type 3 according to an exemplary embodiment of the present invention.

In detail, fig. 14 shows an SRS subframe configuration period T_SFCCase 2. That is, the intervals between the SRS subframes SFSRS2a, SFSRS2b, and SFSRS2c may correspond to two subframes 2x1 ms.

Specifically, fig. 14 shows a case where, for two SRS subframes (SFSRS2b and SFSRS2c) among three SRS subframes SFSRS2a, SFSRS2b, and SFSRS2c, an SRS request is triggered together with an uplink grant (UL grant). That is, SRS transmission may be triggered by the SRS request field of the uplink grant DCI for two SRS subframes SFSRS2b and SFSRS2 c. For example, triggering of SRS transmission for the SRS subframe (SFSRS2b) and triggering of SRS transmission for the SRS subframe (SFSRS2c) may be performed by different DCI. The terminal may transmit UL and SRS including at least PUSCH in one of two subframes SFSRS2b and SFSRS2 c.

Fig. 14 shows a case where subframe SFSRS2a is included in the SRS subframe configuration, but the SRS request is not triggered upon uplink grant to subframe SFSRS2 a. A terminal receiving an uplink grant for subframe SFSRS2a may drop SRS transmission in subframe SFSRS2a and configure subframe SFSRS2a to include at least PUSCH (e.g., srsconfigugdiscard).

Meanwhile, when a plurality of subframes in an uplink are granted, only one SRS request field may exist in DCI for granting to the plurality of subframes. In this case, at least one SRS transmission subframe may be configured in the scheduled uplink multiple subframe period. A terminal receiving scheduling of a plurality of subframes may transmit an SRS in all subframes in which SRS transmission may be performed. In this case, the base station may perform a trigger request for aperiodic SRS transmission to a terminal that has been scheduled for a single subframe, so that other terminals receiving a grant (scheduling) of an uplink single subframe transmit SRS in a plurality of subframes. This will be described with reference to fig. 15.

Fig. 15 is a diagram illustrating a method of transmitting an SRS in all subframes corresponding to an SRS subframe configuration when a grant for a plurality of subframes in an uplink and SRS transmission are triggered according to an exemplary embodiment of the present invention. In detail, fig. 15 shows an SRS subframe configuration period T_SFCCase 2. That is, the intervals between the SRS subframes SFSRS3a, SFSRS3b, and SFSRS3c may correspond to two subframes 2 × 1 ms.

Specifically, fig. 15 shows that terminal UE _ a receives a grant for uplink multiple subframes n, n +1, n +2,. and n +4 from the base station, and terminals UE _ b and UE _ c each receive a grant for n-th and n + 4-th single uplink (single subframe) from the base station.

For terminal UE _ a, the base station may trigger SRS transmission in SRS subframes SFSRS3a, SFSRS3b, and SFSRS3c through the SRS request field of the uplink grant DCI for the uplink multiple subframes n, n +1, n + 2.

For terminal UE _ b, the base station may trigger aperiodic SRS transmission in SRS subframe SFSRS3a by the SRS request field of the uplink grant DCI for uplink single subframe SFSRS3 a.

For terminal UE _ c, the base station may trigger SRS transmission in SRS subframe SFSRS3c by the SRS request field of the uplink grant DCI for uplink single subframe SFSRS3 c.

Meanwhile, in multi-subframe scheduling, if a terminal does not transmit an SRS in at least one subframe among subframes configured for SRS transmission, the terminal may transmit the SRS to satisfy a previously defined condition (hereinafter, referred to as 'first SRS transmission condition').

Here, the first SRS transmission condition may include a case where the terminal transmits the SRS only in the first configured SRS transmission subframe (first SRS subframe) among the uplink multiple subframe periods. This has the following advantages: it is possible to start the same LBT when uplink multiple subframes are granted (scheduled) to a terminal and the first subframe of the uplink multiple subframes is granted (scheduled) to other terminals as a single subframe.

Therefore, a plurality of terminals that receive permission (scheduling) of a plurality of subframes of an uplink according to scheduling transmit SRS in a first subframe among SRS subframes corresponding to SRS subframe configuration.

In this case, the base station may perform a trigger request for aperiodic SRS transmission to a terminal receiving the grant of the single subframe, so that other terminals receiving the grant (scheduling) of the uplink single subframe transmit SRS in the first subframe of the plurality of subframes. The base station does not perform a trigger request for a terminal receiving a grant of a single subframe of remaining subframes except a first subframe among subframes corresponding to an SRS subframe configuration.

When a PUSCH transmission is scheduled for an uplink single subframe but triggering of an SRS is not requested, even if the corresponding single subframe corresponds to an SRS subframe configuration, the terminal may not transmit the SRS in the corresponding single subframe but may transmit the PUSCH by configuring the PUSCH until the last time domain symbol of the corresponding single subframe. This will be described with reference to fig. 16.

Fig. 16 is a diagram illustrating a method of transmitting an SRS only in the most advanced subframe among SRS subframes corresponding to an SRS subframe configuration when permission for a plurality of subframes in an uplink and SRS transmission are triggered according to an exemplary embodiment of the present invention. In detail, fig. 16 shows an SRS subframe configuration period T_SFCCase 2. That is, the intervals between the SRS subframes SFSRS4a, SFSRS4b, and SFSRS4c may correspond to two subframes 2 × 1 ms.

Specifically, fig. 16 shows a case where the terminal UE _ a receives grants of a plurality of subframes n, n +1, n +2,.. and n +4, and the terminals UE _ b and UE _ c each receive grants of n-th and n + 4-th single uplinks (single subframes).

Fig. 16 shows a case where SRS transmission is triggered by an SRS request field of an uplink grant DCI for a plurality of subframes n, n +1, ·, n +4 in uplink. Specifically, the base station triggers SRS transmission in the most advanced SRS subframe SFSRS4a of the plurality of SRS subframes SFSRS4a, SFSRS4b and SFSRS4c for the terminal UE _ a, and does not trigger SRS transmission in the remaining SRS subframes SFSRS4b and SFSRS4 c. The terminal UE _ a transmits the SRS only in the first subframe SFSRS4a in which the SRS can be transmitted among the plurality of subframes n, n +1,. and n +4 that have been granted, and does not transmit the SRS in the remaining SRS subframes SFSRS4b and SFSRS4 c.

Fig. 16 shows the case where, for terminal UE _ b, SRS transmission is triggered by the SRS request field of the uplink grant DCI for a single subframe SFSRS4 a. Specifically, the terminal UE _ b transmits the SRS in the subframe SFSRS4 a.

Fig. 16 shows the case where, for terminal UE _ c, SRS transmission is not triggered by the SRS request field of the uplink grant DCI for a single subframe SFSRS4 a. Specifically, the terminal UE _ c does not transmit the SRS in the subframe SFSRS4c, but may transmit the PUSCH.

Therefore, the SRS is not transmitted in the SRS subframes SFSRS4b and SFSRS4c (e.g., SRS configuration discard (SRSconfigDiscard)). PUSCH may be configured in the last time domain symbols of SRS subframes SFSRS4b and SFSRS4 c.

Meanwhile, the first SRS transmission condition may include a case where the terminal transmits the SRS only in an SRS transmission subframe (last SRS subframe) last configured among a plurality of subframe periods of the uplink. This is because uplink transmission in a subframe configured in front of a plurality of subframes may not be performed according to the LBT result. If the terminal transmits the SRS only in the last possible subframe, the transmission probability of the SRS increases.

Therefore, a plurality of terminals receiving permission (scheduling) of a plurality of subframes of an uplink according to scheduling transmit SRS in a last possible subframe among SRS subframes corresponding to SRS subframe configuration.

In this case, the base station may perform a trigger request for aperiodic SRS transmission to a terminal receiving the grant of the single subframe, so that other terminals receiving the grant (scheduling) of the uplink single subframe may transmit an SRS in the last subframe in which SRS transmission may be performed among the plurality of subframes. Further, the base station does not perform the trigger request for a terminal receiving a grant of a single subframe of remaining SRS subframes except for the last SRS subframe among subframes in which SRS transmission of a plurality of subframes can be performed.

When a PUSCH transmission is scheduled for an uplink single subframe but triggering of an SRS is not requested, even if the corresponding single subframe corresponds to an SRS subframe configuration, the terminal may not transmit the SRS in the corresponding single subframe but may transmit the PUSCH by configuring the PUSCH until a last time domain symbol of the corresponding single subframe. This will be described with reference to fig. 17.

Fig. 17 is a diagram illustrating a method of transmitting an SRS only in the last subframe among SRS subframes corresponding to an SRS subframe configuration when permission for a plurality of subframes in an uplink and SRS transmission are triggered according to an exemplary embodiment of the present invention. In detail, fig. 17 shows an SRS subframe configuration period T_SFCCase 2. That is, the intervals between the SRS subframes SFSRS5a, SFSRS5b, and SFSRS5c may correspond to two subframes 2 × 1 ms.

Specifically, fig. 17 shows a case where the terminal UE _ a receives a grant for a plurality of subframes n, n +1, n + 2.., n +4 in the uplink, and the terminals UE _ b and UE _ c each receive a grant for a single uplink (single subframe) of the nth and n +4 th.

Fig. 17 illustrates a case where SRS transmission is triggered by an SRS request field of an uplink grant DCI for uplink multiple subframes n, n + 1.

Specifically, for UE _ a, the base station triggers SRS transmission in the last subframe, SRS subframe SFSRS5c, among the plurality of SRS subframes SFSRS5a, SFSRS5b, and SFSRS5c, and does not trigger SRS transmission in the remaining SRS subframes SFSRS5a and SFSRS5 b. The UE _ a transmits the SRS only in the last SRS subframe SFSRS5c in which the SRS can be transmitted among the plurality of subframes n, n +1,. and n +4 that have been granted, and does not transmit the SRS in the remaining SRS subframes SFSRS5a and SFSRS5 b.

Fig. 17 shows the case where, for terminal UE _ b, SRS transmission is not triggered by the SRS request field of the uplink grant DCI for uplink single subframe SFSRS5 a. Specifically, the terminal UE _ b does not transmit the SRS in the subframe SFSRS5a, but may transmit the PUSCH.

Fig. 17 shows the case where, for terminal UE _ c, SRS transmission is triggered by the SRS request field of the uplink grant DCI for uplink single subframe SFSRS5 c. Specifically, the terminal UE _ c transmits the SRS in the subframe SFSRS5 c.

Therefore, the SRS is not transmitted in the SRS subframes SFSRS5a and SFSRS5b (e.g., SRS configuration discard (SRSconfigDiscard)). PUSCH may be configured in the last time domain symbols of SRS subframes SFSRS5a and SFSRS5 b.

Meanwhile, in order to limit a specific subframe among a plurality of subframes in an uplink to a subframe used for SRS transmission, a method of notifying a terminal through higher layer signaling (e.g., RRC message) may be used in addition to a method of defining a condition (e.g., first SRS transmission condition) in advance. For example, the following methods may be used: by considering the maximum configurable number of the uplink multiple subframes, the location information of a subframe for actually transmitting the SRS among the multiple subframes is included in a table defining the 'SRS-subframe config' parameter, and the terminal is notified of the table.

Alternatively, in order to restrict a specific subframe among the uplink multiple subframes to a subframe for SRS transmission, a method of transmitting an SRS transmission position by including the SRS transmission position in DCI that permits multiple subframes may be used in addition to a method of defining a condition (e.g., a first SRS transmission condition) in advance. This will be described with reference to fig. 18.

Fig. 18 is a diagram illustrating specification of an SRS transmission position by granting Downlink Control Information (DCI) of a plurality of subframes according to an exemplary embodiment of the present invention. In detail, fig. 18 shows an SRS subframe configuration period T_SFCCase 2. That is, the intervals between the SRS subframes SFSRS6a, SFSRS6b, and SFSRS6c may correspond to two subframes 2 × 1 ms.

Specifically, fig. 18 shows that the terminal UE _ a receives a grant of three subframes (from the nth subframe to the n +2 th subframe) as a plurality of subframes, and the terminal UE _ b receives a grant of three subframes (from the n +2 th subframe to the n +4 th subframe) as a plurality of subframes.

When SRS subframe configuration period T_SFCAt time 2, for the terminal UE _ a, 2 subframes (nth subframe, n +2 th subframe) of the plurality of subframes are configured as SRS transmission subframes, and for UE _ b, 2 subframes (n +2 th subframe and n +4 th subframe) of the plurality of subframes are configured as SRS transmission subframes. The SRS transmission timings of the two terminals UE _ a and UE _ b may need to match each other.

As shown in fig. 18, the starting positions of the plurality of subframes that have been granted may differ from terminal to terminal. For example, for UE _ a, the starting position of the plurality of subframes is the nth subframe, and for UE _ b, the starting position of the plurality of subframes is the n +2 th subframe. In this case, since the terminal UE _ a and the terminal UE _ b need to be able to transmit the SRS in the same subframe position (e.g., the n +2 th subframe), information on the SRS transmission subframe may be included in the DCI.

Fig. 18 shows a case where, for a terminal UE _ a, a base station can trigger SRS transmission in an SRS subframe SFSRS6b through an SRS request field of an uplink grant DCI for a plurality of subframes n, n +1, and n +2 in uplink. Further, fig. 18 shows a case where, for the terminal UE _ b, the base station can trigger SRS transmission in the SRS subframe SFSRS6b through the SRS request field of the uplink grant DCI for the uplink multiple subframes n +2, n +3, and n + 4. The SRS is not transmitted in the SRS subframes SFSRS6a and SFSRS6 c.

Meanwhile, when information on an SRS transmission subframe is included in DCI which grants an uplink for a plurality of subframes, the number of bits to configure the information on the SRS transmission subframe and the transmitted information on the SRS transmission subframe may be determined according to a maximum configurable number of the plurality of subframes or a maximum number of subframes which can be configured for SRS transmission among the plurality of subframes.

When the number of subframes in which the SRS is transmitted among the plurality of subframes is limited to 1, a bit number and a bit value may be defined to specify (or indicate) the position of the SRS transmission subframe. For example, when the number of subframes configurable as a plurality of subframes is 4 and the number of subframes corresponding to the SRS subframe configuration is at most 4, the base station may notify the terminal of the SRS transmission position using two bits. That is, the terminal determines a subframe for SRS transmission that the terminal itself can use among the plurality of subframes for the granted uplink, based on the SRS transmission position information (2 bits) received from the base station. In addition, the terminal transmits the SRS in the determined subframe.

As another example, when the number of subframes configurable as a plurality of subframes is 4 and the number of subframes corresponding to the SRS subframe configuration is at most 2, the base station may notify the terminal of the SRS transmission position using one bit.

When the number of subframes in which the SRS is transmitted among the plurality of subframes is configured to be plural, the base station may specify (or indicate) the SRS transmission position using a bitmap.

Meanwhile, for up to 4 configurable multiple subframes, DCI format 0B may use an SRS trigger bit and an additional 1 bit, while DCI format 4B may use a 2-bit SRS trigger field. DCI format 0B is a multiple subframe uplink scheduling format for single layer transmission, and DCI format 4B is a multiple subframe uplink scheduling format for two layer transmission. The base station may indicate to the terminal, using two bits, a case where the SRS is not transmitted, a case where the SRS is configured in the first subframe, a case where the SRS is configured in the second subframe, and a case where the SRS is configured in the last subframe.

Meanwhile, when the number of time domain symbols for which SRS transmission is configurable in a higher layer is one or more, the terminal may determine the number of time domain symbols for SRS transmission according to a trigger condition. For example, when SRS transmission is triggered by an 'SRS request' field (or parameter) of DCI (e.g., DCI format 0, DCI format for multiple subframe allocation, DCI format 4, etc.) allocating an uplink PUSCH, the terminal may determine the number of time domain symbols for SRS transmission to be 1. That is, according to DCI performing uplink grant, aperiodic SRS transmission is triggered and a corresponding subframe is configured as a subframe for SRS transmission, and thus when PUSCH and SRS are temporarily multiplexed, SRS may be transmitted through one time domain symbol.

Meanwhile, when a subframe in which SRS transmission is configured is not authorized for PUSCH transmission, the terminal may expect that at least one time domain symbol configured for SRS transmission exists at the end of the corresponding subframe. Information regarding the position of a time domain symbol used for SRS transmission (hereinafter, "SRS symbol position information") may be included in the UE-specific SRS configuration parameters signaled by higher layers. Alternatively, SRS symbol position information may be included in the DCI for triggering SRS transmission. That is, the terminal determines a time domain symbol for SRS transmission that the terminal itself can use among time domain symbols of a subframe based on the UE-specific SRS configuration parameter or the SRS symbol position information included in the DCI.

The triggering methods (method M100, method M200, and method M300) for the terminal to request only SRS transmission without requesting PUSCH are as follows.

Method M100 is a method of triggering SRS transmission through an 'SRS Request' (SRS Request) field (or parameter) included in a UE-specific DCI format for a downlink grant.

Method M200 is a method of triggering SRS transmission through an 'SRS Request' (SRS Request) field (or parameter) included in a UE-specific DCI format for an uplink grant. Method M200 is used for the following cases: according to the uplink grant, a subframe in which the PUSCH is to be transmitted and a subframe in which the SRS transmission is to be performed may be different from each other.

Method M300 is a method of triggering SRS transmission through an 'SRS Request' (SRS Request) field (or parameter) in a common DCI format (common DCI format) in an unlicensed band cell-specific common DCI format.

Method M100 is a method of triggering aperiodic SRS transmission through an 'SRS request' (SRS request) field of a downlink grant DCI. The terminal determines a subframe for SRS transmission among subframes subsequent to a predetermined number (e.g., 4) of subframes based on a timing (e.g., nth subframe) granted by the base station, and may transmit the SRS in a subframe in which the SRS transmission may be transmitted first among the determined SRS transmission subframes.

Method M200 is a method of triggering aperiodic SRS transmission through an 'SRS request' (SRS request) field of an uplink grant DCI. The method M200 is used when the PUSCH transmission subframe and the SRS transmission subframe are different from each other. If the (n + 4) th subframe does not correspond to the SRS subframe configuration based on the timing when the base station grants the uplink (e.g., the (n) th subframe), the terminal may transmit only the PUSCH in the (n + 4) th subframe, determine a subframe for SRS transmission among subframes subsequent to the (n + 4) th subframe, and transmit the SRS in a subframe in which the SRS transmission may be transmitted first among the determined SRS transmission subframes.

Meanwhile, for a case where uplink transmission of the terminal is not actually fixed, a two-step uplink scheduling method may be used. Here, the two-step uplink scheduling method is a method for scheduling an uplink (first step) and performing uplink transmission through a downlink subframe including scheduling information after a predetermined number (e.g., 4) of subframes (second step).

Fig. 19 is a diagram illustrating a method of transmitting only an SRS according to an exemplary embodiment of the present invention. Specifically, fig. 19 illustrates two methods (e.g., method M100, method M200) for transmitting only the SRS. FIG. 19 shows an SRS subframe configuration period T_SFC4 and the maximum configurable number of time domain symbols for SRS transmission is 2. That is, an interval between the SRS subframes SFSRS7a and SFSRS7b among the plurality of subframes n, n +1, ·, n +4 may correspond to four subframes (4 × 1 ms).

For example, when SRS transmission is triggered by an "SRS request" (SRS request) field of DCI that is downlink-granted to the terminal UE _ a, the terminal UE _ a may transmit SRS in the nth subframe according to SRS parameters signaled by a higher layer.

In another example, terminal UE _ b transmits PUSCH in a subframe (e.g., n +3 th subframe) defined by the uplink grant, but may transmit SRS in the n +4 th subframe since the corresponding subframe does not correspond to the SRS subframe structure. Fig. 19 shows a case where PUSCH is allocated to the terminal UE _ b via the uplink grant DCI and SRS transmission is triggered.

Meanwhile, the method M300 may simultaneously trigger a plurality of terminals included in the terminal group using an 'SRS Request' (SRS Request) field. The number of terminal groups including a plurality of terminals may be one or more, and the number of relevant information bits is determined to satisfy the maximum configurable number of terminal groups. Information on the SRS transmission terminal group together with the 'SRS request' field may be included in DCI, and in particular, may be transmitted by being included in common DCI of the unlicensed band cell.

When SRS transmission for a terminal group is triggered by a common DCI (common DCI in an unlicensed band cell) in which a CRC is masked based on a CC-RNTI, terminals belonging to the corresponding terminal group may transmit an SRS. The information on the terminal group to which the terminal belongs may be notified to the terminal during unlicensed band cell configuration or cell reconfiguration.

Fig. 20 is a diagram illustrating a method of transmitting an SRS when the maximum configurable number of SRS symbols is 2, according to an exemplary embodiment of the present invention. FIG. 20 shows an SRS subframe configuration period T_SFC2 and the maximum configurable number of time domain symbols for SRS transmission is 2. That is, an interval between SRS subframes SFSRS8a, SFSRS8b, and SFSRS8c among the plurality of subframes n, n +1, ·, n +4 may correspond to two subframes (2 × 1 ms).

Specifically, fig. 20 shows a case where SRS transmission is triggered for terminals UE _ a, UE _ b, and UE _ c by an 'SRS request' (SRS request) field of common DCI, and the terminals UE _ a, UE _ b, and UE _ c transmit SRS only in a subframe (e.g., SFSRS8a) in which SRS transmission can be performed. That is, fig. 20 shows an example in which the terminals UE _ a, UE _ b, and UE _ c have confirmed terminal group information through a higher layer message and then triggered SRS transmission for the terminal group. That is, the terminals UE _ a, UE _ b, and UE _ c are included in a terminal group for aperiodic SRS transmission, and information on the terminal group is known to each of the terminals UE _ a, UE _ b, and UE _ c.

Fig. 20 shows a case where SRS transmission is triggered while PUSCH is allocated to the terminal UE _ d via the uplink grant DCI. The maximum configurable number of SRS symbols is 2, but an uplink granted UE _ d may decide to use one time domain symbol of a subframe (e.g., SFSRS 8b) for SRS transmission. That is, the terminal UE _ d does not transmit PUSCH and SRS in the subframe SFSRS8 b.

Fig. 20 shows a case where PUSCH is allocated to terminal UE _ e via uplink grant DCI, but SRS transmission is not triggered. If the SRS is not triggered while the uplink is granted, the UE _ e drops the SRS transmission (e.g., SRS configuration drop) and configures the PUSCH until the last time domain symbol of the corresponding subframe (e.g., SFSRS8 c).

Meanwhile, when the terminal detects a Common Reference Signal (CRS) of a downlink subframe or receives a PDCCH in a subframe in which the SRS can be transmitted according to the SRS subframe configuration information, the terminal discards the SRS transmission of the same subframe. However, if the downlink subframe is a downlink partial subframe of DwPTS length, the terminal may transmit the SRS.

Meanwhile, the above-described aperiodic SRS transmission is performed according to SRS subframe configuration information defined by a higher layer. The terminal expects (expect) a position where the SRS can be transmitted according to the SRS subframe configuration information as cell specific information.

When there is no SRS subframe configuration information for aperiodic SRS transmission, if SRS transmission is triggered via an 'SRS request' (SRS request) field of an uplink grant DCI, a terminal may transmit an SRS together with a PUSCH in a subframe that has been granted. If SRS transmission is triggered via an 'SRS request' (SRS request) field of DCI (e.g., downlink grant DCI or common DCI of an unlicensed band cell) of an nth subframe, the terminal may transmit SRS in an (n +4+ b) th subframe. Here, b may be predefined according to a standard, signaled by a higher layer, or included in DCI.

Meanwhile, when the terminal transmits the SRS without transmitting the PUSCH, the terminal may transmit the SRS after performing the channel access procedure. Here, the channel access procedure may perform a single LBT of 25 μ s or an LBT with random backoff.

The LBT method that the terminal needs to perform may be determined by an information field included in the DCI. If an LBT scheme to be performed by a terminal to which SRS is to be transmitted is not defined in DCI, the terminal may determine the LBT scheme by checking whether a partial subframe of a DwPTS length is included in a subframe for SRS transmission.

If the terminal confirms partial subframe information in the common DCI between the nth partial subframe and the (n-1) th normal subframe (1ms), a single LBT of 25 μ s may be performed in the nth subframe SRS, and then the SRS may be transmitted. In case of the above condition, the base station may request SRS transmission to the terminal only when an nth subframe (nth subframe including partial subframes) needs to be included within a downlink maximum occupation time after the base station occupies a channel through class 4LBT with random backoff.

If partial subframe information is not confirmed in the common DCI between the nth partial subframe and the (n-1) th normal subframe (1ms), the terminal may perform class 4LBT with random backoff, and if it is determined that the channel is empty due to performing LBT, the terminal may transmit SRS. In case that the terminal transmits the SRS without transmitting the PUSCH, a signal for triggering SRS transmission may be included in the downlink grant DCI when the LBT scheme is determined by the terminal. If the downlink grant performs self-scheduling (self-scheduling) in the unlicensed band cell, 1 bit is added to the downlink subframe grant DCI format and it may be signaled whether the terminal performs single LBT of 25 μ s or performs class 4 LBT. In this case, corresponding bits may not be configured in the downlink subframe grant DCI format of the licensed band cell. Therefore, the terminal may expect that the information bit size of the downlink subframe grant capable of triggering SRS transmission in the unlicensed band cell is different from the information bit size of the DL subframe grant capable of triggering SRS transmission in the licensed band cell. The terminal may expect that at least one bit in the unlicensed band cell can be configured for SRS LBT. Accordingly, if a terminal receiving a downlink subframe grant DCI in an unlicensed band triggers SRS transmission through the DCI, the terminal may perform LBT through a predefined LBT method and then transmit SRS. Here, one LBT method defined in advance may be class 4 LBT. Since the terminal receives the SRS trigger information from the licensed band cell that can transmit a signal but does not transmit LBT, the terminal can occupy the channel by performing class 4LBT before SRS transmission.

For example, SRS transmission may be triggered by 'SRS request' (SRS request) information of the downlink subframe grant DCI format 1A, and 1 bit indicating the SRS LBT method may be added to the DCI format 1A transmitted in the unlicensed band cell.

As another method for confirming the LBT scheme by the terminal, there is the following method: when a subframe for transmitting the SRS by the terminal is included within the maximum channel occupying time signaled by the base station, the SRS is transmitted after the terminal performs a single LBT of 25 μ s. The common DCI may include "the number of remaining subframes to the maximum channel occupying time". Alternatively, the PHICH may not be used for ACK/NACK feedback, but may be used for information regarding "the number of remaining subframes to the maximum channel occupying time" (hereinafter, referred to as 'remaining subframe information'). The remaining subframe information included in the common DCI and PHICH means the remaining number of subframes including the current subframe or the remaining number of subframes not including the current subframe.

If a subframe for SRS transmission is not included within the maximum channel occupancy time, the terminal performs class 4LBT and then transmits the SRS. The terminal may select a random backoff value according to table 15 below (a parameter of priority 1 for class 4 LBT).

(watch 15)

Since the terminal does not receive the transmission success or failure of the SRS through the response message, the terminal may select a random backoff using the collision window by fixing the collision window to 3 or 7. That is, even if a collision occurs in actual transmission, the terminal does not need to increase the collision window again. In this case, only one of the values 3 and 7 may be used, or a value signaled by an RRC message among the values 3 and 7 may be used.

The terminal may configure the backoff counter differently and use a backoff counter engine for SRS transmission and a backoff counter engine for PUSCH transmission. That is, a backoff counter for SRS transmission and a backoff counter for PUSCH transmission may be managed differently. The back-off counter engine for SRS transmission may be utilized like the back-off counter engine for PRACH transmission or PUSCH transmission.

The backoff counter value for SRS transmission may be reselected when SRS transmission is triggered. The backoff counter may be initialized if the SRS is not transmitted in the designated subframe.

When the channel is empty prior to SRS transmission, the back-off counter value for SRS transmission may be decreased by 1 in each slot (e.g., LBT slot) interval. The terminal may perform a "self-delay" (self-preferred) operation if the back-off counter value becomes 0 before the SRS transmission is designated. Here, the "self-delaying" operation means that channel detection is further performed on one LBT slot (e.g., 9 μ s) immediately before transmission without changing the back-off counter value. Accordingly, when the back-off counter value becomes 0 in advance, the terminal may perform a "self-delay" operation to further detect a channel of one LBT slot immediately before SRS transmission and then transmit the SRS.

When PUSCH is scheduled without a slot after SRS transmission, a backoff counter engine for PUSCH may be used as described above. Since the PUSCH is transmitted immediately after the SRS transmission, overlapping channel access procedures can be avoided and the terminal can likewise follow the channel access procedure for PUSCH transmissions that are longer than the SRS symbol length.

Meanwhile, after SRS transmission, the terminal may reselect a random backoff value and then perform LBT for normal uplink transmission or SRS transmission.

If the terminal transmits the SRS without a channel access procedure, the SRS needs to be transmitted within 16 μ s after the downlink partial subframe of the DwPTS length. In this case, the terminal may perform SRS transmission in advance, unlike a Timing Advance (TA) value for determining uplink transmission timing. The terminal may determine whether to transmit the SRS and the SRS transmission timing by demodulating partial subframe information included in the common DCI of the nth partial subframe and the (n-1) th normal subframe (1 ms). If the nth subframe corresponds to the SRS subframe configuration and the SRS can be transmitted in the nth subframe, and if the sum of the number of time domain symbols in the partial subframe of the DwPTS length and the number of time domain symbols for SRS transmission is 13, the terminal can actually transmit the SRS.

Fig. 21 is a diagram illustrating a method of aperiodically transmitting an SRS after a downlink partial subframe according to an exemplary embodiment of the present invention.

Specifically, fig. 21 shows a case where, for the terminal UE _ a, SRS transmission is triggered by downlink grant DCI or common DCI, and common DCI information on downlink subframes (downlink partial subframes) in the n +1 th and n +2 th subframes used for SRS transmission is identified. Here, an n +2 th subframe among the plurality of subframes n, n +1,. and n +4 is a subframe configured according to an 'SRS-subframe configuration' parameter for SRS transmission, and includes an ending downlink partial subframe of a DwPTS length.

When the common DCI information is confirmed, the terminal UE _ a transmits the SRS in the (n + 2) th subframe. At this time, the terminal UE _ a may transmit the SRS after performing a single LBT of 25 μ s according to the number of time domain symbols of the ending downlink partial subframe of the DwPTS length, or may transmit the SRS within 16 μ s after the downlink without LBT.

6. Trigger type 2

The uplink resources may be configured according to opportunistic connections in the unlicensed frequency band, and thus the trigger type of the unlicensed frequency band may be defined. When trigger type 2 is used, SRS transmission may be triggered by a message included in DCI of a UE-specific search space (e) PDCCH, similar to trigger type 1, or may be triggered by a message included in DCI of a common search space PDCCH of an unlicensed band cell downlink subframe.

SRS Transmission timing

The transmission timing of the SRS transmitted by the terminal may be different from the uplink transmission timing of the cell group. The terminal can follow TA_SRSThe SRS is transmitted at a timing earlier than the normal uplink transmission timing. The terminal may receive the TA from the base station_SRSWherein TA_SRSMay be signaled via a higher layer message (e.g., RRC message) or included in a DCI message for SRS configuration.

Meanwhile, in a resource configuration for unlicensed band SRS transmission, UpPTS may be extended. The extended UpPTS may include time domain symbols (e.g., SC-FDMA symbols) configuring an ending downlink portion subframe of the unlicensed band and a remaining time interval of the 1ms TTI.

The number of time domain symbols of the ending downlink part subframe, which may be configured to be the same length as the DwPTS, may be one of the set {3,6,9,10,11,12 }. That is, the end downlink partial subframe may have a length corresponding to one of three time domain symbols, six time domain symbols, nine time domain symbols, ten time domain symbols, eleven time domain symbols, and twelve time domain symbols.

The extended UpPTS may be composed of a remaining number of time domain symbols obtained by subtracting the number of time domain symbols of the end portion subframe of the DwPTS length from the total number of time domain symbols of the subframe, wherein the extended UpPTS may be configured to be spaced apart from the end portion subframe of the DwPTS length by a predetermined interval (e.g., a length corresponding to one or more time domain symbols). For example, the number of time domain symbols of the extended UpPTS may be one value of the set {10,7,4,3,2,1 }. The slot parameter values required for SRS sequence generation and resource configuration in the extended UpPTS may be replaced with values mapped by the time domain symbol index of the UpPTS.

Fig. 22 is a diagram illustrating an extended uplink pilot time slot (UpPTS) composed of 10 time domain symbols according to an exemplary embodiment of the present invention.

Specifically, fig. 22 illustrates a case where the extended UpPTS exists after a Guard Period (GP) and includes 10 time domain symbols (numbers 4 to 13). Here, the guard period GP and the propagation delay for the transmission/reception switching exist after the end downlink part subframe (time domain symbols numbered 0 to 2) and may correspond to one time domain symbol.

In the extended UpPTS, several terminals may transmit SRS using the same or different time domain symbols (e.g., SC-FDMA symbols).

The following table 16 shows a case where a time domain symbol numbered 4 among time domain symbols (numbered 4 to 13) included in the extended UpPTS of fig. 22 is mapped to a subframe numbered 0 and a slot is 1. In the following table 16, the symbol Index denotes a time domain symbol Index, Sf _ Index denotes a subframe Index, and n_sIndicating the slot index.

(watch 16)

Symbol index	4	5	6	7	8	9	10	11	12	13
											ns	1	3	5	7	9	11	13	15	17	19
Sf_Index	0	1	2	3	4	5	6	7	8	9

As described above, the transmission timing of the SRS transmitted by the terminal may be different from the uplink transmission timing of the cell group. The terminal may TA earlier than the ordinary uplink transmission timing_SRSAnd sending the SRS. Here, TA_SRSMay be signaled by a higher layer message or may be included in a DCI message for SRS configuration. Alternatively, the terminal may arbitrarily determine the TA_SRSSo that after the downlink transmission is completedWithin 16 mus of the SRS.

Fig. 23 is a diagram illustrating a timing at which a base station receives an SRS when the extended UpPTS of fig. 22 is used according to an exemplary embodiment of the present invention.

It is shown in fig. 23 that the SRS transmission resource is configured and the transmission timing of each terminal such as the cell group shown in fig. 22 is early TA_SRSResult of the case of transmitting SRS.

The effect of the result shown in fig. 23 is that other wireless devices can be prevented from occupying a channel of a transmission length (e.g., about 70 μ s) from the downlink of the DwPTS length to the SRS transmission timing.

Further, a time (e.g., about 70 μ s) from the downlink to the SRS transmission timing of the DwPTS length may be used as the channel occupancy state confirmation time. Here, the channel occupancy state confirmation time is a time required for uplink subframe transmission or downlink subframe transmission that is continuously configured after SRS transmission.

Meanwhile, information on the extended UpPTS may be signaled to the terminal. Here, the signaling may be transmitted through RRC messages of a higher layer. The signaling configuration information may include at least one of: setting information on a candidate length of the extended UpPTS, CCA-related parameters for SRS transmission of the extended UpPTS, time domain symbol information (e.g., time domain symbol offset, time domain symbol bundle) on the extended UpPTS mapped to subframe index information associated with SRS generation, and SRS hopping information.

At least one of a sequence generation parameter of the SRS to be transmitted by each terminal, a frequency domain resource to be transmitted by each terminal, and a time domain symbol resource to be transmitted by each terminal among the resources of the extended UpPTS may be signaled to the terminal. The signaling may be constituted by an RRC message in a higher layer, may be defined by information transmitted via DCI of the unlicensed band common PDCCH, or may be included in each UE-specific DCI.

If the terminal confirms that the nth subframe is the last subframe of the downlink, it is possible to transmit the SRS using the signaled information.

The method of confirming the SRS transmission timing of the terminal may include a method of signaling DCI of an unlicensed band common PDCCH or DCI of a UE-specific PDCCH to the terminal so that the terminal transmits the SRS in the nth subframe. The signaling may include configuration information regarding the SRS. The SRS configuration information may include the number of time domain symbols, a time domain symbol index to be used by each terminal, and the like.

The method of confirming the SRS transmission timing of the terminal may include a method of using SRS transmission period information configured by the terminal. Here, the SRS transmission period information may be configured for UE-specific or may be common to all terminals as cell-specific. The corresponding configuration information (e.g., SRS transmission period information) may be signaled to the terminal through RRC of a higher layer.

Therefore, the terminal can also determine the SRS transmission timing based on a combination of the SRS transmission period information and the DCI information used in the method of confirming the SRS transmission timing of the terminal.

The method of confirming the SRS transmission timing of the terminal may include the following methods: the terminal detects an ending downlink partial subframe of the unlicensed band through DCI of the unlicensed band common PDCCH included in an n-k subframe (e.g., an n-1 subframe), and then transmits the SRS.

Meanwhile, if an extended UpPTS is used, at least the last time domain symbol may be configured not to be used for SRS transmission for CCA after the UpPTS.

Fig. 24 is a diagram illustrating an extended UpPTS that does not include the last time domain symbol according to an exemplary embodiment of the present invention.

In particular, fig. 24 illustrates a case where the extended UpPTS is configured such that the last time domain symbol (e.g., number 13) of the subframe including the extended UpPTS is not used for SRS transmission. The extended UpPTS shown in fig. 24 includes nine time domain symbols (e.g., numbers 4 to 12).

A CCA (e.g., a CCA for an unlicensed band channel) in the last time domain symbol (e.g., No. 13) may be performed by the terminal to transmit a PUSCH or the like in an uplink subframe configured after the UpPTS. Alternatively, CCA in the last time domain symbol (e.g., number 13) may be performed by the base station to transmit the downlink subframe after an extended UpPTS configured according to the SRS transmission period.

Meanwhile, in a resource configuration for unlicensed band SRS transmission, a method of configuring an SRS transmission subframe may include a method of configuring up to 14 time domain symbols within a 1ms TTI subframe for SRS transmission. In this subframe, only the SRS may be transmitted or the SRS and the PRACH may be multiplexed and transmitted. The SRS transmission subframe may be configured independently of other downlink subframes or uplink subframes, or may be configured in some or all of the subframes before or after an uplink transmission burst. To satisfy a limited transmission opportunity (TxOP) length, an SRS transmission subframe may be configured in a first subframe or a last subframe of an uplink transmission burst.

Meanwhile, the number of time domain symbols configured for actual SRS transmission may be defined by DCI included in a PDCCH common search period.

Fig. 25 is a diagram illustrating an SRS transmission subframe in which the first nine time domain symbols are configured for SRS transmission according to an exemplary embodiment of the present invention.

Specifically, fig. 25 shows a case where nine time domain symbols (e.g., numbers 0 to 8) existing in the front of the subframe are configured for (available for) SRS transmission.

Fig. 26 is a diagram illustrating an SRS transmission subframe in which the last eight time domain symbols are configured for SRS transmission according to an exemplary embodiment of the present invention.

Specifically, fig. 26 shows a case where eight time domain symbols (e.g., numbers 6 to 8) existing at the end of a subframe are configured for (available for) SRS transmission.

Table 17 below (mapping for the exemplary embodiment of fig. 25) shows a case where a time domain symbol index is mapped to a subframe index and a slot index in the exemplary embodiment of fig. 25. In the following table 17, symbol Index denotes a time domain symbol Index, Sf _ Index denotes a subframe Index, n_sIndicating the slot index.

(watch 17)

Symbol index	0	1	2	3	4	5	6	7	8
										ns	1	3	5	7	9	11	13	15	17
Sf_Index	0	1	2	3	4	5	6	7	8

The following table 18 (mapping for the exemplary embodiment of fig. 26) shows a case where a time domain symbol index is mapped to a subframe index and a slot index in the exemplary embodiment of fig. 26. In the following table 18, a symbol Index denotes a time domain symbol Index, Sf _ Index denotes a subframe Index, n_sIndicating the slot index.

(watch 18)

Symbol index	6	7	8	9	10	11	12	13
									ns	1	3	5	7	9	11	13	15
Sf_Index	0	1	2	3	4	5	6	7

Meanwhile, for the performance of the CCA, at least one time domain symbol present in at least a first time domain symbol of the SRS transmission subframe, at least one time domain symbol present in at least a last time domain symbol of the SRS transmission subframe, or at least one time domain symbol present in each of the first and last SRS transmission subframes of the SRS transmission subframe may be configured not to be used for SRS transmission. The slot parameter values required for SRS sequence generation and resource configuration in the SRS transmission subframe may be replaced with values mapped by the time domain symbol index of the SRS transmission subframe.

Fig. 27 is a diagram illustrating an SRS transmission subframe in which neither a first time domain symbol nor a last time domain symbol is configured for SRS transmission according to an exemplary embodiment of the present invention.

Specifically, in fig. 27, 12 time domain symbols (e.g., numbers 1 to 12) of time domain symbols of an SRS transmission subframe are configured for SRS transmission, and the remaining time domain symbols (e.g., numbers 0 and 13) are configured not for SRS transmission. For example, the first time domain symbol (e.g., number 0) and the last time domain symbol (e.g., number 13) may be used for CCA.

The SRS transmission subframe shown in fig. 27 may be configured between downlink subframes in frame structure type 3 for periodic SRS transmission. Alternatively, the frame shown in fig. 27 may be configured at the end after the downlink transmission burst. Alternatively, the subframes shown in fig. 27 may be configured between uplink subframes or at the end after an uplink transmission burst.

The following table 19 shows a case where time domain symbols numbered 1 of an SRS transmission subframe are mapped to a subframe numbered 0 and a slot numbered 1 in the exemplary embodiment of fig. 27. In the following table 19, symbol Index denotes a time domain symbol Index, Sf _ Index denotes a subframe Index, n_sIndicating the slot index.

(watch 19)

Symbol index	1	2	3	4	5	6	7	8	9	10	11	12
													ns	1	3	5	7	9	11	13	15	17	19	1	3
Sf_Index	0	1	2	3	4	5	6	7	8	9	0	1

In table 19 above, the time domain symbol numbered 11 is mapped again to the subframe numbered 0 and the slot numbered 1 by a modulo operation (modulo operation). Similarly, in table 19 above, the time domain symbol numbered 12 is mapped to the subframe numbered 1 and the slot numbered 3 again by the modulo operation. In this case, the SRS may be transmitted in a resource different from the time domain symbol numbered 1. Alternatively, the SRS may be transmitted in another resource through a frequency hopping pattern.

Fig. 28 is a diagram illustrating an SRS transmission subframe in which the first one time domain symbol and the last three time domain symbols are not configured for SRS transmission according to an exemplary embodiment of the present invention.

Specifically, fig. 28 shows a case where a terminal performs CCA in a first time domain symbol (for example, number 0) period, and a plurality of terminals transmit SRS during 10 time domain symbols (for example, numbers 1 to 10).

The next three time domain symbols (e.g., numbers 11 through 13) may not be used. Alternatively, the next three time domain symbols (e.g., numbers 11 to 13) may be used for at least CCA performance or for transmission of a channel occupancy signal prior to the start of a consecutive downlink subframe or uplink subframe.

That is, 10 time domain symbols (e.g., numbers 1 to 10) among the time domain symbols of the SRS transmission subframe are configured for SRS transmission, and the remaining time domain symbols (e.g., numbers 0 and 11 to 13) are not configured for SRS transmission. For example, the remaining time domain symbols (e.g., number 0 and numbers 11 through 13) may be used for CCA.

The following table 20 shows a case where time domain symbols numbered 1 of an SRS transmission subframe are mapped to a subframe numbered 0 and a slot numbered 1 in the exemplary embodiment of fig. 28. In the following table 20, a symbol Index denotes a time domain symbol Index, Sf _ Index denotes a subframe Index, n_sIndicating the slot index.

(watch 20)

Symbol index	1	2	3	4	5	6	7	8	9	10
											ns	1	3	5	7	9	11	13	15	17	19
Sf_Index	0	1	2	3	4	5	6	7	8	9

Fig. 29 is a diagram illustrating a case where an SRS transmission subframe is configured in a time domain symbol satisfying (time domain symbol index mod2) ═ 1 according to an exemplary embodiment of the present invention.

Specifically, fig. 29 shows a case where, in order to perform CCA before each terminal transmits an SRS, the SRS is configured only for a time domain symbol satisfying (time domain symbol index mod2) ═ 1.

A total of seven time domain symbols (e.g., numbers 1, 3, 5, 7, 9, 11, and 13) are configured for SRS transmission, and each terminal may perform CCA prior to SRS transmission.

That is, even-numbered time domain symbols (e.g., numbers 1, 3, 5, 7, 9, 11, and 13) among the time domain symbols of the SRS transmission subframe may be configured (available) for SRS transmission, and odd-numbered time domain symbols (e.g., 0, 2, 4, 6, 8, 10, and 12) are configured not for SRS transmission. For example, odd-numbered time domain symbols (e.g., numbers 0, 2, 4, 6, 8, 10, and 12) may be used for CCA.

The following table 21 shows a case where a time domain symbol index of an SRS transmission subframe is mapped to a subframe index or a slot index in the exemplary embodiment of fig. 29. In the following table 21, symbol Index denotes a time domain symbol Index, Sf _ Index denotes a subframe Index, n_sIndicating the slot index.

(watch 21)

Symbol index	1	3	5	7	9	11	13
								ns	1	3	5	7	9	11	13
Sf_Index	0	1	2	3	4	5	6

Meanwhile, information on the SRS transmission subframe may be signaled to the terminal. Here, the signaling may be transmitted through RRC messages of a higher layer. The signaling configuration information may include at least one of: periodicity information of the SRS transmission subframe, a number of time domain symbols used in the SRS transmission subframe, CCA-related parameters, time domain symbol information (e.g., time domain symbol offset, time domain symbol bundle, etc.) regarding the SRS transmission subframe mapped to subframe index information associated with SRS generation, and SRS hopping information.

At least one of a sequence generation parameter of the SRS to be transmitted by each terminal, a frequency domain resource to be transmitted by each terminal, and a time domain symbol to be transmitted by each terminal within the SRS transmission subframe may be signaled to the terminal. Here, the signaling may be composed of an RRC message in a higher layer, may be defined by information transmitted through DCI of the unlicensed band common PDCCH, or may be included in each UE-specific DCI.

The method of confirming the SRS transmission timing of the terminal may include a method of signaling DCI of an unlicensed band common PDCCH or DCI of a UE-specific PDCCH to the terminal so that the terminal transmits the SRS in the nth subframe. The signaling may include configuration information for the SRS. The SRS configuration information may include the number of time domain symbols, a time domain symbol index to be used by each terminal, and the like.

The method of confirming the SRS transmission timing of the terminal may include a method of using SRS transmission period information configured by the terminal. Here, the SRS transmission period information may be configured for UE-specific or may be common to all terminals as cell-specific. The corresponding configuration information (e.g., SRS transmission period information) may be signaled to the terminal through RRC of a higher layer.

Therefore, the terminal can also determine the SRS transmission timing based on a combination of the SRS transmission period information and the DCI information used in the method of confirming the SRS transmission timing of the terminal.

Meanwhile, in a resource configuration for unlicensed band SRS transmission, a subframe including an extended SRS may be used.

A method of extending and configuring the SRS resource configured in the last time domain symbol of the uplink to a plurality of last time domain symbols may be used. The slot parameter values required for SRS sequence generation and resource configuration in a subframe including the extended SRS may be replaced with values mapped by a time domain symbol index of an SRS transmission subframe.

Fig. 30 is a diagram illustrating a case in which a second slot of a subframe is configured for SRS transmission according to an exemplary embodiment of the present invention.

Specifically, fig. 30 shows a case where the second slot of the first and second slots of the uplink subframe may be configured for (available for) SRS transmission. Further, the first slot of the uplink subframe is configured for uplink transmissions (e.g., DMRS, PUSCH).

However, this is only one example. As shown in the exemplary embodiment of fig. 29, for CCA, some time domain symbols in the second slot may also be configured not for SRS transmission.

The following table 22 shows a case where the extended time domain symbol index of the SRS is mapped to a subframe index or a slot index in the exemplary embodiment of fig. 30. In the following table 22, symbol Index denotes a time domain symbol Index, Sf _ Index denotes a subframe Index, n_sIndicating the slot index.

(watch 22)

Symbol index	7	8	9	10	11	12	13
								ns	1	3	5	7	9	11	13
Sf_Index	0	1	2	3	4	5	6

Meanwhile, information on a subframe including the extended SRS may be signaled to the terminal. Here, the signaling may be transmitted through an RRC message of a higher layer. The signaling configuration information may include at least one of: the apparatus may include means for configuring periodicity information of a subframe configuring the extended SRS, a number of time domain symbols configuring the extended SRS, CCA-related parameters, time domain symbol information (e.g., time domain symbol offset, time domain symbol bundle, etc.) mapped to subframe index information associated with SRS generation and configuring the extended SRS, and SRS hopping information.

At least one of a sequence generation parameter of the SRS to be transmitted by each terminal, a frequency domain resource to be transmitted by each terminal, and a time domain symbol resource to be transmitted by each terminal within a subframe including the extended SRS may be signaled to the terminal. Here, the signaling may be composed of an RRC message in a higher layer, may be defined by information transmitted via DCI of the unlicensed band common PDCCH, or may be included in each UE-specific DCI.

The method of confirming the SRS transmission timing of the terminal may include a method of signaling DCI of an unlicensed band common PDCCH or DCI of a UE-specific PDCCH to the terminal so that the terminal transmits the SRS in the nth subframe. The signaling may include configuration information for the SRS. The SRS configuration information may include the number of time domain symbols, a time domain symbol index to be used by each terminal, and the like.

The method of confirming the SRS transmission timing of the terminal may include a method of using SRS transmission period information configured by the terminal. Here, the SRS transmission period information may be configured for UE-specific or may be common to all terminals as cell-specific. The corresponding configuration information (e.g., SRS transmission period information) may be signaled to the terminal through RRC of a higher layer.

Therefore, the terminal can also determine the SRS transmission timing based on a combination of the SRS transmission period information and the DCI information used in the method of confirming the SRS transmission timing of the terminal.

In all of the above exemplary embodiments, the transmission timing of the SRS transmitted by the terminal may be different from the uplink transmission timing of the cell group. The terminal may TA earlier than the normal uplink transmission timing (e.g., the exemplary embodiment in FIG. 23)_SRSAnd sending the SRS. Here, TA_SRSMay be signaled by a higher layer message or may be included in a DCI message for SRS configuration.

The exemplary embodiments of the present invention may be implemented not only by the apparatus and/or method as described above but also by a program implementing functions corresponding to the configuration of the exemplary embodiments of the present invention or a recording medium recording a program that can be easily implemented by a person having ordinary skill in the art to which the present invention pertains from the description of the foregoing exemplary embodiments.

Although the exemplary embodiments of the present invention have been described above in detail, the scope of the present invention is not limited thereto. That is, some modifications and changes by those skilled in the art using the basic idea of the present invention defined in the claims fall within the scope of the present invention.