WO2020050630A1 - Method and device for performing wireless communication in unlicensed band - Google Patents

Abstract

The present embodiments relate to a method and a device for performing wireless communication in an unlicensed band, and one embodiment provides a method for a terminal performing wireless communication in an unlicensed band, the method comprising the steps of: receiving, in a system band comprising a plurality of sub-bands, information for allocating a radio resource; acquiring, for at least one sub-band included in the radio resource, available environment information based on the performing of Listen Before Talk (LBT); and transmitting the available environment information.

Description

Method and apparatus for performing wireless communication in an unlicensed band

The present embodiments propose a method and apparatus for performing wireless communication in consideration of a result of performing a List Before Talk (LBT) for an unlicensed band in a next-generation radio access network (hereinafter referred to as "NR [New Radio]").

3GPP recently approved "Study on New Radio Access Technology", a study item for research on next-generation radio access technology (that is, 5G radio access technology), and based on this, RAN WG1 respectively provides for NR (New Radio) Designs for frame structures, channel coding & modulation, waveform & multiple access schemes, etc. are underway. NR is required to be designed to satisfy various QoS requirements required for each segmented and specific usage scenario as well as an improved data rate compared to LTE.

As representative NR usage scenarios, eMBB (enhancement Mobile BroadBand), mMTC (massive Machine Type Communication), and URLLC (Ultra Reliable and Low Latency Communications) have been defined, and a flexible frame structure compared to LTE to satisfy the needs of each usage scenario Design is required.

Each service scenario (usage scenario) is a data rate (data rates), latency (latency), reliability (reliability), coverage (coverage), etc. because the requirements are different from each other through the frequency band constituting the NR system Based on different numerology (e.g., subcarrier spacing, subframe, transmission time interval (TTI)) as a method for efficiently satisfying the needs of each usage scenario There is a need for a method of efficiently multiplexing radio resource units of the system.

As part of this aspect, a design for performing wireless communication is required according to a result of performing LBT on a plurality of subbands constituting an unlicensed band in NR.

Embodiments of the present disclosure, by sharing the available environment information based on the results of LBT performance for a plurality of subbands in the unlicensed band, to perform efficient band operation in an environment where the probability of LBT success for each subband is independent and variable. It can provide a specific method and apparatus that can.

In one aspect, the present embodiments are a method for a terminal to perform wireless communication in an unlicensed band, receiving information for allocating radio resources in a system band composed of a plurality of subbands, at least one included in the radio resources It is possible to provide a method comprising obtaining available environment information based on performing a Listen Before Talk (LBT) for a subband and transmitting available environment information.

In another aspect, the present embodiments provide a method for a base station to perform wireless communication in an unlicensed band, transmitting information for allocating radio resources in a system band composed of a plurality of subbands, and at least one included in the radio resources. It is possible to provide a method including receiving available environment information based on performing a Listen Before Talk (LBT) for a subband.

In another aspect, the present embodiments are terminals for performing wireless communication in an unlicensed band, a receiving unit receiving information for allocating radio resources in a system band composed of a plurality of subbands, at least one sub included in the radio resources It is possible to provide a terminal including a control unit for obtaining available environment information based on performing a LBT (Listen Before Talk) for a band and a transmitter for transmitting available environment information.

In another aspect, the present embodiments are at least one sub included in a radio resource and a transmitter for transmitting information for allocating radio resources in a system band composed of a plurality of subbands in a base station performing radio communication in an unlicensed band. It is possible to provide a base station including a receiver for receiving available environment information based on performing a LBT (Listen Before Talk) for a band.

According to the present embodiments, by sharing available environment information based on LBT performance results for a plurality of subbands in an unlicensed band, efficient band operation is performed in an environment where the probability of success of LBT for each subband is independent and variable. It is possible to provide a method and apparatus for performing wireless communication in an unlicensed band.

1 is a diagram briefly showing a structure of an NR wireless communication system to which the present embodiment can be applied.

2 is a view for explaining a frame structure in an NR system to which the present embodiment can be applied.

3 is a diagram for describing a resource grid supported by a radio access technology to which an embodiment of the present invention can be applied.

4 is a diagram for describing a bandwidth part supported by a radio access technology to which an embodiment of the present invention can be applied.

5 is a diagram exemplarily illustrating a synchronization signal block in a radio access technology to which the present embodiment can be applied.

FIG. 6 is a diagram for explaining a random access procedure in a radio access technology to which the present embodiment can be applied.

7 is a diagram for explaining CORESET.

8 is a diagram illustrating an example of symbol level alignment among different SCSs in different SCSs to which the present embodiment can be applied.

9 is a diagram illustrating a conceptual example of a bandwidth part to which the present embodiment can be applied.

10 is a diagram illustrating a procedure in which a terminal performs wireless communication using available environment information for at least one subband in an unlicensed band according to an embodiment.

11 is a diagram illustrating a procedure in which a base station performs wireless communication using available environment information for at least one subband in an unlicensed band according to an embodiment.

12 is a diagram for explaining performing LBT for wireless communication in an unlicensed band according to an embodiment.

13 is a diagram for describing a subband of an unlicensed band according to an embodiment.

14 is a diagram for explaining allocation of a plurality of radio resources for transmitting and receiving predetermined data based on available environment information according to an embodiment.

15 is a diagram illustrating the configuration of a user equipment (UE) according to another embodiment.

16 is a diagram showing the configuration of a base station according to another embodiment.

Hereinafter, some embodiments of the present disclosure will be described in detail with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same reference numerals as much as possible even though they are shown in different drawings. In addition, in describing the present embodiments, when it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted. When "include", "have", "consist", or the like, as used herein, other parts may be added unless "only" is used. In the singular form, the plural may include the plural unless specifically stated otherwise.

In addition, in describing the components of the present disclosure, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the component from other components, and the essence, order, order, or number of the component is not limited by the term.

In the description of the positional relationship of the components, when two or more components are described as being "connected", "coupled" or "connected", the two or more components are directly "connected", "coupled" or "connected" It may be understood that "but may be," two or more components and other components may be further "interposed" to be "connected", "coupled" or "connected". Here, other components may be included in one or more of two or more components that are “connected”, “coupled”, or “connected” to each other.

In the description of the temporal flow relations with respect to the components, the operation method, the fabrication method, and the like, for example, the temporal relationship between the temporal relationship of " after ", " following ", " after " Or where flow-benefit relationships are described, they may also include cases where they are not continuous unless "right" or "direct" is used.

On the other hand, when numerical values or corresponding information (e.g., levels) for the component are mentioned, the numerical values or corresponding information may be various factors (e.g., process factors, internal or external shocks, It may be interpreted as including an error range that may be caused by noise).

The wireless communication system in the present specification means a system for providing various communication services such as voice and data packets using radio resources, and may include a terminal, a base station, or a core network.

The embodiments disclosed below can be applied to a wireless communication system using various radio access technologies. For example, the embodiments of the present invention may include code division multiple access (CDMA), frequency division multiple access (FDMA), timedivision multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), and single carrier frequency division multiple access (SC-FDMA). Alternatively, the present invention may be applied to various radio access technologies such as non-orthogonal multiple access (NOMA). In addition, the wireless access technology may mean not only a specific access technology, but also a communication technology for each generation established by various communication consultation organizations such as 3GPP, 3GPP2, WiFi, Bluetooth, IEEE, and ITU. For example, CDMA may be implemented with a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with radio technologies such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE). OFDMA can be implemented with wireless technologies such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and Evolved UTRA (E-UTRA). IEEE 802.16m is an evolution of IEEE 802.16e, and provides backward compatibility with a system based on IEEE 802.16e. UTRA is part of a universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is part of evolved UMTS (E-UMTS) using evolved-UMTS terrestrial radio access (E-UTRA), employing OFDMA in downlink and SC- in uplink FDMA is adopted. As such, the embodiments may be applied to a wireless access technology that is currently disclosed or commercialized, and may be applied to a wireless access technology that is currently under development or will be developed in the future.

Meanwhile, the terminal in the present specification is a comprehensive concept of a device including a wireless communication module for performing communication with a base station in a wireless communication system, and in WCDMA, LTE, NR, HSPA, and IMT-2020 (5G or New Radio), etc. In addition to the user equipment (UE), as well as MS (Mobile Station), User Interface (UT), Subscriber Station (SS), a wireless device (wireless device) and the like in GSM should be interpreted. In addition, the terminal may be a user portable device such as a smart phone according to a usage form, and in the V2X communication system, it may mean a vehicle, a device including a wireless communication module in the vehicle, and the like. In addition, in the case of a machine type communication system, it may mean an MTC terminal, an M2M terminal, a URLLC terminal, etc. equipped with a communication module to perform machine type communication.

A base station or a cell of the present specification refers to an end point that communicates with a terminal in terms of a network, and includes a Node-B, an evolved Node-B, an eNB, a gNode-B, a Low Power Node, and an LPN. Sector, site, various types of antenna, base transceiver system (BTS), access point, point (for example, transmission point, reception point, transmission / reception point), relay node ), A mega cell, a macro cell, a micro cell, a pico cell, a femto cell, a remote radio head (RRH), a radio unit (RU), and a small cell. In addition, the cell may mean a bandwidth part (BWP) in the frequency domain. For example, the serving cell may mean an activation BWP of the terminal.

Since the various cells listed above have a base station that controls one or more cells, the base station can be interpreted in two ways. 1) the device providing the mega cell, the macro cell, the micro cell, the pico cell, the femto cell, the small cell in relation to the radio area, or 2) the radio area itself. In 1) all devices that provide a given wireless area are controlled by the same entity or interact with each other to cooperatively configure the wireless area to the base station. According to the configuration of the wireless area, a point, a transmission point, a transmission point, a reception point, and the like become one embodiment of a base station. In 2), the base station may indicate the radio area itself that receives or transmits a signal from the viewpoint of the user terminal or the position of a neighboring base station.

In the present specification, a cell refers to a component carrier having coverage of a signal transmitted from a transmission / reception point or a signal transmitted from a transmission point or a transmission / reception point, and the transmission / reception point itself. Can be.

Uplink (Uplink, UL, or uplink) means a method of transmitting and receiving data to the base station by the terminal, downlink (Downlink, DL, or downlink) means a method of transmitting and receiving data to the terminal by the base station do. Downlink (downlink) may mean a communication or communication path from the multiple transmission and reception points to the terminal, uplink (uplink) may mean a communication or communication path from the terminal to the multiple transmission and reception points. In this case, in the downlink, the transmitter may be part of multiple transmission / reception points, and the receiver may be part of the terminal. In addition, in uplink, a transmitter may be part of a terminal, and a receiver may be part of multiple transmission / reception points.

The uplink and the downlink transmit and receive control information through a control channel such as a physical downlink control channel (PDCCH), a physical uplink control channel (PUCCH), a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), and the like. Configure the same data channel to send and receive data. Hereinafter, a situation in which a signal is transmitted and received through a channel such as a PUCCH, a PUSCH, a PDCCH, and a PDSCH may be described in the form of 'sending and receiving a PUCCH, a PUSCH, a PDCCH, and a PDSCH.'

For clarity, the following description focuses on the 3GPP LTE / LTE-A / NR (New RAT) communication system, but the present technical features are not limited to the communication system.

After researching 4G (4th-Generation) communication technology, 3GPP develops 5G (5th-Generation) communication technology to meet the requirements of ITU-R's next generation wireless access technology. Specifically, 3GPP develops a new NR communication technology separate from LTE-A pro and 4G communication technology, which is an enhancement of LTE-Advanced technology to the requirements of ITU-R with 5G communication technology. Both LTE-A pro and NR mean 5G communication technology. Hereinafter, 5G communication technology will be described based on NR when a specific communication technology is not specified.

Operational scenarios in NR defined various operational scenarios by adding considerations to satellites, automobiles, and new verticals in the existing 4G LTE scenarios.In terms of service, they have an eMBB (Enhanced Mobile Broadband) scenario and a high terminal density. Supports a range of mass machine communication (MMTC) scenarios that require low data rates and asynchronous connections, and Ultra Reliability and Low Latency (URLLC) scenarios that require high responsiveness and reliability and support high-speed mobility. .

In order to satisfy this scenario, NR discloses a wireless communication system using a new waveform and frame structure technology, low latency technology, mmWave support technology, and forward compatible technology. In particular, the NR system proposes various technological changes in terms of flexibility to provide forward compatibility. The main technical features of the NR will be described with reference to the drawings below.

<NR system general>

1 is a diagram briefly showing a structure of an NR system to which the present embodiment may be applied.

Referring to FIG. 1, the NR system is divided into 5GC (5G Core Network) and NR-RAN parts, and NG-RAN is controlled for a user plane (SDAP / PDCP / RLC / MAC / PHY) and UE (User Equipment). It consists of gNB and ng-eNBs that provide a plane (RRC) protocol termination. gNB interconnection or gNB and ng-eNB are interconnected via Xn interface. gNB and ng-eNB are each connected to 5GC through the NG interface. The 5GC may be configured to include an access and mobility management function (AMF) in charge of a control plane such as a terminal access and mobility control function and a user plane function (UPF) in charge of a control function in user data. NR includes support for sub-6 GHz frequency bands (FR1, Frequency Range 1) and 6 GHz and higher frequency bands (FR2, Frequency Range 2).

gNB means a base station that provides NR user plane and control plane protocol termination to the terminal, and ng-eNB means a base station that provides E-UTRA user plane and control plane protocol termination to the terminal. The base station described in this specification should be understood as a meaning encompassing gNB and ng-eNB, and may be used in a sense to separately refer to gNB or ng-eNB as necessary.

<NR wave form, numerology and frame structure>

In NR, a CP-OFDM waveform using a cyclic prefix is used for downlink transmission, and a CP-OFDM or DFT-s-OFDM is used for uplink transmission. OFDM technology is easy to combine with Multiple Input Multiple Output (MIMO), and has the advantage of using a low complexity receiver with high frequency efficiency.

On the other hand, in the NR, the demands for data rate, delay rate, and coverage for each of the three scenarios described above are different from each other, so it is necessary to efficiently satisfy the requirements for each scenario through the frequency band constituting an arbitrary NR system. . To this end, a technique for efficiently multiplexing a plurality of different numerology-based radio resources has been proposed.

Specifically, the NR transmission neurology is determined based on sub-carrier spacing (sub-carrier spacing) and cyclic prefix (CP), and the μ value is used as an exponential value of 2 based on 15 kHz as shown in Table 1 below. Will be changed.

μ	Subcarrier spacing	Cyclic prefix	Supported for data	Supported for synch
0	15	Normal	Yes	Yes
One	30	Normal	Yes	Yes
2	60	Normal, Extended	Yes	No
3	120	Normal	Yes		Yes
4	240	Normal	No	Yes

As shown in Table 1 above, the NR numerology can be divided into 5 types according to the subcarrier spacing. This is different from that in which the subcarrier spacing of LTE, which is one of 4G communication technologies, is fixed at 15 kHz. Specifically, the subcarrier interval used for data transmission in NR is 15, 30, 60, and 120 kHz, and the subcarrier interval used for synchronization signal transmission is 15, 30, 12, and 240 kHz. In addition, the extended CP is applied only to the 60 kHz subcarrier interval. On the other hand, the frame structure (frame) in NR is a frame having a length of 10ms consisting of 10 subframes having the same length of 1ms is defined. One frame may be divided into half frames of 5 ms, and each half frame includes five subframes. In the case of a 15 kHz subcarrier interval, one subframe is composed of one slot, and each slot is composed of 14 OFDM symbols. 2 is a view for explaining a frame structure in an NR system to which the present embodiment can be applied. Referring to FIG. 2, the slot is fixedly configured with 14 OFDM symbols in the case of a normal CP, but the length of the slot may vary according to the subcarrier spacing. For example, in the case of a numerology with a 15 kHz subcarrier spacing, the slot is 1 ms long and is configured to have the same length as the subframe. On the other hand, in the case of a neurology with a 30 kHz subcarrier spacing, the slot is composed of 14 OFDM symbols, but may have two slots in one subframe with a length of 0.5 ms. That is, the subframe and the frame are defined with a fixed time length, the slot is defined by the number of symbols, the time length may vary according to the subcarrier interval.

Meanwhile, NR defines a basic unit of scheduling as a slot and also introduces a mini slot (or subslot or non-slot based schedule) to reduce transmission delay of a radio section. If a wide subcarrier interval is used, the transmission delay in a radio section can be reduced because the length of one slot is inversely shortened. The mini slot (or sub slot) is for efficient support for the URLLC scenario and can be scheduled in units of 2, 4, and 7 symbols.

In addition, unlike LTE, NR defines uplink and downlink resource allocation at a symbol level in one slot. In order to reduce the HARQ delay, a slot structure capable of transmitting HARQ ACK / NACK in a transmission slot is defined, and this slot structure is described as a self-contained structure.

NR is designed to support a total of 256 slot formats, of which 62 slot formats are used in 3GPP Rel-15. In addition, the combination of various slots supports a common frame structure constituting an FDD or TDD frame. For example, a slot structure in which all symbols of a slot are set to downlink, a slot structure in which all symbols are set to uplink, and a slot structure in which downlink symbol and uplink symbol are combined are supported. NR also supports that data transmission is distributed and scheduled in one or more slots. Accordingly, the base station can inform the terminal whether the slot is a downlink slot, an uplink slot, or a flexible slot by using a slot format indicator (SFI). The base station may indicate the slot format by indicating an index of a table configured through UE-specific RRC signaling using SFI, and may indicate the slot format dynamically through DCI (Downlink Control Information) or statically through RRC. You can also specify quasi-statically.

<NR Physical Resource>

With regard to physical resources in NR, antenna ports, resource grids, resource elements, resource blocks, bandwidth parts, etc. are considered do.

The antenna port is defined so that the channel on which the symbol is carried on the antenna port can be inferred from the channel on which another symbol on the same antenna port is carried. If the large-scale property of a channel carrying a symbol on one antenna port can be inferred from a channel carrying a symbol on another antenna port, the two antenna ports are QC / QCL (quasi co-located or quasi co-location). Here, the broad characteristics include one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

3 is a diagram for describing a resource grid supported by a radio access technology to which an embodiment of the present invention can be applied.

Referring to FIG. 3, since the Resource Grid supports a plurality of numerologies in the same carrier, a resource grid may exist according to each neuralology. In addition, the resource grid may exist according to antenna ports, subcarrier spacing, and transmission direction.

The resource block consists of 12 subcarriers and is defined only in the frequency domain. In addition, a resource element is composed of one OFDM symbol and one subcarrier. Accordingly, as shown in FIG. 3, one resource block may vary in size depending on the subcarrier spacing. In addition, the NR defines "Point A" serving as a common reference point for the resource block grid, a common resource block, a virtual resource block, and the like.

4 is a diagram for describing a bandwidth part supported by a radio access technology to which an embodiment of the present invention can be applied.

Unlike LTE, where the carrier bandwidth is fixed at 20Mhz in NR, the maximum carrier bandwidth is set from 50Mhz to 400Mhz for each subcarrier interval. Therefore, it is not assumed that all terminals use all of these carrier bandwidths. Accordingly, in the NR, as shown in FIG. 4, the UE designates a bandwidth part (BWP) within the carrier bandwidth. In addition, the bandwidth part is associated with one neurology and consists of a subset of consecutive common resource blocks, and can be dynamically activated with time. The UE is configured with up to four bandwidth parts, respectively, for uplink and downlink, and data is transmitted and received using the bandwidth part activated at a given time.

In the case of paired spectrum, uplink and downlink bandwidth parts are set independently, and in the case of unpaired spectrum, to prevent unnecessary frequency re-tunning between downlink and uplink operation. For this purpose, the bandwidth parts of the downlink and the uplink are configured in pairs so as to share the center frequency.

<NR initial connection>

In NR, the UE performs a cell search and random access procedure to access and communicate with a base station.

Cell search is a procedure in which a terminal synchronizes with a cell of a corresponding base station, acquires a physical layer cell ID, and obtains system information by using a synchronization signal block (SSB) transmitted by a base station.

5 is a diagram exemplarily illustrating a synchronization signal block in a radio access technology to which the present embodiment can be applied.

Referring to FIG. 5, the SSB is composed of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), which occupy one symbol and 127 subcarriers, respectively, three OFDM symbols, and a PBCH spanning 240 subcarriers.

The terminal monitors the SSB in time and frequency domain and receives the SSB.

SSB can be transmitted up to 64 times in 5ms. A plurality of SSBs are transmitted in different transmission beams within 5 ms time, and the UE performs detection assuming that the SSB is transmitted every 20 ms period based on a specific beam used for transmission. The number of beams that can be used for SSB transmission within 5 ms time may increase as the frequency band increases. For example, up to 4 SSB beams may be transmitted at 3 GHz or less, and up to 8 different SSBs may be transmitted in a frequency band of 3 to 6 GHz and up to 64 different beams in a frequency band of 6 GHz or more.

Two SSBs are included in one slot, and the start symbol and the number of repetitions in the slot are determined according to the subcarrier spacing.

On the other hand, the SSB is not transmitted at the center frequency of the carrier bandwidth, unlike the SS of the conventional LTE. That is, the SSB may be transmitted even where the center of the system band is not, and when supporting broadband operation, a plurality of SSBs may be transmitted in the frequency domain. Accordingly, the terminal monitors the SSB using a synchronization raster, which is a candidate frequency location for monitoring the SSB. The carrier raster and synchronization raster, which are the center frequency location information of the channel for initial access, are newly defined in NR, and the synchronization raster has a wider frequency interval than the carrier raster, and thus supports fast SSB search of the UE. You can.

The UE may acquire the MIB through the PBCH of the SSB. The MIB (Master Information Block) includes minimum information for the terminal to receive the remaining system information (RMSI, Remaining Minimum System Information) broadcast by the network. In addition, the PBCH is information on the position of the first DM-RS symbol in the time domain, information for the UE to monitor SIB1 (for example, SIB1 neuronological information, information related to SIB1 CORESET, search space information, PDCCH Related parameter information, etc.), offset information between the common resource block and the SSB (the position of the absolute SSB in the carrier is transmitted through SIB1), and the like. Here, the SIB1 neuronological information is equally applied to some messages used in a random access procedure for accessing a base station after the terminal completes a cell search procedure. For example, the neuralology information of SIB1 may be applied to at least one of messages 1 to 4 for the random access procedure.

The aforementioned RMSI may refer to System Information Block 1 (SIB1), which is broadcast periodically (ex, 160ms) in the cell. SIB1 includes information necessary for the UE to perform an initial random access procedure and is periodically transmitted through the PDSCH. In order to receive the SIB1, the UE needs to receive the information on the neuterology used for the SIB1 transmission and the control resource set (CORESET) information used for the scheduling of the SIB1 through the PBCH. The UE checks scheduling information on SIB1 using SI-RNTI in CORESET and obtains SIB1 on PDSCH according to the scheduling information. The remaining SIBs except for SIB1 may be periodically transmitted or may be transmitted at the request of the UE.

FIG. 6 is a diagram for explaining a random access procedure in a radio access technology to which the present embodiment can be applied.

Referring to FIG. 6, when the cell search is completed, the terminal transmits a random access preamble for random access to the base station. The random access preamble is transmitted on the PRACH. Specifically, the random access preamble is transmitted to the base station through a PRACH composed of consecutive radio resources in a specific slot that is periodically repeated. In general, when a UE initially accesses a cell, a contention-based random access procedure is performed, and when a UE performs random access for beam failure recovery (BFR), a contention-free random access procedure is performed.

The terminal receives a random access response to the transmitted random access preamble. The random access response may include a random access preamble identifier (ID), an UL grant (uplink radio resource), a temporary C-RNTI (Temporary Cell-Radio Network Temporary Identifier), and a time alignment command (TAC). Since one random access response may include random access response information for one or more terminals, the random access preamble identifier may be included to indicate to which UE the included UL Grant, temporary C-RNTI, and TAC are valid. The random access preamble identifier may be an identifier for the random access preamble received by the base station. The TAC may be included as information for the UE to adjust uplink synchronization. The random access response may be indicated by a random access identifier on the PDCCH, that is, a random access-radio network temporary identifier (RA-RNTI).

Upon receiving a valid random access response, the terminal processes the information included in the random access response and performs scheduled transmission to the base station. For example, the terminal applies TAC and stores a temporary C-RNTI. In addition, by using the UL Grant, data or newly generated data stored in the buffer of the terminal is transmitted to the base station. In this case, information that can identify the terminal should be included.

Finally, the terminal receives a downlink message for contention resolution.

<NR CORESET>

The downlink control channel in NR is transmitted in a control resource set (CORESET) having a length of 1 to 3 symbols, and transmits up / down scheduling information, slot format index (SFI), and transmit power control (TPC) information. .

As such, the NR introduced the concept of CORESET in order to secure the flexibility of the system. CORESET (Control Resource Set) means a time-frequency resource for the downlink control signal. The terminal may decode the control channel candidate using one or more search spaces in the CORESET time-frequency resource. The QCL (Quasi CoLocation) assumption for each CORESET has been set, which is used to inform the analog beam direction in addition to the delay spread, Doppler spread, Doppler shift, and average delay, which are assumed by conventional QCL.

7 is a diagram for explaining CORESET.

Referring to FIG. 7, CORESET may exist in various forms within a carrier bandwidth in one slot, and CORESET may be configured with up to three OFDM symbols in the time domain. In addition, CORESET is defined as a multiple of six resource blocks up to the carrier bandwidth in the frequency domain.

The first CORESET is indicated through the MIB as part of the initial bandwidth part configuration to receive additional configuration information and system information from the network. After establishing the connection with the base station, the terminal may receive and configure one or more CORESET information through RRC signaling.

In this specification, frequency, frame, subframe, resource, resource block, region, band, subband, control channel, data channel, synchronization signal, various reference signals, various signals or various messages related to NR (New Radio) Can be interpreted as meaning used in the past or present or various meanings used in the future.

NR (New Radio)

3GPP recently approved “Study on New Radio Access Technology”, a study item for research on next-generation radio access technology (ie 5G radio access technology), and based on this, the RAN WG1 has a frame structure for each NR (New Radio). The design of (frame structure), channel coding & modulation, waveform & multiple access scheme, etc. is ongoing. NR is required to be designed to satisfy various QoS demands required for each segmented and specified service scenario (usage scenario) as well as improved data rate compared to LTE / LTE-Advanced.

As a representative service scenario of NR, enhancement mobile BroadBand (eMBB), massive Machine Type Communication (mMTC) and Ultra Reliable and Low Latency Communications (URLLC) have been defined and satisfy the needs of each service scenario (usage scenario). As a method for doing so, a flexible frame structure design compared to LTE / LTE-Advanced is required.

Each service scenario (usage scenario) is a data rate (data rates), latency (latency), reliability (reliability), coverage (requirements), etc. because the requirements (requirements) are different from each other to configure the frequency of the NR system A radio resource unit based on different numerology (eg, subcarrier spacing, subframe, TTI, etc.) as a method for efficiently satisfying the needs of each service requirement through a band. There is a need for a method to efficiently multiplex multiplexing.

As a method for this, TDM, FDM or TDM / FDM based on one or more NR component carriers (s) for numerology having different subcarrier spacing values Discussion was made on a method of supporting multiplexing and supporting one or more time units in configuring a scheduling unit in a time domain. In this regard, in NR, a subframe has been defined as a type of time domain structure, and a reference numerology for defining a corresponding subframe duration. As it was decided to define a single subframe duration consisting of 14 OFDM symbols of normal CP overhead based on 15 kHz SCS (Sub-Carrier Spacing), which is the same as LTE. Accordingly, in NR, a subframe has a time duration of 1 ms. However, unlike LTE, the subframe of NR is an absolute reference time duration, which is a time unit based on real uplink / downlink data scheduling and a slot and a mini-slot. ) Can be defined. In this case, the number of OFDM symbols constituting the slot and the y value are determined to have a value of y = 14 regardless of the SCS value in the case of a normal CP.

Accordingly, an arbitrary slot is composed of 14 symbols, and according to a transmission direction of the corresponding slot, all symbols are used for DL transmission, or all symbols are transmitted through UL. It may be used for transmission, or may be used in the form of a DL portion + gap + UL portion.

In addition, a mini-slot consisting of a smaller number of symbols than the slot is defined in an arbitrary numerology (or SCS), and based on this, a short-length time domain scheduling interval for transmitting and receiving uplink / downlink data (time-domain) The scheduling interval may be set, or a long time-domain scheduling interval for transmitting / receiving uplink / downlink data through slot aggregation may be configured.

In particular, in the case of transmitting / receiving data that is critical to latency, such as URLLC, based on 1ms (14 symbols) defined in a numerology-based frame structure with a small SCS value such as 15 kHz. When scheduling is performed on a slot-by-slot basis, it may be difficult to satisfy the latency requirement, so for this purpose, a mini-slot consisting of fewer OFDM symbols than the corresponding slot is defined, and based on this, a delay rate equal to the corresponding URLLC is critical. It can be defined so that scheduling of (latency critical) data is performed.

Or, as described above, by supporting multiplexing in a NR carrier (Carrier) having a different SCS value (numerology) by TDM and / or FDM method, by each numerology (numerology) A method of scheduling data according to a latency requirement based on a defined slot (or mini-slot) length is also considered. For example, as shown in FIG. 8 below, when the SCS is 60 kHz, the length of the symbol is reduced by about 1/4 compared to the case of the SCS 15 kHz, so if one slot is composed of 14 OFDM symbols, the corresponding 15 kHz based The slot length is 1 ms, while the slot length based on 60 kHz is reduced to about 0.25 ms.

In this way, by defining different SCS or different TTI lengths in NR, discussions are being made on how to satisfy the requirements of URLLC and eMBB, respectively.

Wider bandwidth operations

In the case of an existing LTE system, a scalable bandwidth operation for an arbitrary LTC component carrier (CC) was supported. That is, in accordance with the frequency deployment scenario (deployment scenario), any LTE operator can configure a single LTE CC, and can configure a minimum bandwidth of 1.4 MHz to a maximum of 20 MHz, and a normal LTE terminal uses one LTE For CC, 20 MHz bandwidth transmission / reception capability was supported.

However, in the case of NR, the design is made to support NR terminals having different transmit / receive bandwidth capabilities through one wideband NR CC. Likewise, by configuring one or more bandwidth parts (BWP, bandwidth part (s)) composed of subdivided bandwidths for arbitrary NR CCs, the flexible parts are configured through different bandwidth part configurations and activation for each terminal. flexible) is required to support a wider bandwidth operation.

Specifically, in the NR, one or more bandwidth parts may be configured through one serving cell configured from the terminal point of view, and the corresponding terminal may have one downlink bandwidth part in the serving cell ( DL bandwidth part) and one UL bandwidth part (activation) are defined to be used to transmit / receive uplink / downlink data. In addition, when a plurality of serving cells are set in a corresponding terminal, that is, for a terminal to which a CA is applied, one downlink bandwidth part and / or an uplink bandwidth part is activated for each serving cell. Therefore, it is defined to be used for transmitting / receiving data of uplink / downlink by using radio resources of a corresponding serving cell.

Specifically, an initial bandwidth part for an initial access procedure of a terminal is defined in an arbitrary serving cell, and one or more terminals are specified through dedicated RRC signaling for each terminal (UE -specific) A bandwidth part (bandwidth part (s)) is configured, and a default bandwidth part for a fallback operation may be defined for each terminal.

However, a plurality of downlink and / or uplink bandwidth parts are activated at the same time according to the capability and bandwidth part (s) configuration of the terminal in an arbitrary serving cell. It can be defined as, but in NR rel-15, it is defined to be used by activating (activation) only one downlink bandwidth part (DL bandwidth part) and uplink bandwidth part (UL bandwidth part) at any time at any terminal. .

NR-U

In the case of the unlicensed band, unlike the licensed band, any operator or individual can be used to provide wireless communication services within the regulation of each country, not a wireless channel exclusively used by any operator. Accordingly, when providing NR service through an unlicensed band, co-existence problems with various short-range wireless communication protocols such as WiFi, Bluetooth, and NFC, which are already provided through the unlicensed band, and also between each NR operator or LTE operator A solution to the co-existence problem is needed.

Accordingly, when providing an NR service through an unlicensed band, the power level of a radio channel or carrier to be used is sensed prior to transmission of a radio signal to avoid interference or collision between respective radio communication services. There is a need to support a radio channel access (LBT) based on a List Before Talk (LBT) that determines whether a channel or a carrier is available. In this case, if a specific radio channel or carrier in the unlicensed band is being used by other wireless communication protocols or other operators, there is a possibility that the provision of NR service through the band may be restricted. Unlike the wireless communication service through, QoS cannot be guaranteed by the user.

In particular, in the case of NR-U, unlike the existing LTE, which necessarily supported the unlicensed spectrum through carrier aggregation (CA) with a licensed spectrum, the deployment scenario of an unlicensed band NR As a (deployment scenario) stand-alone (stand-alone) NR-U cell, or a licensed band (licensed band) NR cell or a dual connectivity (DC) -based NR-U cell with an LTE cell is considered, the unlicensed band It is necessary to design a method for transmitting and receiving data to satisfy minimum QoS by itself.

Hereinafter, a method of performing wireless communication using available environment information for at least one subband constituting a system band in an unlicensed band will be described in detail with reference to related drawings.

10 is a diagram illustrating a procedure in which a terminal performs wireless communication using available environment information for at least one subband in an unlicensed band according to an embodiment.

Referring to FIG. 10, the terminal may receive information for allocating radio resources in a system band composed of a plurality of subbands (S1000).

According to an example, it is assumed that the system band consists of a plurality of subbands corresponding to 20 MHz, which is an LBT performance unit, in an unlicensed band. For example, a band of 100 MHz composed of 5 subbands can be assumed. At least one subband among a plurality of subbands may be configured as a bandwidth part (BWP) of the terminal.

The base station may allocate radio resources to be used by the terminal to receive downlink data or to transmit uplink data for a bandwidth part of the terminal. The UE may receive allocation information for a resource block (RB) in the frequency domain or allocation information for a subband constituting a bandwidth part. Alternatively, the terminal may receive transmission start symbol and duration allocation information in the time domain. According to an example, allocation information for a radio resource may be indicated through downlink control information (DCI).

Referring to FIG. 10 again, the terminal may acquire available environment information based on performing a Listen Before Talk (LBT) for at least one subband included in the radio resource (S1010).

According to an example, the terminal may perform LBT for each of the at least one subband included in the allocated radio resource. The terminal may obtain available environment information based on the LBT result for the subband. Here, the available environment information refers to information indicating whether a subband is available, and the term is for convenience of description and is not limited thereto. In the present disclosure, available environment information may be referred to as band available environment information.

According to an example, available environment information may be determined based on the number of successes and failures of the LBT for each of the at least one subband. For example, the UE may obtain values of LBT success ratios, such as LBT 1 success failure times, LBT 1 failure failure success ratios, or LBT success ratios for a specific subband as available environment information.

 Referring to FIG. 10 again, the terminal may transmit available environment information to the base station (S1020).

The UE may independently transmit available environment information for each subband. Alternatively, the terminal may combine and transmit status information for all subbands related to data transmission. For example, an index for subbands having the best channel availability can be delivered. Alternatively, an average value of all subbands or subband groups in the currently active bandwidth part (BWP) may be transmitted.

According to an example, the UE may explicitly transmit available environment information by including it in uplink control information. For example, available environment information may be included in UCI for channel state information feedback (CSI feedback) and transmitted. Alternatively, available environment information may be transmitted to an independent PUCCH channel by performing channel information feedback based on a subband corresponding to an LBT performance unit. In this case, the terminal may feedback when requested, as in the case of the existing CSI, or may feedback according to a certain period.

According to another example, the terminal may explicitly transmit available environment information through a sounding reference signal (SRS). If the base station allocates radio resources to transmit the SRS, the terminal can perform LBT when sending the SRS. When the LBT fails for the allocated resource, when the next SRS is transmitted, the terminal may transmit the modified SRS in the form of reflecting the number of failures of the LBT performed when attempting to transmit the previously performed SRS.

To this end, the modification method of SRS may be set in advance in relation to the base station. According to an example, the modification method of SRS may be interleaving in a mutually promising form, such as a change in SRS generation parameters, a symbol phase shift, or a cyclic shift. For example, if k LBT failures occur continuously during an SRS transmission attempt, the UE may transmit the SRS by cyclic shifting by k.

According to another example, available environment information may be explicitly transmitted through an RRC message of the terminal. For example, a channel busy ratio (CBR) may be calculated based on the frequency of LBT failure in each subband in the uplink BWP, and this may be transmitted through a CBR reporting RRC message. The base station may acquire channel availability information for each uplink subband of a corresponding user through a CBR reporting RRC message.

According to another example, available environment information may be implicitly transmitted according to transmission of uplink data of the terminal. The frequency of LBT failure in each subband in the uplink BWP can be expressed as the frequency in which transmission is performed in the allocated resource region. Accordingly, the base station can indirectly obtain the related information by counting the transmissions successfully received.

However, in this case, transmission failure due to channel error is not reflected in addition to transmission failure due to LBT failure. Accordingly, in order to consider transmission failure due to channel error, a plurality of radio resource areas may be allocated in the form of multiple resources for transmission of uplink data. The plurality of radio resources may be allocated in different time / frequency bands, or may be in a form in which different base sequences, messages using different formats, and different spreading / scrambling codes are applied. When the LBT failure occurs, the terminal may select another resource among the allocated multiple radio resources according to a predetermined condition and transmit uplink data.

The base station can determine which of the plurality of allocated radio resource areas is used to transmit uplink data. Accordingly, the base station can determine available environment information for the corresponding band uplink channel. For example, if n resource regions are allocated in the time axis in advance, and transmission is actually performed in the k-th resource region, the base station can know that k-1 LBT failures have occurred, where the LBT success rate is It can be seen that it is approximately 1 / k.

The base station may allocate radio resources for transmission and reception of downlink or uplink data based on the received available environment information.

According to an example, a plurality of radio resources may be allocated based on available environment information for transmission and reception of predetermined data. The terminal may receive downlink control information including information on a plurality of radio resources. For example, the predetermined data may be an essential transmission control message such as a Synchronization Signal Block (SSB) or a paging message.

The base station may set a plurality of candidate transmission regions to be used instead if it cannot transmit at an allocated time with respect to transmission of a control message transmitted through the downlink based on the band available environment information for each of the downlink subbands. . In this case, the base station can set more candidate transmission areas when the band available environment is bad. The terminal may receive information on a candidate transmission region to attempt further detection when the message detection fails from the base station. Accordingly, it is possible to increase the reception success rate for the essential control message.

Alternatively, the base station may allocate a plurality of radio resources capable of transmitting predetermined information in the uplink based on the band available environment information for each subband. Accordingly, the terminal is given a plurality of opportunities to transmit the same information in the time domain, and can perform transmission without additional control feedback even when an LBT failure occurs.

At this time, as the number of candidates in the allocated region increases, the transmission success rate increases, but resource allocation for other uses cannot be allocated to each candidate transmission region, resulting in a decrease in resource efficiency. Accordingly, the base station can adjust the number of candidate transmission regions for each subband based on the received band available environment information for each subband.

According to an example, the base station may select a specific subband from at least one subband included in a radio resource based on available environment information. The terminal may receive downlink control information including information indicating the selected subband. For example, in the uplink environment, such as a CSI feedback control message, messages having a large difference between an allocation time and an actual use time are affected by a variable band availability environment with time. In the case of control messages that do not need to be transmitted depending on the band, it is advantageous to select a subband with a good available environment.

Accordingly, the base station can pre-allocate a plurality of transmission regions for the corresponding control messages for each subband. The UE may receive information indicating a subband to be actually used at a specific time in the form of an index. Through this, the terminal can determine the subband to be used at the time.

In order to change the subband, the terminal may attempt to detect a change control message when the situation of the currently used subband deteriorates above a threshold value. In this case, the base station should perform the corresponding indication only when a channel condition deteriorated above a threshold is received. Alternatively, the terminal may be set to always attempt to detect the change control message. Alternatively, the DCI transmitted periodically may be configured to include the corresponding message.

According to this, by sharing available environment information based on LBT performance results for a plurality of subbands in an unlicensed band, efficient band operation can be performed in an environment where the probability of success of LBT for each subband is independent and variable.

11 is a diagram illustrating a procedure in which a base station performs wireless communication using available environment information for at least one subband in an unlicensed band according to an embodiment.

Referring to FIG. 11, the base station may transmit information for allocating radio resources in a system band composed of a plurality of subbands (S1100).

The base station may allocate radio resources to be used by the terminal to receive downlink data or to transmit uplink data for a bandwidth part of the terminal. The base station may transmit allocation information for a resource block (RB) in the frequency domain or allocation information for a subband constituting a bandwidth part to the terminal. Alternatively, the base station may transmit the allocation information for the transmission start symbol and duration in the time domain to the terminal. According to an example, allocation information for a radio resource may be indicated through downlink control information (DCI).

Referring to FIG. 11 again, the base station may receive available environment information based on LBT performance for at least one subband included in the radio resource (S1110).

According to an example, the terminal may perform LBT for each of the at least one subband included in the allocated radio resource. The terminal may obtain available environment information based on the LBT result for the subband. Available environment information may be determined based on the number of successes and failures of the LBT for each of the at least one subband. For example, the UE may obtain values of LBT success ratios, such as LBT 1 success failure times, LBT 1 failure failure success ratios, or LBT success ratios for a specific subband as available environment information.

According to an example, the base station may receive uplink control information including available environment information. For example, available environment information may be transmitted by being included in UCI for CSI feedback. Alternatively, the base station may receive available environment information as an independent PUCCH channel according to channel information feedback based on a subband corresponding to the LBT performance unit.

According to another example, the base station may explicitly receive available environment information through the SRS. If the base station allocates radio resources to transmit the SRS, the terminal can perform LBT when sending the SRS. When the LBT fails for the allocated resource, when the next SRS is transmitted, the terminal may transmit the modified SRS in the form of reflecting the number of failures of the LBT performed when attempting to transmit the previously performed SRS.

To this end, the modification method of SRS may be set in advance in relation to the base station. According to an example, the modification method of SRS may be interleaving in a mutually promising form, such as a change in SRS generation parameters, a symbol phase shift, or a cyclic shift. For example, if k LBT failures occur continuously in an attempt to transmit SRS, the base station may receive SRS cyclically shifted by k.

According to another example, available environment information may be implicitly transmitted according to transmission of uplink data of the terminal. The frequency of LBT failure in each subband in the uplink BWP can be expressed as the frequency in which transmission is performed in the allocated resource region. Accordingly, the base station can indirectly obtain the related information by counting the transmissions successfully received.

However, in this case, transmission failure due to channel error is not reflected in addition to transmission failure due to LBT failure. Accordingly, in order to consider transmission failure due to channel error, a plurality of radio resource areas may be allocated in the form of multiple resources for transmission of uplink data. The plurality of radio resources may be allocated in different time / frequency bands, or may be in a form in which different base sequences, messages using different formats, and different spreading / scrambling codes are applied. When the LBT failure occurs, the terminal may select another resource among the allocated multiple radio resources according to a predetermined condition and transmit uplink data.

The base station can determine which of the plurality of allocated radio resource areas is used to transmit uplink data. Accordingly, the base station can determine available environment information for the corresponding band uplink channel. For example, if n resource regions are allocated in the time axis in advance, and transmission is actually performed in the k-th resource region, the base station can know that k-1 LBT failures have occurred, where the LBT success rate is It can be seen that it is approximately 1 / k.

The base station may allocate radio resources for transmission and reception of downlink or uplink data based on the received available environment information.

According to an example, a plurality of radio resources may be allocated based on available environment information for transmission and reception of predetermined data. The base station may transmit downlink control information including information on a plurality of radio resources. For example, the predetermined data may be an essential transmission control message such as a Synchronization Signal Block (SSB) or a paging message.

The base station may set a plurality of candidate transmission regions to be used instead if it cannot transmit at an allocated time with respect to transmission of a control message transmitted through the downlink based on the band available environment information for each of the downlink subbands. . In this case, the base station can set more candidate transmission areas when the band available environment is bad. If the message detection fails, the base station may transmit information on a candidate transmission region to which additional detection is attempted to the terminal. Accordingly, it is possible to increase the reception success rate for the essential control message.

Alternatively, the base station may allocate a plurality of radio resources capable of transmitting predetermined information in the uplink based on the band available environment information for each subband. Accordingly, the terminal is given a plurality of opportunities to transmit the same information in the time domain, and can perform transmission without additional control feedback even when an LBT failure occurs.

At this time, as the number of candidates in the allocated region increases, the transmission success rate increases, but resource allocation for other uses cannot be allocated to each candidate transmission region, resulting in a decrease in resource efficiency. Accordingly, the base station can adjust the number of candidate transmission regions for each subband based on the received band available environment information for each subband.

According to an example, the base station may select a specific subband from at least one subband included in a radio resource based on available environment information. The terminal may receive downlink control information including information indicating the selected subband. For example, in the uplink environment, such as a CSI feedback control message, messages having a large difference between an allocation time and an actual use time are affected by a variable band availability environment with time. In the case of control messages that do not need to be transmitted depending on the band, it is advantageous to select a subband with a good available environment.

Accordingly, the base station can pre-allocate a plurality of transmission regions for the corresponding control messages for each subband. The UE may receive information indicating a subband to be actually used at a specific time in the form of an index. Through this, the terminal can determine the subband to be used at the time.

In order to change the subband, the terminal may attempt to detect a change control message when the situation of the currently used subband deteriorates above a threshold value. In this case, the base station should perform the corresponding indication only when a channel condition deteriorated above a threshold is received. Alternatively, the terminal may be set to always attempt to detect the change control message. Alternatively, the DCI transmitted periodically may be configured to include the corresponding message.

According to this, by sharing available environment information based on LBT performance results for a plurality of subbands in an unlicensed band, efficient band operation can be performed in an environment where the probability of success of LBT for each subband is independent and variable.

Hereinafter, with reference to the related drawings, each embodiment of performing wireless communication using available environment information for a subband in an NR unlicensed band will be described in detail.

As described above, in order to transmit a radio signal from an arbitrary node in an unlicensed band, it is necessary to undergo a List Before Talk (LBT) process to check whether a corresponding radio channel is occupy by another node.

Accordingly, in order to transmit a PDSCH for an arbitrary UE in an NR-U cell of an unlicensed band configured by an arbitrary NR base station, the base station must perform LBT for the unlicensed band. As a result of performing LBT, when the radio channel of the corresponding unlicensed band is empty, the base station may transmit the PDCCH and the corresponding PDSCH to the terminal.

Likewise, in order to transmit an uplink signal in an unlicensed band, a terminal is required to perform LBT on an unlicensed band before transmitting the uplink signal.

12 is a diagram for explaining performing LBT for wireless communication in an unlicensed band according to an embodiment.

According to an example, when allocating a PUCCH transmission resource for an arbitrary UE, or when allocating a PUSCH transmission resource, at a corresponding PUCCH or PUSCH transmission time point, it may be defined to indicate whether the LBT is performed in the corresponding UE at the base station. The UE may transmit uplink control information (UCI) such as HARQ ACK / NACK feedback information or CQI / CSI reporting information through the PUCCH to the base station. In this regard, in NR, time resources and frequency resources, which are PUCCH resources for transmitting HARQ feedback, may be indicated by a base station through DL assignment DCI (DCI). Alternatively, the PUCCH resource for transmitting HARQ feedback may be semi-static through RRC signaling. In particular, in the case of time resources, a timing gap value between a PDSCH reception slot and a corresponding HARQ feedback information transmission slot may be transmitted to a terminal through DL assignment DCI (DLI) or RRC signaling.

PUCCH resources for CQI / CSI reporting can also be allocated through RRC signaling and DL assignment DCI (DCI).

Referring to FIG. 12, the LBT (DL LBT) for downlink transmission is successful in the base station, and it is indicated by hatching that the downlink transmission is performed through the unlicensed band at a later time. According to an example, the downlink transmission may be transmission of a downlink channel or a signal indicating uplink transmission. For example, PUCCH for PDSCH transmission and HARQ feedback according thereto, DCI requiring CQI / CSI reporting, and PUCCH for reporting accordingly, or DCI transmitting scheduling information for PUSCH and PUSCH according thereto, and the like. You can. In this case, a timing gap occurs between downlink transmission and uplink transmission.

For example, when a downlink signal or a channel according to downlink transmission indicates PUCCH transmission in an NR-U cell that is an unlicensed band, the UE basically transmits the corresponding PUCCH according to regulation of an unlicensed spectrum. It is necessary to first perform LBT for, and it is determined whether to transmit PUCCH at the indicated time point according to the LBT result. If, as a result of the LBT, the corresponding radio channel is occupied by another node, that is, when an LBT failure occurs, the UE may not perform PUCCH transmission at the indicated time.

However, a downlink allocation DCI (DL assignment DCI) transmission slot or a downlink allocation DCI (DL assignment DCI) PDSCH transmission slot including the PUCCH resource allocation information and the PUCCH transmission indication information, and the corresponding PUCCH transmission slot corresponding to the base station If within the channel occupancy time (Channel Occupancy Time; COT), the UE may be able to transmit PUCCH without performing LBT. This is because the base station has already occupied the base station for downlink transmission in the unlicensed band and is not occupied by another node. That is, according to the setting of the COT of the base station and the timing gap value, HARQ feedback transmission through PUCCH may be possible in the corresponding terminal without LBT.

Similarly, when CSI / CQI reporting through PUCCH is indicated through DL assignment DCI (DLI), slots in which the corresponding DL assignment DCI (DLI) is transmitted and CQI / CSI reporting accordingly ( reporting) CSI / CQI reporting through PUCCH without LBT may be possible in a corresponding terminal according to a timing gap value between slots in which PUCCH transmission including information and a base station's COT are performed.

In addition, the timing gap value between the UL grant DCI (UL grant DCI) transmitted by the base station and the slot in which the PUSCH transmission is performed is similar to the case of PUCCH for the PUSCH transmission of the UE, and the RRC by the base station. It may be set to semi-static through signaling or may be set to dynamic through UL grant DCI (ULI). Even in this case, if the UL grant DCI (UL grant DCI) transmission slot including the corresponding PUSCH transmission resource allocation information and the corresponding PUSCH transmission slot belong to a channel occupancy time (COT) of the corresponding base station, the UE does not perform LBT without performing PUSCH Transmission may be possible.

In this regard, according to an embodiment of the present disclosure, the base station may set an LBT method for performing LBT when PUCCH or PUSHC is transmitted from any UE and instruct the UE. According to an example, the LBT method may be divided into a plurality of methods by at least one of whether LBT is performed, whether a random back off is performed, and a random back off time. In the present disclosure, a method for performing LBT is referred to as an 'LBT method', but is not limited thereto. The method of performing LBT may be variously referred to as an LBT category.

According to an example, the LBT method is a first LBT method that does not perform LBT, a second LBT method that performs LBT but does not perform random back off, and performs a random back off with LBT, but a random back off time interval is fixed. The third LBT method and the LBT and the random back off may be performed, but the random back off time interval may include a variable fourth LBT method or the like.

According to an example, the base station may be defined to directly indicate whether to perform LBT for uplink transmission of the terminal through L1 control signaling. Specifically, it may be defined to include a corresponding LBT indication information area in a DL assignment DCI format for transmitting PDSCH scheduling control information.

For example, the LBT indication information may be 1-bit indication information. In this case, according to the value (0, 1) of the corresponding bit, when transmitting the PUCCH of the terminal corresponding to the corresponding DL assignment DCI format (DL assignment DCI format), it can be defined to determine whether to perform LBT in the terminal. have. That is, in this case, the value of the corresponding bit may mean distinguishing between the first LBT scheme and the remaining LBT schemes among the aforementioned LBT schemes.

According to another example, the LBT indication information may be 2-bit indication information. In this case, when transmitting the PUCCH of the terminal corresponding to the DL assignment DCI format (DCI assignment) according to the value of the bit (00, 01, 10, 11), the LBT method for performing LBT in the terminal It can be defined to be determined. That is, in this case, the value of the corresponding bit may mean distinguishing between the first LBT scheme and the fourth LBT scheme among the aforementioned LBT schemes.

In this case, PUCCH transmission of a terminal corresponding to the above-described downlink allocation DCI format (DL assignment DCI format) transmits HARQ feedback information of the terminal according to PDSCH reception of the terminal based on the corresponding downlink allocation DCI format (DL assignment DCI format) It may be a PUCCH transmission for. Or, in another case of PUCCH transmission of a UE corresponding to a DL assignment DCI format (DL assignment DCI format), CQI / CSI reporting is triggered by a corresponding DL assignment DCI format (DL assignment DCI format). ), It may be PUCCH transmission for CQI / CSI reporting accordingly.

Similarly, a UL grant DCI format (UL grant DCI format) for transmitting PUSCH scheduling control information may be defined to include a corresponding LBT indication information area.

For example, the LBT indication information may be 1-bit indication information. In this case, when PUSCH transmission of a UE corresponding to a corresponding uplink grant DCI format (UL grant DCI format) is transmitted according to the value (0, 1) of the corresponding bit, it can be defined to determine whether to perform LBT in the corresponding UE. have. That is, in this case, the value of the corresponding bit may mean distinguishing between the first scheme and the remaining schemes among the aforementioned LBT schemes.

According to another example, the LBT indication information may be 2-bit indication information. In this case, according to the value (00, 01, 10, 11) of the corresponding bit, when transmitting the PUSCH of the UE corresponding to the corresponding UL grant DCI format (UL grant DCI format), the LBT method for performing LBT in the UE It can be defined to be determined. That is, in this case, the value of the corresponding bit may mean distinguishing between the first method and the fourth method among the aforementioned LBT methods.

However, the PUSCH transmission of the terminal corresponding to the UL grant DCI format (UL grant DCI format) may be a PUSCH transmission for uplink data transmission of the terminal or a PUSCH transmission for UCI transmission of the terminal.

As another embodiment of whether the terminal performs LBT for uplink transmission or defines the LBT method, whether the corresponding LBT is performed, as illustrated in FIG. 12, the downlink transmission in which the corresponding uplink transmission is indicated and the uplink accordingly It can be defined to be determined by a timing gap value between transmissions.

According to an example, when the timing gap value is smaller than an arbitrary threshold value, it may be defined to enable transmission of the indicated PUCCH or PUSCH without LBT in the corresponding UE. Alternatively, when a timing gap value is greater than a corresponding threshold, after the LBT is performed by the terminal, it may be defined to transmit the corresponding PUCCH or PUSCH accordingly.

According to an example, the corresponding threshold (threshold) is determined by the COT value in the corresponding NR-U, or accordingly, cell-specific RRC signaling (cell-specific RRC signaling) or UE-specific RRC signaling (UE-) by the base station It may be set through specific RRC signaling, or may be set through cell-specific RRC signaling or UE-specific RRC signaling by a base station regardless of COT.

Additionally, the corresponding threshold is defined as a single threshold for each uplink transmission case, or is defined as a different threshold, and cell specific RRC signaling by the base station (cell- It may be set through specific RRC signaling or UE-specific RRC signaling.

According to this, the LBT method to be performed to transmit the uplink signal in the unlicensed band can be determined, and the uplink signal can be transmitted in the unlicensed band according to the determined LBT method.

Hereinafter, a method of controlling a transmission mechanism in a case in which a channel availability situation is independent of a sender's intention in a 3GPP NR system according to embodiments of the present disclosure is provided. In particular, a method for setting a transmission mechanism according to a channel availability situation in an NR-based access to Unlicensed Spectrum (NR-U) system environment using a common channel as a transmission space is provided.

As a method of using an unlicensed band in the conventional 3GPP LTE, the control channel is operated through a licensed band, which is a band exclusively operated by a communication manager, and the data channel is an unlicensed band which is a band occupied / usable by any user. A LAA system that can be operated through is proposed. Also, in NR, studies are being conducted to introduce an NR-U system capable of transmitting and receiving in an unlicensed band as a new feature.

As described above, for an unlicensed band, after checking whether there is another device occupying a channel band to perform transmission through a process called List-Before-Talk (LBT), communication is performed only when the corresponding band is empty. Can be initiated. That is, communication is started only when there is no other device performing wireless communication in the corresponding band. In this case, since it is inefficient to perform the LBT process for all frequency components, it is generally determined whether the communication is possible in the corresponding band by examining the occupancy status in the corresponding band in units of 20 MHz.

NR basically assumes a scenario of using / transmitting a band larger than 20 MHz, which is an LBT unit, and thus, methods operating in a band of 20 MHz or higher are also discussed in NR-U. In this case, there are a plurality of LBT sections divided into 20 MHz units, and accordingly, each of the plurality of LBT sections is divided into subbands or subbands within one band.

The occupancy status of the band in the unlicensed band varies depending on the presence or absence of other communication devices in the range that the radio signal can reach and whether the devices are activated. When many devices perform communication in an active band, it is inevitably difficult to secure communication resources in the corresponding band. Therefore, in a system that secures a plurality of subbands as an available communication area, it is advantageous to perform communication while avoiding a band in which a relatively large number of devices are activated.

As described above, in a system that secures a plurality of subbands as an available communication area, it is advantageous to perform resource allocation preferentially to the subbands with the lowest failure probability by estimating the probability of LBT failure of each band. In the downlink environment, since a resource region is allocated by itself, a band in which LBT failures are frequently determined can be assigned as a next priority in scheduling. However, in the uplink environment, since the receiver does not know the band in which the LBT failure is frequent at the transmitting end side, a problem may arise in which the resource allocated by the base station serving as the receiving end may be a band in which LBT failure is frequent. In addition, even if the difference between resource allocation time and usage time is large, such as semi-persistent scheduling (SPS) or paging, it may not be possible to properly apply an environment that changes depending on the situation.

Hereinafter, the present disclosure provides an efficient band operating method in an environment in which transmission is performed across a plurality of subbands in an NR-U environment, and the LBT success / failure probability of each subband is independent and variable. To this end, a method of sharing information related to channel occupancy status for efficient band operation and a method of band operation in periodic resource allocation and paging operation are provided based on the information.

The present disclosure provides a method for transmitting information related to a band available environment, a method for operating a control message for each provided band available environment, and a method for resetting resources for each provided band available environment. Terms used in the present disclosure may be replaced with other terms having substantially the same meaning in the future, and for convenience of description, the scope of the description is not limited by the terms used.

13 is a diagram for describing a subband of an unlicensed band according to an embodiment. 14 is a diagram for explaining allocation of a plurality of radio resources for transmitting and receiving predetermined data based on available environment information according to an embodiment.

As shown in FIG. 13, it is assumed that the system band is composed of a plurality of subbands that are LBT performance units. For example, a band of 100 MHz composed of 5 subbands can be assumed. It is assumed that the corresponding band is composed of c resource blocks (RBs) represented by numbers from 1 to c, and a band from a to b is composed of a bandwidth part (BWP) of the terminal. In addition, it is assumed that the number of RBs in which divisions for each subband are present are s, t, u, and v, respectively, from below. In this case, as illustrated in FIG. 13, it is assumed that a relationship of 1 <s ≤ a <t <u <b ≤ v <c is established. In FIG. 13, the values of s, a, b, and v are all shown in different cases, but this is not limited thereto. The values of s and a, b and v may be equal.

In FIG. 13, the number of OFDM symbol units is 7, but as an example, the method provided in the present disclosure may be applied regardless of values such as the number of RBs or slot lengths constituting each subband. The configuration of the system band and subband shown in FIG. 13 or the setting of the BWP of the terminal is an example for convenience of description and is not limited thereto. It is natural that the number of RBs or the number of subbands and the number of component RBs or the BWP of the terminal may be set differently depending on the case.

Each of the embodiments described below may be performed independently or in various combinations of the respective embodiments.

First embodiment: Method for transmitting information related to band available environment

According to an embodiment, the UE (UE) may transmit the band available environment information to the base station through the LBT performance of the subbands allocated to or allocated to the UE. Hereinafter, a method of transmitting band available environment information is largely divided into a physical layer and an upper layer. In addition, the description will be given by dividing the band available environment information in an explicit and implicit manner. The methods are independent of each other and can be selectively applied as needed.

According to an example, the information delivered as the band available environment information value may be a value such as the number of LBT successes versus failures of a specific subband, the number of successes against LBT failures, or the ratio of LBT successes expressed in an index. According to an example, status information for one subband may be transmitted independently, or status information for all subbands related to data transmission may be transmitted in a combined form. For example, the channel availability according to the LBT attempt may be in the form of transmitting the indexes of the best subbands, or the average value of all subbands or subband groups in the current bandwidth part (BWP). .

According to an example, band available environment information may be explicitly transmitted through a physical layer. Band available environment information through the physical layer may be transmitted through uplink control information (UCI) or a reference signal (RS). For example, the band available environment information may be transmitted by being included in UCI for channel state information feedback (CSI feedback). Alternatively, channel information feedback similar to CSI feedback based on the LBT performance unit subband may be performed and transmitted to an independent PUCCH channel. In this case, as in the case of the existing CSI, feedback may be performed at the time of request or periodically.

Transmission through RS may be transmitted through a sounding reference signal (SRS) that is transmitted periodically or when necessary. For example, if the periodically transmitted SRS is set, the base station allocates a physical resource location for the UE to transmit the SRS, and the UE can perform LBT when sending the SRS. When the LBT fails, the terminal should not transmit the SRS to the resource. In this case, when the terminal transmits the next SRS, the terminal may transmit the modified SRS in the form of reflecting the number of LBT failures when attempting to transmit the SRS.

In this case, the modification of the SRS should be sufficiently predictable by the base station through the past SRS detection history, etc., and the number of inter-promised types of interleaving such as a change in SRS generation parameters, a symbol phase shift, or a cyclic shift. have. For example, if an LBT failure occurs continuously for k times during the previous SRS transmission attempt, the UE may transmit the SRS by cyclic shifting by k.

According to another example, band available environment information may be implicitly transmitted through a physical layer. The frequency of LBT failure in each subband in the uplink BWP can be effectively expressed by how often the actual transmission is performed on the corresponding resource at the time requested by the base station. Accordingly, related information can be obtained indirectly by counting the transmissions that are successfully received.

However, in this case, since the probability of transmission failure due to a channel error is not taken into account, it is necessary to know in a separate method that the transmission signal reception failure in a specific location is caused by a case where transmission is not due to an LBT failure. Particularly, in consideration of LBT failure in SRS, PUCCH, PRACH, etc., a plurality of resources capable of transmitting a specific message in multiple resource types are allocated in advance, and other resources can be selected and transmitted according to the degree of LBT failure. In this case, the LBT failure rate of the corresponding band uplink channel can be determined by determining which region the base station actually uses to transmit the signal later. The plurality of resources may be divided and allocated to different time / frequency bands, or may be in a form in which different base sequences, messages using different formats, and different spreading / scrambling codes are applied.

For example, if n resource regions are acquired on the time axis in advance for resource transmission and then transmission is performed on the actual k-th resource, the base station knows that k-1 LBT failures occurred before one transmission. , It can be seen here that the LBT success rate is approximately 1 / k.

According to another example, band available environment information may be explicitly transmitted through an upper layer. Under the assumption that the band-available environment does not change rapidly with time, performance can be secured by transmitting information through a higher layer. In this case, the available environment information of each subband in the BWP set for the terminal may be transmitted to the base station in RRC, and the available environment information of all subbands that can be set to the terminal may be transmitted to RRC. Such a transmission may be periodically transmitted along with the range, or may be transmitted by a base station upon request or as required by the terminal itself. For example, the corresponding information may be transmitted using a channel occupancy ratio (CR) and a channel busy ratio (CBR) used in V2X, etc. At this time, each metric is transmitted to each of the currently available subbands previously indicated by the base station. Can be assigned. For example, if the total number of subbands is 5, the UE may determine 5 CR or CBR values according to the situation of each subband, and transmit the corresponding values in an RRC message in the form of CR / CBR reporting.

According to another example, band available environment information may be implicitly transmitted through an upper layer. If it is determined that the band available environment of a specific subband among the transmission areas allocated to the terminal is bad, the terminal may request an active BWP switching to a specific BWP among a plurality of BWPs or a change to the assigned BWP. The change request message may include subband-related information to be avoided, or may request a BWP allocation that does not include the current BWP itself. Through the request, the base station may implicitly identify a subband that the UE avoids, that is, a bad band availability environment.

Second embodiment: Method of operating a control message for each provided band available environment

According to an embodiment, the base station may operate a control message transmitted through an unlicensed band based on a band available environment. In particular, a resource allocation method that can be selected by a base station in order to receive an essential transmission control message may be defined differently according to a band available environment to allocate resources.

According to an example, a method of operating a control message in a downlink may be defined. The base station may store band available environment information for each subband of the downlink, and combine and operate related information when transmitting a control message transmitted through the downlink. For example, if a control message at a predetermined location cannot be transmitted at a corresponding time, such as a synchronization signal block (SSB) or a paging message, a candidate region to be transmitted instead may be defined. At this time, if the band availability environment is bad, there is a need to secure more candidate areas. Accordingly, if the base station fails to detect a control message in the corresponding area, the base station can determine and transmit information, such as the number of additional areas to be tried, based on the corresponding information. Accordingly, it is possible to increase the reception success rate for the essential control message instead of increasing the search complexity of the terminal.

According to another example, a method of operating a control message in uplink may be defined. The base station may allocate a plurality of candidates of a region capable of transmitting the same information in the uplink from the time point of view in consideration of the uplink LBT failure. Accordingly, by giving the opportunity to transmit the same information multiple times in the time domain, transmission can be performed without additional control feedback even when a certain amount of LBT failure occurs.

At this time, as the number of candidates in the allocated region increases, the transmission success rate increases, but resource allocation for other uses cannot be allocated to each candidate region, thereby reducing resource efficiency. The base station may adjust and allocate the number of candidates for each subband based on the band available environment information for each subband previously provided by the terminal. For example, referring to FIG. 14, on average, multiple opportunities are allocated by repeatedly transmitting a region twice in a subband in which LBT succeeds only once in two times and four times in a subband in which LBT succeeds only once in four times. Can be given.

The number of opportunity grants may be indicated when the base station allocates resources, but may be determined depending on the value transmitted in the uplink. For example, if the number of LBT transmission failures is k times compared to the average LBT success once in an uplink specific subband, and the corresponding value k is shared between the UE and the base station, the base station determines f (k) dependent on k. It is possible to automatically allocate as many candidate areas as possible without additional instructions.

Third embodiment: A method of resetting resources for each provided band available environment

In general, in an uplink environment, messages having a large difference between an allocation time and an actual use time are affected by a variable band availability environment with time. For example, a CSI feedback control message or SRS periodically transmitted, a resource region defined by semi-persistent scheduling, and a configured grant region may correspond to this. Among them, it is advantageous to select a subband having a good band availability environment, since it is not necessary to transmit the rest of the band except for the RS for the channel environment of the measurement band depending on the band.

According to an example, a method of indicating only subbands to be actually used may be defined after allocating a plurality of subband duplicate resources. According to this, a plurality of transmission regions allocated for CSI feedback, semi-persistent scheduling, and configured grants may be pre-allocated for each subband, and then a subband to be actually used at a specific time may be transmitted in the form of an index. Through this, the terminal can determine the subband to be used at the time.

The terminal may attempt to detect a change control message when the situation of the currently used subband becomes worse than a threshold value. In this case, the base station should perform the indication only when a channel condition above a threshold is received. Alternatively, the detection of the change control message may be always attempted, or the DCI transmitted periodically may be designed to include the message.

In the above, it has been basically described based on NR-U transmission, but the above-described embodiments can be applied substantially the same in all environments where channel availability is applied due to external factors. In addition, the above-described first to third embodiments and sub-methods of each embodiment may be applied independently of each other or may be applied in arbitrary combination.

Through an embodiment according to the present disclosure, more stable transmission can be performed through flexible allocation according to a band available environment in a channel environment in which some channels cannot be used intermittently due to external factors such as NR-U. In addition, according to the present disclosure, the base station may acquire auxiliary information capable of increasing resource operation efficiency, and based on such information, control message and transmission block resource allocation may be performed according to the channel environment.

Hereinafter, a configuration of a terminal and a base station capable of performing some or all of the embodiments described with reference to FIGS. 1 to 14 will be described with reference to the drawings.

15 is a diagram showing the configuration of a user terminal 1500 according to another embodiment.

15, the user terminal 1500 according to another embodiment includes a control unit 1510, a transmitter 1520 and a receiver 1530.

The control unit 1510 controls the operation of the overall user terminal 1500 according to a method of performing wireless communication in an unlicensed band required to perform the above-described present disclosure. The transmitter 1520 transmits uplink control information, data, and messages to the base station through a corresponding channel. The receiving unit 1530 receives downlink control information, data, and messages from the base station through a corresponding channel.

The receiver 1530 may receive information for allocating radio resources in a system band composed of a plurality of subbands. The base station may allocate radio resources to be used by the terminal to receive downlink data or to transmit uplink data for a bandwidth part of the terminal. The receiver 1530 may receive allocation information for a resource block (RB) in the frequency domain or allocation information for a subband constituting a bandwidth part. Alternatively, the receiver 1530 may receive transmission start symbol and duration allocation information in the time domain. According to an example, allocation information for a radio resource may be indicated through downlink control information (DCI).

The controller 1510 may acquire available environment information based on LBT performance for at least one subband included in the radio resource. According to an example, the controller 1510 may perform LBT for each of at least one subband included in the allocated radio resource. The controller 1510 may obtain available environment information based on the LBT result for the subband.

According to an example, available environment information may be determined based on the number of successes and failures of the LBT for each of the at least one subband. For example, the UE may obtain values of LBT success ratios, such as LBT 1 success failure times, LBT 1 failure failure success ratios, or LBT success ratios for a specific subband as available environment information.

The transmitter 1520 may transmit the obtained available environment information to the base station. The transmitter 1520 may independently transmit available environment information for each subband. Alternatively, the transmitter 1520 may combine and transmit status information for all subbands related to data transmission. For example, an index for subbands having the best channel availability can be delivered. Alternatively, an average value of all subbands or subband groups in the currently active bandwidth part (BWP) may be transmitted.

According to an example, the transmitter 1520 may explicitly transmit available environment information by including it in uplink control information. For example, available environment information may be transmitted by being included in UCI for CSI feedback. Alternatively, the transmitter 1520 may transmit available environment information to an independent PUCCH channel by performing channel information feedback based on a subband corresponding to the LBT performance unit. In this case, the terminal may feedback when requested, as in the case of the existing CSI, or may feedback according to a certain period.

According to another example, the transmitter 1520 may explicitly transmit available environment information through SRS. If the base station allocates radio resources to transmit the SRS, the control unit 1510 may perform LBT when sending the SRS. The transmitter 1520 may transmit the modified SRS in the form of reflecting the number of failures of the LBT performed when attempting to transmit the previously performed SRS when the LBT fails for the allocated resource, the next SRS is transmitted.

To this end, the modification method of SRS may be set in advance in relation to the base station. According to an example, the modification method of SRS may be interleaving in a mutually promising form, such as a change in SRS generation parameters, a symbol phase shift, or a cyclic shift. For example, when k consecutive LBT failures occur during an SRS transmission attempt, the transmitter 1520 may transmit the SRS by cyclic shifting by k.

According to another example, available environment information may be implicitly transmitted according to transmission of uplink data of the terminal. The frequency of LBT failure in each subband in the uplink BWP can be expressed as the frequency in which transmission is performed in the allocated resource region. Accordingly, the base station can indirectly obtain the related information by counting the transmissions successfully received.

However, in this case, transmission failure due to channel error is not reflected in addition to transmission failure due to LBT failure. Accordingly, in order to consider transmission failure due to channel error, a plurality of radio resource areas may be allocated in the form of multiple resources for transmission of uplink data. The plurality of radio resources may be allocated in different time / frequency bands, or may be in a form in which different base sequences, messages using different formats, and different spreading / scrambling codes are applied. When an LBT failure occurs, the transmitter 1520 may select another resource among the allocated multiple radio resources according to a predetermined condition and transmit uplink data.

The base station can determine which of the plurality of allocated radio resource areas is used to transmit uplink data. Accordingly, the base station can determine available environment information for the corresponding band uplink channel. For example, if n resource regions are allocated in the time axis in advance, and transmission is actually performed in the k-th resource region, the base station can know that k-1 LBT failures have occurred, where the LBT success rate is It can be seen that it is approximately 1 / k.

The base station may allocate radio resources for transmission and reception of downlink or uplink data based on the received available environment information.

According to an example, a plurality of radio resources may be allocated based on available environment information for transmission and reception of predetermined data. The receiver 1530 may receive downlink control information including information on a plurality of radio resources. For example, the predetermined data may be an essential transmission control message such as a Synchronization Signal Block (SSB) or a paging message.

The base station may set a plurality of candidate transmission regions to be used instead if it cannot transmit at an allocated time with respect to transmission of a control message transmitted through the downlink based on the band available environment information for each of the downlink subbands. . In this case, the base station can set more candidate transmission areas when the band available environment is bad. The receiving unit 1530 may receive information on a candidate transmission region to attempt additional detection when a message detection fails from the base station. Accordingly, it is possible to increase the reception success rate for the essential control message.

Alternatively, the base station may allocate a plurality of radio resources capable of transmitting predetermined information in the uplink based on the band available environment information for each subband. Accordingly, the terminal is given a plurality of opportunities to transmit the same information in the time domain, and can perform transmission without additional control feedback even when an LBT failure occurs.

At this time, as the number of candidates in the allocated region increases, the transmission success rate increases, but resource allocation for other uses cannot be allocated to each candidate transmission region, resulting in a decrease in resource efficiency. Accordingly, the base station can adjust the number of candidate transmission regions for each subband based on the received band available environment information for each subband.

According to an example, the base station may select a specific subband from at least one subband included in a radio resource based on available environment information. The receiver 1530 may receive downlink control information including information indicating the selected subband. For example, in the uplink environment, such as a CSI feedback control message, messages having a large difference between an allocation time and an actual use time are affected by a variable band availability environment with time. In the case of control messages that do not need to be transmitted depending on the band, it is advantageous to select a subband with a good available environment.

Accordingly, the base station can pre-allocate a plurality of transmission regions for the corresponding control messages for each subband. The receiver 1530 may receive information indicating a subband to be actually used at a specific time in the form of an index. Through this, the terminal can determine the subband to be used at the time.

To change the subband, the controller 1510 may attempt to detect a change control message when the situation of the currently used subband deteriorates above a threshold value. In this case, the base station should perform the corresponding indication only when a channel condition deteriorated above a threshold is received. Alternatively, the control unit 1510 may be set to always attempt to detect the change control message. Alternatively, the DCI transmitted periodically may be configured to include the corresponding message.

According to this, by sharing available environment information based on LBT performance results for a plurality of subbands in an unlicensed band, efficient band operation can be performed in an environment where the probability of success of LBT for each subband is independent and variable.

16 is a diagram showing the configuration of a base station 1600 according to another embodiment.

Referring to FIG. 16, the base station 1600 according to another embodiment includes a control unit 1610, a transmission unit 1620, and a reception unit 1630.

The control unit 1610 controls the operation of the overall base station 1600 according to a method of performing wireless communication in an unlicensed band required to perform the above-described present disclosure. The transmitting unit 1620 and the receiving unit 1630 are used to transmit and receive signals, messages, and data necessary to perform the present disclosure described above.

The transmitter 1620 may transmit information for allocating radio resources in a system band composed of a plurality of subbands. The control unit 1610 may allocate radio resources to be used by the terminal to receive downlink data or to transmit uplink data for a bandwidth part of the terminal. The transmitter 1620 may transmit allocation information for a resource block (RB) in the frequency domain or allocation information for a subband constituting a bandwidth part to the terminal. Alternatively, the transmitter 1620 may transmit allocation information for a transmission start symbol and duration in the time domain to the terminal. According to an example, allocation information for a radio resource may be indicated through downlink control information (DCI).

The receiver 1630 may receive available environment information based on LBT performance for at least one subband included in a radio resource.

According to an example, the terminal may perform LBT for each of the at least one subband included in the allocated radio resource. The terminal may obtain available environment information based on the LBT result for the subband. Available environment information may be determined based on the number of successes and failures of the LBT for each of the at least one subband. For example, the UE may obtain values of LBT success ratios, such as LBT 1 success failure times, LBT 1 failure failure success ratios, or LBT success ratios for a specific subband as available environment information.

According to an example, the reception unit 1630 may receive uplink control information including available environment information. For example, available environment information may be transmitted by being included in UCI for CSI feedback. Alternatively, the reception unit 1630 may receive available environment information as an independent PUCCH channel according to channel information feedback based on a subband corresponding to the LBT performance unit.

According to another example, the reception unit 1630 may explicitly receive available environment information through SRS. If the base station allocates radio resources to transmit the SRS, the terminal can perform LBT when sending the SRS. When the LBT fails for the allocated resource, when the next SRS is transmitted, the terminal may transmit the modified SRS in the form of reflecting the number of failures of the LBT performed when attempting to transmit the previously performed SRS.

To this end, the modification method of SRS may be set in advance in relation to the base station. According to an example, the modification method of SRS may be interleaving in a mutually promising form, such as a change in SRS generation parameters, a symbol phase shift, or a cyclic shift. For example, if k LBT failures occur continuously during an SRS transmission attempt, the reception unit 1630 may receive the SRS cyclically shifted by k.

According to another example, available environment information may be explicitly transmitted through an RRC message of the terminal. For example, a channel busy ratio (CBR) may be calculated based on the frequency of LBT failure in each subband in the uplink BWP, and this may be transmitted through a CBR reporting RRC message. The controller 1610 may acquire channel availability information for each uplink subband of the corresponding user through a CBR reporting RRC message.

According to another example, available environment information may be implicitly transmitted according to transmission of uplink data of the terminal. The frequency of LBT failure in each subband in the uplink BWP can be expressed as the frequency in which transmission is performed in the allocated resource region. Accordingly, the control unit 1610 may acquire related information indirectly by counting the transmissions that are successfully received.

However, in this case, transmission failure due to channel error is not reflected in addition to transmission failure due to LBT failure. Accordingly, in order to consider transmission failure due to channel error, a plurality of radio resource areas may be allocated in the form of multiple resources for transmission of uplink data. The plurality of radio resources may be allocated in different time / frequency bands, or may be in a form in which different base sequences, messages using different formats, and different spreading / scrambling codes are applied. When the LBT failure occurs, the terminal may select another resource among the allocated multiple radio resources according to a predetermined condition and transmit uplink data.

The control unit 1610 may determine which of the plurality of allocated radio resource areas is used to transmit uplink data. Accordingly, the control unit 1610 may determine available environment information for the corresponding band uplink channel. For example, if n resource regions are allocated in the time axis in advance, and transmission is actually performed in the k-th resource region, the control unit 1610 can know that k-1 LBT failures have been made. It can be seen that the LBT success rate is approximately 1 / k.

The controller 1610 may allocate radio resources for transmission and reception of downlink or uplink data based on the received available environment information.

According to an example, a plurality of radio resources may be allocated based on available environment information for transmission and reception of predetermined data. The transmitter 1620 may transmit downlink control information including information on a plurality of radio resources. For example, the predetermined data may be an essential transmission control message such as a Synchronization Signal Block (SSB) or a paging message.

The control unit 1610 may use a plurality of candidate transmission regions to be used instead if it cannot transmit at an allocated time with respect to transmission of a control message transmitted through the downlink based on the band available environment information for each of the downlink subbands. Can be set. In this case, the control unit 1610 may set more candidate transmission areas when the band available environment is bad. When the message detection fails, the transmitter 1620 may transmit information on a candidate transmission region to which additional detection is attempted to the terminal. Accordingly, it is possible to increase the reception success rate for the essential control message.

Alternatively, the controller 1610 may allocate a plurality of radio resources capable of transmitting predetermined information in the uplink based on the band available environment information for each subband. Accordingly, the terminal is given a plurality of opportunities to transmit the same information in the time domain, and can perform transmission without additional control feedback even when an LBT failure occurs.

At this time, as the number of candidates in the allocated region increases, the transmission success rate increases, but resource allocation for other uses cannot be allocated to each candidate transmission region, resulting in a decrease in resource efficiency. Therefore, the control unit 1610 may adjust the number of candidate transmission regions for each subband based on the received band available environment information for each subband.

According to an example, the controller 1610 may select a specific subband from at least one subband included in the radio resource based on available environment information. The terminal may receive downlink control information including information indicating the selected subband. For example, in the uplink environment, such as a CSI feedback control message, messages having a large difference between an allocation time and an actual use time are affected by a variable band availability environment with time. In the case of control messages that do not need to be transmitted depending on the band, it is advantageous to select a subband with a good available environment.

Accordingly, the controller 1610 may pre-allocate a plurality of transmission regions for the corresponding control messages for each subband. The UE may receive information indicating a subband to be actually used at a specific time in the form of an index. Through this, the terminal can determine the subband to be used at the time.

In order to change the subband, the terminal may attempt to detect a change control message when the situation of the currently used subband deteriorates above a threshold value. In this case, the transmitter 1620 should transmit the corresponding indication only when a channel condition deteriorated above a threshold is received. Alternatively, the terminal may be set to always attempt to detect the change control message. Alternatively, the DCI transmitted periodically may be configured to include the corresponding message.

According to this, by sharing available environment information based on LBT performance results for a plurality of subbands in an unlicensed band, efficient band operation can be performed in an environment where the probability of success of LBT for each subband is independent and variable.

The above-described embodiments may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802, 3GPP and 3GPP2. That is, steps, components, and parts which are not described in order to clearly reveal the present technical spirit of the embodiments may be supported by the aforementioned standard documents. In addition, all terms disclosed in this specification may be described by standard documents disclosed above.

The above-described embodiments may be implemented through various means. For example, the embodiments may be implemented by hardware, firmware, software, or a combination thereof.

In the case of a hardware implementation, the method according to the embodiments may include one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), FPGAs. (Field Programmable Gate Arrays), a processor, a controller, a microcontroller or a microprocessor may be implemented.

In the case of an implementation by firmware or software, the method according to the embodiments may be implemented in the form of an apparatus, procedure, or function for performing the functions or operations described above. The software code can be stored in a memory unit and driven by a processor. The memory unit is located inside or outside the processor, and can exchange data with the processor by various known means.

In addition, the terms "system", "processor", "controller", "component", "module", "interface", "model", or "unit" described above generally refer to computer-related entity hardware, hardware and software. Can mean a combination of, software or running software. For example, the foregoing components may be, but are not limited to, a process driven by a processor, a processor, a controller, a control processor, an object, an execution thread, a program, and / or a computer. For example, both an application running on a controller or processor and a controller or processor can be components. One or more components may be within a process and / or thread of execution, and the components may be located on one device (eg, system, computing device, etc.) or distributed across two or more devices.

The above description is merely illustrative of the technical idea of the present disclosure, and various modifications and variations may be made by those skilled in the art without departing from the essential characteristics of the present disclosure. In addition, the present embodiments are not intended to limit the technical spirit of the present disclosure but to describe the scope of the present inventive concept. The scope of protection of the present disclosure should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto shall be construed as being included in the scope of the present disclosure.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is filed in US Patent Law 119 for patent application No. 10-2018-0107105 filed in Korea on September 07, 2018 and patent application No. 10-2019-0108134 filed in Korea on September 02, 2019. Priority is claimed pursuant to subdivision (a) (35 USC § 119 (a)), all of which is incorporated into this patent application by reference. In addition, if this patent application claims priority to countries other than the United States for the same reason as above, all the contents are incorporated into this patent application as a reference.

Claims (15)

1. In the method for the terminal to perform wireless communication in the unlicensed band,

   Receiving information for allocating radio resources in a system band composed of a plurality of subbands;

   Obtaining available environment information based on performing a List Before Talk (LBT) for at least one subband included in the radio resource; And

   And transmitting the available environment information.
2. The method of claim 1,

   The available environment information,

   A method determined based on the number of successes and failures of the LBT for each of the at least one subband.
3. The method of claim 1,

   The available environment information,

   A method included in uplink control information and transmitted or transmitted through a sounding reference signal (SRS).
4. The method of claim 1,

   And receiving downlink control information including information on a plurality of radio resources allocated to transmission and reception of predetermined data based on the available environment information.
5. The method of claim 1,

   And receiving downlink control information including information indicating a selected subband among at least one subband included in the radio resource based on the available environment information.
6. A method for performing a wireless communication in a base station unlicensed band,

   Transmitting information for allocating radio resources in a system band composed of a plurality of subbands; And

   And receiving available environment information based on performing a Listen Before Talk (LBT) for at least one subband included in the radio resource.
7. The method of claim 6,

   The available environment information,

   A method determined based on the number of successes and failures of the LBT for each of the at least one subband.
8. The method of claim 6,

   The available environment information,

   A method included in uplink control information or received through a sounding reference signal (SRS).
9. The method of claim 6,

   And transmitting downlink control information including information on a plurality of radio resources, allocated for transmission and reception of predetermined data, based on the available environment information.
10. The method of claim 6,

    And transmitting downlink control information including information indicating a selected subband among at least one subband included in the radio resource based on the available environment information.
11. In the terminal for performing wireless communication in the unlicensed band,

    A receiver configured to receive information for allocating radio resources in a system band composed of a plurality of subbands;

    A control unit for obtaining available environment information based on performing a Listen Before Talk (LBT) for at least one subband included in the radio resource; And

    A terminal including a transmitter for transmitting the available environment information.
12. The method of claim 11,

    The available environment information,

    A terminal determined based on the number of successes and failures of the LBT for each of the at least one subband.
13. The method of claim 11,

    The available environment information,

    A terminal included in uplink control information and transmitted or transmitted through a sounding reference signal (SRS).
14. The method of claim 11,

    The receiving unit,

    A terminal receiving downlink control information including information on a plurality of radio resources, which is allocated to transmission and reception of predetermined data based on the available environment information.
15. The method of claim 11,

    The receiving unit,

    A terminal receiving downlink control information including information indicating a selected subband among at least one subband included in the radio resource based on the available environment information.

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