KR20200001870A - Method for retransmitting PUCCH in unlicensed spectrum for new radio and Apparatuses thereof - Google Patents

Abstract

The present invention relates to a method for transmitting an uplink control channel of a terminal for a next generation/5G wireless access network configured through an unlicensed band. According to an embodiment of the present invention, provided is a method of a terminal for retransmitting a physical uplink control channel (PUCCH) in an unlicensed band, which indicates PUCCH retransmission through downlink control information (DCI).

Description

Method and apparatus for retransmission of uplink control information for next generation wireless network in unlicensed band {Method for retransmitting PUCCH in unlicensed spectrum for new radio and Apparatuses

The present invention proposes a method for transmitting an uplink control channel of a terminal for a next generation / 5G wireless access network (hereinafter referred to as NR-U [New Radio Unlicensed spectrum]) configured through an unlicensed band.

One embodiment provides a method for a UE to retransmit a PUCCH in an unlicensed band, and instructs PUCCH retransmission through DCI.

1 illustrates an example of symbol level alignment among different SCSs.
2 is a diagram illustrating a conceptual example of a bandwidth part.
3 is a diagram illustrating a configuration of a base station according to another embodiment.
4 is a diagram illustrating a configuration of a user terminal according to another embodiment.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In the present specification, the wireless communication system refers to a system for providing various communication services such as voice and packet data. The wireless communication system includes a user equipment (UE) and a base station (BS).

A user terminal is a comprehensive concept of a terminal in a wireless communication, and includes a user equipment (UE) in WCDMA, LTE, HSPA, and IMT-2020 (5G or New Radio), as well as a mobile station (MS) and a UT in GSM. It should be interpreted as a concept that includes a user terminal, a subscriber station (SS), and a wireless device.

A base station or cell generally refers to a station that communicates with a user terminal, and includes a Node-B, an evolved Node-B, an eNB, a gNode-B, and a Low Power Node. ), Sector, site, various types of antennas, base transceiver system (BTS), access point, access point (for example, transmission point, reception point, transmission / reception point), relay node ( It is meant to encompass various coverage areas such as a 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.

Since the various cells listed above have a base station for controlling each cell, the base station may be interpreted in two meanings. 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 wireless area, or 2) the wireless area itself. In 1) all devices that provide a given radio area are controlled by the same entity or interact with each other to cooperatively configure the radio 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 a 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.

In the present specification, the user terminal and the base station are used in a comprehensive sense as two entities (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by the terms or words specifically referred to. Do not.

Here, the uplink (Uplink, UL, or uplink) refers to a method for transmitting and receiving data to the base station by the user terminal, the downlink (Downlink, DL, or downlink) means to transmit and receive data to the user terminal by the base station It means the way.

The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, and use a frequency division duplex (FDD) scheme, a TDD scheme, and an FDD scheme, which are transmitted using different frequencies. Mixed mode may be used.

In addition, in a wireless communication system, a standard is configured by configuring uplink and downlink based on one carrier or a pair of carriers.

The uplink and the downlink transmit 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. It is composed of the same data channel to transmit data.

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.

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.'

Meanwhile, high layer signaling described below includes RRC signaling for transmitting RRC information including an RRC parameter.

The base station performs downlink transmission to the terminals. The base station transmits downlink control information such as scheduling required for reception of a downlink data channel, which is a main physical channel for unicast transmission, and a physical downlink for transmitting scheduling grant information for transmission on an uplink data channel. The control channel can be transmitted. Hereinafter, the transmission and reception of signals through each channel will be described in the form of transmission and reception of the corresponding channel.

There is no limitation on the multiple access scheme applied in the wireless communication system. Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Non-Orthogonal Multiple Access (NOMA), OFDM-TDMA, OFDM-FDMA, Various multiple access techniques such as OFDM-CDMA can be used. Here, the NOMA includes a sparse code multiple access (SCMA) and a low density spreading (LDS).

One embodiment of the present invention is for asynchronous radio communication evolving to LTE / LTE-Advanced, IMT-2020 via GSM, WCDMA, HSPA, and synchronous radio communication evolving to CDMA, CDMA-2000 and UMB. Can be applied.

In the present specification, a MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. Alternatively, in the present specification, the MTC terminal may mean a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, in the present specification, the MTC terminal may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type for performing LTE-based MTC related operations. Alternatively, in the present specification, the MTC terminal supports enhanced coverage compared to the existing LTE coverage, or supports UE category / type defined in the existing 3GPP Release-12 or lower, or newly defined Release-13 low cost (or lower power consumption). low complexity) can mean UE category / type. Or, it may mean a further Enhanced MTC terminal defined in Release-14.

In this specification, a NB-IoT (NarrowBand Internet of Things) terminal refers to a terminal that supports radio access for cellular IoT. The objectives of NB-IoT technology include improved Indoor coverage, support for large scale low speed terminals, low sensitivity, low cost terminal cost, low power consumption, and optimized network architecture.

As a typical usage scenario in New Radio (NR), which is recently discussed by 3GPP, enhanced Mobile BroadBand (eMBB), massive machine type communication (MMTC), and Ultra Reliable and Low Latency Communication (URLLC) are being raised.

In this specification, frequencies, frames, subframes, resources, resource blocks, regions, bands, subbands, control channels, data channels, synchronization signals, various reference signals, various signals, and various messages related to NR (New Radio). May 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). Based on this, RAN WG1 has a frame structure for each new radio (NR). The design of channel, channel coding & modulation, waveform & multiple access scheme, etc. is underway. NR is required to be designed to satisfy various QoS requirements required for each detailed and detailed usage scenario as well as improved data rate compared to LTE. Specifically, eMBB (enhancement Mobile BroadBand), mMTC (massive MTC) and URLLC (Ultra Reliable and Low Latency Communications) are defined as typical usage scenarios of NR, and a flexible frame compared to LTE as a method for satisfying requirements for each usage scenario. Structure design is required. Since each usage scenario has different requirements for data rates, latency, reliability, coverage, etc., it is a method to efficiently satisfy the requirements of each usage scenario through a frequency band constituting an arbitrary NR system. For example, there is a need for a method of efficiently multiplexing a radio resource unit based on subcarrier spacing, subframe, TTI, etc.).

As one method for this, a method of multiplexing and supporting scheduling units in a time domain based on TDM, FDM, or TDM / FDM through one or a plurality of NR component carriers for numerology having different subcarrier spacing values In constructing, discussions were made on how to support more than one time unit. In this regard, in NR, a subframe is defined as a kind of time domain structure, and as a reference numerology for defining the subframe duration, 14 OFDM symbols of 15 kHz sub-carrier spacing (SCS) -based normal CP overhead, which is the same as LTE, are used. We decided to define a single subframe duration consisting of. Accordingly, in NR, the subframe has a time duration of 1 ms. However, unlike LTE, the subframe of NR is an absolute reference time duration, and slots and mini-slots may be defined as time units that are the basis of actual uplink / downlink data scheduling. In this case, the number of OFDM symbols and the y value of the corresponding slot are determined to have a value of y = 14 regardless of the SCS value in the case of normal CP.

Accordingly, any slot consists of 14 symbols, and depending on the transmission direction of the slot, all symbols are used for DL transmission, all symbols are used for UL transmission, or DL portion + (gap) + It can be used in the form of a UL portion.

In addition, in any numerology (or SCS), a mini-slot configured with fewer symbols than the slot is defined, and a short time-domain scheduling interval for transmitting / receiving uplink / downlink data is set or slot aggregation based on this. Through this, a long time-domain scheduling interval for transmitting / receiving uplink / downlink data may be configured. In particular, in case of transmission / reception of latency critical data such as URLLC, it is difficult to meet latency requirement when scheduling is performed by slot based on 1ms (14 symbols) defined in numerology-based frame structure with small SCS value such as 15kHz. For this purpose, a mini-slot consisting of fewer OFDM symbols than the corresponding slot can be defined for this purpose, and based on this, a scheduling for latency critical data such as URLLC can be defined.

Or, as described above, by supporting multiplexing numerology having different SCS values in one NR carrier by TDM and / or FDM method, based on slot (or mini-slot) length defined for each numerology Scheduling data based on latency requirements is also being considered. For example, as shown in FIG. 1 below, when the SCS is 60 kHz, the symbol length is reduced to about 1/4 compared to the case of the SCS 15 kHz. Thus, when one slot is configured with 14 OFDM symbols, the slot is based on the corresponding 15 kHz. The length is 1ms, while the 60kHz-based slot length is reduced to about 0.25ms.

As described above, in NR, a method of satisfying the requirements of URLLC and eMBB by defining different SCS or different TTI length is being discussed.

In NR and LTE / LTE-A systems, L1 control information such as DL assignment Downlink Control Information (DCI) and UL grant DCI is transmitted and received through a PDCCH. A control channel element (CCE) is defined as a resource unit for transmitting the PDCCH, and in the NR, a control resource set (CORESET), which is a frequency / time resource for transmitting the PDCCH, may be set for each terminal. In addition, each CORESET may be configured with one or more search spaces consisting of one or more PDCCH candidates for the UE to monitor the PDCCH. For details of the PDCCH in NR, the contents of TS 38.211 and TS 38.213 are extracted and attached through TS 38.211 of appendix [1] and TS 38.213_PDCCH of appendix [2].

Wider bandwidth operations

In case of the existing LTE system, it supported scalable bandwidth operation for any LTC CC (Component Carrier). That is, according to the frequency deployment scenario, any LTE operator may configure a bandwidth of at least 1.4 MHz and up to 20 MHz in configuring one LTE CC, and a normal LTE terminal may have a bandwidth of 20 MHz for one LTE CC. Supports transmission and reception capability.

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. Accordingly, the NR is subdivided for an arbitrary NR CC as shown in FIG. 2 below. By configuring one or more bandwidth part (s) consisting of the configured bandwidth, it is required to support flexible wider bandwidth operation through different bandwidth part configuration and activation for each terminal.

In more detail, in NR, one or more bandwidth parts may be configured through one serving cell configured from the perspective of the terminal, and the terminal activates one DL bandwidth part and one UL bandwidth part in the corresponding serving cell and uplink / downlink data. It is defined to be used for sending and receiving. In addition, when a plurality of serving cells are configured in the corresponding UE, that is, even for the UE to which the CA is applied, one DL bandwidth part and / or UL bandwidth part is activated for each serving cell to use up / down radio resources of the corresponding serving cell. It is defined to be used for link data transmission and reception.

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

However, depending on the capability and configuration of the bandwidth part (s) of the terminal in any serving cell can be defined to activate and use a plurality of DL and / or UL bandwidth parts at the same time, in the NR rel-15 any terminal It is defined to activate and use only one DL bandwidth part and UL bandwidth part at a time.

PUCCH

According to the PUCCH resource allocation method for HARQ ACK / NACK feedback of the UE defined in the NR, when the PDSCH resources are allocated, the base station performs HARQ ACK feedback for the PDSCH through the ARI (ACK Resource Indicator) information region of the DL assignment DCI format It indicates the PUCCH resource allocation information for. In more detail, the base station transmits one or more PUCCH resource set configuration information consisting of one or more PUCCH resources for each UL BWP configured for an arbitrary terminal to each terminal through RRC signaling. Accordingly, the ARI is defined to indicate the PUCCH resource index for HARQ ACK feedback for any PDSCH, and the PUCCH resource set is determined by the payload size of the UCI to be transmitted through the PUCCH of the corresponding slot.

The specific PUCCH resource allocation method of NR is attached through appendix [3] TS 38.213_PUCCH.

NR-U

In the case of unlicensed bands, unlike licensed bands, any carrier or individual can be used to provide wireless communication service within the regulation of each country, not a radio channel exclusively used by any operator. Accordingly, when providing NR service through unlicensed band, co-existence problem with various short-range wireless communication protocols such as WiFi, Bluetooth, and NFC already provided through the unlicensed band and co-existence between respective NR operators or LTE providers The problem needs to be solved. Accordingly, when providing NR service through the unlicensed band, the power level of the radio channel or carrier to be used is sensed before transmitting the radio signal in order to avoid interference or collision between the respective radio communication services to determine whether the corresponding radio channel or carrier is available. There is a need to support an LBT (Listen Before Talk) based wireless channel access method. In this case, if a specific radio channel or carrier of the unlicensed band is in use by another radio communication protocol or another operator, the radio communication service through the unlicensed band may be restricted to the provision of NR service through the band. Unlike the wireless communication service through the LAN, the QoS required by the user cannot be guaranteed.

In particular, in the case of NR-U, unlike existing LTE, which must support unlicensed spectrum through CA with licensed spectrum, it is a deployment scenario of unlicensed band NR as a stand-alone NR-U cell or licensed band NR cell or LTE cell. Since NR-U cells based on Dual Connectivity (DC) are being considered, a design of a data transmission / reception method is required to satisfy the minimum QoS in the unlicensed band itself.

The present invention proposes a method for retransmitting uplink control information of a terminal in an NR-U cell.

As described above, in order to transmit a radio signal from any node in the unlicensed band, an LBT process must be performed to check whether the corresponding radio channel is occupied by another node.

Accordingly, in order to transmit PDSCH for an arbitrary UE in an NR-U cell configured by an arbitrary NR base station, after performing LBT for the corresponding unlicensed band at the base station, if the corresponding radio channel is empty, PDCCH and PDSCH transmission accordingly are performed. can do.

Similarly, the UE is required to perform LBT before uplink signal transmission.

In NR, a base station may set an RRC for HARQ ACK / NACK feedback timing for PDSCH reception of a terminal or may indicate a corresponding terminal through a DL assignment DCI. However, as described above, in the NR-U cell, PUCCH transmission including HARQ ACK / NACK feedback information may not be possible at the time indicated by the base station according to the LBT result of the UE. That is, when LBT failure occurs (that is, when the corresponding wireless channel is occupied by another node as a result of the LBT), the corresponding UE cannot transmit HARQ ACK / NACK feedback information according to PDSCH reception at the indicated time. This may cause serious degradation in HARQ performance in the NR-U cell.

Similarly, when a PUCCH resource for periodic CSI reporting of an arbitrary UE is configured in an NR-U cell, when LBT failure occurs in a PUCCH transmission slot for corresponding CSI reporting, the periodic CSI reporting may not be performed.

In view of the above issue, the present invention proposes a HARQ ACK / NACK feedback method for a UE for an NR-U cell, and additionally includes HARQ ACK feedback as well as other types of UCI (eg SR or CSI / CQI feedback). It also includes a PUCCH transmission method.

PUCCH retransmission indication method through DCI

As described above, when UCI transmission is not performed through the PUCCH resources allocated due to LBT failure in any UE, the BS may be defined to indicate retransmission for the corresponding PUCCH.

Specifically, when a PUCCH transmission for transmitting HARQ ACK / NACK feedback information fails in any UE, the base station is a method for PUCCH retransmission indication including corresponding HARQ ACK / NACK feedback information. In the present invention, 1) the existing DL assignment DCI We propose a method to use the format and 2) define a new DCI format for PUCCH retransmission.

Scheme 1. How to use the existing DL assignment DCI format (blank PDSCH scheduling DCI-based method)

As a method of utilizing an existing DL assignment DCI format, in transmitting a DL assignment DCI format for an arbitrary terminal from a base station, any information area (s) among the information areas included in the corresponding DL assignment DCI format are specified as a specific value ( By setting), it can be defined to indicate PUCCH retransmission for the terminal. That is, the base station sets specific information area (s) of the DL assignment DCI format to a specific value, so that the UE does not receive the PDSCH for the HARQ process indicated through the corresponding DL assignment DCI format (that is, PDSCH retransmission of the base station). It may be defined to retransmit HARQ feedback information on the previous PDSCH transmission corresponding to the corresponding HARQ process. That is, it may be defined that the DL assignment DCI for PUCCH retransmission purely without any PDSCH allocation is transmitted by the base station. As a method of configuring a DL assignment DCI format for the corresponding blank PDSCH allocation, that is, PUCCH retransmission, the DL assignment DCI for the PUCCH retransmission is configured by setting the MCS indication information region of the DL assignment DCI format to a specific value. can do. As another method, PUCCH retransmission through the corresponding DL assignment DCI may be defined by setting the PRB allocation information region to a specific value. Alternatively, for all combinations of all information regions included in the other DL assignment DCI format, the information regions of the combination are set to a specific value, so that all cases of defining PUCCH retransmission for any UE are indicated. Included in the category.

As another method for indicating PUCCH retransmission for an arbitrary UE in a base station, a separate information area for indicating blank PDSCH scheduling or PUCCH retransmission may be defined and included in a corresponding DL assignment DCI format. In addition, whether to include the corresponding PUCCH retransmission indication information region may be configured for each UE through UE-specific RRC signaling.

As another method for instructing a PUCCH retransmission for an arbitrary UE in a base station, a separate RNTI for PUCCH retransmission may be defined, and the corresponding PUCCH retransmission may be defined based on this. That is, by transmitting a CR assignment to the PUCCH retransmission RNTI assigned to the corresponding PUCCH retransmission RNTI DL DL DCI configured to monitor any terminal, it can be defined to indicate the PUCCH retransmission for the corresponding UE, the terminal is the PUCCH retransmission RNTI If is additionally allocated through the RRC signaling by the base station, according to the monitoring according to the DL assignment DCI format in the USS or CSS configured for the terminal, in addition to the C-RNTI to define the additional PUCCH retransmission RNTI-based monitoring Can be.

Scheme 2. Define a new DCI format for separate PUCCH retransmission

By defining a separate DCI format for PUCCH retransmission, it can be defined to indicate PUCCH retransmission for any terminal based on this. The PUCCH retransmission DCI format may be defined as a UE-group common DCI format. As described above, when the PUCCH retransmission DCI format is defined in a UE-group common format, the PUCCH retransmission DCI format includes slot-related information (eg slot index information, a slot that fails to receive a PUCCH and a corresponding PUCCH retransmission DCI format). Timing gap information between transmitted slots) and slot allocation information for PUCCH retransmission (eg slot index information, or timing gap information between a slot where a corresponding PUCCH retransmission DCI format is transmitted and a slot where a PUCCH retransmission is performed accordingly). Can be defined In addition, according to the UE, the PUCCH resource (eg symbol, PRB, code, etc.) to be used for the corresponding UCI retransmission in the slot indicated by the PUCCH retransmission DCI format indicates that the previous PUCCH resource (that is, the slot that failed to receive the PUCCH at the base station) In the UE, PUCCH resources used by respective terminals may be defined as they are. The PUCCH retransmission DCI format may be defined in a UE-specific DCI format. In this case, among the information areas included in the existing DL assignment DCI format for PUCCH retransmission for each UE, HARQ process number indication information requiring PUCCH retransmission and PUCCH resource allocation related information area (eg ARI, slot indication information, etc.) It may include.

Additionally, even when the PUCCH transmission for periodic CSI reporting of the UE fails due to the LBT failure, in the case of the HARQ ACK / NACK feedback, the PUCCH retransmission may be indicated by the base station in the same manner. That is, PUCCH resource allocation for retransmission of periodic CSI reporting information missing by LBT failure is performed through the blank PDSCH allocation-based DL assignment DCI format, or corresponding through the separate PUCCH retransmission DCI format of Scheme 2 above. PUCCH retransmission including periodic CSI reporting information may be indicated.

3 is a diagram illustrating a configuration of a base station 1000 according to another embodiment.

Referring to FIG. 3, the base station 1000 according to another embodiment includes a controller 1010, a transmitter 1020, and a receiver 1030.

The control unit 1010 in the method for the UE to retransmit PUCCH in the unlicensed band required to perform the above-described present invention, the overall base station 1000 according to the method characterized in that instructs PUCCH retransmission through the DCI To control the operation.

The transmitter 1020 and the receiver 1030 are used to transmit and receive signals, messages, and data necessary for carrying out the above-described present invention.

4 is a diagram illustrating a configuration of a user terminal 1100 according to another embodiment.

Referring to FIG. 4, the user terminal 1100 according to another embodiment includes a receiver 1110, a controller 1120, and a transmitter 1130.

The receiver 1110 receives downlink control information, data, and a message from a base station through a corresponding channel.

In addition, the control unit 1120 is a method for retransmitting a PUCCH by a terminal in an unlicensed band required for carrying out the above-described present invention, and the overall user terminal according to the method characterized by instructing PUCCH retransmission through a DCI ( The operation of 1100 is controlled.

The transmitter 1130 transmits uplink control information, data, and a message to a base station through a corresponding channel.

Also, the terms "system", "processor", "controller", "component", "module", "interface", "model", "unit" generally refer to computer-related entity hardware, a combination of hardware and software, May mean software or running software. For example, the aforementioned 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 can reside within a process and / or thread of execution and a component can be located on one system or deployed on more than one system.

The standard contents or standard documents mentioned in the above embodiments are omitted to simplify the description of the specification and form a part of the present specification. Therefore, the addition of the contents of the standard and part of the standard documents to the specification or the description in the claims should be construed as falling within the scope of the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims (1)

In the method for the UE to retransmit PUCCH in the unlicensed band,
And instructing PUCCH retransmission through DCI.

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