KR20210157320A - Method and apparatus for controlling search space for power saving - Google Patents

Abstract

Embodiments of the present invention relate to a method and apparatus for controlling a search space for power saving. One embodiment provides a method, in a method for a terminal to control a search space, which comprises the steps of: receiving configuration information for at least one search space; receiving indication information for at least one of time period information for not monitoring a downlink control channel and search space information for at least one search space; and monitoring a downlink control channel based on the indication information.

Description

METHOD AND APPARATUS FOR CONTROLLING SEARCH SPACE FOR POWER SAVING

The present embodiments propose a method and apparatus for setting and operating a downlink control message search area for a low-power terminal in a next-generation radio access network (hereinafter referred to as “New Radio [NR]”).

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 for NR (New Radio) Designs for a frame structure, channel coding & modulation, waveform & multiple access scheme, and the like are in progress. NR is required to be designed to satisfy various QoS requirements required for each segmented and detailed usage scenario as well as an improved data rate compared to LTE.

As representative usage scenarios of NR, eMBB (enhancement Mobile BroadBand), mMTC (massive machine type communication), and URLLC (Ultra Reliable and Low Latency Communications) have been defined. design is required.

Since each service requirement (usage scenario) has different requirements for data rates, latency, reliability, coverage, etc., through the frequency band constituting an arbitrary NR system As a method to efficiently satisfy the needs of each usage scenario, different numerology (eg, subcarrier spacing, subframe, TTI (Transmission Time Interval), etc.) based There is a need for a method for efficiently multiplexing a radio resource unit of

As part of this aspect, a design for setting and operating a search area for a low-power terminal is required.

Embodiments of the present disclosure may provide a specific method and apparatus capable of controlling a search area for a low-power terminal in NR.

In one aspect, the present embodiments provide a method for a terminal to control a search space, comprising: receiving configuration information for at least one search area; and monitoring a downlink control channel for at least one search area It is possible to provide a method comprising the steps of receiving indication information on at least one of non-noted time period information and search area information, and monitoring a downlink control channel based on the indication information.

In another aspect, the present embodiments provide a method for a base station to control a search space, transmitting configuration information for at least one search area to the terminal, and a downlink control channel for at least one search area. It is possible to provide a method comprising the step of transmitting indication information on at least one of time period information for not monitoring and search area information.

In another aspect, the present embodiments, in a terminal controlling a search space, receive configuration information for at least one search area and do not monitor a downlink control channel for at least one search area. It is possible to provide a terminal including a receiver for receiving indication information on at least one of time period information and search area information, and a control unit for monitoring a downlink control channel based on the indication information.

In another aspect, the present embodiments provide a base station that controls a search space, transmits configuration information for at least one search area to the terminal, and monitors a downlink control channel for at least one search area. It is possible to provide a base station including a transmitter that transmits indication information for at least one of non-noted time period information and search area information, and a controller that controls the operation of the transmitter.

According to the present embodiments, it is possible to provide a specific method and apparatus capable of reducing power required for a low-power terminal to transmit and receive a downlink control message by controlling a search region for a low-power terminal in NR.

1 is a diagram schematically illustrating a structure of an NR wireless communication system to which this embodiment can be applied.
2 is a diagram for explaining a frame structure in an NR system to which this embodiment can be applied.
3 is a diagram for explaining a resource grid supported by a radio access technology to which this embodiment can be applied.
4 is a diagram for explaining a bandwidth part supported by a radio access technology to which the present embodiment 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.
6 is a diagram for explaining a random access procedure in a radio access technology to which this 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 to which this 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 for a terminal to control a search space according to an embodiment.
11 is a diagram illustrating a procedure in which a base station controls a search space according to an embodiment.
12 is a diagram showing the configuration of a terminal according to another embodiment.
13 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 indicated in different drawings. In addition, in describing the present embodiments, if it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present technical idea, the detailed description may be omitted. When "includes", "having", "consisting of", etc. mentioned in this specification are used, other parts may be added unless "only" is used. When a component is expressed in the singular, it may include a case in which the plural is included unless otherwise explicitly stated.

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

In the description of the positional relationship of the components, when it is described that two or more components are "connected", "coupled" or "connected", two or more components are directly "connected", "coupled" or "connected" It should be understood that, however, two or more components and other components may be further “interposed” and “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 relationship related to the components, the operation method or the production method, for example, the temporal precedence relationship such as "after", "after", "after", "before", etc. Alternatively, when a flow precedence relationship is described, it may include a case where it is not continuous unless "immediately" or "directly" is used.

On the other hand, when numerical values or corresponding information (eg, level, etc.) for a component are mentioned, even if there is no separate explicit description, the numerical value or the corresponding information is based on various factors (eg, process factors, internal or external shock, Noise, etc.) may be interpreted as including an error range that may occur.

A wireless communication system in the present specification refers to 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 present embodiments disclosed below may be applied to a wireless communication system using various wireless access technologies. For example, the present embodiments are CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple access) Alternatively, it 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 a radio technology such as global system for mobile communications (GSM)/general packet radio service (GPRS)/enhanced datarates for GSM evolution (EDGE). OFDMA may be implemented with a radio technology such as 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 the universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of evolved UMTS (E-UMTS) that uses evolved-UMTSterrestrial radio access (E-UTRA), and employs OFDMA in the downlink and SC- FDMA is employed. As such, the present embodiments may be applied to currently disclosed or commercialized radio access technologies, or may be applied to radio access technologies currently under development or to be developed in the future.

On the other hand, the terminal in the present specification is a comprehensive concept meaning a device including a wireless communication module that performs communication with a base station in a wireless communication system, WCDMA, LTE, NR, HSPA and IMT-2020 (5G or New Radio), etc. It should be interpreted as a concept including all of UE (User Equipment), MS (Mobile Station), UT (User Terminal), SS (Subscriber Station), wireless device, etc. in GSM. In addition, the terminal may be a user's portable device such as a smart phone depending on the type of use, and in a V2X communication system 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 (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 cell of the present specification refers to an end that communicates with a terminal in terms of a network, a Node-B (Node-B), an evolved Node-B (eNB), gNode-B (gNB), a Low Power Node (LPN), Sector, site, various types of antennas, base transceiver system (BTS), access point, point (eg, transmission point, reception point, transmission/reception point), relay node ), mega cell, macro cell, micro cell, pico cell, femto cell, RRH (Remote Radio Head), RU (Radio Unit), small cell (small cell), such as a variety of coverage areas. In addition, the cell may mean including a BWP (Bandwidth Part) in the frequency domain. For example, the serving cell may mean the Activation BWP of the UE.

In the various cells listed above, since there is a base station controlling one or more cells, the base station can be interpreted in two meanings. 1) in relation to the radio area, it may be the device itself providing a mega cell, a macro cell, a micro cell, a pico cell, a femto cell, or a small cell, or 2) may indicate the radio area itself. In 1), the devices providing a predetermined radio area are controlled by the same entity, or all devices interacting to form a radio area cooperatively are directed to the base station. A point, a transmission/reception point, a transmission point, a reception point, etc. become an embodiment of a base station according to a configuration method of a wireless area. In 2), the radio area itself in which signals are received or transmitted from the point of view of the user terminal or the neighboring base station may be indicated to the base station.

In the present specification, a cell is a component carrier having a coverage of a signal transmitted from a transmission/reception point or a coverage of a signal transmitted from a transmission/reception point (transmission point or transmission/reception point), and the transmission/reception point itself. can

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

The uplink and downlink transmit and receive control information through a control channel such as a Physical Downlink Control CHannel (PDCCH), a Physical Uplink Control CHannel (PUCCH), etc. Data is transmitted and received by configuring the same data channel. Hereinafter, a situation in which signals are transmitted/received through channels such as PUCCH, PUSCH, PDCCH, and PDSCH may be expressed in the form of 'transmitting and receiving PUCCH, PUSCH, PDCCH and PDSCH'.

For clarity of explanation, the present technical idea will be mainly described below for the 3GPP LTE/LTE-A/NR (New RAT) communication system, but the present technical characteristics are not limited to the corresponding communication system.

In 3GPP, after research on 4G (4th-Generation) communication technology, 5G (5th-Generation) communication technology is developed to meet the requirements of ITU-R's next-generation wireless access technology. Specifically, 3GPP develops LTE-A pro, which improved LTE-Advanced technology to meet the requirements of ITU-R as a 5G communication technology, and a new NR communication technology separate from 4G communication technology. LTE-A pro and NR both refer to 5G communication technology. Hereinafter, 5G communication technology will be described with a focus on NR unless a specific communication technology is specified.

In the NR operation scenario, various operation scenarios were defined by adding consideration of satellites, automobiles, and new verticals to the existing 4G LTE scenarios. It is deployed in a range and supports the mMTC (Massive Machine Communication) scenario that requires a low data rate and asynchronous connection, and the URLLC (Ultra Reliability and Low Latency) scenario that requires high responsiveness and reliability and supports high-speed mobility. .

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

<Normal NR system>

1 is a diagram schematically illustrating a structure of an NR system to which this embodiment can be applied.

1, the NR system is divided into a 5G Core Network (5GC) and an NR-RAN part, and the NG-RAN controls the user plane (SDAP/PDCP/RLC/MAC/PHY) and UE (User Equipment) It consists of gNBs and ng-eNBs that provide planar (RRC) protocol termination. gNB interconnection or gNB and ng-eNB interconnect via Xn interface. gNB and ng-eNB are each connected to 5GC through the NG interface. 5GC may be configured to include an Access and Mobility Management Function (AMF) in charge of a control plane such as terminal access and mobility control functions, and a User Plane Function (UPF) in charge of a control function for user data. NR includes support for both the frequency band below 6 GHz (FR1, Frequency Range 1) and the frequency band above 6 GHz (FR2, Frequency Range 2).

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

<NR Waveform, Pneumologic and Frame Structure>

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

On the other hand, in NR, since the requirements for data rate, delay rate, coverage, etc. are different for each of the three scenarios described above, 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, NR transmission numerology is determined based on 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. is changed negatively.

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 five types according to the subcarrier spacing. This is different from the fact that the subcarrier interval of LTE, one of the 4G communication technologies, is fixed to 15 kHz. Specifically, subcarrier intervals used for data transmission in NR are 15, 30, 60, and 120 kHz, and subcarrier intervals used for synchronization signal transmission are 15, 30, 120 and 240 kHz. In addition, the extended CP is applied only to the 60 kHz subcarrier interval. On the other hand, as for the frame structure in NR, a frame having a length of 10 ms is defined, which is composed of 10 subframes having the same length of 1 ms. One frame can be divided into half frames of 5 ms, and each half frame includes 5 subframes. In the case of a 15 kHz subcarrier interval, one subframe consists of one slot, and each slot consists of 14 OFDM symbols. 2 is a diagram for explaining a frame structure in an NR system to which this embodiment can be applied.

Referring to FIG. 2 , a slot is fixedly composed of 14 OFDM symbols in the case of a normal CP, but the length of the slot in the time domain may vary according to the subcarrier interval. For example, in the case of a numerology having a 15 kHz subcarrier interval, the slot is 1 ms long and is configured with the same length as the subframe. On the other hand, in the case of numerology having a 30 kHz subcarrier interval, a slot consists of 14 OFDM symbols, but two slots may be included in one subframe with a length of 0.5 ms. That is, the subframe and the frame are defined to have a fixed time length, and the slot is defined by the number of symbols, so that 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 a sub-slot or a non-slot based schedule) in order to reduce transmission delay in a radio section. When a wide subcarrier interval is used, the length of one slot is shortened in inverse proportion, so that transmission delay in a radio section can be reduced. The mini-slot (or sub-slot) is for efficient support of the URLLC scenario and can be scheduled in units of 2, 4, or 7 symbols.

Also, unlike LTE, NR defines uplink and downlink resource allocation at a symbol level within one slot. In order to reduce the HARQ delay, a slot structure capable of transmitting HARQ ACK/NACK directly within a transmission slot has been defined, and this slot structure will be 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, a common frame structure constituting an FDD or TDD frame is supported through a combination of various slots. 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 symbols and uplink symbols are combined are supported. In addition, NR supports that data transmission is scheduled to be distributed in one or more slots. Accordingly, the base station may inform the terminal whether the slot is a downlink slot, an uplink slot, or a flexible slot using a slot format indicator (SFI). The base station may indicate the slot format by indicating the index of the table configured through UE-specific RRC signaling using SFI, and may indicate dynamically through DCI (Downlink Control Information) or statically or through RRC. It can also be ordered quasi-statically.

<NR Physical Resources>

In relation to a physical resource in NR, an antenna port, a resource grid, a resource element, a resource block, a bandwidth part, etc. are considered do.

An antenna port is defined such that a channel on which a symbol on an antenna port is carried can be inferred from a channel on which another symbol on the same antenna port is carried. When the large-scale property of a channel on which a symbol on one antenna port is carried can be inferred from a channel on which a symbol on another antenna port is carried, the two antenna ports are QC/QCL (quasi co-located or QC/QCL) It can be said that there is a quasi co-location) relationship. Here, the wide range characteristic includes one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

3 is a diagram for explaining a resource grid supported by a radio access technology to which this embodiment can be applied.

Referring to FIG. 3 , in the resource grid, since NR supports a plurality of numerologies on the same carrier, a resource grid may exist according to each numerology. In addition, the resource grid may exist according to an antenna port, a subcarrier interval, and a transmission direction.

A 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 in FIG. 3 , the size of one resource block may vary according to the subcarrier interval. In addition, NR defines "Point A" serving as a common reference point for a resource block grid, a common resource block, a virtual resource block, and the like.

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

In NR, unlike LTE in which the carrier bandwidth is fixed at 20Mhz, 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 NR, as shown in FIG. 4, a bandwidth part (BWP) may be designated within the carrier bandwidth and used by the terminal. In addition, the bandwidth part is associated with one neurology and is composed of a subset of continuous common resource blocks, and may be dynamically activated according to time. Up to four bandwidth parts are configured in the terminal, respectively, in uplink and downlink, and data is transmitted/received using the activated bandwidth part at a given time.

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

<NR Initial Connection>

In NR, the terminal accesses the base station and performs a cell search and random access procedure in order to perform communication.

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

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 consists of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) occupying 1 symbol and 127 subcarriers, respectively, and a PBCH spanning 3 OFDM symbols and 240 subcarriers.

The UE receives the SSB by monitoring the SSB in the time and frequency domains.

SSB can be transmitted up to 64 times in 5ms. A plurality of SSBs are transmitted using different transmission beams within 5 ms, and the UE performs detection on the assumption that SSBs are transmitted every 20 ms when viewed based on one 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 can be transmitted in 3 GHz or less, and SSB can be transmitted using up to 8 different beams 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 within the slot are determined according to the subcarrier interval as follows.

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 in a place other than the center of the system band, and a plurality of SSBs may be transmitted in the frequency domain when wideband operation is supported. Accordingly, the UE monitors the SSB using a synchronization raster that 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. Compared to the carrier raster, the synchronization raster has a wider frequency interval than that of the carrier raster. can

The UE may acquire the MIB through the PBCH of the SSB. 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 includes information on the position of the first DM-RS symbol in the time domain, information for the UE to monitor SIB1 (eg, SIB1 neurology 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 neurology information is equally applied to some messages used in the random access procedure for accessing the base station after the UE completes the cell search procedure. For example, the neurology information of SIB1 may be applied to at least one of messages 1 to 4 for the random access procedure.

The aforementioned RMSI may mean System Information Block 1 (SIB1), and SIB1 is periodically broadcast (eg, 160 ms) 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 for the UE to receive SIB1, it must receive neurology information used for SIB1 transmission and CORESET (Control Resource Set) information used for scheduling SIB1 through the PBCH. The UE checks scheduling information for SIB1 by using SI-RNTI in CORESET, and acquires SIB1 on PDSCH according to the scheduling information. SIBs other than SIB1 may be transmitted periodically or may be transmitted according to the request of the terminal.

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

Referring to FIG. 6 , upon completion of cell search, the terminal transmits a random access channel preamble for random access to the base station. The random access channel preamble is transmitted through the PRACH. Specifically, the random access channel preamble is transmitted to the base station through a PRACH consisting of continuous radio resources in a periodically repeated specific slot. In general, when a UE initially accesses a cell, a contention-based random access procedure is performed, and when random access is performed 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 channel preamble. The random access response may include a random access channel preamble identifier (ID), a 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 channel preamble identifier may be included to inform which terminal the included UL Grant, temporary C-RNTI, and TAC are valid. . The random access channel preamble identifier may be an identifier for the random access channel 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, RA-RNTI (Random Access - Radio Network Temporary Identifier).

Upon receiving the valid random access response, the terminal processes information included in the random access response and performs scheduled transmission to the base station. For example, the UE applies the TAC and stores the temporary C-RNTI. In addition, data stored in the buffer of the terminal or newly generated data is transmitted to the base station by using the UL grant. In this case, information for identifying 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 CORESET (Control Resource Set) having a length of 1 to 3 symbols, and transmits uplink/downlink scheduling information, SFI (Slot Format Index), and TPC (Transmit Power Control) information. .

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

7 is a diagram for explaining CORESET.

Referring to FIG. 7 , CORESET may exist in various forms within a carrier bandwidth within one slot, and CORESET may consist of up to three OFDM symbols in the time domain. In addition, CORESET is defined as a multiple of 6 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 connection establishment with the base station, the terminal may receive and configure one or more pieces of CORESET information through RRC signaling.

In the present specification, frequencies, frames, subframes, resources, resource blocks, regions, bands, subbands, control channels, data channels, synchronization signals, various reference signals, various signals or various messages related to NR (New Radio) can be interpreted in various meanings used in the past or present or used in the future.

New Radio (NR)

Recently, NR conducted in 3GPP was designed to satisfy various QoS requirements required for each segmented and detailed service requirement (usage scenario) as well as an improved data rate compared to LTE. In particular, eMBB (enhancement Mobile BroadBand), mMTC (massive machine type communication), and URLLC (Ultra Reliable and Low Latency Communications) have been defined as representative service requirements (usage scenario) of NR, and each service requirement (usage scenario) requires As a method to satisfy , a flexible frame structure design compared to LTE/LTE-Advanced is required.

Frequency constituting an arbitrary NR system because each service requirement (usage scenario) has different requirements for data rates, latency, reliability, coverage, etc. 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 (usage scenario) through the band It is designed to efficiently multiplex the

As one method for this, TDM, FDM or TDM/FDM-based through one or a plurality of NR component carriers (s) for numerology with different subcarrier spacing values Discussion was made on a method of supporting by multiplexing to and supporting one or more time units in configuring a scheduling unit in a time domain. In this regard, in NR, a subframe is defined as a type of time domain structure, and reference numerology for defining the subframe duration is used. As such, it was decided to define a single subframe duration composed of 14 OFDM symbols of the same 15 kHz Sub-Carrier Spacing (SCS)-based normal CP overhead as LTE. Accordingly, in NR, a subframe has a duration of 1 ms. However, unlike LTE, a subframe of NR is an absolute reference time duration, and a slot and a mini-slot as a time unit that is the basis of actual up/downlink data scheduling. ) can be defined. In this case, the number of OFDM symbols constituting the corresponding slot, y value, is 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 according to the transmission direction of the slot, all symbols are used for downlink transmission (DL transmission), or all symbols are used for uplink transmission (UL). transmission), or may be used in the form of a downlink portion (DL portion) + a gap + an uplink portion (UL portion).

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

In particular, in the case of transmission and reception of latency critical data such as URLLC, 1ms (14 symbols) defined in a numerology-based frame structure with a small SCS value such as 15kHz When scheduling is performed in units of slots, it may be difficult to satisfy the latency requirement. For this purpose, a mini-slot composed of fewer OFDM symbols than the slot is defined, and based on this, it is critical to the same latency as the URLLC. It can be defined so that scheduling of (latency critical) data is performed.

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

As such, in NR, by defining different SCS or different TTI lengths, a discussion is ongoing on a method of satisfying the requirements of URLLC and eMBB, respectively.

Wider bandwidth operations

In the case of the existing LTE system, a scalable bandwidth operation for an arbitrary LTE CC (Component Carrier) was supported. That is, according to a frequency distribution scenario (deployment scenario), any LTE operator was able to configure a bandwidth of at least 1.4 MHz to a maximum of 20 MHz in configuring one LTE CC, and a normal LTE terminal is one LTE For CC, the transmit/receive capability of 20 MHz bandwidth was supported.

However, in the case of NR, the design is made to enable support for NR terminals having different transmission/reception bandwidth capabilities through one wideband NR CC. By configuring one or more bandwidth parts (BWP, bandwidth part(s)) composed of a segmented bandwidth for an arbitrary NR CC, flexible (bandwidth part configuration) and activation (activation) different for each terminal It is required to support a wider bandwidth operation that is flexible.

Specifically, in NR, one or more bandwidth parts may be configured through one serving cell configured from the viewpoint of the terminal, and the terminal may configure one downlink bandwidth part in the corresponding serving cell (serving cell). DL bandwidth part) and one uplink bandwidth part (UL bandwidth part) are activated and defined to be used for uplink/downlink data transmission/reception. In addition, when a plurality of serving cells are configured in the corresponding terminal, that is, one downlink bandwidth part and/or uplink bandwidth part is activated for each serving cell even for a terminal to which CA is applied. Thus, it is defined to be used for uplink/downlink data transmission/reception using radio resources of the 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 terminal specific (UE) through dedicated RRC signaling for each terminal -specific) A 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 and used at the same time according to the configuration of the terminal's capability and bandwidth part(s) in an arbitrary serving cell. However, in NR rel-15, it is defined to activate and use only one downlink bandwidth part (DL bandwidth part) and an uplink bandwidth part (UL bandwidth part) at any time in any terminal. .

In the conventional 3GPP NR, for transmission of a downlink control message, that is, downlink control information (DCI), a control message is divided for each purpose, and a search space in which a specific control message to be received by a user is transmitted is defined. set to the user. Thereafter, if necessary, a method of transmitting a downlink control message through a preset corresponding search area is used. At this time, the search area is largely set to the corresponding base station, to be precise, to all users within the corresponding BWP, and is set to a common search space (hereinafter referred to as CSS) that searches simultaneously, and is set only to a specific user and searches only for that user. It is divided into a search area (UE-specific search space, hereinafter USS). Among them, CSS is largely divided into four types as follows.

- Type 0: It is set through pdcch-ConfigSIB1 in the MIB, and is an area for transmitting a control message for transmitting SIB1 (System Information Block 1, RMSI information transfer). A control message transmitted through the corresponding region is scrambled through the SI-RNTI.

- Type-0A: It is set through pdcch-ConfigCommon in SIB1, and it is an area to transmit a control message to transmit OSI (Other System Information). A control message transmitted through the corresponding region is also scrambled through the SI-RNTI.

- Type-1: Similarly, it is set through pdcch-ConfigCommon in SIB1, and it is an area for transmitting a control message for transmitting the RACH response in response to the user's random access preamble. The control message transmitted through the corresponding area is scrambled through the RA-RNTI and, in the case of the unlicensed band, the TC-RNTI.

- Type-2: It is set through pdcch-ConfigCommon, and it is the area where the paging control message to be received by the user entering the idle/inactive state is transmitted. A control message transmitted through the corresponding region is scrambled through the P-RNTI.

- Type-3: It is set through pdcch-Config. At this time, if the search area type is commonly designated, it becomes Type-3 CSS. In general, group common control messages such as slot format indication (SFI), pre-emption presence (interruption) indication (INT), group transmission power control (TPC), cancellation indication (CI), power saving (PS), etc. are transmitted In this area, PDCCH 0_0/1_0 may also be transmitted to this area. Each control message is identified by an RNTI, and is scrambled to SFI-/INT-/TPC-x-/CI-/PS- and C-/CS-/MCS-C- RNTI, respectively.

At this time, the USS can be set according to each user's situation, but in the case of CSS, it is generally set at the same location within the same BWP, because it is an area for transmitting control messages that all users need to use.

In such an existing system, since the same performance was assumed for each user, there was no problem in using the common search area. However, when the low-power terminal support is introduced, setting the same common search area as that of an existing user causes frequent attempts to detect the common search area due to the characteristic that the corresponding area must be detected, thereby causing a power problem.

Accordingly, the present disclosure provides a method for enabling a low-power terminal to perform a control message detection attempt less frequently in NR. In particular, to this end, a method for indicating and operating a common search area for a low-power terminal and a method for skipping a control message detection attempt through a downlink control message for a predetermined time are provided.

Hereinafter, a method of setting and operating a downlink control message search area for a low-power terminal will be specifically described with reference to the related drawings.

10 is a diagram illustrating a procedure in which a terminal controls a search space to save power according to an embodiment.

Referring to FIG. 10 , the terminal may receive configuration information for at least one search area ( S1000 ).

The terminal may receive, from the base station, configuration information for a search area for receiving downlink control information (DCI) transmitted from the base station to the terminal. The search area includes control channel candidates that may exist in the control channel element at a specific aggregation level, and a plurality of search areas may be configured for one terminal.

According to an example, the configuration information for the search area may include configuration information for a search space set group including at least one search area. In this case, the search area set group may be composed of two search area set groups for each of at least one bandwidth part configured for the terminal. Also, the group ID of the configured search area set group may be set to 0 or 1.

Referring back to FIG. 10 , the terminal may receive indication information on at least one of time period information for not monitoring a downlink control channel (PDCCH) for at least one discovery region and information on the discovery region ( S1010 ).

Indicative information on at least one of time period information for not monitoring the downlink control channel and search area information may be configured for at least one search area configured in a bandwidth part activated for the terminal while the terminal is activated. have. That is, the corresponding indication information may indicate whether to monitor the search areas set in the currently active bandwidth part on the premise that the terminal itself is in an active state.

According to an example, the indication information may include time duration information for not monitoring a downlink control channel (PDCCH). The time period information may include at least one of a duration for not monitoring a downlink control channel and a periodic interval. Such indication information may be indicated by a predetermined field value in downlink control information.

When such indication information is received through the downlink control information, the terminal may not perform monitoring of the downlink control channel for the indicated duration from the time the corresponding indication information is received. Alternatively, the UE may not periodically perform monitoring for the downlink control channel during the interval according to the indicated periodic interval.

Alternatively, according to another example, the indication information may include group ID information for a set group of search areas including a search area that does not monitor a downlink control channel among at least one search area. Such indication information may be indicated by a predetermined field value in downlink control information.

For example, the indication information may indicate switching of a search area set group to be monitored according to a search area set group switching field value in DCI format 2_0. That is, as described above, it is assumed that the group ID of the two search area set groups is set to 0 or 1 for the terminal. In this case, when the value of the search area set group switching field is 0, the terminal may monitor the search area set group having the group ID of 0 and stop monitoring the search area set group having the group ID of 1. .

In this case, according to an example, a delay value may be set for switching of the search area set group based on the capability of the terminal. The delay value required for switching of the search area set group may be set differently according to the processing capability of the terminal and the value of subcarrier spacing applied to the corresponding bandwidth part. For example, the delay value may be set to the number of symbols, and may be set larger as the subcarrier spacing value is larger, or set larger as the processing capability of the UE is lower. The corresponding delay value may be indicated to the terminal through higher layer signaling, and the terminal may further reflect the indicated delay value to determine whether to switch to the monitoring area set group.

Referring back to FIG. 10, the terminal may monitor the downlink control channel based on the received indication information (S1020).

Based on the received indication information, the terminal may attempt blind decoding in a time period other than the time period in which monitoring is not performed or in a search area other than the search area in which monitoring is not performed. Therefore, regardless of whether the base station transmits the downlink control channel, power can be saved by not monitoring a predetermined time period or search area.

Accordingly, it is possible to provide a specific method and apparatus capable of reducing power required for a low-power terminal to transmit and receive a downlink control message in an NR communication system.

11 is a diagram illustrating a procedure in which a base station controls a search space to save power according to an embodiment.

Referring to FIG. 11 , the base station may transmit configuration information for at least one search area ( S1100 ).

The base station may transmit configuration information for a search area for transmitting downlink control information (DCI) to the terminal to the terminal. The search area includes control channel candidates that may exist in the control channel element at a specific aggregation level, and a plurality of search areas may be configured for one terminal.

According to an example, the configuration information for the search area may include configuration information for a search space set group including at least one search area. In this case, the search area set group may be composed of two search area set groups for each of at least one bandwidth part configured for the terminal. Also, the group ID of the configured search area set group may be set to 0 or 1.

Referring back to FIG. 11 , the base station may transmit indication information on at least one of time period information for not monitoring a downlink control channel and search area information for at least one search area ( S1110 ).

Indicative information on at least one of time period information for not monitoring the downlink control channel and search area information may be configured for at least one search area configured in a bandwidth part activated for the terminal while the terminal is activated. have. That is, the corresponding indication information may indicate whether to monitor the search areas set in the currently active bandwidth part on the premise that the terminal itself is in an active state.

According to an example, the base station may transmit indication information including time duration information for not monitoring a downlink control channel (PDCCH) to the terminal. The time period information may include at least one of a duration for not monitoring a downlink control channel and a periodic interval. Such indication information may be indicated by a predetermined field value in downlink control information.

When such indication information is received through the downlink control information, the terminal may not perform monitoring of the downlink control channel for the indicated duration from the time the corresponding indication information is received. Alternatively, the UE may not periodically perform monitoring for the downlink control channel during the interval according to the indicated periodic interval.

Alternatively, according to another example, the base station may transmit indication information including group ID information for a set group of search areas including a search area that does not monitor a downlink control channel among at least one search area to the terminal. Such indication information may be indicated by a predetermined field value in downlink control information.

For example, the indication information may indicate switching of a search area set group to be monitored according to a search area set group switching field value in DCI format 2_0. That is, as described above, it is assumed that the group ID of the two search area set groups is set to 0 or 1 for the terminal. In this case, when the value of the search area set group switching field is 0, the terminal may monitor the search area set group having the group ID of 0 and stop monitoring the search area set group having the group ID of 1. .

In this case, according to an example, a delay value may be set for switching of the search area set group based on the capability of the terminal. The delay value required for switching of the search area set group may be set differently according to the processing capability of the terminal and the value of subcarrier spacing applied to the corresponding bandwidth part. For example, the delay value may be set to the number of symbols, and may be set larger as the subcarrier spacing value is larger, or set larger as the processing capability of the UE is lower. The corresponding delay value may be indicated to the terminal through higher layer signaling, and the terminal may further reflect the indicated delay value to determine whether to switch to the monitoring area set group.

Based on the received indication information, the terminal may attempt blind decoding in a time period other than the time period in which monitoring is not performed or in a search area other than the search area in which monitoring is not performed. Therefore, regardless of whether the base station transmits the downlink control channel, power can be saved by not monitoring a predetermined time period or search area.

Accordingly, it is possible to provide a specific method and apparatus capable of reducing power required for a low-power terminal to transmit and receive a downlink control message in an NR communication system.

Hereinafter, each embodiment related to a method of controlling a search space in NR will be described in detail with reference to the related drawings. The embodiments described below may be applied individually or in any combination.

The present disclosure provides a method for enabling a low-power terminal to perform control message detection attempts less frequently in NR. In particular, to this end, a method for indicating and operating a common search area for a low-power terminal and a method for skipping a control message detection attempt through a downlink control message for a predetermined time are provided.

In the present disclosure, (1) a method for indicating and operating a common search area for a low-power terminal , (2) a method for instructing a search area skip through DCI , and (3) a method for instructing a search area skip through a higher layer control signal can provide

Embodiment 1. A method for indicating and operating a common search area for a low-power terminal

The embodiment is a method of additionally delivering configuration information related to the search area to the low-power terminal on the assumption that the low-power terminal can transmit information to be received through only a part of the common search area. Specifically, it can be divided into a method for setting an additional period for a low-power terminal and a method for resetting time/frequency resources.

① How to additionally set a cycle for a low-power terminal

The method is a method of additionally setting a period different from the previously set search area period for the low-power terminal. As an example, it may be set in a manner of resetting the absolute period value of the search area period. Alternatively, it may be set as a multiple of a previously set period or a value obtained by subtracting 1 from it. In the latter case, this is an integer indicating how many search areas the corresponding terminal skips within a period. Separately, the position of the effective search area may be set in a manner of expressing and transmitting the position of a valid search area in the form of a bitmap defined within a predetermined period.

When the corresponding information is set, the low-power terminal may perform control message detection only for a valid area set to itself in the common search area.

② A method of separately setting a resource area of a search area for a low-power terminal

The method is a method of separately setting a location on a search area to be preferentially searched by a low-power terminal. The low-power terminal may perform a first detection attempt in the corresponding discovery area, and may not perform a detection attempt in the remaining areas.

For example, the low-power terminal can always exist in a temporally preceding symbol, but in a temporally lower frequency. Alternatively, a specific aggregation level (AL) may be selected so that the downlink control message is not transmitted at the corresponding aggregation level, or only a specific AL may be selected to transmit the downlink control message.

In this case, whether a control message detection attempt is performed on an area that is not set as a priority area may vary depending on whether a control message is detected in the priority detection area. In particular, by limiting the number of control messages, it is possible to prevent further detection in the same search area when a specific amount of control messages is detected.

Embodiment 2. Method of instructing skipping of a search area through DCI

This embodiment is a method of instructing not to perform detection in a specific search area for a predetermined time or a predetermined resource area through downlink control information (DCI). Broadly, it can be divided into a method of collectively instructing a specific search area and a method of instructing a specific control message.

① How to skip a specific search area for a certain period of time

The method is a method of instructing to skip detection of a control message in a specific search area for a predetermined time for a predetermined time after the reception of the control message. In this case, the search area may be pre-indicated in a standard manner such as, for example, a Type-3 common search area or by RRC. Alternatively, the search area may be dynamically delivered as an ID for every DCI or as an index value of a preset ID table. Alternatively, the valid/invalid region of the reconfigured common resource region in Embodiment 1 may be indicated.

② A method of skipping the reception of a specific control message for a certain period of time

The method assumes that a specific control message is not transmitted for a certain period of time and excludes the number of cases in which the corresponding control message is scrammed, thereby reducing the detection complexity as a result. For example, since the slot format indication or group transmission power control is not information that is transmitted frequently, it can be skipped for a certain time through the corresponding control message, and DCI 1_0/0_0 is not used for a certain period of time and 1_1/0_1 is not used for that time. can be used alone or vice versa.

Through this, the user can determine the RNTI scrambling that the user will not attempt to detect, and as a result, the detection complexity can be reduced. Also, when a specific search area transmits only a control message that is being skipped or does not need to be received, an attempt to detect the entire corresponding area may not be indirectly performed.

Embodiment 3. A method of instructing skipping of a search area through a higher layer control signal

This embodiment is a method of instructing not to perform detection in a specific search area for a predetermined time or a predetermined resource area through a higher layer control signal such as RRC. Similar to the above-described embodiment 2, it can be largely divided into a method of collectively indicating a specific search area and a method of indicating a specific control message.

① How to skip a specific search area for a certain period of time

The method is a method of instructing a control message to skip detection of a control message in a specific search area for a predetermined time after reception during a frame or slot indicated by a higher layer control signal.

② A method of skipping the reception of a specific control message for a certain period of time

The method is a method of reducing detection complexity by assuming that a specific control message is not transmitted for a predetermined time indicated by an upper layer control signal, as in the second embodiment.

The methods provided in the present disclosure may be applied independently, or may be operated in combination in any form. In addition, in the case of a new term, an arbitrary name that is easy to understand the meaning of the term used in the present disclosure is used, and the present disclosure may be applied even when other terms having the same meaning are actually used.

Accordingly, power required for the low-power terminal to transmit and receive a downlink control message in the NR communication system can be reduced.

Hereinafter, configurations of a terminal and a base station capable of performing some or all of the embodiments described with reference to FIGS. 1 to 11 will be described with reference to the drawings.

12 is a diagram showing the configuration of a terminal 1200 according to another embodiment.

Referring to FIG. 12 , the terminal 1200 according to another embodiment includes a controller 1210 , a transmitter 1220 , and a receiver 1230 .

The controller 1210 controls the overall operation of the terminal 1200 according to a method for the terminal to control a search space necessary for carrying out the above-described present invention. The transmitter 1220 transmits uplink control information, data, and a message to the base station through a corresponding channel. The receiving unit 1230 receives downlink control information, data, and messages from the base station through a corresponding channel.

The receiver 1230 may receive configuration information for at least one search area. The receiver 1230 may receive, from the base station, configuration information for a search area for receiving downlink control information transmitted from the base station to the terminal.

According to an example, the configuration information for the search area may include configuration information for a search area set group including at least one search area. In this case, the search area set group may be composed of two search area set groups for each of at least one bandwidth part configured for the terminal. Also, the group ID of the configured search area set group may be set to 0 or 1.

The receiver 1230 may receive indication information on at least one of time period information for not monitoring a downlink control channel for at least one search area and search area information. Indicative information on at least one of time period information for not monitoring the downlink control channel and search area information may be configured for at least one search area configured in a bandwidth part activated for the terminal while the terminal is activated. have. That is, the corresponding indication information may indicate whether to monitor the search areas set in the currently active bandwidth part on the premise that the terminal itself is in an active state.

According to an example, the indication information may include time period information for not monitoring a downlink control channel. The time period information may include at least one of a duration for not monitoring a downlink control channel and a periodic interval. Such indication information may be indicated by a predetermined field value in downlink control information.

When such indication information is received through the downlink control information, the controller 1210 may not perform monitoring of the downlink control channel for the indicated duration from the point in time when the corresponding indication information is received. Alternatively, the controller 1210 may not periodically monitor the downlink control channel during the indicated periodic interval.

Alternatively, according to another example, the indication information may include group ID information for a set group of search areas including a search area that does not monitor a downlink control channel among at least one search area. Such indication information may be indicated by a predetermined field value in downlink control information.

For example, the indication information may indicate switching of a search area set group to be monitored according to a search area set group switching field value in DCI format 2_0. That is, as described above, it is assumed that the group ID of the two search area set groups is set to 0 or 1 for the terminal. In this case, when the value of the search area set group switching field is 0, the control unit 1210 performs monitoring on the search area set group having the group ID of 0, and stops monitoring the search area set group with the group ID of 1 can do.

In this case, according to an example, a delay value may be set for switching of the search area set group based on the capability of the terminal. For example, a delay value for switching the search area set group may be set differently according to the processing capability of the terminal and the value of the subcarrier spacing applied to the corresponding bandwidth part. The corresponding delay value may be indicated to the terminal through higher layer signaling, and the controller 1210 may further reflect the indicated delay value to determine whether to switch to the monitoring area set group.

The controller 1210 may monitor the downlink control channel based on the received indication information. Based on the received indication information, the controller 1210 may attempt blind decoding in a time period other than a time period in which monitoring is not performed or in a search area other than a search area in which monitoring is not performed. Therefore, regardless of whether the base station transmits the downlink control channel, power can be saved by not monitoring a predetermined time period or search area.

Accordingly, it is possible to provide a specific method and apparatus capable of reducing power required for a low-power terminal to transmit and receive a downlink control message in an NR communication system.

13 is a diagram showing the configuration of a base station 1300 according to another embodiment.

Referring to FIG. 13 , a base station 1300 according to another embodiment includes a controller 1310 , a transmitter 1320 , and a receiver 1330 .

The controller 1310 controls the overall operation of the base station 1300 according to a method for the base station to control a search space necessary for carrying out the above-described present invention. The transmitter 1320 and the receiver 1330 are used to transmit/receive signals, messages, and data necessary for carrying out the present invention to and from the terminal.

The transmitter 1320 may transmit configuration information for at least one search area. The transmitter 1320 may transmit configuration information for a search area for transmitting downlink control information to the terminal to the terminal.

According to an example, the configuration information for the search area may include configuration information for a search area set group including at least one search area. In this case, the search area set group may be composed of two search area set groups for each of at least one bandwidth part configured for the terminal. Also, the group ID of the configured search area set group may be set to 0 or 1.

The transmitter 1320 may transmit indication information on at least one of time period information for not monitoring a downlink control channel and search area information for at least one search area. The control unit 1310 provides indication information on at least one of time period information for not monitoring a downlink control channel and search area information, and at least one search area configured in a bandwidth part activated for the terminal in a state in which the terminal is activated. can be configured for That is, the corresponding indication information may indicate whether to monitor the search areas set in the currently active bandwidth part on the premise that the terminal itself is in an active state.

According to an example, the transmitter 1320 may transmit indication information including time period information for not monitoring the downlink control channel to the terminal. The time period information may include at least one of a duration for not monitoring a downlink control channel and a periodic interval. Such indication information may be indicated by a predetermined field value in downlink control information.

When the transmitter 1320 transmits such indication information through downlink control information, the terminal may not perform monitoring of the downlink control channel for the indicated duration from the point in time when the corresponding indication information is received. Alternatively, the UE may not periodically perform monitoring for the downlink control channel during the interval according to the indicated periodic interval.

Alternatively, according to another example, the transmitter 1320 transmits, to the terminal, indication information including group ID information for a set group of search areas including a search area that does not monitor a downlink control channel among at least one search area. can Such indication information may be indicated by a predetermined field value in downlink control information.

For example, the indication information may indicate switching of a search area set group to be monitored according to a search area set group switching field value in DCI format 2_0. That is, as described above, it is assumed that the group ID of the two search area set groups is set to 0 or 1 for the terminal. In this case, when the value of the search area set group switching field is 0, the terminal may monitor the search area set group having the group ID of 0 and stop monitoring the search area set group having the group ID of 1. .

In this case, according to an example, a delay value may be set for the switching of the search area set group based on the capability of the terminal. For example, a delay value for switching the search area set group may be set differently according to the processing capability of the terminal and the value of the subcarrier spacing applied to the corresponding bandwidth part. The transmitter 1320 may indicate the corresponding delay value to the terminal through higher layer signaling, and the terminal may further reflect the indicated delay value to determine whether to switch to the monitoring area set group.

Based on the received indication information, the terminal may attempt blind decoding in a time period other than the time period in which monitoring is not performed or in a search area other than the search area in which monitoring is not performed. Therefore, regardless of whether the base station transmits the downlink control channel, power can be saved by not monitoring a predetermined time period or search area.

Accordingly, it is possible to provide a specific method and apparatus capable of reducing power required for a low-power terminal to transmit and receive a downlink control message in an NR communication system.

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

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

In the case of implementation by hardware, the method according to the present 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), may be implemented by a processor, a controller, a microcontroller or a microprocessor.

In the case of implementation by firmware or software, the method according to the present embodiments may be implemented in the form of an apparatus, procedure, or function that performs the functions or operations described above. The software code may be stored in the memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may transmit/receive data to and from the processor by various well-known means.

Also, as described above, terms such as "system", "processor", "controller", "component", "module", "interface", "model", or "unit" generally refer to computer-related entities hardware, hardware and software. may mean a combination of, software, or running software. For example, the aforementioned component may be, but is not limited to, a process run by a processor, a processor, a controller, a controlling processor, an object, a thread of execution, a program, and/or a computer. For example, both an application running on a controller or processor and a controller or processor can be a component. One or more components may reside within a process and/or thread of execution, and the components may be located on one device (eg, a system, computing device, etc.) or distributed across two or more devices.

The above description is merely illustrative of the technical spirit of the present disclosure, and various modifications and variations will be possible without departing from the essential characteristics of the present disclosure by those skilled in the art to which the present disclosure pertains. In addition, the present embodiments are not intended to limit the technical spirit of the present disclosure, but rather to explain, so the scope of the present technical spirit is not limited by these embodiments. The protection scope of the present disclosure should be construed 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 disclosure.

Claims (20)

A method for a terminal to control a search space, the method comprising:
receiving configuration information for at least one search area;
receiving indication information on at least one of time period information for not monitoring a downlink control channel for the at least one search area and search area information; and
and monitoring the downlink control channel based on the indication information. The method of claim 1,
The instruction information is
In a state in which the terminal is activated, the method is configured for the at least one search area configured in a bandwidth part activated for the terminal. The method of claim 1,
The instruction information is
The method includes time duration information including at least one of a duration and a periodic interval for not monitoring the downlink control channel, and is indicated through downlink control information. The method of claim 1,
The configuration information is
and configuration information for a search space set group including the at least one search area;
The instruction information is
The method includes group ID information for a set group of search areas including a search area that does not monitor the downlink control channel among the at least one search area, and is indicated through downlink control information. 5. The method of claim 4,
The search area set group is,
A method in which two search area set groups are configured for each of at least one bandwidth part configured for the terminal, and the group ID is set to 0 or 1. A method for a base station to control a search space, the method comprising:
transmitting configuration information for at least one search area to the terminal; and
and transmitting indication information on at least one of time period information for not monitoring a downlink control channel and search area information for the at least one search area. 7. The method of claim 6,
The instruction information is
In a state in which the terminal is activated, the method is configured for the at least one search area configured in a bandwidth part activated for the terminal. 7. The method of claim 6,
The instruction information is
The method includes time duration information including at least one of a duration for not monitoring the downlink control channel and a periodic interval, and is indicated through downlink control information. 7. The method of claim 6,
The configuration information is
and configuration information for a search space set group including the at least one search area;
The instruction information is
The method includes group ID information for a set group of search areas including a search area that does not monitor the downlink control channel among the at least one search area, and is indicated through downlink control information. 10. The method of claim 9,
The search area set group is,
A method in which two search area set groups are configured for each of at least one bandwidth part configured for the terminal, and the group ID is set to 0 or 1. In the terminal for controlling a search space (search space),
a receiving unit configured to receive configuration information for at least one search area and to receive indication information on at least one of time period information for not monitoring a downlink control channel for the at least one search area and information on the search area; and
A terminal comprising a controller for monitoring the downlink control channel based on the indication information. 12. The method of claim 11,
The instruction information is
A terminal configured for the at least one search area configured in a bandwidth part activated for the terminal in a state in which the terminal is activated. 12. The method of claim 11,
The instruction information is
The terminal includes time duration information including at least one of a duration for not monitoring the downlink control channel and a periodic interval, and is indicated through downlink control information. 12. The method of claim 11,
The configuration information is
and configuration information for a search space set group including the at least one search area;
The instruction information is
The terminal includes group ID information for a set group of search areas including a search area that does not monitor the downlink control channel among the at least one search area, and is indicated through downlink control information. 15. The method of claim 14,
The search area set group is,
A terminal comprising two search area set groups for each of at least one bandwidth part configured for the terminal, and wherein the group ID is set to 0 or 1. In the base station for controlling a search space (search space),
a transmitter configured to transmit configuration information for at least one discovery region to the terminal and to transmit indication information on at least one of time period information for not monitoring a downlink control channel for the at least one discovery region and information on the discovery region; and
A base station comprising a controller for controlling the operation of the transmitter. 17. The method of claim 16,
The instruction information is
A base station configured for the at least one search area configured in a bandwidth part activated for the terminal in a state in which the terminal is activated. 17. The method of claim 16,
The instruction information is
The base station includes time duration information including at least one of a duration and a periodic interval for not monitoring the downlink control channel, and is indicated through downlink control information. 17. The method of claim 16,
The configuration information is
and configuration information for a search space set group including the at least one search area;
The instruction information is
The base station includes group ID information for a set group of search areas including a search area that does not monitor the downlink control channel among the at least one search area, and is indicated through downlink control information. 20. The method of claim 19,
The search area set group is,
A base station comprising two search area set groups for each of at least one bandwidth part configured for the terminal, and wherein the group ID is set to 0 or 1.

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