KR20220007516A - Method and apparatus for performing initial access in limited bandwidth - Google Patents

Abstract

Embodiments of the present invention relate to a method and apparatus for performing initial access in a limited bandwidth. The method includes the steps of: receiving at least one of first configuration information and second configuration information used for initial access; and performing initial access based on one of the first configuration information and the second configuration information. The first configuration information is set for a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth.

Description

METHOD AND APPARATUS FOR PERFORMING INITIAL ACCESS IN LIMITED BANDWIDTH

The present embodiments propose a method and apparatus for performing initial access in a limited bandwidth 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 performing initial access to a terminal having reduced capability in NR is required.

Embodiments of the present disclosure may provide a method and apparatus for performing initial access in a limited bandwidth with respect to a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth.

In one aspect, the present embodiments provide a method for a terminal to perform initial access, the steps of receiving at least one of first configuration information and second configuration information used for initial access, and first and second configuration information It may provide a method in which an available bandwidth is set for a terminal having a limited bandwidth that is narrower than a predetermined bandwidth, including performing an initial connection based on any one of the first configuration information.

In another aspect, the present embodiments provide a method for a base station to perform initial access, the steps of transmitting at least one of the first configuration information and the second configuration information used for the initial access, and the first configuration information and the second configuration information It may provide a method in which an available bandwidth is set for a terminal having a limited bandwidth that is narrower than a predetermined bandwidth, including performing an initial connection based on any one of the first configuration information.

In another aspect, in the present embodiments, in a terminal performing initial access, a receiver configured to receive at least one of first configuration information and second configuration information used for initial access, and among the first configuration information and the second configuration information Based on any one, including a control unit for performing an initial connection, the first configuration information, the available bandwidth may provide a terminal set for a terminal having a limited bandwidth narrower than a predetermined bandwidth.

In another aspect, the present embodiments provide a base station for initial access, a transmitter for transmitting at least one of first configuration information and second configuration information used for initial access, and among the first configuration information and second configuration information Based on any one, including a control unit for performing the initial connection, the first configuration information, the available bandwidth may provide a base station set for a terminal having a limited bandwidth narrower than a predetermined bandwidth.

According to the present embodiments, it is possible to provide a method and apparatus for performing initial access in a limited bandwidth with respect to a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth.

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 perform initial access according to an embodiment.
11 is a diagram illustrating a procedure in which a base station performs initial access according to an embodiment.
12 is a diagram showing the configuration of a user 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.

Uplink and downlink transmit and receive control information through control channels such as Physical Downlink Control CHannel (PDCCH), 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 focusing 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, in NR, subcarrier intervals used for data transmission are 15, 30, 60, and 120 kHz, and subcarrier intervals used for synchronization signal transmission are 15, 30, 12, 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 preamble for random access to the base station. The random access preamble is transmitted through the PRACH. Specifically, the random access preamble is transmitted to the base station through a PRACH consisting of continuous radio resources in a specific slot that is periodically repeated. In general, when a UE initially accesses a cell, a contention-based random access procedure is performed, and when 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 preamble. The random access response may include a random access 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 preamble identifier may be included to inform which terminal the included UL Grant, temporary C-RNTI, and TAC are valid. The random access preamble identifier may be an identifier for the random access preamble received by the base station. The TAC may be included as information for the UE to adjust uplink synchronization. The random access response may be indicated by a random access identifier on the PDCCH, that is, 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) are defined as typical usage scenarios of NR. As a method to satisfy the requirement, a frame structure design that is flexible compared to LTE 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 a result, 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, the NR subframe is an absolute reference time duration, and a slot and a mini-slot as a time unit that is the basis of actual uplink/downlink data scheduling. ) can be defined. In this case, the number of OFDM symbols constituting the corresponding slot, the y value, is determined to have a value of y=14 regardless of the SCS value in the case of a 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.

Physical resources

A physical resource for NR may be configured to be flexible compared to LTE. A Common Resource Block (CRB) is defined from point A, which is a reference point of a frequency radio resource unit of an arbitrary NR cell, and a BWP configuration for transmission and reception of an arbitrary terminal is made based on the CRB. In addition, when a plurality of SCSs are supported in an arbitrary cell, a configuration for each subcarrier spacing-specific carrier bandwidth may also be made. In addition, PRB and VRB, which are units of radio resource allocation for an arbitrary terminal, are configured for each BWP configured for the terminal.

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) were 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 by using the radio resource 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. .

The bandwidth part may consist of continuous resource blocks (RBs) on the frequency axis, and one BWP may correspond to one numerology (eg, sub-carrier spacing, CP length, slot/mini-slot duration, etc.). can

On the other hand, the base station may set a plurality of BWPs within one CC set in the terminal. The base station may configure at least one DL / UL BWP to the terminal associated with the broadband CC, and at least one DL / UL BWP among DL / UL BWP(s) set at a specific time (first layer signaling ( For example: DCI, etc.), MAC, RRC signaling, etc.) can be activated. In this case, the activated DL/UL BWP may be called an active DL/UL BWP. The UE may not receive the configuration for the DL/UL BWP from the base station before the initial access process or the RRC connection is set up. The DL/UL BWP assumed for such a terminal may be defined as an initial active DL/UL BWP.

More specifically, the terminal according to various embodiments of the present disclosure may perform the following bandwidth part operation.

The terminal configured to operate in the bandwidth parts of the serving cell is set by a higher layer parameter (eg, DL-BWP or BWP-Downlink), up to four DL BWPs in the DL bandwidth on the serving cell, and a higher layer parameter (eg : UL-BWP or BWP-Uplink), up to 4 UL BWPs in the UL bandwidth on the serving cell are configured.

When the UE does not receive the upper layer parameter initialDownlinkBWP, the initial active DL BWP (initial active DL BWP) is the smallest among the PRBs included in the CORESET (control resource set) for the Type-0 PDCCH CSS (Common Search Space) set. It is defined by the position and number of consecutive PRBs from the index to the largest index. In addition, the initially activated DL BWP is defined by subcarrier spacing (SCS) and cyclic prefix for PDCCH reception in CORESET for Type-0 PDCCH CSS set. Alternatively, the initially activated DL BWP is provided by the upper layer parameter initialDownlinkBWP. For operation in a primary cell or a secondary cell, the UE is provided with an initial activation UL BWP by a higher layer parameter initialuplinkBWP. If a supplementary UL carrier is configured for the terminal, the terminal may be provided with an initially activated UL BWP on the supplementary UL carrier by initialUplinkBWP in the upper layer parameter supplementaryUplink.

In the conventional 3GPP NR, it is designed to operate under the assumption that all UEs basically support 100 MHz in FR1 and 400 MHz in FR2. However, in the Reduced Capability environment for terminals that require only performance lower than the NR basic performance such as IoT, communication between the terminal and the base station must be performed using only a limited frequency band.

In this case, unlike data communication in which the bandwidth part (BWP) and the UE-specific search space (USS) can be set separately, and a band suitable for each terminal can be set, the initial access process does not provide a procedure for distinguishing and accessing these terminals. Accordingly, with respect to the 3GPP NR-RedCap SI currently under discussion, for FR1, the maximum terminal bandwidth in the initial access is at least 20 MHz, other bandwidths will be discussed later, and for FR2, the maximum terminal bandwidth in the initial access is 50 MHz and 100 MHz, and other bandwidths will be discussed later.

The system band required in each procedure of initial access in the conventional NR has the following properties.

1) A synchronization signal block (SSB) transmitting a synchronization signal and initial system information has a frequency width of 20 RB (resource block). This has a band of approximately 7.5 MHz when the subcarrier frequency is 30 kHz, which is the maximum value supported by FR1. In addition, in the case of 240 kHz, which is the maximum value supported by FR2, it has a band of about 60 MHz.

2) Initial system information includes an initial bandwidth part (initial BWP-related information and PDCCH (Physical Downlink Control Channel) indicating the PDSCH) for a transmission period of a Physical Downlink Shared Channel (PDSCH) that carries System Information Block 1 (SIB1). The information on how the CORESET (Control Resource Set) and SSB are multiplexed is specified in the MIB (Master Information Block) within the SSB In the case of FR1, CORESET RB 96RB is supported with a maximum offset of 56RB at PDSCH 15kHz, and in the case of 30kHz Supports CORESET RB 48RB with a maximum offset of 28RB. Each of them also requires a band of about 30MHz for operation. Meanwhile, FR2 supports CORESET RB 96RB with a maximum offset of 97RB at 60kHz PDSCH, and supports a maximum offset of 49RB for 120kHz. supports CORESET RB 48. They each have a band around 140MHz for operation.

3) The UE attempts initial access through the PRACH and PUSCH resources set as rach-ConfigCommon in the BWP-UplinkCommon message in the UplinkConfigCommonSIB message in the ServingCellConfigCommonSIB message included in SIB1. At this time, the PRACH and PUSCH follow the location in the Initial BWP set in UplinkConfigCommonSIB.

According to the above, the terminal completely receives the SSB already provided before transmitting any information about itself, receives SIB1 according to the Initial DL BWP setting, and performs the Initial UL BWP setting accordingly. do.

In the existing system, it was assumed that the performance of each user was the same, so the initial uplink/downlink BWP settings were performed without information about the terminal, and from the base station's point of view, within the mandatory support range of the terminal, FR1 100MHz / FR2 400MHz. It was possible to set the initial BWP band arbitrarily. Of course, it is possible to set each Initial BWP to have a low band by considering the case where a terminal supporting only a lower band is accessing in advance, but setting it in this way for all terminals is inefficient in terms of resource utilization and arbitrarily different from each other. In the case of setting, a UE that cannot support the corresponding band may have to perform synchronization signal reception and SIB analysis several times until it finds a setting within the range it supports.

Reduced capability NR devices

In the case of Rel-15/16 NR devices, a high-end device-based system design was made for the purpose of maximizing the performance of the initial 5G system. That is, to maximize the data transmission speed of 5G, the wireless transmission section was designed based on a high complexity NR device. In Rel-17, a radio section design to support a low-end NR device having a lower complexity compared to the high-end NR device described above is scheduled to be made. A corresponding low-end device, that is, a reduced complexity NR device, may assume the following terminal complexity reduction.

- Reduced number of UE receiving / transmitting antennas (Reduced number of UE RX / TX antennas)

- UE bandwidth reduction (UE Bandwidth reduction)

- Rel-15 SSB bandwidth is reused, and L1 changes should be minimized (Rel-15 SSB bandwidth should be reused and L1 changes minimized).

- Half-Duplex-FDD

- Relaxed UE processing time (Relaxed UE processing time)

- Relaxed UE processing capability (Relaxed UE processing capability)

In the present disclosure, 'Reduced capability NR devices' may be described as 'low power terminal', 'terminal with limited bandwidth', etc., and it will be understood to collectively refer to a terminal with reduced performance than a terminal generally assumed in NR. can

The present disclosure provides a method for a low-power terminal to successfully perform initial access with a low operating band in NR. In particular, a method of pre-discovering and avoiding a synchronization signal that provides system information that the user cannot receive, a method of transmitting a setting message in advance so that a low-power terminal can receive it, and a method of separately configuring a setting space to be used provides

Hereinafter, a method for performing an initial access in a specific limited bandwidth will be described with reference to the related drawings.

10 is a diagram illustrating a procedure for a terminal to perform initial access according to an embodiment.

Referring to FIG. 10 , the terminal may receive at least one of first configuration information and second configuration information used for initial access from the base station ( S1000 ).

In NR, initial access refers to a process of initially finding a cell when a terminal enters the coverage of a system, or a process in which a terminal in an idle/inactive state accesses a network, generally referred to as random access can be

In the initial access process, the terminal receives PSS and SSS, which are synchronization signals transmitted in downlink from each cell in order to search for a cell. PSS/SSS is received as a synchronization signal block (SSB) together with a physical broadcast channel (PBCH). The UE receives the MIB providing information on the PDCCH-related parameters necessary for monitoring SIB1 through the PBCH.

The UE receives SIB1 transmitted through the PDSCH based on the information in the MIB. SIB1 is generally provided through a PDSCH scheduled with a period of 160 ms, and includes information necessary for the UE to perform initial access and scheduling related information for other system information.

The pdcch-ConfigSIB1 message in the MIB is used to configure CORESET#0 and search space#0, and an initial downlink bandwidth part may be defined and activated based on the values of CORESET#0 and search space#0. In addition, the configuration of the initial uplink bandwidth part may be made through SIB1 scheduled using the PDCCH.

In this way, the terminal may acquire the downlink and uplink settings for initial access by at least one of MIB and SIB1. The above description of MIB and SIB1 relates to MIB and SIB1 for a terminal generally assumed in the NR system, and in the following, the second configuration information may be used to mean the corresponding MIB and SIB1.

According to an example, it is assumed that a terminal performing initial access to a cell is a terminal having a limited bandwidth, in which an available bandwidth is narrower than a predetermined bandwidth. In this case, MIB and SIB1 in separate formats for the above-described initial access may be configured for a terminal having a corresponding limited bandwidth. That is, the first configuration information may be used to mean MIB and SIB1 and other system information that are separately set for a terminal having a limited bandwidth.

The first configuration information may include configuration information on at least one of an initial downlink bandwidth part (initial DL BWP) and an initial uplink bandwidth part (initial UL BWP) that are separately configured for a terminal having a limited bandwidth. That is, the MIB and SIB1 and other system information included in the first configuration information will be defined so that the initial downlink bandwidth part and the initial uplink bandwidth part can be set separately from the existing general terminal for a terminal having a limited bandwidth. can

In this case, the initial downlink bandwidth part and the initial uplink bandwidth part separately configured for a terminal having a limited bandwidth may be set to have a bandwidth equal to or smaller than a limited bandwidth configured in the terminal.

In addition, the first configuration information may further include information related to a random access operation performed in an initial access process. That is, information related to a random access operation may also be separately set for a terminal having a limited bandwidth.

According to an example, the uplink bandwidth part separately configured for a terminal having a limited bandwidth may be configured to include at least one random access channel occurrence separately configured for a terminal having a limited bandwidth (RACH occasion). . Preamble transmission may occur within a slot configured as a RACH slot for every RACH configuration period. There may be K RACH occurrences within this RACH slot. In this regard, for a terminal having a limited bandwidth, a RACH attack may be configured based on the bandwidth of an initial uplink bandwidth part configured in the corresponding terminal.

In addition, the first configuration information may include information on a random access channel resource configured based on a sequence set separately for a terminal having a limited bandwidth. That is, for a terminal having a limited bandwidth, a random access channel resource may be configured by applying a separate sequence. That is, the sequence applied to generate the random access preamble may be applied as a sequence different from that of a general terminal assumed in the NR system.

According to an example, the first configuration information may be configured to be received not only by a terminal having a limited bandwidth but also by a general terminal assumed in the NR system. Alternatively, the first configuration information may be set to be received only by a terminal having a limited bandwidth. In addition, the second configuration information may be set not to be received by a terminal having a limited bandwidth.

Referring back to FIG. 10 , the terminal may perform initial access based on any one of the first configuration information and the second configuration information ( S1010 ).

According to an example, the first configuration information and the second configuration information may be defined separately from each other. Alternatively, it may be defined that a setting corresponding to the first configuration information is selected according to a value of an arbitrary field in the second configuration information. Alternatively, in the second configuration information, it may be defined that a setting corresponding to the first configuration information is further separately added.

In the case of a general terminal assumed in the NR system, the terminal may perform an initial access procedure based on the second configuration information.

In the case of a terminal having a limited bandwidth, the terminal may perform an initial access process based on the first configuration information. That is, a terminal having a limited bandwidth may perform an initial access according to setting information corresponding to the first configuration information.

In addition, a terminal having a limited bandwidth may generate a random access preamble by applying a separate sequence or transmit it through at least one randomly configured random access channel occupancy. In this case, the base station may determine that the corresponding terminal is a terminal having a limited bandwidth without additional information, and then perform a random access operation.

Accordingly, it is possible to provide a method and apparatus for performing initial access in a limited bandwidth with respect to a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth.

Hereinafter, the operation of the base station related to the operation of the above-described terminal will be described with reference to the drawings.

11 is a diagram illustrating a procedure in which a base station performs initial access according to an embodiment.

Referring to FIG. 11 , the base station may transmit at least one of first configuration information and second configuration information used for initial access ( S1100 ).

In the initial access process, in order to support cell search of the terminal, the base station transmits synchronization signals PSS and SSS. The PSS/SSS is received as a sync signal block together with the PBCH. The base station transmits the MIB providing information on the PDCCH-related parameters necessary for monitoring SIB1 through the PBCH.

The base station transmits SIB1 through the PDSCH based on the information in the MIB. SIB1 is generally provided through a PDSCH scheduled with a period of 160 ms, and includes information necessary for the UE to perform initial access and scheduling related information for other system information.

The pdcch-ConfigSIB1 message in the MIB is used to configure CORESET#0 and search space#0, and an initial downlink bandwidth part may be defined and activated based on the values of CORESET#0 and search space#0. In addition, the configuration of the initial uplink bandwidth part may be made through SIB1 scheduled using the PDCCH.

In this way, the base station may transmit the downlink and uplink settings for initial access through at least one of MIB and SIB1. The above description of MIB and SIB1 relates to MIB and SIB1 for a terminal generally assumed in the NR system, and in the following, the second configuration information may be used to mean the corresponding MIB and SIB1.

According to an example, it is assumed that a terminal performing initial access to a cell is a terminal having a limited bandwidth, in which an available bandwidth is narrower than a predetermined bandwidth. In this case, MIB and SIB1 in separate formats for the above-described initial access may be configured for a terminal having a corresponding limited bandwidth. That is, the first configuration information may be used to mean MIB and SIB1 and other system information that are separately set for a terminal having a limited bandwidth.

The first configuration information may include configuration information on at least one of an initial downlink bandwidth part (initial DL BWP) and an initial uplink bandwidth part (initial UL BWP) that are separately configured for a terminal having a limited bandwidth. That is, the MIB and SIB1 and other system information included in the first configuration information will be defined so that the initial downlink bandwidth part and the initial uplink bandwidth part can be set separately from the existing general terminal for a terminal having a limited bandwidth. can

In this case, the initial downlink bandwidth part and the initial uplink bandwidth part separately configured for a terminal having a limited bandwidth may be set to have a bandwidth equal to or smaller than a limited bandwidth configured in the terminal.

In addition, the first configuration information may further include information related to a random access operation performed in an initial access process. That is, information related to a random access operation may also be separately set for a terminal having a limited bandwidth.

According to an example, the uplink bandwidth part separately configured for a terminal having a limited bandwidth may be configured to include at least one random access channel occurrence separately configured for a terminal having a limited bandwidth (RACH occasion). . Preamble transmission may occur within a slot configured as a RACH slot for every RACH configuration period. There may be K RACH occurrences within this RACH slot. In this regard, for a terminal having a limited bandwidth, a RACH attack may be configured based on the bandwidth of an initial uplink bandwidth part configured in the corresponding terminal.

In addition, the first configuration information may include information on a random access channel resource configured based on a sequence set separately for a terminal having a limited bandwidth. That is, for a terminal having a limited bandwidth, a random access channel resource may be configured by applying a separate sequence. That is, the sequence applied to generate the random access preamble may be applied as a sequence different from that of a general terminal assumed in the NR system.

According to an example, the first configuration information may be configured to be received not only by a terminal having a limited bandwidth but also by a general terminal assumed in the NR system. Alternatively, the first configuration information may be set to be received only by a terminal having a limited bandwidth. In addition, the second configuration information may be set not to be received by a terminal having a limited bandwidth.

Referring back to FIG. 11 , the base station may perform initial access based on any one of the first configuration information and the second configuration information ( S1110 ).

According to an example, the first configuration information and the second configuration information may be defined separately from each other. Alternatively, it may be defined that a setting corresponding to the first configuration information is selected according to a value of an arbitrary field in the second configuration information. Alternatively, in the second configuration information, it may be defined that a setting corresponding to the first configuration information is further separately added.

In the case of a general terminal assumed in the NR system, the base station may perform an initial access process with the corresponding terminal based on the second configuration information.

In the case of a terminal having a limited bandwidth, the base station may perform an initial access process with the corresponding terminal based on the first configuration information. That is, a terminal having a limited bandwidth may perform an initial access according to setting information corresponding to the first configuration information.

In addition, a terminal having a limited bandwidth may generate a random access preamble by applying a separate sequence or transmit it through at least one randomly configured random access channel occupancy. In this case, the base station may determine that the corresponding terminal is a terminal having a limited bandwidth without additional information, and then perform a random access operation.

Accordingly, it is possible to provide a method and apparatus for performing initial access in a limited bandwidth with respect to a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth.

Hereinafter, each embodiment related to a method of performing initial access in a limited bandwidth in NR will be described in detail with reference to related drawings. The embodiments described below may be applied individually or in any combination.

The present disclosure provides a method for a low-power terminal to successfully perform initial access with a low operating band in NR. In particular, a method of pre-discovering and avoiding a synchronization signal that provides system information that the low-power terminal cannot receive, a method of transmitting a pre-configuration message so that the low-power terminal can receive it, and configuring a setting space to be used separately provides a way to

The present disclosure largely relates to (1) a synchronization signal operation method for a low-power terminal, (2) an initial downlink configuration method for a low-power terminal, (3) an initial uplink configuration method for a low-power terminal, and (4) an initial low-power terminal Provided is a random access method capable of notifying that it is a low-power terminal upon access.

Embodiment 1. Synchronization signal operation method for low-power terminal

A corresponding embodiment is a method of operating a synchronization signal that a low-power terminal can access. This allows the low-power terminal to receive only the SSB that will provide it with a valid initial connection establishment. Specifically, a PSS/SSS (primary synchronization signal/secondary synchronization signal) sequence setting method for a low-power terminal, a new GSCN (Global Synchronization Channel Number) setting method, a SSB introduction method of a new structure, a DMRS arrangement change method, and an environment restriction method can be distinguished as

① PSS/SSS sequence setting for low-power terminals

For the low-power terminal, a restriction on the signal of the PSS/SSS of the SSB accessed by the corresponding terminal may be set. In particular, the conventionally used PSS signal uses a Zadoff-Chu sequence of length 127, and the SSS signal uses a Gold sequence of the same length. Some of the previously used sequence determination parameters or previously unused parameters may be introduced. . Some of these previously used sequence determination parameters or previously unused parameters may be set as synchronization signal parameters for low-power terminals. The low-power terminal may reduce cell search complexity by searching only the signal of the corresponding parameter.

② Set up a new GSCN

For a low-power terminal, a restriction on a frequency domain in which the corresponding terminal searches for a synchronization signal may be set. To this end, a restriction on a GSCN number that is conventionally used may be set, or a frequency domain that has not been used conventionally may be designated. For example, GSCN numbers are arranged at intervals of approximately 1.44 MHz in FR1 and 17.28 MHz in FR2, and the interval value of each GSCN parameter may be set to a frequency position at which a synchronization signal for a low-power terminal is transmitted.

③ Introduction of new structure of SSB

For a low-power terminal, a new type of SSB to be received by the terminal may be introduced. In the existing SSB, PSS, PBCH, SSS, and PBCH are placed using 4 symbols within 20RB, and the PBCH is placed in 8 RBs above and below the symbol where PSS and SSS are located. This type is used as an SSB for the terminal. For this, an SSB of a completely different structure may be introduced for a low-power terminal, or an SSB of the same/similar type as the S-SSB, which is a sidelink synchronization signal, may be used. In this case, erroneous synchronization can be avoided by using a PSS/SSS sequence different from that used in the sidelink.

④ DMRS placement change

For a low-power terminal, a type of a DMRS sequence included in a PBCH to be received by the terminal may be set differently, or a location may be set to be different from a location used in the past. To this end, a DMRS sequence type of a PBCH for a low-power terminal may be limited or a sequence not previously used may be used. In addition, the PBCH DMRS, which are conventionally arranged one by one at intervals of 4REs, may be located in different patterns, such as changing the RE interval, transmitting only specific symbols/positions, or transmitting some REs with zero power.

⑤ Environmental restrictions

For the low-power terminal, a restriction on the parameter of the synchronization signal block to be received by the corresponding terminal may be set. In this regard, the type of the PSS/SSS sequence of the SSB for the low power terminal may be limited. Alternatively, the location of the slot/SFN in which the corresponding SSB exists may be restricted, or the Cell ID may be restricted.

Embodiment 2. Initial downlink setting method for low-power terminal

The embodiment is a method of establishing an initial downlink in a synchronization signal intended to be received by a low-power terminal. In particular, in the case of the n79 band, it is assumed that the minimum value of the frequency band is 40 MHz, and the setting of the initial downlink BWP for the low-power terminal in the corresponding environment may be made in a different format from the existing ones. For band limitation, there may be a method of limiting the setting range of pdcch-ConfigSIB1 and a method of introducing a new table.

① Limit the setting range of pdcch-ConfigSIB1

For the low-power terminal, a value that can be set by pdcch-ConfigSIB1 may be limited. The message consists of a 4-bit CORESET setting value and a 4-bit Search Space setting value, which are mapped to index values of various tables. At this time, with respect to the synchronization signal for the low-power terminal, the PDCCH BWP setting value due to this value may be set to be limited to a specific range that does not exceed the use range of the terminal. For example, when it is identified as a synchronization signal for a low-power terminal through the above-described embodiment 1, when the SCS of the PDCCH is 15 kHz, the CORESET length may not set a value of 96.

② Introduce a new table

For the low-power terminal, a table defining CORESET #0 and Search Space #0 for the low-power terminal may be newly defined. When it is identified as a synchronization signal for a low-power terminal through the above-described embodiment 1, a corresponding table may be set using a table newly defined for a low-power terminal.

Embodiment 3. Initial uplink setting method for low-power terminal

This embodiment is a method of performing initial configuration of uplink that the low-power terminal can receive in SIB1 that the low-power terminal is expected to receive. Specifically, it can be divided into an uplink setting method when the low-power terminal is also expected to receive, and an uplink setting method when only the low-power terminal is expected to receive.

① Uplink setting in SIB that low-power terminal and general terminal receive in common

In general, in most cases, the downlink SIB1 comes within a band that the low-power terminal can receive, and in this case, it may be a problem whether the uplink configuration that the low-power terminal can receive is made. Through this, the uplink configuration in SIB1 can be divided into two and performed. In particular, a transmission region of a new SIBx to be transmitted can be configured only in the case of a low-power terminal. In this case, the uplink configuration for the low-power terminal may be configured to be transmitted in the corresponding SIBx.

② Uplink configuration in SIB that only low-power terminals receive

With respect to the low-power terminal, the uplink may be configured in the SIB that only the low-power terminal receives. This may be SIB1 delivered through the above-described embodiments 1 and 2, and may be SIBx delivered through ① of the third embodiment. The uplink configuration set through the corresponding SIB is subject to parameter restrictions so that the width of the frequency band is within a specific value in the standard.

Embodiment 4. Random access method in which a low-power terminal can inform that it is a low-power terminal upon initial access

The embodiment is a method of notifying a low-power terminal in the random access step so that the base station recognizes in advance that the low-power terminal has connected to the network and does not perform uplink/downlink setting that exceeds the allowable range to the accessed terminal in advance to be. Specifically, there are a method of performing from the viewpoint of a base station and a method of performing from a viewpoint of a terminal.

① Determining low-power terminals from the base station's point of view

With respect to a low-power terminal, by separately defining a PRACH region provided to the corresponding terminal, the base station can know that the terminal that has transmitted the RACH preamble through the corresponding resource region is a low-power terminal without notice. In particular, the PRACH defined through the rach-Config information delivered through ② of Embodiment 3 may be predefined as a space accessed only by low-power terminals.

② Determining low-power terminals from the terminal's point of view

With respect to a low-power terminal, it is a method of allowing the corresponding terminal to notify the base station that it is a low-power terminal. To this end, the PRACH sequence used by the low-power terminal may be set differently, or related information may be multiplexed into the MSG3 PUSCH region.

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 embodiments according to the present disclosure may be applied even when other terms having the same meaning are actually used.

Through the method provided in the present disclosure, a terminal supporting only an operating band lower than an operating band required by an existing terminal in NR can successfully perform network access.

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. However, in order to avoid overlapping descriptions, some of the above descriptions will be omitted.

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

Referring to FIG. 12 , the user 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 user terminal 1200 according to a method of performing an initial access in a limited bandwidth required for carrying out the above-described present disclosure. The transmitter 1220 transmits uplink control information, data, and messages 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 at least one of the first configuration information and the second configuration information used for initial access from the base station.

In the initial access process, the receiver 1230 receives PSS and SSS, which are synchronization signals transmitted in downlink from each cell in order to search for a cell. PSS/SSS is received as a synchronization signal block (SSB) together with a physical broadcast channel (PBCH). The UE receives the MIB providing information on the PDCCH-related parameters necessary for monitoring SIB1 through the PBCH.

The receiver 1230 receives SIB1 transmitted through the PDSCH based on the information in the MIB. SIB1 is generally provided through a PDSCH scheduled with a period of 160 ms, and includes information necessary for the UE to perform initial access and scheduling related information for other system information.

The pdcch-ConfigSIB1 message in the MIB is used to configure CORESET#0 and search space#0, and an initial downlink bandwidth part may be defined and activated based on the values of CORESET#0 and search space#0. In addition, the configuration of the initial uplink bandwidth part may be made through SIB1 scheduled using the PDCCH.

In this way, the receiver 1230 may acquire the downlink and uplink settings for initial access by at least one of MIB and SIB1. The above description of MIB and SIB1 relates to MIB and SIB1 for a terminal generally assumed in the NR system, and in the following, the second configuration information may be used to mean the corresponding MIB and SIB1.

According to an example, it is assumed that a terminal performing initial access to a cell is a terminal having a limited bandwidth, in which an available bandwidth is narrower than a predetermined bandwidth. In this case, MIB and SIB1 in separate formats for the above-described initial access may be configured for a terminal having a corresponding limited bandwidth. That is, the first configuration information may be used to mean MIB and SIB1 and other system information that are separately set for a terminal having a limited bandwidth.

The first configuration information may include configuration information on at least one of an initial downlink bandwidth part (initial DL BWP) and an initial uplink bandwidth part (initial UL BWP) that are separately configured for a terminal having a limited bandwidth. That is, the MIB and SIB1 and other system information included in the first configuration information will be defined so that the initial downlink bandwidth part and the initial uplink bandwidth part can be set separately from the existing general terminal for a terminal having a limited bandwidth. can

In this case, the initial downlink bandwidth part and the initial uplink bandwidth part separately configured for a terminal having a limited bandwidth may be set to have a bandwidth equal to or smaller than a limited bandwidth configured in the terminal.

In addition, the first configuration information may further include information related to a random access operation performed in an initial access process. That is, information related to a random access operation may also be separately set for a terminal having a limited bandwidth.

According to an example, the uplink bandwidth part separately configured for a terminal having a limited bandwidth may be configured to include at least one random access channel occurrence separately configured for a terminal having a limited bandwidth (RACH occasion). . Preamble transmission may occur within a slot configured as a RACH slot for every RACH configuration period. There may be K RACH occurrences within this RACH slot. In this regard, for a terminal having a limited bandwidth, the RACH attack may be configured based on the bandwidth of an initial uplink bandwidth part configured in the corresponding terminal.

In addition, the first configuration information may include information on a random access channel resource configured based on a sequence set separately for a terminal having a limited bandwidth. That is, for a terminal having a limited bandwidth, a random access channel resource may be configured by applying a separate sequence. That is, the sequence applied to generate the random access preamble may be applied as a sequence different from that of a general terminal assumed in the NR system.

According to an example, the first configuration information may be configured to be received not only by a terminal having a limited bandwidth but also by a general terminal assumed in the NR system. Alternatively, the first configuration information may be set to be received only by a terminal having a limited bandwidth. In addition, the second configuration information may be set not to be received by a terminal having a limited bandwidth.

The controller 1210 may control to perform an initial connection based on any one of the first configuration information and the second configuration information.

According to an example, the first configuration information and the second configuration information may be defined separately from each other. Alternatively, it may be defined that a setting corresponding to the first configuration information is selected according to a value of an arbitrary field in the second configuration information. Alternatively, in the second configuration information, it may be defined that a setting corresponding to the first configuration information is further separately added.

In the case of a general terminal assumed in the NR system, the controller 1210 may perform an initial access process based on the second configuration information.

In the case of a terminal having a limited bandwidth, the controller 1210 may perform an initial access process based on the first configuration information. That is, the control unit 1210 of the terminal having a limited bandwidth may perform an initial access according to setting information corresponding to the first configuration information.

In addition, the control unit 1210 of the terminal having a limited bandwidth may generate a random access preamble by applying a separate sequence, or control to transmit the random access preamble through at least one randomly configured random access channel error. In this case, the base station may determine that the corresponding terminal is a terminal having a limited bandwidth without additional information, and then perform a random access operation.

Accordingly, it is possible to provide a method and apparatus for performing initial access in a limited bandwidth with respect to a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth.

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 of performing an initial access in a limited bandwidth necessary for carrying out the above-described present disclosure. The transmitter 1320 and the receiver 1330 are used to transmit and receive signals, messages, and data necessary for carrying out the above-described present disclosure with the terminal.

The transmitter 1320 may transmit at least one of the first configuration information and the second configuration information used for initial access.

In the initial access process, in order to support cell search of the terminal, the transmitter 1320 transmits synchronization signals PSS and SSS. The PSS/SSS is received as a sync signal block together with the PBCH. The transmitter 1320 transmits an MIB providing information on a PDCCH-related parameter necessary for monitoring SIB1 through the PBCH.

The transmitter 1320 transmits SIB1 through the PDSCH based on the information in the MIB. SIB1 is generally provided through a PDSCH scheduled with a period of 160 ms, and includes information necessary for the UE to perform initial access and scheduling related information for other system information.

The pdcch-ConfigSIB1 message in the MIB is used to configure CORESET#0 and search space#0, and an initial downlink bandwidth part may be defined and activated based on the values of CORESET#0 and search space#0. In addition, the configuration of the initial uplink bandwidth part may be made through SIB1 scheduled using the PDCCH.

In this way, the transmitter 1320 may transmit the downlink and uplink settings for initial access through at least one of MIB and SIB1. The above description of MIB and SIB1 relates to MIB and SIB1 for a terminal generally assumed in the NR system, and in the following, the second configuration information may be used to mean the corresponding MIB and SIB1.

According to an example, it is assumed that a terminal performing initial access to a cell is a terminal having a limited bandwidth, in which an available bandwidth is narrower than a predetermined bandwidth. In this case, MIB and SIB1 in separate formats for the above-described initial access may be configured for a terminal having a corresponding limited bandwidth. That is, the first configuration information may be used to mean MIB and SIB1 and other system information that are separately set for a terminal having a limited bandwidth.

The first configuration information may include configuration information on at least one of an initial downlink bandwidth part (initial DL BWP) and an initial uplink bandwidth part (initial UL BWP) that are separately configured for a terminal having a limited bandwidth. That is, the MIB and SIB1 and other system information included in the first configuration information will be defined so that the initial downlink bandwidth part and the initial uplink bandwidth part can be set separately from the existing general terminal for a terminal having a limited bandwidth. can

In this case, the initial downlink bandwidth part and the initial uplink bandwidth part separately configured for a terminal having a limited bandwidth may be set to have a bandwidth equal to or smaller than a limited bandwidth configured in the terminal.

In addition, the first configuration information may further include information related to a random access operation performed in an initial access process. That is, information related to a random access operation may also be separately set for a terminal having a limited bandwidth.

According to an example, the uplink bandwidth part separately configured for a terminal having a limited bandwidth may be configured to include at least one random access channel occurrence separately configured for a terminal having a limited bandwidth (RACH occasion). . Preamble transmission may occur within a slot configured as a RACH slot for every RACH configuration period. There may be K RACH occurrences within this RACH slot. In this regard, for a terminal having a limited bandwidth, a RACH attack may be configured based on the bandwidth of an initial uplink bandwidth part configured in the corresponding terminal.

In addition, the first configuration information may include information on a random access channel resource configured based on a sequence set separately for a terminal having a limited bandwidth. That is, for a terminal having a limited bandwidth, a random access channel resource may be configured by applying a separate sequence. That is, the sequence applied to generate the random access preamble may be applied as a sequence different from that of a general terminal assumed in the NR system.

According to an example, the first configuration information may be configured to be received not only by a terminal having a limited bandwidth but also by a general terminal assumed in the NR system. Alternatively, the first configuration information may be set to be received only by a terminal having a limited bandwidth. In addition, the second configuration information may be set not to be received by a terminal having a limited bandwidth.

The controller 1310 may control to perform an initial connection based on any one of the first configuration information and the second configuration information.

According to an example, the first configuration information and the second configuration information may be defined separately from each other. Alternatively, it may be defined that a setting corresponding to the first configuration information is selected according to a value of an arbitrary field in the second configuration information. Alternatively, in the second configuration information, it may be defined that a setting corresponding to the first configuration information is further separately added.

In the case of a general terminal assumed in the NR system, the controller 1310 may perform an initial access process with the corresponding terminal based on the second configuration information.

In the case of a terminal having a limited bandwidth, the controller 1310 may perform an initial access process with the corresponding terminal based on the first configuration information. That is, the controller 1310 may perform an initial connection with a terminal having a limited bandwidth according to setting information corresponding to the first configuration information.

In addition, a terminal having a limited bandwidth may generate a random access preamble by applying a separate sequence or transmit it through at least one randomly configured random access channel occupancy. In this case, the controller 1310 may determine that the corresponding terminal is a terminal having a limited bandwidth without additional information, and then perform a random access operation.

Accordingly, it is possible to provide a method and apparatus for performing initial access in a limited bandwidth with respect to a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth.

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 to explain, and thus the scope of the present technical spirit is not limited by these embodiments. The protection scope of the present disclosure 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 disclosure.

Claims (20)

In a method for a terminal to perform initial access,
receiving at least one of first configuration information and second configuration information used for initial access; and
Based on any one of the first configuration information and the second configuration information, comprising the step of performing an initial connection,
The first configuration information is set for a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth. The method of claim 1,
The first configuration information,
A method including configuration information on at least one of an initial downlink bandwidth part (initial DL BWP) and an initial uplink bandwidth part (initial UL BWP) configured separately for the terminal having the limited bandwidth. 3. The method of claim 2,
The initial downlink bandwidth part and the initial uplink bandwidth part separately configured for the terminal having the limited bandwidth are,
A method configured to have a bandwidth less than or equal to the limited bandwidth. 4. The method of claim 3,
The initial uplink bandwidth part separately configured for the terminal having the limited bandwidth is,
A method including at least one random access channel occurrence (RACH occasion) configured separately for the terminal having the limited bandwidth. The method of claim 1,
The first configuration information,
A method comprising information on a random access channel resource configured based on a sequence set separately for the terminal having the limited bandwidth. A method for a base station to perform initial access, the method comprising:
transmitting at least one of first configuration information and second configuration information used for initial access; and
Based on any one of the first configuration information and the second configuration information, comprising the step of performing an initial connection,
The first configuration information is set for a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth. 7. The method of claim 6,
The first configuration information,
A method including configuration information on at least one of an initial downlink bandwidth part (initial DL BWP) and an initial uplink bandwidth part (initial UL BWP) configured separately for the terminal having the limited bandwidth. 8. The method of claim 7,
The initial downlink bandwidth part and the initial uplink bandwidth part separately configured for the terminal having the limited bandwidth are,
A method configured to have a bandwidth less than or equal to the limited bandwidth. 9. The method of claim 8,
The initial uplink bandwidth part separately configured for the terminal having the limited bandwidth is,
A method including at least one random access channel occurrence (RACH occasion) configured separately for the terminal having the limited bandwidth. 7. The method of claim 6,
The first configuration information,
A method comprising information on a random access channel resource configured based on a sequence set separately for the terminal having the limited bandwidth. In a terminal performing initial access,
a receiving unit configured to receive at least one of first configuration information and second configuration information used for initial access; and
A control unit for performing an initial connection based on any one of the first configuration information and the second configuration information,
The first configuration information is a terminal configured for a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth. 12. The method of claim 11,
The first configuration information,
A terminal including configuration information on at least one of an initial downlink bandwidth part (initial DL BWP) and an initial uplink bandwidth part (initial UL BWP) configured separately for the terminal having the limited bandwidth. 13. The method of claim 12,
The initial downlink bandwidth part and the initial uplink bandwidth part separately configured for the terminal having the limited bandwidth are,
A terminal configured to have a bandwidth less than or equal to the limited bandwidth. 14. The method of claim 13,
The initial uplink bandwidth part separately configured for the terminal having the limited bandwidth is,
A terminal including at least one random access channel occurrence (RACH occasion) configured separately for the terminal having the limited bandwidth. 12. The method of claim 11,
The first configuration information,
A terminal including information on a random access channel resource configured based on a sequence set separately for the terminal having the limited bandwidth. In the base station performing initial access,
a transmitter for transmitting at least one of first configuration information and second configuration information used for initial access; and
A control unit for performing an initial connection based on any one of the first configuration information and the second configuration information,
The first configuration information is a base station configured for a terminal having a limited bandwidth in which an available bandwidth is narrower than a predetermined bandwidth. 17. The method of claim 16,
The first configuration information,
A base station including configuration information on at least one of an initial downlink bandwidth part (initial DL BWP) and an initial uplink bandwidth part (initial UL BWP) configured separately for the terminal having the limited bandwidth. 18. The method of claim 17,
The initial downlink bandwidth part and the initial uplink bandwidth part separately configured for the terminal having the limited bandwidth are,
A base station configured to have a bandwidth less than or equal to the limited bandwidth. 19. The method of claim 18,
The initial uplink bandwidth part separately configured for the terminal having the limited bandwidth is,
A base station including at least one random access channel occurrence (RACH occasion) configured separately for the terminal having the limited bandwidth. 17. The method of claim 16,
The first configuration information,
A base station including information on a random access channel resource configured based on a sequence set separately for the terminal having the limited bandwidth.

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