KR20230007947A - Method and apparatus for transmitting and receiving multi synchronization signal block in communication system - Google Patents

Abstract

Disclosed are a method and an apparatus for transmitting and receiving multi synchronization signal block (SSB) in a communication system. The method of a terminal comprises the steps of: receiving, from a base station, a first SSB having an SSB candidate #n at a first frequency position during a first time period; receiving, from the base station, first mapping relationship information between SSB candidate indexes and SSB indexes; identifying an SSB #k mapped to the SSB candidate #n based on the first mapping relationship information for the first frequency position; acquiring time synchronization with respect to the base station based on the SSB candidate #n; and obtaining beam information for the first frequency position based on the SSB #k. Therefore, ambiguity about time synchronization and/or beam information in the terminal can be resolved.

Description

Method and device for transmitting and receiving multiple SSBs in a communication system

The present invention relates to communication technology, and more particularly, to a technology for transmitting and receiving multiple synchronization signal blocks (SSBs) in a broadband.

To process rapidly increasing wireless data, a frequency band (eg, 6 GHz) higher than the frequency band (eg, a frequency band of 6 GHz or less) of a long term evolution (LTE) communication system (or LTE-A communication system) A communication system (eg, a new radio (NR) communication system, a 6G communication system) using the above frequency bands) is being considered. The NR system can support a frequency band of 6 GHz or less as well as a frequency band of 6 GHz or more, and can support a variety of communication services and scenarios compared to the LTE system. Also, requirements of the NR system may include enhanced mobile broadband (eMBB), ultra reliable low latency communication (URLLC), massive machine type communication (mMTC), and the like.

Meanwhile, the base station may transmit synchronization signal blocks (SSBs) multiplexed in the frequency domain, and the SSBs multiplexed in the frequency domain may be transmitted through different beams. When SSBs multiplexed in the frequency domain have the same SSB index, ambiguity regarding beam information may occur in the UE. When SSBs multiplexed in the frequency domain have different SSB indices, time synchronization ambiguity may occur in the UE.

An object of the present invention to solve the above problems is to provide a method and apparatus for transmitting and receiving multiple synchronization signal blocks (SSBs) in a wideband.

A method of a terminal according to a first embodiment of the present invention for achieving the above object includes receiving a first SSB having SSB candidate #n from a base station during a first time interval at a first frequency location, and receiving an SSB from the base station. Receiving first mapping relationship information between a candidate index and an SSB index, identifying SSB #k mapped to the SSB candidate #n based on the first mapping relationship information for the first frequency location, the SSB obtaining time synchronization for the base station based on candidate #n, and acquiring beam information for the first frequency location based on SSB #k, wherein each of n and k is 0 is an integer of more than

The method of the terminal includes receiving a second SSB having SSB candidate #n+1 from the base station during a second time interval at the first frequency location, in the first mapping relationship information for the first frequency location. identifying SSB #k+1 mapped to the SSB candidate #n+1 based on the SSB candidate #n+1, obtaining time synchronization for the base station based on the SSB candidate #n+1, and the SSB #k+1 The method may further include obtaining beam information for the first frequency position based on .

The first mapping relationship information may indicate a mapping relationship between the SSB candidate index of the SSB located first in the time domain and the SSB index.

The method of the terminal includes receiving a third SSB having the SSB candidate #n from the base station during the first time interval at a second frequency location, and second mapping between the SSB candidate index and the SSB index from the base station. Receiving relationship information; checking SSB #j mapped to the SSB candidate #n based on the second mapping relationship information for the second frequency location; determining the base station based on the SSB candidate #n The method may further include obtaining time synchronization for , and obtaining beam information for the second frequency location based on the SSB #j, where j may be an integer greater than or equal to 0.

The first SSB and the third SSB may be multiplexed in a frequency domain, and a first beam pattern used for transmission of SSBs at the first frequency location is used for transmission of SSBs at the second frequency location. 2 may differ from the beam pattern.

The SSB candidate #n may be identified based on the PBCH DMRS and PBCH payload included in the first SSB.

The first mapping relationship information may be obtained through at least one of PBCH, RMSI, system information, or RRC message received from the base station.

The beam information may mean QCL information.

A method of a terminal according to a second embodiment of the present invention for achieving the above object includes receiving a first SSB having SSB candidate #n from a base station during a first time period at a first frequency location, the first frequency confirming that the SSB index of the SSB candidate #n is SSB #n at the location, receiving a second SSB having the SSB candidate #n from the base station during the first time interval at a second frequency location, the Receiving first information indicating an offset of the SSB index and second information indicating the number of total beams used for transmission of SSBs from the base station, and the SSB #n, the first information, and the first information 2, and identifying SSB #k mapped to the SSB candidate #n of the second SSB at the second frequency location based on information of 2, wherein each of n and k is an integer greater than or equal to 0.

The SSB #k may be a result of "(SSB #n + first information) mod second information".

The first SSB received at the first frequency location may be a cell-defined SSB, and an SSB candidate index of the cell-defined SSB and the SSB index may be set to the same value.

The first information and the second information may be obtained through at least one of PBCH, RMSI, system information, or RRC message received from the base station.

The method of the terminal may further include receiving at least one of third information indicating the number of beams multiplexed in the frequency domain or fourth information indicating an application method of the first information from the base station, , The fourth information may indicate that the first information is applied in descending order or ascending order based on the frequency position.

The first SSB and the second SSB may be multiplexed in a frequency domain, and a first beam pattern used for transmission of SSBs at the first frequency location is used for transmission of SSBs at the second frequency location. 2 beam pattern, time synchronization for the base station may be obtained based on the SSB candidate #n, beam information for the first frequency location may be obtained based on the SSB #n, Beam information for the second frequency location may be obtained based on the SSB #k.

A method of a base station according to a third embodiment of the present invention for achieving the above object includes transmitting a reference cell definition SSB to a terminal during a first time interval at a first frequency location, the first time interval at a second frequency location. Transmitting a non-reference cell definition SSB to the terminal during an interval, transmitting an RMSI based on the first frequency location to the terminal, and transmitting information about the reference cell definition SSB to the terminal and the RMSI is not transmitted based on one or more frequency positions in which the reference cell definition SSB is not transmitted.

The information on the reference cell definition SSB is information indicating whether the SSB detected by the terminal corresponds to the reference cell definition SSB, and information indicating that the SSB detected at the first frequency location is the reference cell definition SSB. , or at least one of mapping relationship information between the reference cell definition SSB and the non-reference cell definition SSB.

The information on the reference cell definition SSB may be included in at least one of the PBCH transmitted from the base station, the RMSI, system information, or an RRC message.

The reference cell definition SSB and the non-reference cell definition SSB may have the same SSB candidate index and different SSB indexes, and the SSB candidate index may be used by the terminal to obtain time synchronization for the base station, and the SSB The index may be used to obtain beam information for each frequency location in the terminal.

The method of the base station may further include transmitting mapping relationship information between the SSB candidate index and the SSB index to the terminal, wherein the SSB candidate index is the reference cell definition SSB and the non-reference cell definition SSB. It can be checked based on the PBCH DMRS and PBCH payload included in each, and the SSB index mapped to the SSB candidate index can be checked based on the mapping relationship information for each frequency location.

The reference cell definition SSB and the non-reference cell definition SSB may be multiplexed in a frequency domain, and a first beam pattern used for transmission of reference cell definition SSBs at the first frequency location may be multiplexed at the second frequency location. -It may be different from the second beam pattern used for transmission of reference cell definition SSBs.

According to the present application, a base station can transmit synchronization signal blocks (SSBs) multiplexed in the frequency domain using different beams. SSBs multiplexed in the frequency domain during the same time interval may have the same SSB candidate index and different SSB indices. A mapping relationship between an SSB candidate index and an SSB index at each frequency location may be set. The SSB candidate index may be identified based on a physical broadcast channel (PBCH) demodulation reference signal (DMRS) included in the SSB and the PBCH payload. The SSB index may be identified based on the SSB candidate index and mapping relationship information. The terminal may obtain time synchronization based on the SSB candidate index and may obtain beam information based on the SSB index. Therefore, ambiguity about time synchronization and/or beam information in the terminal can be resolved, and performance of the communication system can be improved.

1 is a conceptual diagram illustrating a first embodiment of a communication system.
2 is a block diagram showing a first embodiment of a communication node constituting a communication system.
3 is a conceptual diagram illustrating a first embodiment of a type 1 frame structure.
4 is a conceptual diagram illustrating a first embodiment of a type 2 frame structure.
5 is a conceptual diagram illustrating a first embodiment of a method of transmitting an SS/PBCH block in a communication system.
6 is a conceptual diagram illustrating a first embodiment of an SS/PBCH block in a communication system.
7 is a conceptual diagram illustrating a second embodiment of a method of transmitting an SS/PBCH block in a communication system.
8A is a conceptual diagram illustrating RMSI CORESET mapping pattern #1 in a communication system.
8B is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system.
8C is a conceptual diagram illustrating RMSI CORESET mapping pattern #3 in a communication system.
9 is a conceptual diagram illustrating embodiments of a method of multiplexing a control channel and a data channel in sidelink communication.
10 is a conceptual diagram illustrating a first embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.
11 is a conceptual diagram illustrating a second embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.
12 is a conceptual diagram illustrating a third embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.
13 is a conceptual diagram illustrating a fourth embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.
14 is a conceptual diagram illustrating a fifth embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.
15 is a conceptual diagram illustrating a sixth embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.
16 is a conceptual diagram illustrating a seventh embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.

Since the present invention can make various changes and have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The term "and/or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

In embodiments of the present application, “at least one of A and B” may mean “at least one of A or B” or “at least one of combinations of one or more of A and B”. Also, in the embodiments of the present application, “one or more of A and B” may mean “one or more of A or B” or “one or more of combinations of one or more of A and B”.

In embodiments of the present application, (re)transfer may mean “send”, “retransmit”, or “send and retransmit”, and (re)set may mean “set”, “reset”, or “set and "Reset", (re)connect can mean "connect", "reconnect", or "connect and reconnect", (re)connect can mean "connect", "reconnect", or "reconnect" connection and reconnection”.

It is understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may exist in the middle. It should be. On the other hand, when an element is referred to as “directly connected” or “directly connected” to another element, it should be understood that no other element exists in the middle.

Terms used in this application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "include" or "have" are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this application, they should not be interpreted in an ideal or excessively formal meaning. don't

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail. In order to facilitate overall understanding in the description of the present invention, the same reference numerals are used for the same components in the drawings, and redundant descriptions of the same components are omitted.

A communication system to which embodiments according to the present invention are applied will be described. A communication system to which embodiments according to the present invention are applied is not limited to the contents described below, and embodiments according to the present invention can be applied to various communication systems. Here, the communication system may be used in the same sense as a communication network.

In an embodiment, “setting an operation (eg, transmission operation)” means “setting information for the corresponding operation (eg, information element, parameter)” and/or “performing the corresponding operation”. It may mean that the "instructing information" is signaled. "Setting an information element (eg, parameter)" may mean that a corresponding information element is signaled. Signaling is system information (SI) signaling (eg, transmission of system information block (SIB) and / or master information block (MIB)), RRC signaling (eg, transmission of RRC parameters and / or higher layer parameters) , MAC control element (CE) signaling, or PHY signaling (eg, transmission of downlink control information (DCI), uplink control information (UCI), and/or sidelink control information (SCI)).

1 is a conceptual diagram illustrating a first embodiment of a communication system.

Referring to FIG. 1, a communication system 100 includes a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, 130-6). In addition, the communication system 100 includes a core network (eg, a serving-gateway (S-GW), a packet data network (PDN)-gateway (P-GW), and a mobility management entity (MME)). can include more. When the communication system 100 is a 5G communication system (eg, a new radio (NR) system), the core network includes an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), and the like. can include

The plurality of communication nodes 110 to 130 may support communication protocols (eg, LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.) defined in the 3rd generation partnership project (3GPP) standard. The plurality of communication nodes 110 to 130 are CDMA (code division multiple access) technology, WCDMA (wideband CDMA) technology, TDMA (time division multiple access) technology, FDMA (frequency division multiple access) technology, OFDM (orthogonal frequency division) multiplexing) technology, filtered OFDM technology, CP (cyclic prefix)-OFDM technology, DFT-s-OFDM (discrete Fourier transform-spread-OFDM) technology, OFDMA (orthogonal frequency division multiple access) technology, SC (single carrier)-FDMA technology, NOMA (Non-orthogonal Multiple Access) technology, GFDM (generalized frequency division multiplexing) technology, FBMC (filter bank multi-carrier) technology, UFMC (universal filtered multi-carrier) technology, SDMA (Space Division Multiple Access) technology, etc. can support Each of the plurality of communication nodes may have the following structure.

2 is a block diagram showing a first embodiment of a communication node constituting a communication system.

Referring to FIG. 2 , a communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to a network to perform communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, and the like. Each component included in the communication node 200 may be connected by a bus 270 to communicate with each other.

However, each component included in the communication node 200 may be connected through an individual interface or an individual bus centered on the processor 210 instead of the common bus 270 . For example, the processor 210 may be connected to at least one of the memory 220, the transmission/reception device 230, the input interface device 240, the output interface device 250, and the storage device 260 through a dedicated interface. .

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260 . The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may include at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may include at least one of a read only memory (ROM) and a random access memory (RAM).

Referring back to FIG. 1, the communication system 100 includes a plurality of base stations (110-1, 110-2, 110-3, 120-1, 120-2), a plurality of terminals 130- 1, 130-2, 130-3, 130-4, 130-5, 130-6). Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell. Each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. The second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. The fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the cell coverage of the third base station 110-3. there is. The first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1. The sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

Here, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 is a NodeB (NB), an evolved NodeB (eNB), a gNB, an advanced base station (ABS), and a HR -BS (high reliability-base station), BTS (base transceiver station), radio base station, radio transceiver, access point, access node, radio access station (RAS) ), MMR-BS (mobile multihop relay-base station), RS (relay station), ARS (advanced relay station), HR-RS (high reliability-relay station), HNB (home NodeB), HeNB (home eNodeB), It may be referred to as a road side unit (RSU), a radio remote head (RRH), a transmission point (TP), a transmission and reception point (TRP), and the like.

Each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 includes user equipment (UE), terminal equipment (TE), advanced mobile station (AMS), HR-MS (high reliability-mobile station), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, mobile It may be referred to as a portable subscriber station, a node, a device, an on board unit (OBU), and the like.

Meanwhile, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may operate in different frequency bands or may operate in the same frequency band. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to each other through an ideal backhaul link or a non-ideal backhaul link, and , information can be exchanged with each other through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be connected to the core network through an ideal backhaul link or a non-ideal backhaul link. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits a signal received from the core network to a corresponding terminal 130-1, 130-2, 130-3, and 130 -4, 130-5, 130-6), and signals received from corresponding terminals 130-1, 130-2, 130-3, 130-4, 130-5, 130-6 are transmitted to the core network can be sent to

In addition, each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 transmits MIMO (eg, single user (SU)-MIMO, multi-user (MU)- MIMO, massive MIMO, etc.), coordinated multipoint (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, direct communication between devices (device to device communication, D2D) (or , proximity services (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), etc. may be supported. Here, each of the plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 is a base station 110-1, 110-2, 110-3, 120-1 , 120-2) and operations supported by the base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may be performed. For example, the second base station 110-2 can transmit a signal to the fourth terminal 130-4 based on the SU-MIMO scheme, and the fourth terminal 130-4 uses the SU-MIMO scheme. A signal may be received from the second base station 110-2. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 based on the MU-MIMO scheme, and the fourth terminal 130-4 And each of the fifth terminal 130-5 may receive a signal from the second base station 110-2 by the MU-MIMO method.

Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may transmit a signal to the fourth terminal 130-4 based on the CoMP scheme, and The terminal 130-4 may receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 by CoMP. Each of the plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2 includes a terminal 130-1, 130-2, 130-3, and 130-4 belonging to its own cell coverage. , 130-5, 130-6) and a CA method. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 controls D2D between the fourth terminal 130-4 and the fifth terminal 130-5. and each of the fourth terminal 130-4 and the fifth terminal 130-5 may perform D2D under the control of the second base station 110-2 and the third base station 110-3, respectively. .

Meanwhile, the communication system may support three types of frame structures. The type 1 frame structure can be applied to a frequency division duplex (FDD) communication system, the type 2 frame structure can be applied to a time division duplex (TDD) communication system, and the type 3 frame structure can be applied to an unlicensed band-based communication system (eg For example, it may be applied to a licensed assisted access (LAA) communication system.

3 is a conceptual diagram illustrating a first embodiment of a type 1 frame structure.

Referring to FIG. 3 , a radio frame 300 may include 10 subframes, and each subframe may include 2 slots. Accordingly, the radio frame 300 may include 20 slots (eg, slot #0, slot #1, slot #2, slot #3, ..., slot #18, slot #19). The radio frame 300 may have a length (T _f ) of 10 ms (millisecond), a subframe length of 1 ms, and a slot length (T _slot ) of 0.5 ms. Here, T _s may indicate a sampling time and may be 1/30,720,000s (second).

A slot may consist of a plurality of OFDM symbols in the time domain and may consist of a plurality of resource blocks (RBs) in the frequency domain. A resource block may be composed of a plurality of subcarriers in the frequency domain. The number of OFDM symbols constituting a slot may vary depending on the configuration of a cyclic prefix (CP). CP may be classified into a normal CP and an extended CP. If a normal CP is used, a slot may consist of 7 OFDM symbols, and in this case, a subframe may consist of 14 OFDM symbols. If the extended CP is used, a slot may consist of 6 OFDM symbols, and in this case, a subframe may consist of 12 OFDM symbols.

4 is a conceptual diagram illustrating a first embodiment of a type 2 frame structure.

Referring to FIG. 4 , a radio frame 400 may include two half frames, and each half frame may include five subframes. Accordingly, the radio frame 400 may include 10 subframes. The length of the radio frame 400 (T _f ) may be 10 ms. The length of the half frame may be 5 ms. The subframe length may be 1 ms. Here, T _s may be 1/30,720,000s.

The radio frame 400 may include a downlink subframe, an uplink subframe, and a special subframe. Each of the downlink subframe and the uplink subframe may include two slots. The slot length (T _slot ) may be 0.5 ms. Among the subframes included in the radio frame 400, each of subframe #1 and subframe #6 may be a special subframe. For example, when the downlink-uplink switching period is 5 ms, the radio frame 400 may include two special subframes. Alternatively, when the downlink-uplink switching period is 10 ms, the radio frame 400 may include one special subframe. The special subframe may include a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS).

The downlink pilot time slot may be regarded as a downlink interval and may be used for cell search of the terminal, acquisition of time and frequency synchronization, channel estimation, and the like. The guard period may be used to solve an interference problem of uplink data transmission caused by a downlink data reception delay. In addition, the guard period may include a time required for switching from a downlink data reception operation to an uplink data transmission operation. The uplink pilot time slot may be used for uplink channel estimation, time and frequency synchronization acquisition, and the like. Transmission of a physical random access channel (PRACH) or a sounding reference signal (SRS) may be performed in an uplink pilot time slot.

Lengths of each of the downlink pilot time slot, guard period, and uplink pilot time slot included in the special subframe may be variably adjusted as needed. Also, the number and location of each of the downlink subframes, uplink subframes, and special subframes included in the radio frame 400 may be changed as needed.

In a communication system, a transmission time interval (TTI) may be a basic time unit for transmitting coded data through a physical layer. A short TTI may be used to support low latency requirements in a communication system. The length of the short TTI may be less than 1 ms. An existing TTI having a length of 1 ms may be referred to as a base TTI or a regular TTI. That is, the basic TTI may consist of one subframe. To support transmission in basic TTI units, signals and channels may be set in units of subframes. For example, a cell-specific reference signal (CRS), a physical downlink control channel (PDCCH), a physical downlink shared channel (PDSCH), a physical uplink control channel (PUCCH), and a physical uplink shared channel (PUSCH) exist for each subframe. can

On the other hand, synchronization signals (eg, primary synchronization signal (PSS), secondary synchronization signal (SSS)) may exist every 5 subframes, and a physical broadcast channel (PBCH) may exist every 10 subframes. And radio frames can be distinguished by SFN, and SFN is a signal whose transmission period is longer than one radio frame (eg, a paging signal, a reference signal for channel estimation, a signal indicating channel state information, etc.) can be used to define the transmission of The period of SFN may be 1024.

In the LTE system, the PBCH may be a physical layer channel used for transmission of system information (eg, master information block (MIB)). PBCH may be transmitted every 10 subframes. That is, the transmission period of the PBCH may be 10 ms, and the PBCH may be transmitted once in a radio frame. The same MIB may be transmitted during 4 consecutive radio frames, and after 4 consecutive radio frames, the MIB may be changed according to the situation of the LTE system. The transmission period of the same MIB may be referred to as "PBCH TTI", and the PBCH TTI may be 40 ms. That is, the MIB may be changed for each PBCH TTI.

MIB may consist of 40 bits. Among the 40 bits constituting the MIB, 3 bits may be used to indicate the system bandwidth, 3 bits may be used to indicate PHICH (physical hybrid automatic repeat request (ARQ) indicator channel) related information, and 8 bits may be used to indicate It can be used to indicate SFN, 10 bits can be set as reserved bits, and 16 bits can be used for cyclic redundancy check (CRC).

The SFN that distinguishes the radio frame may consist of a total of 10 bits (B9 to B0), and among the 10 bits, 8 bits (B9 to B2) of the most significant bit (MSB) may be indicated by the PBCH (ie, MIB) . MSB 8 bits (B9 to B2) of SFN indicated by PBCH (ie, MIB) may be the same during 4 consecutive radio frames (ie, PBCH TTI). The least significant bit (LSB) 2 bits (B1-B0) of SFN may change during 4 consecutive radio frames (i.e., PBCH TTI) and may not be explicitly indicated by the PBCH (i.e., MIB). there is. LSB 2 bits (B1 to B0) of SFN may be implicitly indicated by a scrambling sequence for PBCH (hereinafter, referred to as "PBCH scrambling sequence").

As the PBCH scrambling sequence, a gold sequence generated by initialization with a cell ID may be used, and the PBCH scrambling sequence may be initialized every 4 consecutive radio frames (ie, PBCH TTI) according to mod(SFN,4). there is. A PBCH transmitted in a radio frame corresponding to an SFN in which LSB 2 bits (B1 to B0) are set to “00” may be scrambled by a Gold sequence generated by initialization with a cell ID. Subsequently, the gold sequences generated according to mod(SFN,4) are used to scramble the PBCH transmitted in radio frames in which the LSB 2 bits (B1 to B0) of SFN are “01”, “10” and “11”. can

Therefore, in the initial cell search process, the UE acquires the cell ID through the PBCH scrambling sequence in the PBCH (ie, MIB) decoding process to obtain the values of the LSB 2 bits (B1 to B0) of the SFN (e.g., "00", " 01", "10", "11") can be found implicitly. The UE uses the LSB 2 bits (B1 to B0) of the SFN identified based on the PBCH scrambling sequence and the MSB 8 bits (B9 to B2) of the SFN indicated by the PBCH (ie MIB). You can check all bits (B9~B0)).

Meanwhile, the communication system can support technical requirements for various service scenarios as well as high transmission rates. For example, the communication system may support enhanced mobile broadband (eMBB), ultra reliable low latency communication (URLLC), massive machine type communication (mMTC), and the like.

A subcarrier spacing of a communication system (eg, an OFDM-based communication system) may be determined based on a carrier frequency offset (CFO) or the like. CFO may be caused by a Doppler effect, phase drift, or the like, and may increase in proportion to an operating frequency. Therefore, in order to prevent performance degradation of the communication system due to the CFO, the subcarrier spacing may increase in proportion to the operating frequency. On the other hand, CP overhead may increase as the subcarrier spacing increases. Accordingly, the subcarrier interval may be set based on channel characteristics according to frequency bands, radio frequency (RF) characteristics, and the like.

The communication system may support the numerology defined in Table 1 below.

For example, the subcarrier spacing of the communication system may be set to 15 kHz, 30 kHz, 60 kHz or 120 kHz. The subcarrier spacing of the LTE system may be 15 kHz, and the subcarrier spacing of the NR system may be 1, 2, 4, or 8 times the existing subcarrier spacing of 15 kHz. When the subcarrier spacing increases in units of powers of 2 of the existing subcarrier spacing, the frame structure can be easily designed.

The communication system can support FR2 as well as FR1. FR2 can be classified into FR2-1 and FR2-2. FR1 may be a frequency band of 6 GHz or less, FR2-1 may be a 24.25 ~ 52.6 GHz band, and FR2-2 may be a 52.6 ~ 71 GHz band. In an embodiment, FR2 may be FR2-1, FR2-2, or a frequency band including FR2-1 and FR2-2. Subcarrier intervals usable for data transmission in each of FR1, FR2-1, and FR2-2 may be defined as shown in Table 2 below. Subcarrier intervals usable for SSB (synchronization signal block) transmission in each of FR1, FR2-1, and FR2-2 may be defined as shown in Table 3 below. Subcarrier intervals usable for random access channel (RACH) transmission (eg, Msg1 or Msg-A) in each of FR1, FR2-1, and FR2-2 may be defined as shown in Table 4 below.

The communication system may support a wide frequency band (eg, several hundred MHz to several tens of GHz). Since diffraction and reflection characteristics of radio waves are not good in a high frequency band, propagation loss (eg, path loss, reflection loss, etc.) in a high frequency band may be greater than propagation loss in a low frequency band. Accordingly, cell coverage of a communication system supporting a high frequency band may be smaller than cell coverage of a communication system supporting a low frequency band. In order to solve this problem, a beamforming method based on a plurality of antenna elements may be used to increase cell coverage in a communication system supporting a high frequency band.

The beamforming method may include a digital beamforming method, an analog beamforming method, a hybrid beamforming method, and the like. In a communication system using a digital beamforming method, a beamforming gain may be obtained using a plurality of RF paths based on a digital precoder or codebook. In a communication system using an analog beamforming method, a beamforming gain is obtained through an analog RF device (eg, a phase shifter, a power amplifier (PA), a variable gain amplifier (VGA), etc.) and an antenna array. can

Since the digital beamforming method requires expensive digital to analog converters (DACs) or analog to digital converters (ADCs) and transceiver units corresponding to the number of antenna elements, an antenna to increase beamforming gain Implementation complexity may increase. Since a plurality of antenna elements are connected to one transceiver unit through a phase shifter in a communication system using an analog beamforming method, the complexity of antenna implementation may not significantly increase even when a beamforming gain is increased. However, beamforming performance of a communication system using an analog beamforming method may be lower than beamforming performance of a communication system using a digital beamforming method. Also, since the phase shifter is adjusted in the time domain in a communication system using an analog beamforming method, frequency resources may not be efficiently used. Therefore, a hybrid beamforming method, which is a combination of a digital method and an analog method, may be used.

When cell coverage is increased by the use of the beamforming method, a common control channel and a common signal (eg, a reference signal, a synchronization signal) for all UEs belonging to the cell coverage as well as a control channel and a data channel of each of the UEs Also, it may be transmitted based on a beamforming scheme. In this case, a common control channel and a common signal for all terminals belonging to cell coverage may be transmitted based on a beam sweeping method.

In addition, in the NR system, SSB may also be transmitted in a beam sweeping scheme. SSB may mean a synchronization block/physical broadcast channel (SS/PBCH) block. The SSB may be composed of PSS, SSS, PBCH, etc., and within the SSB, the PSS, SSS, and PBCH may be composed of a time division multiplexing (TDM) method. One SSB may be transmitted using N consecutive OFDM symbols. Here, N may be an integer of 4 or greater. The base station may periodically transmit the SSB, and the terminal may obtain frequency/time synchronization, cell ID, system information, etc. based on the SSB received from the base station. SSB can be transmitted as follows.

5 is a conceptual diagram illustrating a first embodiment of a method for transmitting an SSB in a communication system.

Referring to FIG. 5, one or more SSBs within an SSB burst set may be transmitted in a beam sweeping manner. A maximum of L SSBs can be transmitted within one SSB burst set. L may be an integer of 2 or more and may be defined in the 3GPP standard. Depending on the system frequency range, L may vary. Within an SSB burst set, SSBs may be located contiguously or dispersively. Consecutive SSBs may be referred to as "SS/PBCH block burst" or "SSB burst". An SSB burst set may be repeated periodically, and system information (eg, MIB) transmitted through PBCHs of SSBs in the SSB burst set may be the same. SSB index, SSB burst index, OFDM symbol index, slot index, etc. may be explicitly or implicitly indicated by the PBCH.

6 is a conceptual diagram illustrating a first embodiment of an SSB in a communication system.

Referring to FIG. 6, the arrangement order in the SSB may be “PSS → PBCH → SSS → PBCH”. Within the SSB, PSS, SSS, and PBCH may be configured in a TDM manner. In the symbol where the SSS is located, the PBCH may be allocated to higher frequency resources and lower frequency resources than the SSS. If the maximum number of SSBs is 8 in a frequency band of 6 GHz or less, the SSB index can be identified based on a demodulation reference signal (DMRS) used for demodulation of the PBCH (hereinafter referred to as "PBCH DMRS"). If the maximum number of SSBs is 64 in a frequency band of 6 GHz or higher, among 6 bits representing the SSB index, LSB 3 bits can be identified based on the PBCH DMRS, and the remaining MSB 3 bits can be identified based on the PBCH payload. can

The maximum system bandwidth supportable in the NR system may be 400 MHz. The size of the maximum bandwidth supportable by the terminal may vary according to the capability of the terminal. Accordingly, the terminal may perform an initial access procedure (eg, an initial connection procedure) by using some of the system bandwidth of the NR system supporting wideband. In order to support access procedures of terminals supporting bandwidths of various sizes, SSBs can be multiplexed in the frequency axis within the system bandwidth of the NR system supporting wideband. In this case, the SSB may be transmitted as follows.

7 is a conceptual diagram illustrating a second embodiment of a SSB transmission method in a communication system.

Referring to FIG. 7 , a wideband component carrier (CC) may include a plurality of bandwidth parts (BWPs). For example, a wideband CC may include 4 BWPs. The base station may transmit the SSB in each of BWPs #0 to 3 belonging to the wideband CC. The terminal may receive the SSB from one or more BWPs of BWP #0 to 3, and may perform an initial access procedure using the received SSB.

After detecting the SSB, the UE may obtain system information (eg, remaining minimum system information (RMSI)), and may perform a cell access procedure based on the system information. RMSI may mean SIB1. RMSI may be transmitted through PDSCH scheduled by PDCCH. Configuration information of a control resource set (CORESET) through which a PDCCH including scheduling information of a PDSCH through which an RMSI is transmitted may be transmitted through a PBCH in the SSB. A plurality of SSBs may be transmitted in the entire system band, and one or more SSBs among the plurality of SSBs may be SSBs associated with RMSI. The remaining SSBs may not be associated with RMSI. SSB associated with RMSI may be defined as "cell defining SSB". The UE may perform a cell search procedure and an initial access procedure using the cell-defined SSB. An SSB not associated with RMSI (eg, another SSB) may be used for a synchronization procedure and/or a measurement procedure in a corresponding BWP. The BWP through which the SSB is transmitted may be limited to one or more BWPs within a wide bandwidth.

RMSI is “Acquisition of configuration information of CORESET from SSB (eg, PBCH) → Operation of detecting PDCCH based on configuration information of CORESET → Operation of obtaining scheduling information of PDSCH from PDCCH → Operation of receiving RMSI through PDSCH It can be obtained by performing "operation". Transmission resources of the PDCCH may be set by configuration information of CORESET. The RMSI CORESET mapping pattern can be defined as follows. RMSI CORESET may be a CORESET used for transmission and reception of RMSI.

8A is a conceptual diagram illustrating RMSI CORESET mapping pattern #1 in a communication system, FIG. 8B is a conceptual diagram illustrating RMSI CORESET mapping pattern #2 in a communication system, and FIG. 8C illustrates RMSI CORESET mapping pattern #3 in a communication system. It is a concept diagram.

Referring to FIGS. 8A to 8C , one RMSI CORESET mapping pattern among RMSI CORESET mapping patterns #1-3 may be used, and detailed settings according to one RMSI CORESET mapping pattern may be completed. In RMSI CORESET mapping pattern #1, SSB, CORESET (eg, RMSI CORESET), and PDSCH (eg, RMSI PDSCH) may be configured in a TDM manner. RMSI PDSCH may mean a PDSCH through which RMSI is transmitted. In RMSI CORESET mapping pattern #2, CORESET (eg, RMSI CORESET) and PDSCH (eg, RMSI PDSCH) may be set in a TDM manner, and PDSCH (eg, RMSI PDSCH) is SSB and FDM (eg, RMSI PDSCH). frequency division multiplexing) method. In RMSI CORESET mapping pattern #3, CORESET (eg RMSI CORESET) and PDSCH (eg RMSI PDSCH) may be set in a TDM manner, and CORESET (eg RMSI CORESET) and PDSCH (eg RMSI CORESET) For example, RMSI PDSCH) may be configured in SSB and FDM schemes.

Only RMSI CORESET mapping pattern #1 can be used in a frequency band of 6 GHz or less. In frequency bands above 6 GHz, RMSI CORESET mapping patterns #1, #2, and #3 may all be used. The numerology of SSB may be different from that of "RMSI CORESET and RMSI PDSCH". Here, the numerology may be a subcarrier spacing. A combination of all numerologies can be used in RMSI CORESET mapping pattern #1. In RMSI CORESET mapping pattern #2, a combination of "SSB, RMSI CORESET/PDSCH = 120 kHz, 60 kHz or 240 kHz, 120 kHz" may be used. In RMSI CORESET mapping pattern #3, a combination of "SSN, RMSI CORESET/PDSCH = 120 kHz, 120 kHz" may be used.

One RMSI CORESET mapping pattern may be selected from among RMSI CORESET mapping patterns #1-3 according to a combination of the numerology of SSB and the numerology of RMSI CORESET/PDSCH. The setting information of RMSI CORESET may include table A and table B. Table A shows the number of RBs (resource blocks) of RMSI CORESET, the number of symbols of RMSI CORESET, and the RBs of SSB (eg, start RB or end RB) and RBs (eg, start RB or end RB) of RMSI CORESET. ) may indicate an offset between them. Table B may indicate the number of search space sets per slot in each of the RMSI CORESET mapping patterns, an offset of the RMSI CORESET, and an OFDM symbol index. Table B may indicate information for setting a monitoring occasion of the RMSI PDCCH. Each of Table A and Table B may be composed of a plurality of tables. For example, Table A may include Tables 13-1 to 13-8 specified in TS 38.213, and Table B may include Tables 13-9 to 13-13 specified in TS 38.213. The size of each of Table A and Table B may be 4 bits.

In the NR system, PDSCH may be mapped to the time domain according to PDSCH mapping type A or B. PDSCH mapping types A and B may be defined as shown in Table 5 below.

Type A (ie, PDSCH mapping type A) may be slot-based transmission. When type A is used, the position of the start symbol of the PDSCH may be set to one of {0, 1, 2, 3}. When type A and normal CP are used, the number of symbols constituting the PDSCH (eg, the duration of the PDSCH) may be set to one value from 3 to 14 within a symbol boundary. Type B (ie, PDSCH mapping type B) may be non slot-based transmission. When type B is used, the position of the start symbol of the PDSCH may be set to one of 0 to 12. When type B and normal CP are used, the number of symbols constituting the PDSCH (eg, the duration of the PDSCH) may be set to one of {2, 4, 7} within a symbol boundary. A DMRS (hereinafter referred to as "PDSCH DMRS") for demodulation of PDSCH (eg, data) may be determined based on a PDSCH mapping type (eg, type A or type B) and an ID indicating a length. ID may be defined differently according to the PDSCH mapping type.

Meanwhile, NR-U (unlicensed) is being discussed at the NR standardization meeting. The NR-U system can increase network capacity by improving utilization of limited frequency resources. An NR-U system may support operation in an unlicensed band (eg, unlicensed spectrum).

In the NR-U system, the terminal can determine whether a signal is transmitted from the corresponding base station based on a discovery reference signal (DRS) received from the base station as in the general NR system. In the NR-U system in Stand-Alone (SA) mode, the UE may obtain synchronization and/or system information based on DRS. In the NR-U system, DRS may be transmitted according to the regulations of the unlicensed band (eg, transmission band, transmission power, transmission time, etc.). For example, according to Occupied Channel Bandwidth (OCB) regulations, a signal may be configured and/or transmitted to occupy 80% of the entire channel bandwidth (eg, 20 MHz).

In the NR-U system, a communication node (eg, a base station or a terminal) may perform Listen Before Talk (LBT) before transmitting signals and/or channels for coexistence with other systems. The signal may be a synchronization signal, a reference signal (eg, DRS, DMRS, channel state information (CSI)-RS, phase tracking (PT)-RS, sounding reference signal (SRS)), and the like. The channel may be a downlink channel, an uplink channel, a sidelink channel, and the like. In embodiments, signal may mean "signal", "channel", or "signal and channel". LBT may be an operation for checking whether a signal is transmitted by another communication node. If it is determined that there is no transmission signal by the LBT (eg, if the LBT is successful), the communication node may transmit a signal in the unlicensed band. If it is determined that the transmission signal exists by the LBT (eg, if the LBT fails), the communication node may not be able to transmit a signal in the unlicensed band. The communication node may perform LBT according to various categories before transmission of a signal. The category of LBT may vary depending on the type of transmission signal.

Meanwhile, NR V2X (vehicular to everything) communication technology is being discussed at the NR standardization meeting. NR V2X communication technology may be a technology that supports communication between vehicles, communication between vehicles and infrastructure, and communication between vehicles and pedestrians based on device to device (D2D) communication technology.

NR V2X communication (eg, sidelink communication) is performed according to three transmission schemes (eg, unicast scheme, broadcast scheme, groupcast scheme) can When the unicast method is used, a PC5-RRC connection may be established between a first terminal (eg, a transmitting terminal for transmitting data) and a second terminal (eg, a receiving terminal for receiving data), The PC5-RRC connection may mean a logical connection for a pair between a source ID of a first terminal and a destination ID of a second terminal. The first terminal may transmit data (eg, sidelink data) to the second terminal. When a broadcast method is used, the first terminal may transmit data to all terminals. When a groupcast method is used, the first terminal may transmit data to a group (eg, a groupcast group) composed of a plurality of terminals.

When the unicast method is used, the second terminal may transmit feedback information (eg, acknowledgment (ACK) or negative ACK (NACK)) for data received from the first terminal to the first terminal. In the following embodiments, the feedback information may be referred to as "HARQ-ACK", "feedback signal", "physical sidelink feedback channel (PSFCH) signal", and the like. When an ACK is received from the second terminal, the first terminal may determine that data has been successfully received from the second terminal. When a NACK is received from the second terminal, the first terminal may determine that the second terminal has failed to receive data. In this case, the first terminal may transmit additional information to the second terminal based on a hybrid automatic repeat request (HARQ) scheme. Alternatively, the first terminal can improve the probability of receiving data from the second terminal by retransmitting the same data to the second terminal.

When a broadcast method is used, a procedure for transmitting feedback information about data may not be performed. For example, the system information may be transmitted in a broadcast manner, and the terminal may not transmit feedback information on the system information to the base station. Accordingly, the base station may not know whether system information has been successfully received from the terminal. To solve this problem, the base station may periodically broadcast system information.

When a groupcast method is used, a procedure for transmitting feedback information about data may not be performed. For example, necessary information may be periodically transmitted in a group cast method without a transmission procedure of feedback information. However, the target and/or number of terminals participating in communication based on the group cast method is limited, and the data transmitted by the group cast method is data that must be received within a preset time (eg, delay-sensitive data). In this case, a transmission procedure of feedback information may be required even in groupcast sidelink communication. Groupcast sidelink communication may refer to sidelink communication performed in a groupcast manner. When a transmission procedure of feedback information is performed in groupcast sidelink communication, data can be transmitted and received efficiently and stably.

In groupcast sidelink communication, two HARQ-ACK feedback schemes (ie, feedback information transmission procedures) can be supported. If "the number of receiving terminals in the sidelink group is large and service scenario 1 is supported", some receiving terminals belonging to a specific range in the sidelink group may transmit NACK through PSFCH when data reception fails. This method may be "groupcast HARQ-ACK feedback option 1". In service scenario 1, it may be allowed for some receiving terminals belonging to a specific range to receive in a best-effort manner instead of all receiving terminals in a sidelink group. Service scenario 1 may be an extended sensor scenario in which some receiving terminals belonging to a specific range need to receive the same sensor information from a transmitting terminal. In embodiments, a transmitting terminal may refer to a terminal transmitting data, and a receiving terminal may refer to a terminal receiving data.

"If the number of receiving terminals in the sidelink group is limited and service scenario 2 is supported", all receiving terminals belonging to the sidelink group may individually report HARQ-ACK for data through a separate PSFCH. there is. This method may be "groupcast HARQ-ACK feedback option 2". In service scenario 2, since PSFCH resources are sufficient, the transmitting terminal can monitor the HARQ-ACK feedback of all receiving terminals belonging to the sidelink group, and data reception is guaranteed by all receiving terminals belonging to the sidelink group. It can be.

In addition, data reliability in the receiving terminal can be improved by appropriately adjusting the power of the transmitting terminal according to the transmission environment. Interference to other terminals can be mitigated by appropriately adjusting the power of the transmitting terminal. Energy efficiency can be improved by reducing unnecessary transmission power. Power control schemes can be classified into open-loop power control schemes and closed-loop power control schemes. In the open-loop power control scheme, a transmitting terminal may determine transmission power in consideration of settings and measured environments. In the closed-loop power control scheme, a transmitting terminal may determine transmit power based on a transmit power control (TPC) command received from a receiving terminal.

Predicting the received signal strength at the receiving terminal may be difficult due to various causes including multi-path fading channels, interference, and the like. Therefore, the receiving terminal can adjust the received power level (eg, the received power range) by performing an automatic gain control (AGC) operation to prevent quantization errors of the received signal and maintain appropriate received power. In a communication system, a terminal may perform an AGC operation using a reference signal received from a base station. However, in sidelink communication (eg, V2X communication), the reference signal may not be transmitted from the base station. That is, communication between terminals may be performed without a base station in sidelink communication. Therefore, it may be difficult to perform an AGC operation in sidelink communication. In sidelink communication, a transmitting terminal may first transmit a signal (eg, a reference signal) to a receiving terminal before transmission of data, and the receiving terminal performs an AGC operation based on a signal received from the transmitting terminal to range the received power. (eg, received power level) may be adjusted. After that, the transmitting terminal may transmit sidelink data to the receiving terminal. A signal used for the AGC operation may be a duplicated signal for a signal to be transmitted later or a preset signal between terminals.

A time interval required for the AGC operation may be 15 μs. When the subcarrier interval is 15 kHz in the NR system, the time interval (eg, length) of one symbol (eg, OFDM symbol) may be 66.7 μs. When the subcarrier interval is 30 kHz in the NR system, the time interval of one symbol (eg, OFDM symbol) may be 33.3 μs. In the following embodiments, a symbol may mean an OFDM symbol. That is, the time interval of one symbol may be twice or more than the time interval necessary for the AGC operation.

For sidelink communication, transmission of a data channel for data transmission and a control channel including scheduling information for data resource allocation may be required. In sidelink communication, the data channel may be PSSCH (Physical Sidelink Shared CHannel), and the control channel may be PSCCH (Physical Sidelink Control CHannel). Data channels and control channels may be multiplexed in resource domains (eg, time and frequency resource domains).

9 is a conceptual diagram illustrating embodiments of a method of multiplexing a control channel and a data channel in sidelink communication.

Referring to FIG. 9 , sidelink communication may support option 1A, option 1B, option 2, and option 3. When Option 1A and/or Option 1B are supported, the control and data channels may be multiplexed in the time domain. If option 2 is supported, the control channel and data channel can be multiplexed in the frequency domain. If option 3 is supported, the control and data channels can be multiplexed in the time and frequency domains. Sidelink communication may basically support option 3.

In sidelink communication (eg, NR-V2X sidelink communication), a basic unit of resource configuration may be a subchannel. A subchannel can be defined with time and frequency resources. For example, a subchannel may consist of a plurality of symbols (eg, OFDM symbols) in the time domain and may consist of a plurality of resource blocks (RBs) in the frequency domain. A subchannel may be referred to as an RB set. Within a subchannel, data channels and control channels can be multiplexed based on option 3.

In sidelink communication (eg, NR-V2X sidelink communication), transmission resources may be allocated based on mode 1 or mode 2. When mode 1 is used, the base station may allocate sidelink resources for data transmission to the transmitting terminal within a resource pool, and the transmitting terminal receives data using the sidelink resources allocated by the base station. can be transmitted to the terminal. Here, the transmitting terminal may be a terminal transmitting data in sidelink communication, and the receiving terminal may be a terminal receiving data in sidelink communication.

When mode 2 is used, the transmitting terminal can autonomously select a sidelink resource to be used for data transmission by performing a resource sensing operation and/or a resource selection operation within a resource pool. The base station may configure a resource pool for mode 1 and a resource pool for mode 2 in the terminal(s). The resource pool for mode 1 can be set independently of the resource pool for mode 2. Alternatively, a common resource pool may be configured for mode 1 and mode 2.

When mode 1 is used, the base station may schedule resources used for sidelink data transmission to the transmitting terminal, and the transmitting terminal may transmit sidelink data to the receiving terminal using resources scheduled by the base station. Therefore, resource collision between terminals can be prevented. When mode 2 is used, the transmitting terminal can select an arbitrary resource by performing a resource sensing operation and/or a resource selection operation, and can transmit sidelink data using the selected arbitrary resource. Since the above-described procedure is performed based on an individual resource sensing operation and/or resource selection operation of each transmitting terminal, collision between selected resources may occur.

A sidelink communication system supporting Rel-16 can be designed for terminals (eg, terminals mounted in automobiles, vehicle UEs (V-UEs)) that are not significantly limited in battery capacity. Therefore, the power saving issue may not be greatly considered in the resource sensing/selection operation of the terminal. In a sidelink communication system supporting Rel-17, a terminal with restrictions on battery capacity (e.g., a terminal carried by a pedestrian, a terminal mounted on a bicycle, a terminal mounted on a motorcycle, a P-UE (pedestrian UE)) ), power saving methods will be needed. In the present application, a V-UE may mean a terminal that is not significantly limited in battery capacity, a P-UE may mean a terminal with limitations on battery capacity, and "resource sensing/selection operation" means "resource sensing/selection operation" A sensing operation and/or a resource selection operation" may be included. A resource sensing operation may mean a partial sensing operation or a full sensing operation. The resource selection operation may mean a random selection operation. Also, in the present application, "operation of UE" may be interpreted as "operation of V-UE" and/or "operation of P-UE".

For power saving in LTE V2X, partial sensing operation and / or random selection operation may be introduced. When the partial sensing operation is supported, the terminal may perform the resource sensing operation in a partial interval instead of the entire interval within the sensing window and select a resource based on the result of the partial sensing operation. According to this operation, power consumption of the terminal can be reduced. When a random selection operation is supported, the terminal may randomly select a resource without performing a resource sensing operation. Alternatively, the random selection operation may be performed together with the resource sensing operation. For example, the terminal may determine resources by performing a resource sensing operation, and may select resource(s) by performing a random selection operation within the determined resources.

In LTE V2X supporting Rel-14, a resource pool capable of performing a partial sensing operation and/or a random selection operation may be set independently of a resource pool capable of performing a complete sensing operation. A resource pool capable of performing a random selection operation, a resource pool capable of performing a partial sensing operation, and a resource pool capable of performing a complete sensing operation may be independently set. The terminal may select a resource by performing a random selection operation, a partial sensing operation, and/or a complete sensing operation in the resource pool. The terminal may select one operation from among the random selection operation and the partial sensing operation, select a resource by performing the selected operation, and perform sidelink communication using the selected resource.

In LTE V2X supporting Rel-14, sidelink (SL) data may be transmitted periodically based on a broadcast method. In the NR communication system, SL data may be transmitted based on a broadcast method, a multicast method, a groupcast method, or a unicast method. Also, in the NR communication system, SL data may be transmitted periodically or aperiodically. The transmitting terminal may transmit SL data to the receiving terminal, and the receiving terminal may transmit HARQ feedback (eg, ACK or NACK) for the SL data to the transmitting terminal through the PSFCH. In the present application, a transmitting terminal may mean a terminal transmitting SL data, and a receiving terminal may mean a terminal receiving SL data.

A terminal having reduced capability (hereinafter, referred to as a "RedCap terminal") may operate in a specific use environment. The capability of a RedCap terminal may be lower than that of a new radio (NR) normal terminal, and LTE-machine type communication (MTC) terminals, narrow band (NB)-internet of things (IoT) terminals, and LPWA (Low Power Wide Area) terminals. For example, a terminal requiring "high data rate and low latency conditions" (eg, a surveillance camera) and/or "low data rate, high latency conditions, and high reliability ( A terminal (eg, a wearable device) requiring "reliability" may exist. To support the aforementioned terminals, the maximum carrier bandwidth in FR1 may be reduced from 100 MHz to 20 MHz, and the maximum carrier bandwidth in FR2 may be reduced from 400 MHz to 100 MHz. The number of Rx antennas of the Redcap UE may be smaller than the number of Rx antennas of the NR general UE. When the carrier bandwidth and the number of receiving antennas decrease, reception performance of the RedCap terminal may decrease, and thus, coverage of the RedCap terminal may decrease.

Next, communication methods will be explained. Even when a method (for example, transmission or reception of a signal) performed in a first communication node among communication nodes is described, a second communication node corresponding thereto is described as a method performed in the first communication node and a method (eg, signal transmission or reception) For example, receiving or transmitting a signal) may be performed. For example, when an operation of a terminal is described, a base station corresponding thereto may perform an operation corresponding to the operation of the terminal. Conversely, when the operation of the base station is described, a terminal corresponding thereto may perform an operation corresponding to the operation of the base station.

In a communication system (eg, NR system, 6G system), the 52.6 GHz frequency band may be extended. FR2 can be classified into FR2-1 and FR2-2. The 24.25 to 52.6 GHz frequency band may be defined as FR2-1, and the 52.6 to 71 GHz frequency band may be defined as FR2-2. As the frequency band in which a communication system operates increases, a frequency offset error and phase noise may increase. The use of a large SCS may be necessary for robust operation in these environments. In the FR2-1 band, 60 kHz SCS and/or 120 kHz SCS may be supported, and additionally 480 kHz SCS and/or 960 kHz SCS may be supported. Also, "physical layer signal and channel design" and "physical layer procedure" according to the new SCS may be required. Regarding the initial access procedure, 120 kHz SSB and / or 240 kHz SSB may be supported in the FR2-1 band, and 120 kHz SSB and / or 480 kHz SSB may be supported in the FR2-2 band. Here, the 480 kHz SSB may mean an SSB transmitted in a radio resource to which a 480 kHz SCS is applied. To support the new SCS, "initial BWP configuration method", "initial access related signal and channel design method", and "initial access procedure" may be necessary.

As various services requiring high data transmission rates are required, the need for a broadband system (eg, a communication system supporting broadband) is increasing. The need for a communication system supporting a frequency band higher than FR2-2 is increasing. Since relatively available frequency resources are abundant in a high frequency band, a wide system bandwidth can be supported. If it is possible to simultaneously transmit a plurality of beams using a plurality of panels in a communication system supporting a wide band, the initial access time and/or measurement time of the terminal may be reduced by transmitting a plurality of SSBs in the frequency domain. can It is necessary to newly define the initial access procedure and/or measurement procedure considering this.

As in the above-described embodiment of FIG. 7, when a base station transmits a plurality of SSBs in the frequency domain in a wideband system (ie, when a plurality of SSBs are multiplexed in the frequency domain), the terminal associates with the RMSI among the plurality of SSBs An initial access procedure may be performed using the configured SSB (eg, cell defining SSB). When an SSB other than the cell-defined SSB is detected, the UE determines that "the detected SSB is not the cell-defined SSB" and "the frequency at which the cell-defined SSB is transmitted" based on the information of the PBCH payload of the detected SSB. Additional information about the location". Therefore, the UE can find the cell definition SSB. Other SSB(s) may be used for a “time and/or frequency synchronization acquisition procedure” and/or “measurement procedure” in a corresponding frequency band (eg, a frequency band in which the other SSB(s) are detected). Another SSB may be a non-cell defined SSB.

10 is a conceptual diagram illustrating a first embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.

Referring to FIG. 10, SSBs having the same beam pattern may be multiplexed in the frequency domain. A beam pattern may refer to a pattern of a beam used for transmission of a signal and/or channel. In sync rasters #0 to #3, the beam pattern may be "beam #0 → beam #1 → beam #2 → beam #3 → beam #4 → beam #5 → beam #6 → beam #7". SSBs having the same SSB index may be transmitted in the same time interval. For example, SSBs having SSB #0 may be transmitted in a first time interval, and SSBs having SSB #1 may be transmitted in a second time interval after the first time interval.

A base station may transmit a plurality of SSBs in the frequency domain of a wideband system. Different hatching applied to the SSB may mean different beams. SSBs to which the same hatching is applied may mean SSBs transmitted through the same beam. Each of the sync rasters #0 to #3 may be a frequency location at which the SSB can be transmitted. SSB(s) may be transmitted in sync rasters #0 to #3, respectively. SSBs transmitted in sync rasters #0 to #2 may be other SSBs (eg, non-cell defined SSBs). The SSB transmitted in sync raster #3 may be a cell-defined SSB used in an initial access procedure. The cell definition SSB may be associated with RMSI. The terminal may receive the cell-defined SSB, obtain system information through RMSI linked to the cell-defined SSB, and perform a procedure for initial access based on the system information.

The UE can detect other SSBs in synchronization rasters #0 to #2. The UE can know that the detected SSB is not the cell-defined SSB based on the PBCH payload information of the detected SSB, and the sync raster through which the cell-defined SSB is transmitted based on the PBCH payload information of the detected SSB. You can also get additional information to locate #3. Additional information for finding the location of synchronization raster #3 is accurate frequency location information, adjacent frequency location information (eg, GSCN (Global Synchronization Channel Number ), or specific frequency range information.

The cell definition SSB may be transmitted at a location of a preset synchronization raster. Other SSBs may be transmitted at any frequency location other than the sync raster. A plurality of SSBs transmitted in the frequency domain during the same time interval may all be transmitted in the same beam, and SSBs transmitted in different time intervals may be SSBs transmitted in different beams. For example, the transmission beam of the SSB in the first time interval may be different from the transmission beam of the SSB in the second time interval. When a base station can simultaneously transmit a plurality of beams (eg, different beams) using a plurality of panels, a plurality of SSBs simultaneously transmitted in the frequency domain may be transmitted through different beams. A UE supporting a reception operation in a wideband can simultaneously perform a reception operation for a plurality of SSBs transmitted through a plurality of beams in the frequency domain.

11 is a conceptual diagram illustrating a second embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.

Referring to FIG. 11, SSBs having different beam patterns may be multiplexed in the frequency domain. Beam patterns may be different from each other in sync rasters #0 to #3. For example, in sync raster #3, the beam pattern may be "Beam #0 → Beam #1 → Beam #2 → Beam #3 → Beam #4 → Beam #5 → Beam #6 → Beam #7", and sync In raster #2, the beam pattern may be “Beam #6 → Beam #7 → Beam #0 → Beam #1 → Beam #2 → Beam #3 → Beam #4 → Beam #5. That is, in sync rasters #3 and #2, beam #0 and beam #6 may be used during the first time interval, beam #1 and beam #7 may be used during the second time interval, and beam #2 and beam #2. #0 may be used during the third time interval.

The base station can simultaneously perform a transmission operation using a plurality of beams. The base station may transmit a plurality of SSBs using different beams in the frequency domain. Different hatching applied to the SSB may mean different beams. SSBs to which the same hatching is applied may mean SSBs transmitted through the same beam. A terminal capable of a receiving operation in a wideband can simultaneously receive a plurality of SSBs transmitted through different beams in the frequency domain. The UE may perform an initial access procedure using the cell-defined SSB. If multiple cell-defined SSBs are not transmitted in the frequency domain, it may be difficult to utilize the multiple cell-defined SSBs in the initial access procedure.

In the measurement procedure, the UE may measure signals (eg, SSBs) simultaneously received through a plurality of beams. Therefore, the execution time of the measurement procedure in the terminal can be shortened. However, when the same SSB index is mapped to different beams, ambiguity in the relationship between beams and SSBs may occur. Since the SSB index may indicate a location where the SSB is transmitted, the terminal may obtain time synchronization based on the SSB index. Since SSB (eg, SSB index) is mapped to a specific beam (eg, beam index), the SSB index may implicitly mean the index of a specific beam. However, in the embodiment of FIG. 11, a plurality of SSBs simultaneously transmitted through different beams in the frequency domain may all have the same SSB index. In this case, it may not be a problem for the terminal to acquire time synchronization using a plurality of SSBs. However, since "the same SSB index is mapped to different beams and information on beams is not separately defined", ambiguity in beam information acquisition may occur.

For example, since a beam transmitting SSB #0 transmitted in synchronization raster #0 during the first time interval is the same as a beam transmitting cell-defined SSB #2 transmitted in synchronization raster #3 during the third time interval, the UE It may be difficult to obtain beam information based on this SSB index. When the relationship between a beam applied to a cell-defined SSB and an SSB index is applied to an SSB transmitted in a different frequency location (eg, sync raster #0, #1, and/or #2), the UE receives beam information can be obtained without ambiguity. However, ambiguity about time information (eg, time synchronization) may occur in the terminal.

12 is a conceptual diagram illustrating a third embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.

Referring to FIG. 12, SSBs having different beam patterns and different SSB indices may be multiplexed in the frequency domain. Different hatching applied to the SSB may mean different beams. SSBs to which the same hatching is applied may mean SSBs transmitted through the same beam. The mapping relationship between the cell-defined SSB index and the beam may be applied to other SSBs transmitted in different frequency locations (eg, sync raster #0, #1, and/or #2). Since the mapping relationship between SSB indexes and beams detected at different frequency locations is the same as that between cell-defined SSB indexes and beams, ambiguity in beam information acquisition in the UE may not occur. However, ambiguity of time information (eg, time synchronization) may occur in the terminal.

For example, since the transmission beam of SSB #2 obtained from synchronization raster #0 during the first time interval is the same as the transmission beam of cell-defined SSB #2 obtained from synchronization raster #3 during the third time interval, the UE transmits the beam Ambiguity of information may not occur. SSB #2 in sync raster #0 and cell definition SSB #0 in sync raster #3 are transmitted over the same time resource (eg, time interval) in the time domain, but two SSBs (ie, SSB #2, SSB # 0) are different, so ambiguity of time information may occur in the terminal. In order to solve the above-described problem, an SSB candidate index indicating a location of an SSB in the time domain may be newly defined instead of an SSB index. The SSB index may be used to convey beam information, and the SSB candidate index may be used to convey time information.

The base station may signal information on a mapping relationship between an SSB candidate index and an SSB index for SSBs multiplexed in the frequency domain to the terminal. Information on a mapping relationship between an SSB candidate index and an SSB index may be referred to as "SSB mapping information" or "mapping relationship information". The terminal may receive information on the mapping relationship between the SSB candidate index and the SSB index (ie, SSB mapping information or mapping relationship information) from the base station, and based on the mapping relationship, "SSB candidate index mapped to the SSB index" and / or "SSB index mapped to SSB candidate index" can be checked. The UE may check beam information based on the SSB index and check time information (eg, time synchronization) based on the SSB candidate index.

13 is a conceptual diagram illustrating a fourth embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.

Referring to FIG. 13, SSBs having different beam patterns and the same SSB candidate index may be multiplexed in the frequency domain. The SSB candidate may be referred to as SSB C (candidate). Different hatching applied to the SSB may mean different beams. SSBs to which the same hatching is applied may mean SSBs transmitted through the same beam. The base station may define an SSB candidate index, and "information on a frequency location (eg, sync raster) at which the SSB is transmitted" and/or "a mapping relationship between the SSB candidate index and the SSB index according to the frequency location at which the SSB is transmitted" Information of (ie, SSB mapping information)" may be signaled to the UE. SSB mapping information may be defined for each frequency location. SSB mapping information may be transmitted through at least one of PBCH, RMSI, system information, or RRC message.

The terminal may receive "information on a frequency location where the SSB is transmitted" and/or "SSB mapping information" from the base station. The terminal may receive the SSB from the base station, check the SSB candidate index for the corresponding SSB based on the PBCH DMRS and PBCH payload included in the SSB, and the SSB index mapped to the SSB candidate index based on the SSB mapping information. can be checked. The UE may check beam information (eg, an index of a beam used for transmission of the corresponding SSB) based on the SSB index, and obtain time information (eg, time synchronization) based on the SSB candidate index. can

The SSB candidate index may be defined based on a transmission position in the time domain (eg, a time interval in which the SSB is transmitted) regardless of a frequency position in the frequency domain. For example, an SSB transmitted first in the time domain (eg, an SSB transmitted during the first time interval) may have SSB candidate #0, and SSB candidate indices of SSBs transmitted thereafter are sequentially transmitted in the transmission order. Accordingly, SSB candidates #1, #2, #3, and #4 may be defined. The base station may signal SSB mapping information for each frequency location (eg, sync raster) where the SSB is transmitted to the terminal. For example, the base station has SSB mapping information #0 for synchronization raster #0, SSB mapping information #1 for synchronization raster #1, SSB mapping information #2 for synchronization raster #2, and SSB for synchronization raster #3. Mapping information #3 may be signaled to the terminal.

SSB candidate indexes of all SSBs transmitted during the first time interval in the time domain may be defined as 0. An SSB index mapped to SSB candidate index = 0 in sync raster #0 may be 2. That is, a mapping relationship of [SSB C #0, SSB #2] in sync raster #0 may be defined. An SSB index mapped to SSB candidate index = 0 in sync raster #1 may be 4. That is, a mapping relationship of [SSB C #0, SSB #4] in sync raster #1 may be defined. An SSB index mapped to SSB candidate index = 0 in sync raster #2 may be 6. That is, a mapping relationship of [SSB C #0, SSB #6] in sync raster #2 may be defined. The base station may signal the above-described mapping relationship information (ie, SSB mapping information) to the terminal.

The UE may receive (eg, detect) the SSB from the base station, and check the SSB candidate index of the corresponding SSB based on the PBCH DMRS and PBCH payload of the corresponding SSB. A method of checking the SSB candidate index may be the same as or similar to the method of checking the SSB index. The UE may check an SSB index mapped to an SSB candidate index based on SSB mapping information (eg, SSB mapping information for each frequency location). The terminal may obtain time information based on the SSB candidate index, and may obtain beam information (eg, beam information for each frequency location) based on the SSB index. For example, the UE may detect SSB C #0 in sync raster #0, and may check an SSB index (eg, SSB #2) mapped to SSB C #0 based on the SSB mapping information. The UE may obtain beam information (eg, a beam index) based on SSB #2 and time synchronization based on SSB C #0.

The base station may signal only information on the mapping relationship between the SSB candidate index (eg, SSB C # 0) of the SSB located in the first time interval of the time domain and the SSB index to the terminal. The terminal may obtain information on the above-described mapping relationship from the base station, and may check an SSB index mapped to an SSB candidate index by applying the above-described mapping relationship to SSBs sequentially received in the time domain. According to the method described above, signaling overhead for information on a mapping relationship between an SSB candidate index and an SSB index (ie, SSB mapping information) can be reduced.

When information on the mapping relationship of [SSB C #0, SSB #2] in sync raster #0 is signaled to the UE, the UE applies the above-described mapping relationship to the SSBs received in sync raster #0 to [SSB C # 2]. 1, SSB #3, mapping relationship of [SSB C #2, SSB #4], mapping relationship of [SSB C #3, SSB #5], etc. can be checked. To support the above-described operation, it may be desirable for the base station to appropriately allocate beams in the time and/or frequency domain. In order to provide the base station with a degree of freedom in beam arrangement, a signaling operation of information on mapping relationships between all SSB candidate indices and all SSB indices at each frequency location may be required. In this case, signaling overhead for information on the above-described mapping relationships may greatly increase.

An SSB candidate index and an SSB index can always be defined to have the same value at a frequency location where the cell-defined SSB is transmitted (eg, sync raster # 3), and the base station is an SSB other than the cell-defined SSB (eg, Information on a mapping relationship between an SSB candidate index and an SSB index may be signaled to the UE at a frequency location where a non-cell defined SSB) is transmitted. That is, the base station may not signal information on the mapping relationship between the SSB candidate index and the SSB index to the terminal at a frequency location where the cell-defined SSB is transmitted. According to the method described above, a UE performing an initial access procedure based on a cell-defined SSB can correctly obtain time information and/or beam information based on a detected SSB index without receiving additional signaling.

As another method of signaling "information on the frequency location where the SSB is transmitted" and/or "information on the mapping relationship between the SSB candidate index and the SSB index according to the frequency location", the base station provides information on the number of beams in the frequency domain (eg, , information on the number of beams multiplexed in the frequency domain), information on the number of all beams (eg, information on the number of all beams used for transmission of SSBs), an offset of an SSB index, or an offset application method (eg, At least one of information in descending order or ascending order based on frequency location) may be signaled to the terminal. The terminal may receive the above-described information from the base station.

In the embodiment of FIG. 13, the total number of beams may be 8, the number of beams multiplexed in the frequency domain among the 8 beams may be 4, the offset of the SSB index may be 6, and the offset of the SSB index may be may be applied in descending order in the frequency domain. The above information may be signaled from the base station to the terminal. In this case, the SSB candidate index and the SSB index may be the same at a frequency location (eg, synchronization raster #3) where the cell-defined SSB is transmitted. An SSB index at a frequency location (eg, sync raster #0, #1, and/or #2) where another SSB (eg, non-cell defined SSB) is transmitted may be determined based on Equation 1 below. there is. In Equation 1, n may be an integer greater than or equal to 0.

For example, based on Equation 1, the SSB index corresponding to SSB C #0 in sync raster #2 may be SSB #6, which is the result of ((SSB #0 + 6) mod 8). Based on Equation 1, the SSB index corresponding to SSB C #0 in sync raster #1 may be SSB #4, which is the result of ((SSB #6 + 6) mod 8). Based on Equation 1, the SSB index corresponding to SSB C #0 in sync raster #0 may be SSB #2, which is the result of ((SSB #4 + 6) mod 8).

"Information on a frequency location through which SSB is transmitted" and/or "SSB mapping information" may be transmitted to the terminal through at least one of PBCH, RMSI, and other system information. Alternatively, the base station may transmit an RRC message (eg, UE-specific RRC message) including "information on a frequency location through which SSB is transmitted" and/or "SSB mapping information" to the terminal. The aforementioned beam information (or beam number information) is quasi-colocation (QCL) information (eg, QCL number information, QCL value information, and/or beam number information) and/or spatial relationship (or information on the number of spatial relationships).

In the above embodiments, some SSBs may not actually be transmitted. Even in this case, it may be desirable to continuously apply the SSB candidate index and the SSB index as they are. In the above-described embodiment, the frequency position at which the SSB is transmitted has been described as a sync raster, but the frequency position at which the SSB is transmitted may not be limited to the sync raster. Since another SSB (eg, non-cell defined SSB) can be transmitted at an arbitrary frequency position, the information of the frequency position is ARFCN (Absolute Radio Frequency Channel Number) instead of GSCN (Global Synchronization Channel Number), which is synchronization raster information. ) can be.

In the above-described embodiments, a procedure for obtaining and/or measuring precise time and frequency synchronization using a plurality of SSBs transmitted through different beams in the frequency domain has been described. According to the above-described embodiments, the delay time can be reduced. When a plurality of cell-defined SSBs are transmitted in the frequency domain (eg, when a plurality of cell-defined SSBs are multiplexed in the frequency domain), the UE performs a cell search procedure and/or initial access based on the plurality of cell-defined SSBs. procedure can be performed. In this case, the delay time in the cell search procedure and/or initial access procedure may be reduced. When the cell-defined SSB is transmitted, the RMSI linked to the cell-defined SSB may be transmitted. Accordingly, when a plurality of cell-defined SSBs are transmitted in the frequency domain, the base station may transmit a plurality of RMSIs associated with the plurality of cell-defined SSBs in the frequency domain. A plurality of RMSIs may be multiplexed in the frequency domain.

14 is a conceptual diagram illustrating a method for transmitting and receiving a plurality of SSBs in a frequency domain according to a fifth embodiment, and FIG. 15 is a conceptual diagram illustrating a method for transmitting and receiving a plurality of SSBs in a frequency domain according to a sixth embodiment.

Referring to FIGS. 14 and 15 , different hatching applied to SSBs may mean different beams. SSBs to which the same hatching is applied may mean SSBs transmitted through the same beam. In the embodiment of FIG. 14 , a plurality of cell-defined SSBs having the same beam pattern may be multiplexed in the frequency domain, and a plurality of RMSIs linked to the plurality of cell-defined SSBs may be transmitted. In the embodiment of FIG. 15 , a plurality of cell-defined SSBs having different beam patterns may be multiplexed in the frequency domain, and a plurality of RMSIs linked to the plurality of cell-defined SSBs may be transmitted.

In the embodiment of FIG. 14, since a plurality of cell-defined SSBs are simultaneously transmitted through the same beam in the frequency domain, the terminal can perform an initial access procedure using any cell-defined SSB among the plurality of cell-defined SSBs. In this case, the delay time reduction effect in the initial access procedure and/or measurement procedure may not be large. In the embodiment of FIG. 15, a plurality of cell-defined SSBs can be simultaneously transmitted through different beams in the frequency domain, and a delay time can be greatly reduced in a terminal capable of receiving a plurality of cell-defined SSBs in different beams. . In this case, since the same SSB index is mapped to different beams as in the embodiment of FIG. 11 , ambiguity may occur in a relationship between a beam and an SSB index.

In general, since the SSB index indicates the location where the SSB is transmitted, the UE can obtain time synchronization based on the SSB index. Since an SSB index is generally mapped to a specific beam, the SSB index may indicate an index for a specific beam. However, in the embodiment of FIG. 11, since a plurality of SSBs multiplexed in the frequency domain all have the same SSB index and the plurality of SSBs are transmitted through different beams, ambiguity regarding beam information may occur in the terminal. That is, the terminal can obtain time information based on the same SSB index of a plurality of SSBs, but when the same SSB index is mapped to different beams and the beam information is not separately defined, the ambiguity of the beam information can happen

For example, in the embodiment of FIG. 15, since the transmission beam of SSB #0 in sync raster #0 during the first time interval is the same as the transmission beam of cell definition SSB #2 in sync raster #3 during the third time interval, It may be difficult to obtain beam information based on the SSB index. When the relationship between the beam and the SSB index applied to the cell-defined SSB is applied to an SSB transmitted in a different frequency location (eg, a non-cell-defined SSB), the terminal can obtain beam information without ambiguity, but the terminal Ambiguity of time information may occur. When a plurality of cell-defined SSBs and a plurality of RMSIs associated with the plurality of cell-defined SSBs are transmitted together, transmission overhead may greatly increase. Therefore, resources may not be utilized efficiently.

When a plurality of cell-defined SSBs are transmitted in the frequency domain for efficient resource utilization, a cell-defined SSB transmitted at a specific frequency location among the plurality of cell-defined SSBs may be defined as a reference cell-defined SSB. The base station can only transmit RMSI associated with the reference cell definition SSB. That is, the base station may not transmit the RMSI associated with a cell-defined SSB other than the reference cell-defined SSB. A cell definition SSB that is not a reference cell definition SSB may be referred to as a non-reference cell definition SSB. A mapping relationship between the reference cell definition SSB and the non-reference cell definition SSB may be configured, and the base station may signal information of the above-described mapping relationship to the terminal. The UE may receive information on a mapping relationship between a reference cell definition SSB and a non-reference cell definition SSB from the base station.

The UE may receive the non-reference cell definition SSB from the base station, check the reference cell definition SSB mapped to the non-reference cell definition SSB based on the mapping relationship, and receive the RMSI associated with the reference cell definition SSB from the base station can receive In order to support the above-described operation, as in the embodiment of FIG. 13, the base station may define an SSB candidate index, and "information on the location of a frequency at which the SSB is transmitted" and/or "SSB according to the location of a frequency at which the SSB is transmitted" "Information on the mapping relationship between the candidate index and the SSB index" may be additionally signaled to the UE. When the non-reference cell definition SSB is received, the UE can check the location of the reference cell definition SSB index mapped to the non-reference cell definition SSB index based on the above-described mapping relationship. For example, the UE can identify the location of the reference cell definition SSB having the same index as the non-reference cell definition SSB index based on the mapping relationship. The UE may receive the RMSI linked to the identified reference cell definition SSB, and may perform an additional initial access procedure based on the RMSI.

16 is a conceptual diagram illustrating a seventh embodiment of a method for transmitting and receiving a plurality of SSBs in the frequency domain.

Referring to FIG. 16, a plurality of cell-defined SSBs (eg, reference cell-defined SSB(s) and non-reference cell-defined SSB(s)) having different beam patterns and the same SSB candidate index are in the frequency domain. can be multiplexed. Different hatching applied to the SSB may mean different beams. SSBs to which the same hatching is applied may mean SSBs transmitted through the same beam. Same as or similar to the embodiment of FIG. 13 , the base station may transmit a plurality of SSBs (eg, a plurality of cell-defined SSBs) in the frequency domain. The base station may define an SSB candidate index (eg, SSB candidate #0) from the first SSB in the time domain regardless of the frequency location, and mapping between the SSB candidate index and the SSB index at the frequency location where the SSB is transmitted. Relationship information may be signaled to the terminal.

As a method of signaling information on a mapping relationship between an SSB candidate index and an SSB index, a base station may signal information on a mapping relationship between a first SSB candidate index and an SSB index at each frequency location to a UE. In this case, the terminal can check the SSB index by sequentially applying the mapping relation information received from the base station starting from the second SSB candidate index at each frequency location.

As another method of signaling information on the mapping relationship between the SSB candidate index and the SSB index, the base station provides information on the number of beams in the frequency domain (eg, information on the number of beams multiplexed in the frequency domain), information on the number of total beams, and SSB. At least one of an index offset or information on an offset application method (eg, application in descending order or application in ascending order) may be signaled to the terminal. The terminal can check the SSB index mapped to the SSB candidate index by performing a modulo operation (eg, the same or similar modulo operation as Equation 1) based on the information received from the base station.

Unlike the embodiment of FIG. 13, since a plurality of cell-defined SSBs are transmitted in the frequency domain, signaling may be required to inform whether the SSB(s) transmitted at which frequency location are the reference cell-defined SSB(s). . In the embodiment of FIG. 16, SSBs transmitted in sync raster #3 may be configured as reference cell-defined SSBs, and SSBs transmitted in sync rasters #0, #1, and #2 are non-reference cell-defined SSBs. can be set to The UE may attempt to receive a plurality of cell-defined SSBs in the frequency domain. When SSB C #0 is detected in sync raster #0, the UE can confirm that SSB C #0 is mapped to SSB #2 based on the mapping relationship between the SSB candidate index and the SSB index, and reference cell definition SSB #2 RMSI associated with can be received from the base station.

The RMSI may be transmitted based on a frequency location (eg, sync raster #3) at which the reference cell definition SSB is transmitted. That is, the RMSI will not be transmitted based on all frequency positions (eg, sync rasters #0 to #3) at which cell definition SSBs (eg, reference cell definition SSB and non-reference cell definition SSB) are transmitted. can The base station may signal information on the frequency location (eg, sync raster #3) at which the reference cell definition SSB is transmitted to the terminal. When it is confirmed that the index of the SSB received in sync raster #0 is SSB #2, the UE can receive RMSI #2 associated with SSB #2 in sync raster #3.

If the UE cannot receive a plurality of SSBs in the frequency domain, cell-defined SSBs are transmitted through all sync rasters, so the UE can perform an initial access procedure based on the cell-defined SSB received through any sync raster. can In order to utilize a plurality of SSBs in an initial access procedure, it may be desirable to transmit information on a reference cell definition SSB, information on a frequency location where the SSB is transmitted, and/or SSB mapping information through a PBCH payload. The base station may transmit information on the reference cell definition SSB, information on a frequency location where the SSB is transmitted, and/or SSB mapping information to the terminal through at least one of PBCH, RMSI, or other system information. Alternatively, the base station may transmit information on the reference cell definition SSB, information on the frequency location where the SSB is transmitted, and / or SSB mapping information to the terminal through an RRC message (eg, a UE-specific RRC message). . The information on the reference cell definition SSB may be an indication indicating whether the detected SSB corresponds to the reference cell definition SSB. Alternatively, the information on the reference cell-defined SSB may be information indicating whether the SSB received at a certain frequency position (eg, which sync raster) is the reference cell-defined SSB. Information on the reference cell definition SSB may be information on a frequency location at which the reference cell definition SSB is transmitted. Information on the reference cell definition SSB may be information of a mapping relationship between the reference cell definition SSB and the non-reference cell definition SSB.

When a base station can simultaneously perform a transmission operation using a plurality of beams, the base station can transmit a plurality of SSBs using different beams in the frequency domain. If the terminal can receive a plurality of SSBs through different beams in the wideband, the terminal can perform an initial access procedure using the plurality of cell-defined SSBs received from the base station. In this case, the delay time for the initial access procedure in the terminal may be reduced. Since the cell-defined SSB can be transmitted through an arbitrary sync raster (eg, arbitrary frequency position), if the location and/or number of sync rasters capable of transmitting the cell-defined SSB are not fixed within the wideband frequency domain, , UE complexity and delay time for the initial access procedure may increase.

When a secondary serving cell is added for an operation such as CA (carrier aggregation), the UE transmits information related to transmission of a plurality of SSBs in the frequency domain of the newly added secondary serving cell to the primary cell. ), and a delay time for cell search and time/frequency synchronization for adding a secondary cell (eg, secondary serving cell) can be reduced by utilizing the received information.

The above-described embodiments are "case in which a plurality of SSBs including one cell-defined SSB and one or more non-cell-defined SSBs are transmitted in the frequency domain" and/or "case in which a plurality of cell-defined SSBs are transmitted in the frequency domain" can be applied to In addition, the above-described embodiments may be applied not only to the above-described cases but also to "a case in which a plurality of cell-defined SSBs and a plurality of non-cell-defined SSBs are transmitted in the frequency domain". The above-described embodiments can be applied to the time domain considering Listen Before Talk (LBT) in an NR-U (unlicensed) system in combination with a method of setting a mapping relationship between an SSB candidate index and an SSB index.

When a plurality of SSBs are configured to be transmitted in the time domain, some SSBs among the plurality of SSBs may not actually be transmitted. In order to perform a rate-matching operation in a data reception procedure in a resource region where some SSBs are not actually transmitted, the base station transmits information on whether SSBs are actually transmitted through RMSI and / or UE-specific RRC signaling can be transmitted to the terminal. When a plurality of SSBs are transmitted not only in the time domain but also in the frequency domain, the base station can signal information on whether SSBs are actually transmitted in the time and frequency domains to the terminal. When the above-described information is transmitted through RMSI, information on whether the SSB is actually transmitted in the time domain in consideration of RMSI signaling overhead may be applied to the frequency domain in the same pattern.

The actual transmission pattern of the SSB in the time domain may be set (eg, signaled) based on the cell-defined SSB, and the actual transmission pattern is SSBs transmitted in different frequency locations (eg, non-cell-defined SSBs). ) can be equally applied. When a plurality of cell-defined SSBs are transmitted in the frequency domain, an actual transmission pattern of the SSB may be set (eg, signaled) based on a reference cell-defined SSB among the plurality of cell-defined SSBs, and the actual transmission pattern is It may be applied to cell defined SSBs and/or non-cell defined SSBs transmitted in different frequency locations. Even when information on whether the SSB is actually transmitted (eg, actual transmission pattern) is transmitted through UE-specific RRC signaling, the actual transmission pattern of the SSB is set based on the cell-defined SSB or the reference cell-defined SSB (eg, the actual transmission pattern) For example, signaling). A corresponding actual transmission pattern may be applied to SSBs transmitted in different frequency locations. An actual transmission pattern of the SSB may be transmitted at each of the frequency positions in consideration of SSBs transmitted at all frequency positions.

Methods according to the present application may be implemented in the form of program instructions that can be executed by various computer means and recorded on a computer readable medium. Computer readable media may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on a computer readable medium may be specially designed and configured for the present invention or may be known and usable to those skilled in computer software.

Examples of computer readable media include hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language codes that can be executed by a computer using an interpreter or the like as well as machine language codes generated by a compiler. The hardware device described above may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

Although described with reference to the above embodiments, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the present invention described in the claims below. You will be able to.

Claims (20)

As a terminal method,
Receiving a first SSB having a synchronization signal block (SSB) candidate #n from a base station during a first time interval at a first frequency location;
Receiving first mapping relationship information between an SSB candidate index and an SSB index from the base station;
checking SSB #k mapped to the SSB candidate #n based on the first mapping relationship information for the first frequency location;
obtaining time synchronization for the base station based on the SSB candidate #n; and
Acquiring beam information for the first frequency position based on the SSB #k,
Each of the n and the k is an integer greater than or equal to 0, the method of the terminal. The method of claim 1,
The method of the terminal,
receiving a second SSB having SSB candidate #n+1 from the base station during a second time interval at the first frequency location;
identifying SSB #k+1 mapped to the SSB candidate #n+1 based on the first mapping relationship information for the first frequency location;
obtaining time synchronization for the base station based on the SSB candidate #n+1; and
The method of the terminal further comprising obtaining beam information for the first frequency position based on the SSB #k+1. The method of claim 1,
The first mapping relationship information indicates a mapping relationship between the SSB candidate index of the SSB located at the front in the time domain and the SSB index. The method of claim 1,
The method of the terminal,
receiving a third SSB having the SSB candidate #n from the base station during the first time interval at a second frequency location;
Receiving second mapping relationship information between the SSB candidate index and the SSB index from the base station;
checking SSB #j mapped to the SSB candidate #n based on the second mapping relationship information for the second frequency location;
obtaining time synchronization for the base station based on the SSB candidate #n; and
Further comprising obtaining beam information for the second frequency position based on the SSB #j,
Wherein j is an integer greater than or equal to 0, the method of the terminal. The method of claim 4,
The first SSB and the third SSB are multiplexed in the frequency domain, and a first beam pattern used for transmission of SSBs at the first frequency location is a second beam used for transmission of SSBs at the second frequency location. A method of a terminal that is different from a pattern. The method of claim 1,
The SSB candidate #n is identified based on a physical broadcast channel (PBCH) demodulation reference signal (DMRS) and a PBCH payload included in the first SSB. The method of claim 1,
The first mapping relationship information is obtained through at least one of a PBCH, remaining minimum system information (RMSI), system information, or a radio resource control (RRC) message received from the base station. The method of claim 1,
The beam information means quasi-colocation (QCL) information. As a terminal method,
Receiving a first SSB having synchronization signal block (SSB) candidate #n from a base station during a first time interval at a first frequency location;
confirming that the SSB index of the SSB candidate #n is SSB #n at the first frequency location;
receiving a second SSB having the SSB candidate #n from the base station during the first time interval at a second frequency location;
Receiving first information indicating an offset of the SSB index and second information indicating the number of total beams used for transmission of SSBs from the base station; and
Checking SSB #k mapped to the SSB candidate #n of the second SSB at the second frequency location based on the SSB #n, the first information, and the second information;
Each of the n and the k is an integer greater than or equal to 0, the method of the terminal. The method of claim 9,
The SSB #k is a result of "(SSB #n + first information) mod second information". The method of claim 9,
The first SSB received at the first frequency location is a cell defining SSB, and an SSB candidate index of the cell defining SSB and the SSB index are set to the same value. The method of claim 9,
The first information and the second information are obtained through at least one of a physical broadcast channel (PBCH), a remaining minimum system information (RMSI), system information, or a radio resource control (RRC) message received from the base station. way of. The method of claim 9,
The method of the terminal,
Receiving at least one of third information indicating the number of beams multiplexed in the frequency domain or fourth information indicating an application method of the first information from the base station,
The fourth information indicates that the first information is applied in descending order or ascending order based on the frequency position. The method of claim 9,
The first SSB and the second SSB are multiplexed in a frequency domain, and a first beam pattern used for transmission of SSBs at the first frequency location is a second beam used for transmission of SSBs at the second frequency location. pattern, time synchronization for the base station is obtained based on the SSB candidate #n, beam information for the first frequency location is obtained based on the SSB #n, and beam information for the second frequency location is obtained. Information is obtained based on the SSB #k, the method of the terminal. As a base station method,
Transmitting a reference cell defining synchronization signal block (SSB) to a terminal during a first time interval at a first frequency location;
Transmitting a non-reference cell definition SSB to the terminal during the first time interval at a second frequency location;
Transmitting remaining minimum system information (RMSI) to the terminal based on the first frequency location; and
Transmitting information about the reference cell definition SSB to the terminal,
The RMSI is not transmitted based on one or more frequency positions in which the reference cell definition SSB is not transmitted. The method of claim 15
The information on the reference cell definition SSB is information indicating whether the SSB detected by the terminal corresponds to the reference cell definition SSB, and information indicating that the SSB detected at the first frequency location is the reference cell definition SSB. , or at least one of information of a mapping relationship between the reference cell definition SSB and the non-reference cell definition SSB. The method of claim 15
Information on the reference cell definition SSB is included in at least one of a physical broadcast channel (PBCH) transmitted from the base station, the RMSI, system information, or a radio resource control (RRC) message. The method of claim 15
The reference cell definition SSB and the non-reference cell definition SSB have the same SSB candidate index and different SSB indexes, the SSB candidate index is used to obtain time synchronization for the base station in the terminal, and the SSB index is the terminal A method of a base station used to obtain beam information for each frequency location in The method of claim 18
The method of the base station,
Further comprising transmitting mapping relationship information between the SSB candidate index and the SSB index to the terminal,
The SSB candidate index is identified based on a PBCH demodulation reference signal (DMRS) and a PBCH payload included in each of the reference cell definition SSB and the non-reference cell definition SSB, and based on the mapping relationship information for each frequency location The method of the base station in which the SSB index mapped to the SSB candidate index is checked. The method of claim 15
The reference cell definition SSB and the non-reference cell definition SSB are multiplexed in a frequency domain, and a first beam pattern used for transmission of reference cell definition SSBs at the first frequency location is non-referenced at the second frequency location. Different from the second beam pattern used for transmission of cell-defined SSBs, a method of a base station.

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