WO2019066575A1 - Method and apparatus for transmitting or receiving wireless signal in wireless communication system - Google Patents

Abstract

The present invention relates to a wireless communication system and, more specifically, provides a method and an apparatus therefor, the method comprising the steps of: detecting one or more SSBs in a cell; acquiring downlink synchronization on the basis of the one or more SSBs; and transmitting a RACH preamble by using a PRACH resource corresponding to the best SSB among the one or more SSBs, wherein the downlink synchronization is acquired on the basis of first SSB index information in each of the SSBs, and the PRACH resource is determined on the basis of second SSB index information configured for the best SSB by the cell.

Description

Method and apparatus for transmitting and receiving wireless signals in a wireless communication system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system, and more particularly, to a wireless signal transmission and reception method and apparatus.

Background of the Invention [0002] Wireless communication systems are widely deployed to provide various types of communication services such as voice and data. Generally, a wireless communication system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, a single carrier frequency division multiple access) systems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for efficiently performing a wireless signal transmission and reception process.

The technical problems to be solved by the present invention are not limited to the technical problems and other technical problems which are not mentioned can be understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a method for a UE to acquire downlink synchronization in a wireless communication system, the method comprising: detecting at least one Synchronization Signal Block (SSB) in a cell; Acquiring downlink synchronization based on the at least one SSB; And transmitting a RACH preamble using a Physical Random Access Channel (PRACH) resource corresponding to a best SSB among the one or more SSBs, wherein the downlink synchronization is acquired based on first SSB index information in each SSB , And the PRACH resource is determined by the cell based on second SSB index information set for the best SSB.

According to another aspect of the present invention, there is provided a terminal used in a wireless communication system, the terminal comprising: a Radio Frequency (RF) module; And a processor for detecting one or more SSB (Synchronization Signal Block) in the cell, acquiring downlink synchronization based on the one or more SSBs, and transmitting the PRACH corresponding to the best SSB among the one or more SSBs Wherein the downlink synchronization is obtained based on first SSB index information in each SSB, and the PRACH resource is set by the cell for the best SSB A terminal determined based on the second SSB index information is provided.

Preferably, the index value indicated by the first SSB index information may be different from the index value indicated by the second SSB index information for the best SSB.

Preferably, the at least one SSB includes a plurality of SSBs, and the plurality of first SSB index information in the plurality of SSBs may represent a plurality of continuous index values.

Preferably, the plurality of second SSB index information set for the plurality of SSBs may represent a plurality of discontinuous index values.

Preferably, each SSB includes a SS (Synchronization Signal), a PBCH (Physical Broadcast Channel), and a Demodulation Reference Signal (DMRS) for the PBCH, and the LSB (Least Significant Bit) Lt; RTI ID = 0.0 > DMRS. ≪ / RTI >

Preferably, the MSB (Most Significant Bit) portion of the first SSB index information may be included in a MIB (Master Information Block) in the PBCH.

Preferably, the second index information may be received via an upper layer signal. The higher layer signal may include system information (other than MIB), e.g., Remaining Minimum System Information (RMSI).

According to the present invention, wireless signal transmission and reception can be efficiently performed in a wireless communication system.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 illustrates physical channels used in a 3GPP (Third Generation Partnership Project) -based system as an example of a wireless communication system and a general signal transmission method using the same.

Figure 2 illustrates the frame structure defined in 3GPP NR.

Figure 3 illustrates a resource grid of slots.

Figure 4 illustrates Synchronize Signal Block (SSB) transmission.

Figure 5 illustrates the structure of SSB.

Figure 6 illustrates multi-beam transmission of SSB.

Figure 7 illustrates a beam alignment process.

FIG. 8 illustrates a method of indicating the actually transmitted SSB (SSB_tx).

Figure 9 illustrates the merging of licensed bands and unlicensed bands.

Figure 10 illustrates a method of occupying resources within a license-exempt band.

Figure 11 illustrates the problem of SSB transmission within a license-exempt band.

Figures 12-16 illustrate SSB transmission in accordance with the present invention.

17 illustrates a base station and a terminal that can be applied to the present invention.

The following description is to be understood as illustrative and non-limiting, such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access And can be used in various wireless access systems. CDMA may be implemented in radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. The TDMA may be implemented in a wireless technology such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long term evolution (LTE) is part of E-UMTS (Evolved UMTS) using E-UTRA and LTE-A (Advanced) is an evolved version of 3GPP LTE. 3GPP NR (New Radio or New Radio Access Technology) is an evolved version of 3GPP LTE / LTE-A.

As more and more communication devices require more communication capacity, there is a need for improved mobile broadband communication over existing RAT (Radio Access Technology). In addition, massive MTC (Machine Type Communications), which provides a variety of services by connecting many devices and objects, is one of the major issues to be considered in next generation communications. In addition, a communication system design considering a service / terminal sensitive to reliability and latency is being discussed. The introduction of the next generation RAT considering eMBB, massive MTC, URLLC (Ultra-Reliable and Low Latency Communication) is discussed. In the present invention, the corresponding technology is referred to as NR (New Radio or New RAT) .

For the sake of clarity, the 3GPP NR is mainly described, but the technical idea of the present invention is not limited thereto.

In a wireless communication system, a terminal receives information from a base station through a downlink (DL), and the terminal transmits information through an uplink (UL) to a base station. The information transmitted and received by the base station and the terminal includes data and various control information, and various physical channels exist depending on the type / use of the information transmitted / received.

1 is a view for explaining a physical channel used in a 3GPP NR system and a general signal transmission method using the same.

The terminal that is powered on again or the cell that has entered a new cell performs an initial cell search operation such as synchronizing with the base station in step S101. To this end, a mobile station receives a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from a base station and synchronizes with the base station and stores information such as a cell identity . Also, the UE can receive the physical broadcast channel (PBCH) from the base station and obtain the in-cell broadcast information. Meanwhile, the UE can receive the downlink reference signal (DL RS) in the initial cell search step to check the downlink channel state.

Upon completion of the initial cell search, the UE receives a Physical Downlink Control Channel (PDCCH) and a physical downlink control channel (PDSCH) according to physical downlink control channel information in step S102, System information can be obtained.

Then, the terminal may perform a random access procedure such as steps S103 to S106 to complete the connection to the base station. To this end, the UE transmits a preamble through a Physical Random Access Channel (PRACH) (S103), and transmits a response message for a preamble through the physical downlink control channel and the corresponding physical downlink shared channel (S104). In the case of contention based random access, the transmission of the additional physical random access channel (S105) and the physical downlink control channel and corresponding physical downlink shared channel reception (S106) ). ≪ / RTI >

The UE having performed the procedure described above transmits a physical downlink control channel / physical downlink shared channel reception step S107 and a physical uplink shared channel (PUSCH) / physical downlink shared channel A Physical Uplink Control Channel (PUCCH) transmission (S108) may be performed. The control information transmitted from the UE to the Node B is collectively referred to as Uplink Control Information (UCI). The UCI includes HARQ ACK / NACK (Hybrid Automatic Repeat and Request Acknowledgment / Negative ACK), SR (Scheduling Request), CSI (Channel State Information) The CSI includes a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), a Rank Indication (RI), and the like. The UCI is generally transmitted through the PUCCH, but may be transmitted via the PUSCH when the control information and the traffic data are to be simultaneously transmitted. In addition, UCI can be transmitted non-periodically through the PUSCH according to the request / instruction of the network.

Fig. 2 illustrates the structure of a radio frame. In NR, uplink and downlink transmission are composed of frames. Each radio frame has a length of 10ms and is divided into two 5ms half-frames. Each half-frame is divided into five 1 ms sub-frames. A subframe is divided into one or more slots, and the number of slots in a subframe depends on SCS (Subcarrier Spacing). Each slot includes 12 or 14 Orthogonal Frequency Division Multiplexing (OFDM) symbols according to a cyclic prefix (CP). If a normal CP is used, each slot contains 14 OFDM symbols. When an extended CP is used, each slot includes 12 OFDM symbols.

Table 1 illustrates that the number of symbols per slot, the number of slots per frame, and the number of slots per subframe are different according to the SCS when CP is usually used.

SCS (15 * 2 ^ u)	N slot symb	N frame, u slot	N subframe, u slot
15KHz (u = 0)	14	10	One
30 kHz (u = 1)	14	20	2
60 kHz (u = 2)	14	40	4
120KHz (u = 3)	14	80	8
240 kHz (u = 4)	14	160	16

* N ^slot _symb : number of symbols in slot * N ^{frame, u} _slot : number of slots in frame

* N ^{subframe, u} _slot : number of slots in ^subframe

Table 2 illustrates that the number of symbols per slot, the number of slots per frame, and the number of slots per subframe are different according to the SCS when the extended CP is used.

SCS (15 * 2 ^ u)	N slot symb	N frame, u slot	N subframe, u slot
60 kHz (u = 2)	12	40	4

The structure of the frame is merely an example, and the number of subframes, the number of slots, and the number of symbols in a frame can be variously changed. In the NR system, OFDM paramoregions between a plurality of cells merged into one terminal (E.g., SCS) may be set differently. Accordingly, the (absolute time) interval of a time resource (e.g., SF, slot or TTI) (for convenience, TU (Time Unit)) composed of the same number of symbols can be set differently between merged cells. Here, the symbol may include an OFDM symbol (or a CP-OFDM symbol), an SC-FDMA symbol (or a Discrete Fourier Transform-spread-OFDM symbol, a DFT-s-OFDM symbol).

Figure 3 illustrates a resource grid within a slot. A slot contains a plurality (e.g., 14 or 12) symbols in the time domain. The carrier includes a plurality of subcarriers in the frequency domain. An RB (Resource Block) includes a plurality of (e.g., 12) consecutive subcarriers, and a BWP (Bandwidth Part) includes a plurality of consecutive RBs. The carrier may include up to N (e.g., five) BWPs. Data communication is performed through activated BWP, and only one BWP can be activated for one terminal. In the resource grid, each element is referred to as a Resource Element (RE), and one complex symbol can be mapped.

The 3GPP NR frame is characterized by a self-contained structure in which a DL control channel, DL or UL data, a UL control channel, etc., can all be contained in one slot. For example, the first N symbols in a slot are used to transmit a DL control channel (hereinafter referred to as a DL control area), and the last M symbols in a slot can be used to transmit UL control channels (hereinafter referred to as a UL control area). N and M are each an integer of 0 or more. A resource area (hereinafter referred to as a data area) between the DL control area and the UL control area can be used for DL data transmission or can be used for UL data transmission. There may be a time gap for DL-to-UL or UL-to-DL switching between the control area and the data area. For example, the following configuration may be considered. Each section was listed in chronological order.

1. DL only configuration

2. UL only configuration

3. Mixed UL-DL configuration

- DL area + Guard period (GP) + UL control area

- DL control area + GP + UL area

DL area: (i) DL data area, (ii) DL control area + DL data area

UL area: (i) UL data area, (ii) UL data area + DL control area

The PDCCH can be transmitted in the DL control region, and the PDSCH can be transmitted in the DL data region. In the UL control region, the PUCCH can be transmitted, and in the UL data region, the PUSCH can be transmitted. In the PDCCH, downlink control information (DCI), for example, DL data scheduling information, UL data scheduling information, and the like may be transmitted. In the PUCCH, Uplink Control Information (UCI), ACK / NACK information, DL CSI information, and Scheduling Request (SR), for example, can be transmitted. The GP provides a time gap in the process of switching from the transmission mode to the reception mode or from the reception mode to the transmission mode. Some OFDM symbols at the time of switching from DL to UL within a subframe can be set to GP.

4 illustrates Synchronization Signal Block (SSB) transmission. SSB consists of SS / PBCH blocks and is periodically transmitted according to SSB periodicity. The SSB basic period used for initial cell selection is defined as 20 ms. After cell connection, the SSB period can be set to one of {5 ms, 10 ms, 20 ms, 40 ms, 80 ms, 160 ms}. An SSB burst set is configured at the beginning of each SS period. The SSB burst set consists of a 5 ms time window and the SSB can be sent up to a maximum of N times within the SS burst set. The candidate location of the SSB may be predefined within the SS burst set. The maximum number of transmission times L of the SSB can be given as follows according to the carrier frequency band.

- For frequency range up to 3 GHz, L = 4

- For frequency range from 3 GHz to 6 GHz, L = 8

- For frequency range from 6 GHz to 52.6 GHz, L = 64

The UE can acquire a DL synchronization (eg, OFDM symbol / slot / half-frame boundary detection), a cell ID (eg, Physical Cell Identifier, PCID) based on SSB, beam alignment for initial connection, DL measurement and so on.

5 illustrates the structure of SSB. A slot may include up to two SSB blocks. SSB is composed of four consecutive OFDM symbols, and PSS, PBCH, SSS / PBCH and PBCH are transmitted for each OFDM symbol. The PSS is used to detect the cell ID in the cell ID group, and the SSS can be used to detect the cell ID group. The PBCH is used for SSB (time) index detection and half-frame detection, and includes the MIB. The PBCH is composed of data RE and demodulation reference signal (DMRS) RE for each OFDM symbol. There are three DMRS REs per RB, and there are three data REs between each DMRS RE.

Table 3 shows the payload configuration of the PBCH.

Field	Size (bits)
Cyclic Redundancy Check (CRC)	24
System Frame Number (SFN)	10
Physical RB (PRB) grid offset	4
SCS indication	One
Half frame Indication	One
Most Significant Bit (SSB) of SSB index (for above 6GHz)	3

The SSB time location is indexed from 0 to L-1 within the SSB burst set (i.e., half-frame) (SSB index). For L = 8 or 64, the Least Significant Bit (LSB) 3 bits of the SSB index may be indicated using eight different PBCH-DMRS sequences. For L = 2, the LSB 2 bits of the SSB index can be indicated using four different PBCH-DMRS sequences. In case of L = 4, 1 bit indicating the SSB index out of 3 bits which can be indicated using 8 PBCH-DMRS sequences can be used for half-frame indication purpose. Can be obtained. Specifically, the terminal can identify the structure of the SSB burst set based on the detected SSB index, and thereby detect the OFDM symbol / slot / half-frame boundary. The number of the frame to which the detected SSB belongs is identified using the SFN information in the MIB, and the number of the half-frame to which the detected SSB belongs can be identified using the half-frame indication information in the MIB.

6 illustrates SSB transmission and multi-beam sweeping. Beam sweeping means that a Transmission Reception Point (TRP) (e.g., base station / cell) makes the beam (direction) of the wireless signal different over time (hereafter the beam and beam directions can be mixed). SSB can be periodically transmitted using beam sweeping. In this case, the SSB index is implicitly linked to the SSB beam. The SSB beam can be changed in SSB (index) units or SSB (index) group units. In the latter case, the SSB beam remains the same in the SSB (index) group. That is, the transmission beam echo of the SSB is repeated in a plurality of consecutive SSBs. In the SSB burst set, the maximum transmission number L of SSBs has a value of 4, 8, or 64 according to the frequency band to which the carrier belongs. Therefore, the maximum number of SSB beams in the set of SSB bursts can also be given as follows according to the frequency band of the carrier.

- For frequency range up to 3 GHz, Max number of beams = 4

- For frequency range from 3 GHz to 6 GHz, Max number of beams = 8

- For frequency range from 6 GHz to 52.6 GHz, Max number of beams = 64

* If multi-beam transmission is not applied, the number of SSB beams is one.

Figure 7 illustrates a beam-management process. In 3GPP NR, a physical channel, a reference signal can be transmitted using beam-forming. In this case, the beams must be aligned / managed between the base station and the terminals in order to perform signal transmission / reception. RRC (Radio Resource Control) In IDLE mode, beam alignment can be performed based on SSB. On the other hand, beam alignment in RRC CONNECTED mode may be performed based on CSI-RS (in DL) and SRS (in UL).

Referring to FIG. 7, a BS (e.g., BS) may periodically transmit SSB (S702). Here, SSB includes PSS / SSS / PBCH. SSB may be transmitted using beam sweep (see FIG. 6). Thereafter, the BS may transmit Remaining Minimum System Information (RMSI) and Other System Information (OSI) (S704). The RMSI may include information (e.g., PRACH configuration information) necessary for the UE to initially access the base station. Meanwhile, the terminal performs SSB detection and identifies the best SSB. The UE can then transmit the RACH preamble (Message 1, Msg1) to the base station using the PRACH resource that is linked / indexed to the index (i.e., beam) of the best SSB (s706). The beam direction of the RACH preamble is associated with the PRACH resource. The association between the PRACH resource (and / or the RACH preamble) and the SSB (index) may be established through system information (e.g., RMSI). As a part of the RACH process, the BS transmits RAR (Random Access Response) (Msg2) in response to the RACH preamble (S708), and the MS transmits Msg3 (e.g., RRC Connection Request) using the UL grant in the RAR (S710), and the base station may transmit a contention resolution message Msg4 (S720). Msg4 may include an RRC Connection Setup.

If an RRC connection is established between the base station and the UE through the RACH process, subsequent beam alignment can be performed based on SSB / CSI-RS (in DL) and SRS (in UL). For example, the SS can receive SSB / CSI-RS (S714). The SSB / CSI-RS may be used by the UE to generate the beam / CSI report. Meanwhile, the base station can request beam / CSI reporting from the terminal through the DCI (S716). In this case, the terminal generates a beam / CSI report based on the SSB / CSI-RS and transmits the generated beam / CSI report to the base station via the PUSCH / PUCCH (S718). The beam / CSI report may include beam measurement results, information about the preferred beam, and the like. The base station and the terminal may switch the beam based on the beam / CSI report (S720a, S720b).

FIG. 8 illustrates a method of indicating the actually transmitted SSB. Within the SSB burst set, up to L SSBs may be transmitted, and the number / location at which the SSB is actually transmitted may vary from base station to cell. The number / position at which the SSB is actually transmitted is used for rate-matching and measurement, and the information about the actually transmitted SSB is indicated as follows.

In case of rate-matching: can be indicated via terminal-specific RRC signaling or RMSI. The terminal-specific RRC signaling includes both full (e.g., length L) bitmaps in the below 6 GHz and above 6 GHz frequency ranges. The half, RMSI, contains a full bitmap at below 6 GHz and a bitmap in compressed form as shown at 6 GHz above. Specifically, information on the actually transmitted SSB can be indicated using group-bitmap (8 bits) + intra-group bitmap (8 bits). Here, the resource indicated through the UE-specific RRC signaling or RMSI is reserved for SSB transmission, and the PDSCH / PUSCH can be rate-matched considering SSB resources.

- For measurement: When in RRC connected mode, the network (eg base station) can indicate the SSB set to be measured within the measurement interval. The set of SSBs may be indicated by a frequency layer. If there is no indication as to the SSB set, the default SSB set is used. The default SSB set includes all SSBs within the measurement interval. The set of SSBs may be indicated using a full (e.g., length L) bitmap of RRC signaling. When in RRC idle mode, the default SSB set is used.

Figure 9 illustrates carrier aggregation of license and license-exempt bands. 9, when a base station transmits a signal to a mobile station under a carrier aggregation state of a license band (LTE-A band, L-band) and a license-exempt band (hereinafter, LTE-U band and U-band) A signal can be transmitted to the base station. Here, a cell (e.g., PCell, SCell) operating in the L-band is defined by LCell, and a carrier of the LCell is defined by (DL / UL) LCC. In addition, a cell operating in a U-band (e.g., SCell) is defined as UCell, and a carrier of UCell is defined as (DL / UL) UCC. The carrier / carrier frequency of the cell may mean the operating frequency of the cell (e.g., center frequency). A cell / carrier (e.g., CC) is collectively referred to as a cell.

Figure 10 illustrates a method of occupying resources within a license-exempt band. As an example of a license-exempt band operation operating in a contention-based random access scheme, a base station first carries out CS (Carrier Sensing) before data transmission / reception to check whether the current channel state of the UCell is busy or idle. For example, if there is a Clear Channel Assessment (CCA) threshold set by a predefined or higher-layer (eg, RRC) signaling, it may be considered busy or idle if an energy above the threshold is detected. If it is determined to be children, the base station can start signal transmission in the UCell. This sequence of processes is called Listen-Before-Talk (LBT).

In Europe, two LBT operations, named as Frame Based Equipment (FBE) and Load Based Equipment (LBE), are illustrated. The FBE includes a channel occupancy time (e.g., 1 to 10 ms), which means a time when the communication node can continue transmission when the channel is successfully connected (for example, 1 to 10 ms), and an idle period the idle period constitutes one fixed frame and the CCA is defined as the operation of observing the channel for the CCA slot (at least 20 μs) at the end of the idle period. The communication node periodically performs CCA on a fixed frame basis. When the channel is unoccupied, the communication node transmits data during the channel occupancy time. If the channel is occupied, the communication node suspends the transmission, Wait until the CCA slot.

On the other hand, in the case of LBE, the communication node first sets q∈ {4, 5, ... , 32} and then perform CCA for one CCA slot. If the channel is not occupied in the first CCA slot, the maximum time (13/32) q ms is secured and data can be transmitted. If the channel is occupied in the first CCA slot, the communication node randomly selects N ∈ {1, 2, ... , q} are stored as the initial value of the counter. Then, when the channel is not occupied by CCA slot while sensing the channel state in CCA slot unit, the value stored in the counter is decreased by one. When the counter value becomes 0, the communication node can transmit data by securing the maximum time (13/32) q ms.

Example: SSB configuration

The SSB of the above NR is defined for the license carrier. The existing license band SSB, on the other hand, can be used for the unlicensed band for the transmit power per frequency (eg, maximum / minimum transmit power per 1 MHz) and the occupied band (eg the transmit signal occupies a bandwidth of at least X-GHz) Regulatory and LBT procedures. Therefore, the SSB of the new structure can be defined in the U-band and can be different according to the frequency of the U-band (for example, the 5 GHz band, the 60 GHz band, etc.). In particular, the SSB configuration may vary depending on the NR operation mode (e.g., SA (standalone) or NSA (non-standalone) mode) in the U-band.

Hereinafter, the present invention proposes a method of indicating the actually transmitted SSB information when the NR system operates in the license-exempt band (U-band), and a method of configuring the SSB transmission when some SSB transmissions are omitted. Also, the present invention proposes a method of indicating SSB transmission period and actually transmitted SSB information when a base station using multi-panel (or multi-carrier) transmits SSB by FDM.

The term " U-band SSB " in the present invention can be used to refer to SSB to be used in the U-band as a unit rather than to the L-band and other SSBs. In the present invention, the SSB index in the U-band and the symbol position in the slot or radio frame are not specified. Also, the technique proposed by the present invention can be applied not only to the U-band but also to the L-band, and particularly to the FDD of the L-band NR system. For convenience, the present invention will be described on the basis of a U-band, and in the absence of special restrictions, the content / synchronization proposed in the present invention is also applicable to the L-band.

1. How to tell SSB information actually transmitted

There are two main reasons why the base station reports the SSB actually transmitted in the L-band.

(1) rate-matching of the serving cell

If the SSB transmission is omitted from the place where the SSB transmission is reserved, another channel such as the PDCCH or the PDSCH can use the SSB transmission resource. However, if the SSB detection fails in the UE, the UE determines whether the SSB transmission is omitted from the base station or the SSB reception fails (e.g., the directions of the transmission / reception beams do not coincide with each other) I can not. Therefore, the base station needs to inform the terminal about the SSB index to be actually transmitted or transmitted.

(2) Neighbor-cell and serving-cell measurements

In order to measure the RSR (Received Signal Strength Indication) and the RSSR (Received Signal Strength Indication) based on the SSB of the neighboring cell, the UE needs to know the SSB actually transmitted in the neighboring cell. To do this, the SS assumes that the SSB of the same index as the SSB index actually transmitted in the serving cell is transmitted in the neighboring cell, or receives information on the SSB index actually transmitted from the neighboring cell from the serving cell have.

For this reason, the terminal needs to know the SSB index actually transmitted in the cell. For convenience, SSB actually transmitted is denoted by SSB_tx. Information about the SSB_tx index may be conveyed via the RMSI or via UE-specific RRC signaling. If both pieces of information are given, the UE may prioritize the SSB_tx index information included in the UE-specific RRC signaling. Depending on the number of bits used, the range or unit (resolution) in which SSB_tx information can be represented may differ between the two methods as follows.

(1) When SSB_tx information is transmitted through RMSI

The SSB_tx index can be transmitted using a 16-bit bitmap composed of an 8-bit group-bitmap and an 8-bit group-in-bitmap. Here, for example, if the total number of SSBs is 64, the group-bitmap indicates 8 consecutive SSB indexes as one group, and indicates whether any one SSB belonging to the corresponding SSB group is transmitted. In addition, the intra-group bitmap indicates which SSB among the 8 SSBs in the SSB group indicated by '1' in the group-bitmap is transmitted.

(2) When SSB_tx information is transmitted through UE-specific RRC signaling

A full bitmap can be used to accurately indicate which SSB was transmitted among the entire SSBs that can be supported in the frequency band. For example, if a maximum of 64 SSB transmissions are possible within an SSB burst set, the full bitmap can be configured with 64 bits.

As described above, in the L-band, SSB transmission is notified at a position where SSB transmission is possible, and SSB can be discontinuously transmitted in the SSB burst set. That is, when a maximum of L SSBs can be transmitted within the set of SSB bursts, the number of actually transmitted SSBs (i.e., SSB_tx) may be less than L, and the SSB_tx index (s) may not be contiguous. The reason for discontinuous SSB transmission in the L-band is as follows: (1) the (analog) beam used for a specific SSB transmission is extended for a certain period, (2) the SSB transmission is omitted, Or to support services that are sensitive to delays or have a high priority, such as < RTI ID = 0.0 >

However, in the U-band, there is a high possibility that there is no use-case to support discontinuous SSB transmission or discontinuous SSB transmission due to LBT / CCA / MCOT (Maximum Channel Occupancy Time). However, in the U-band, since it is uncertain depending on the LBT or the like, whether to start transmission of SSB and how many SSBs are to be transmitted consecutively, a method of notifying the SSB index actually transmitted is needed. In particular, since the SSB index can be implicitly associated with a different physical channel and a QCL (Quasi Co-located) like the PRACH configuration, it is possible to require accurate understanding of the BS and the UE.

In the present invention, the following simple example will first be considered in order to explain the " method of informing the SSB index actually transmitted in the U-band ". (Example) In the U-band, up to 8 SSB transmissions are allowed per SS period, and the base station can transmit only SSBs corresponding to even indexes. Here, the transmission order of the 8 SSB indexes may be sequentially " 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ", and the transmission order of each SSB index during a specific time (in OFDM symbol units or multiples thereof) There is a gap. However, since the SSB considers only resources that can be transmitted in the present invention, such a gap is not separately described. The concrete values used in the example can be defined with different parameters, for example 8 in the above example can be generalized to SSB maximum number of transmissions L.

[Method # 1] A method of transmitting additional signals to the position of the omitted SSB while permitting discontinuous transmission of the SSB

The SSB actually transmitted in the previous example may be equal to "X | 2 | X | 4 | X | 6 | X | 8". Here, X denotes a resource where SSB transmission is reserved, but actually indicates a resource for which SSB transmission has not occurred, and the number indicates an SSB index. At this time, the indication method for the SSB_tx index may be the same as the method used in the L-band. However, in the U-band, the third signal can be transmitted at the X position because of the LBT / CCA of another device (NR system using the same band or different types of systems). The third signal may be a training signal to aid AGC (Automatic Gain Control) or a signal such as a TRS (Tracking Reference Signal). Here, the third signal may have a QCL relationship with the beam of the adjacent SSB or the beam of the SSB whose transmission is omitted at the corresponding position. Also, the terminal can expect rate matching or puncturing of a specific pattern regardless of whether the SSB is actually transmitted at the X position. The size of the rate-matching and puncturing may differ from the SSB size and may be determined, for example, by the size of the third signal to be transmitted at the X position.

In the above example, the base station may intentionally omit a specific SSB index transmission and transmit a third signal at the X position. Here, the third signal may be to repeatedly transmit some of the signals belonging to the preceding SSB index (or QCL in beam perspective) for the SSB length. For example, when the SSB transmission at the X position is omitted, such as " 1 | X | 3 | X | 5 | X | 7 | X ", the base station sets SSB to " 1 | 1 '| 3 | 5 | 5 '| 7 | 7' '. Here, n 'may be the SSS and / or PBCH belonging to the SSB index n (i.e., the SSB index transmitted before n'). When the SSB is transmitted, the UE measures the RSRP, RSSI, and the like of the SSB index n by measuring the SSB index n and the interval during which n 'is transmitted (if the SSB index is continuously omitted, n' It is possible to measure the SSB index n while changing the receiving beam at the same time. This is because the terminal is designed to be unable to sweep reception beams in a specific SSB in the current L-band, and thus can be a more important feature in a U-band that can occupy a radio channel for a limited time . (I) SSS of SSB index n, (ii) PBCH, (iii) SSS and PBCH can be repeatedly transmitted in the n 'interval since RSRP and RSSI of SSB can be measured based on SSS or PBCH DMRS . In this case, the structure of the SSS / PBCH transmitted in the n 'interval may be different from SSB, but SSB index n and QCL should be established. Also, if wideband transmission is required to increase the measurement accuracy, the SSS / PBCH of the interval n 'may be transmitted at a frequency different from the SSB index n. At this time, the corresponding frequency information needs to be periodically defined, broadcasted from the base station, or UE-specific RRC signaled so that there is no problem in rate-matching of other channels (e.g., PDCCH, PDSCH, etc.). The information needs to be notified to the terminal so that the terminal can know the information of the punctured channel even in the case of puncturing instead of rate matching. In addition, the SSS / PBCH transmitted in the n 'interval can be transmitted at a frequency different from the SSB index n, and can be repeatedly transmitted in the frequency domain for the wideband transmission. For example, in a specific OFDM symbol of an n 'interval, the SSS of the SSB index n, SSS of the SSB index n, SSS of the SSB index n, SSS of the SSB index n, or PBCH of the SSB index PBCH of SSB index n | PBCH of SSB index n | " PBCH of SSB index n " or " SSS of SSB index n | PBCH of SSB index n | Lt; / RTI >

In this proposal, in addition to the method of transmitting the SSS and / or PBCH of the SSB index n in the n 'interval, the SSB index n may be transmitted equally, only the PSS / and SSS may be transmitted, or only the PSS and PBCH may be transmitted. This may help the SS to detect SSB as the UE changes the receive beam in the interval in which SSB index n and n 'are transmitted. However, if the SSB (when the PBCH data and / or the SSB index included in the PBCH DMRS is equal to n) is transmitted in the n 'interval or the PSS is transmitted, the SSB index and the slot or frame and the OFDM symbol Boundary mapping can be confusing. In order to solve this problem, time information (e.g., slot number or symbol number) used in the DMRS sequence generation and scrambling process of the n 'interval may be different from the n interval.

[Method # 2] A method of continuously transmitting the SSBs actually transmitted within the SS period

In the U-band, the time for a specific system to occupy a wireless channel is limited, and the time occupied by the LBT parameter and the like can be changed flexibly. Therefore, as in method 1, regardless of the number of SSBs to which transmission is omitted, when the position to which SSB can be transmitted is fixedly allocated, transmission opportunities between the SSB index and the SSB index may be statistically different have. That is, a beam having a high SSB index may be relatively unlikely to be transmitted. Therefore, it is desirable to arrange the SSBs continuously so that they can be transmitted as quickly as possible.

In this method, the base station can maintain the SSB index of the U-band in a bitmap form like the L-band. Referring to the example of method 1, the bitmap indicating the SSB_tx index may be indicated as '01010101'. Each bit corresponds to SSB index 0 to 7 in order, and SSBs corresponding to the bit indicated by '1' can be transmitted continuously within the SS period. That is, the SSB is transmitted continuously but the actually transmitted SSB index may be discontinuous. Here, the SSB index represents the SSB beam index and can be distinguished from the SSB index indicated by the PBCH-DMRS / MIB. The SSB index indicated by the PBCH-DMRS / MIB is used for the boundary detection of the OFDM symbol / slot / half-frame, so that the location / symbol to which the SSB is transmitted has a fixed value within the SS period. That is, the SSB index in the L-band is used equally for synchronization acquisition and beam alignment /. On the other hand, in the U-band, the SSB index for the synchronization acquisition and the SSB index for the beam alignment can be distinguished. In the following description related to the U-band, the SSB index may mean an SSB beam index (or direction), and the SSB index indicated by the PBCH-DMRS / MIB has a fixed value according to the SSB transmission position in the frame . For example, in the following description, when the SSB index is set / indicated differently from the SSB transmission position, the SSB index may mean the SSB beam index (or direction), and the index indicated by the PBCH-DMRS / And may have a predefined value depending on the SSB transmission location.

Figure 12 illustrates SSB transmission / beam sweeping in L-band and U-band. It is assumed that the bitmap indicating SSB_tx is signaled as '01010101'. The bitmap may be signaled via RMSI or UE-specific RRC signaling. In this case, the SSB in the L-band SSB burst set is transmitted discontinuously according to the bit value, and the SSB index indicated by PBCH-DMRS / MIB is used for symbol / slot / half-frame boundary detection and beam alignment 12 (a)). That is, the SSB index and the SSB beam (index, direction) are aligned with each other. On the other hand, in the U-band SSB burst set, the SSB is consecutively transmitted as many as the number of bits indicated by 1 (Fig. 13 (b)). At this time, the SSB index indicated by the PBCH-DMRS / MIB is determined according to the SSB transmission position, and the SSB beam (index, direction) has a value corresponding to the indicated bit. Thus, although the SSB is transmitted continuously, the SSB beam (index, direction) can be discontinuously swept depending on the configuration of the bitmap.

Figure 13 illustrates SSB detection / beam alignment in accordance with an example of the present invention. In the drawing, a terminal can transmit and receive radio signals through a radio frequency (RF) unit under the control of a processor, and can perform operations shown through the processor. Here, the terminal may be implemented with a chip including a communication modem.

Referring to FIG. 13, a UE can detect one or more SSBs in a cell (S 1302). In step S1304, the UE acquires downlink synchronization based on the one or more SSBs, and transmits the RACH preamble using the PRACH resource corresponding to the best SSB among the one or more SSBs in step S1306. Here, the downlink synchronization is obtained based on first SSB index information in each SSB, and the PRACH resource can be determined based on second SSB index information set for the best SSB by the cell.

14 illustrates SSB transmission / beam alignment in accordance with an example of the present invention. In the drawing, a base station can transmit and receive a radio signal through a radio frequency (RF) unit under the control of a processor, and can perform the operations shown through the processor. Here, the terminal may be implemented with a chip including a communication modem.

Referring to FIG. 14, a base station (or a cell) can transmit one or more SSBs (S1402). Here, each SSB includes first SSB index information. Here, the first SSB index information in each SSB has a fixed value according to the SSB transmission position in the frame, and is used to provide downlink synchronization. In addition, the base station may transmit the second index information to the one or more SSBs (S1404). Thereafter, the BS may receive the RACH preamble using the PRACH resource corresponding to the best SSB among the one or more SSBs (S1406). The PRACH resource may be determined based on the second SSB index information set for the best SSB by the cell.

13 to 14, the index value indicated by the first SSB index information may differ from the index value indicated by the second SSB index information for the best SSB. In addition, the at least one SSB includes a plurality of SSBs, and the plurality of first SSB index information in the plurality of SSBs may represent a plurality of continuous index values. The plurality of second SSB index information set for the plurality of SSBs may represent a plurality of discontinuous index values. In addition, each SSB includes a SS, a PBCH and a DMRS for the PBCH, and the LSB portion of the first SSB index information may be indicated by a sequence of DMRSs for the PBCH. The MSB portion of the first SSB index information may be included in the MIB in the PBCH. The first SSB index information in each SSB has a fixed value according to the SSB transmission position in the frame, and the second index information can be received through an upper layer signaling (e.g. RMSI, UE-specific RRC signaling).

Alternatively, the SSB transmission and the actually transmitted SSB index may all be consecutive. In this case, the base station continuously transmits N SSBs within the SS period, and the SSB indexes consecutively use 1 to N (i.e., " 1 | 2 | ... | N) (I.e., " n | n + 1 | ... | n + N-1 "). In this case, the actually transmitted SSB index can be indicated by a method other than a bitmap type.

(1) How to tell the actual number of SSBs transmitted

The base station informs the UE of the actual number of SSBs transmitted, and the SSB can always be transmitted by the "number of indicated SSBs" from the first SSB index. In this case, SSB can always be transmitted from the first SSB index even if the SSB transmission start time is non-periodic depending on the LBT result or the like. That is, even if the reference time such as a slot or a symbol is not fixed in the U-band, the relative position between the SSB indexes in the frame or slot may not be varied by always transmitting the SSB from the first SSB index.

(2) How to tell the start and length of SSB_tx index

If each base station does not have enough SSBs to transmit, the SSB indexes can be shared among the base stations. In this method, when measuring the RSRP of another base station based on the PBCH DMRS of the SSB, the UE can omit cell detection and can implicitly divide the cell based on the SSB index, . To do this, each base station may indicate the actually transmitted SSB index with parameters such as start-offset and length. Here, the start-offset represents the value of the start / start index of the SSB to be actually transmitted by each base station, and the length represents the number of SSBs actually transmitted by each base station.

(3) How to tell SSB_tx index by using table type

The maximum ceil (log ₂ (L)) * 2 bits are needed to tell the SSB_tx index to start-offset and length. L is the total number of SSBs. However, if all of the L SSBs are actually transmitted, no start-offset is required. In general, if the length is A, the number of start-offset values is only (LA) (A> 0), which is less than the number of cases in which "start-offset" and "length" . However, even in this case, the number of all cases (

) Is the same as ceil (log2 (L)) * 2. However, if the actual transmitted SSB index is arranged in the form of a table and ceil (log2 (L)) *

The reserved state can be additionally secured. The spare state can be used for discontinuous SSB index transmission.

Table 4 shows a simple example in the case of L = 4.

	Table Index	Actually transmitted SSB index (SSB_tx index)
When SSB indexes are consecutive	0	[1 0 0 0]
	One	[0 1 0 0]
	2	[0 0 1 0]
	3	[0 0 0 1]
	4	[1 1 0 0]
	5	[0 1 1 0]
	6	[0 0 1 1]
	7	[1 1 1 0]
	8	[0 1 1 1]
	9	[1 1 1 1]
When SSB indexes are non-consecutive	10	[1 0 1 0]
	11	[0 1 0 1]
	12	[1 0 0 1]
	13	[1 0 1 1]
	14	[1 1 0 1]
	15	reserved

[Method # 3] The SSB_tx index is the same but the transmission order is different.

The SSB_tx index may be informed to the UE based on RMSI or UE-specific RRC signaling. When signaling the SSB_tx index through the RMSI, for a UE entering the cell (or base station) for the first time, the cell always needs to broadcast the SSB_tx index every certain period or at the period and time indicated by the PBCH . However, when the SSB_tx index is notified to the UE through the UE-specific RRC signaling, the cell (or the base station) can perform signaling only when the SSB_tx index is changed. Here, the change of the SSB_tx index can be classified into (1) when the SSB index to be transmitted or transmitted is changed, and (2) when the SSB sequence is changed and transmitted. If the UE-specific RRC signaling is renewed only in case (1), the SS can not know that the SSB transmission index is the same but the SSB transmission order has changed. For example, if the SSB_tx index is known in bitmap form, even if the SSB index is transmitted as "2 | 4 | 6 | 8" and then changed to "4 | 6 | 8 | 2" Therefore, the UE can not know that the SSB transmission order has been changed. Also, in the method of notifying the actually transmitted SSB indexes in the form of "continuous SSB index length" rather than bitmap type, when the SSB_tx has the same length (that is, the number), the SS knows that the SSB_tx index is changed none. For example, even if the SSB index is transmitted as " 2 | 4 | 6 | 8 " and is changed to " 1 | 3 | 5 | 7 ", the UE transmits the SSB index do not know.

In order to solve this problem, the following condition may be added to the condition for informing the SSB_tx index information or the conditions for re-transmission of the SSB_tx index information.

(1) If the SSB_tx index is indicated in bitmap form,

  A. If the SSB_tx index (set) changes

  B. Even if the SSB_tx index (set) is the same, if the SSB transmission order is changed

(2) When SSB configuration is indicated by the length information of SSB_tx,

  A. When the length (that is, the number) of SSB_tx changes

  B. Even if the length of SSB_tx is the same, if the SSB_tx index is changed

It is common to assume that the SSB_tx index does not change for a relatively long time. Therefore, if the SS detects the SSB_tx index information once, it can be assumed that the same SSB is repeatedly transmitted during a specific period. However, as described above, even if the SSB index (set) is the same, the SSB transmission order may be changed or the SSB index (set) may be changed even when the number of SSBs to be transmitted is the same. In this way, when the configuration of the actually transmitted SSB is changed, the cell / base station can indicate whether to change the configuration of SSB_tx by using additional information such as " SSB value tag " It may not accumulate / combine the previously received SSB with the previously received SSB. The "SSB value tag" holds the value when the SSB transmission is the same as before, and the value can be changed (eg, increased) by 1 when the SSB transmission is different from the previous one. If the " SSB value tag " is changed M times, it is initialized again to '0', and the above process can be repeated. M represents the upper limit value of the "SSB value tag", and the range of the "SSB value tag" can be determined in consideration of the decoding performance ("SSB value tag" detection performance) of the terminal.

For example, if the value of the "SSB value tag" is the same as the previous value, the terminal does not need to detect the actually transmitted SSB index or length information again. If the value is different from the previous one, the SSB_tx index or the length information, have. If the SSB_tx index or length information is the same as before, even though the value of "SSB value tag" is different from the previous value, it is assumed that the SSB transmission order has been changed or the SSB index has been changed, Do not accumulate / combine. As a simple example, in SSB-based RSRP measurements, accumulation of SSB RSRP measurements may not be allowed between different intervals of "SSB value tag".

The " SSB value tag " can be broadcast independently of the period in which the SSB_tx index is transmitted, and may preferably have a period equal to or shorter than the transmission period of the SSB_tx index. For this reason, the " SSB value tag " may be transmitted over the PBCH or through the third channel / signal. Also, the "SSB value tag" indicates whether the SSB_tx index is changed in the interval in which the "SSB value tag" is transmitted, or (2) after the SSB value tag transmission time, It is possible to inform in advance that the SSB_tx index will change in the period (i.e., the SS period). Further, when the U-band operates in the NSA mode, the " SSB value tag " can be transmitted from the L-band cell. When an "SSB value tag" is transmitted from the L-band, the "SSB value tag" can be transmitted in the L-band with the ID of the U-band cell via RRC signaling, not the PBCH. Also, if there is a time-offset between the U-band and the L-band, etc., the time point at which the SSB value tag of the L-band means / is applied is (i) additionally indicated by the RRC message or ii) It can be interpreted as the next SSB transmission period (ie, SS period) of the corresponding U-band closest to the time when the "SSB value tag" is received.

2. How a base station supporting multi-panel (or multi-frequency resources) transmits multiple SSBs in FDM

Even in the L-band, SSBs can be transmitted at different frequency resources at specific times. However, this is not a case in which a plurality of SSB indexes are transmitted by FDM, but a case in which separate SSBs are transmitted on different frequency resources in consideration of the RF capability of the terminal or services of one or more BWPs in the base station. That is, regardless of the number of SSBs simultaneously transmitted in different frequency resources at a specific time, the transmission time of the L SSBs that can be transmitted in each frequency resource is the same. 15 shows an example of transmitting SSBs in a plurality of L-bands. The figure assumes L = 8. Here, the time / frequency gap between SSBs is not limited to a specific value, but may be defined as a specific value according to the U-band SSB transmission structure. However, since the content proposed by the present invention is not related to the time / frequency gap between SSBs, the gap will be omitted or an arbitrary value will be assumed.

[Method # 4] SSB can be transmitted by FDM, and the time required to transmit the entire SSB is reduced in proportion to the number of carriers transmitting SSB

Unlike in the L-band in the U-band, SSB can be transmitted using different frequency resources at the same time, for the following reasons.

(1) Since the time to occupy the wireless channel is limited, it is necessary to transmit all the L SSBs as soon as possible.

(2) In the U-band, there is a regulation related to the minimum bandwidth of the transmission signal. In order to satisfy this, SSB needs to be transmitted in a wide band.

For the above reasons, when the SSB is transmitted in the FDM mode in the U-band, it is necessary to reduce the transmission time of all L SSBs in proportion to the number of FDM-SSBs unlike in the L-band. 16 illustrates that the SSB is transmitted in FDM in the U-band. 16A to 16D, it is assumed that there are 1, 2, 4, and 8 carriers for transmitting SSB, respectively.

When the SSB is transmitted by FDM as shown in the example of FIG. 16, the time for transmitting all the L SSBs may be reduced, and the period for transmitting the SSB may be shortened. For example, assuming that the SSB transmission period is 0.5 ms when SSB is transmitted using only one carrier, the SSB transmission time when transmitting SSB using two carriers is reduced to 0.25 ms, The SSB can be transmitted in a cycle. If the SSB indexes are different from each other while SSB is FDM in the wideband, the UE can simultaneously find SSBs of various transmission beams for one reception beam at a specific time. Also, since the SSB transmission period is shortened, the time for detecting the pair of the transmission beam of the base station and the reception beam of the terminal can be shortened by searching SSB.

In addition, the SSB index can be mapped to increase first in the frequency axis in a frequency-first mapping manner as in the example of FIG. This is because the SSB_tx information can be effectively mapped if it is informed using a method such as SSB_tx number or length instead of bitmap type. Also, when the number of SSBs to be transmitted increases or decreases, space is not generated between SSBs in the time domain. Here, the frequency-first mapping scheme can (1) SSB index sequentially increase according to the carrier index on the frequency axis, (2) SSB index mapping can be performed without following the carrier index order on the frequency axis Do. (2), when L SSBs are FDM-transmitted on K carriers, the SSB index FDM on the K carriers at the time of SSB transmission is {K * (n-1) +1, K * (n -1) +2, ... , K * n}, and can be mapped differently from the carrier index order in K carriers. Here, n (n = {1, 2, ..., N}, N = ceil (L / K)). However, if the number of SSB remaining at the time of transmitting the last SSB index (N) is smaller than K, the SSB index is {K * (N-1) +1, k * (N-1) +2, ... , L}, which means that there may be K * N-L carriers that do not transmit SSB at time N.

After detecting the SSB index, the UE can receive SSB_tx information through RMSI or UE-specific RRC signaling. At this time, the base station needs to notify the SSB_tx information as well as the number of frequencies used for SSB transmission. The terminal can specify the index of the detected SSB and the symbol position of the corresponding SSB in the wireless frame or slot using the SSB_tx information received from the base station and the frequency information used for SSB transmission. Alternatively, in the U-band, the frequency index n 'that can start with the SSB index n can be predetermined. In this case, a terminal that supports only a single-panel or can not use a multi-panel for a specific reason may first be defined / implemented to attempt SSB detection on the default carrier. The default carrier indicates a carrier to which all SSBs can be transmitted (e.g., f1 in FIG. 16).

In the above proposal, the time during which the entire SSB can be transmitted is reduced in proportion to the number of frequencies used for SSB transmission, but the SSB repeated transmission period can be set separately from the frequency number. For example, in FIG. 16, when the SSB is transmitted on eight frequencies (or carriers), the SSB repeat transmission period may be one. That is, the SSB can be transmitted every subframe (or slot). Of course, in this case, the SSB repetition transmission can be limited to the maximum interval in which the SSB is transmitted in one carrier (8 subframes in the above example). The period in which the SSB is repeated may be set to the same as when the SSB is transmitted in only one frequency. In this case, a terminal supporting only a single-panel can detect / measure different SSB indexes while shifting frequencies every sub-frame, and a terminal supporting a multi-panel can detect and measure a specific reception beam in one sub- Detection / measurement of all SSB indexes can be performed. With this, the multi-panel terminal can detect the SSS / PBCH of the FDM-SSB without using a filter for each frequency in SSB detection / measurement. Of course, for PSS detection requiring processing in the time domain, the UE may use only the filtered signal for a specific frequency.

17 illustrates a base station and a terminal that can be applied to the present invention.

Referring to FIG. 17, a wireless communication system includes a base station (BS) 110 and a terminal (UE) 120. If the wireless communication system includes a relay, the base station or the terminal may be replaced by a relay.

The base station 110 includes a processor 112, a memory 114, and a radio frequency (RF) unit 116. The processor 112 may be configured to implement the procedures and / or methods suggested by the present invention. The memory 114 is coupled to the processor 112 and stores various information related to the operation of the processor 112. [ The RF unit 116 is coupled to the processor 112 and transmits and / or receives wireless signals. Here, processor 112 and memory 114 may be part of a chip (e.g., System on a Chip, SoC). The terminal 120 includes a processor 122, a memory 124 and a radio frequency unit 126. The processor 122 may be configured to implement the procedures and / or methods suggested by the present invention. The memory 124 is coupled to the processor 122 and stores various information related to the operation of the processor 122. [ The RF unit 126 is coupled to the processor 122 and transmits and / or receives radio signals. Here, processor 122 and memory 124 may be part of a chip (e.g., SoC).

The embodiments described above are those in which the elements and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

In the present document, the embodiments of the present invention have been mainly described with reference to a signal transmission / reception relationship between a terminal and a base station. This transmission / reception relationship is equally or similarly extended to the signal transmission / reception between the terminal and the relay or between the base station and the relay. The specific operation described herein as being performed by the base station may be performed by its upper node, in some cases. That is, it is apparent that various operations performed for communication with a terminal in a network including a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A base station may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. In addition, the terminal may be replaced by terms such as a UE (User Equipment), a Mobile Station (MS), and a Mobile Subscriber Station (MSS).

Embodiments in accordance with the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) field programmable gate arrays, processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, a procedure, a function, or the like for performing the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various well-known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

The present invention can be used in a terminal, a base station, or other equipment of a wireless mobile communication system.

Claims (14)

1. A method for a terminal to acquire downlink synchronization in a wireless communication system,

   Detecting at least one Synchronization Signal Block (SSB) in the cell;

   Acquiring downlink synchronization based on the at least one SSB; And

   Transmitting a RACH preamble using a Physical Random Access Channel (PRACH) resource corresponding to a best SSB among the one or more SSBs,

   The downlink synchronization is obtained based on first SSB index information in each SSB,

   Wherein the PRACH resource is determined by the cell based on second SSB index information set for the best SSB.
2. The method according to claim 1,

   Wherein an index value indicated by the first SSB index information is different from an index value indicated by the second SSB index information for the best SSB.
3. The method according to claim 1,

   Wherein the at least one SSB comprises a plurality of SSBs,

   Wherein the plurality of first SSB index information in the plurality of SSBs represents a plurality of consecutive index values.
4. The method of claim 3,

   Wherein the plurality of second SSB index information set for the plurality of SSBs represents a plurality of discrete index values.
5. The method according to claim 1,

   Each SSB includes a Synchronization Signal (SS), a Physical Broadcast Channel (PBCH), and a Demodulation Reference Signal (DMRS) for the PBCH,

   Wherein the LSB (Least Significant Bit) portion of the first SSB index information is indicated by a sequence of DMRSs for the PBCH.
6. 6. The method of claim 5,

   Wherein a MSB (Most Significant Bit) portion of the first SSB index information is included in a MIB (Master Information Block) in the PBCH.
7. The method according to claim 1,

   And the second index information is received via an upper layer signal.
8. A terminal used in a wireless communication system,

   An RF (Radio Frequency) module; And

   The processor comprising:

   Detects at least one Synchronization Signal Block (SSB) in the cell,

   Acquiring downlink synchronization based on the at least one SSB,

   And to transmit a RACH preamble using a Physical Random Access Channel (PRACH) resource corresponding to a best SSB among the one or more SSBs,

   The downlink synchronization is obtained based on first SSB index information in each SSB,

   Wherein the PRACH resource is determined by the cell based on second SSB index information set for the best SSB.
9. 9. The method of claim 8,

   Wherein the index value indicated by the first SSB index information is different from the index value indicated by the second SSB index information for the best SSB.
10. 9. The method of claim 8,

    Wherein the at least one SSB comprises a plurality of SSBs,

    Wherein the plurality of first SSB index information in the plurality of SSBs represents a plurality of continuous index values.
11. 11. The method of claim 10,

    Wherein the plurality of second SSB index information set for the plurality of SSBs represents a plurality of discontinuous index values.
12. 9. The method of claim 8,

    Each SSB includes a Synchronization Signal (SS), a Physical Broadcast Channel (PBCH), and a Demodulation Reference Signal (DMRS) for the PBCH,

    Wherein an LSB (Least Significant Bit) portion of the first SSB index information is indicated by a sequence of DMRSs for the PBCH.
13. 13. The method of claim 12,

    Wherein the MSB (Most Significant Bit) portion of the first SSB index information is included in a Master Information Block (MIB) in the PBCH.
14. 9. The method of claim 8,

    And the second index information is received via an upper layer signal.

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