Method and device for transmitting and receiving synchronization signal and physical broadcast channel block

Abstract

The present application relates to methods and devices for transmitting and receiving synchronization signals and physical broadcast channel blocks. A method for a terminal to receive synchronization signals in a wireless communication system is disclosed. Specifically, the method can: receive a message including a synchronization signal block indicator, the synchronization signal block indicator being used to indicate one or more synchronization signal block groups including at least one transmission synchronization signal block among a plurality of synchronization signal block groups obtained by grouping candidate synchronization block positions of synchronization signal blocks including a primary synchronization signal, a secondary synchronization signal, and a physical broadcast channel signal into a predetermined number; and receive the at least one transmission synchronization signal block based on the message.

Description

[0001] This application is a divisional application of the original invention patent application with application number 201880023476.3 (International application number: PCT / KR2018 / 004860, application date: April 26, 2018, invention name: Method and device for receiving synchronization signal). Technical Field

[0002] The present invention relates to a method for receiving a synchronization signal and an apparatus thereof, and more particularly, to a method for indicating an index of an actually transmitted synchronization signal among synchronization signal candidates determined according to a subcarrier spacing, a method for receiving a synchronization signal based on the index, and an apparatus thereof. Background Art

[0003] As more and more communication devices demand greater communication services, the need for next-generation 5G systems, which offer enhanced mobile broadband communications compared to traditional LTE systems, is becoming increasingly apparent. In next-generation 5G systems, scenarios can be categorized into enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC).

[0004] eMBB corresponds to the next-generation mobile communication scenario with characteristics such as high spectral efficiency, high user experience data rate, high peak data rate, etc., URLLC corresponds to the next-generation mobile communication scenario with characteristics such as ultra-reliability, ultra-low latency, ultra-high availability, etc. (for example, V2X, emergency services, remote control), and mMTC corresponds to the next-generation mobile communication scenario with characteristics such as low cost, low energy, short data packets and large-scale connectivity (for example, IoT). Summary of the Invention

[0005] Technical tasks

[0006] An object of the present invention is to provide a method for receiving a synchronization signal and an apparatus thereof.

[0007] The technical tasks that can be obtained from the present invention are not limited to the technical tasks mentioned above. In addition, ordinary technicians in the technical field to which the present invention belongs can clearly know other technical tasks not mentioned from the following description.

[0008] Technical Solution

[0009] To achieve these and other advantages and in accordance with the purposes of the present invention, as implemented and broadly described, according to one embodiment, a method for receiving a synchronization signal received by a user equipment (UE) in a wireless communication system comprises the following steps: receiving a message including a synchronization signal block group indicator, the synchronization signal block group indicator indicating one or more synchronization signal block groups including at least one transmission synchronization signal block among a plurality of synchronization signal block groups that group a specified number of candidate synchronization signal block positions for the synchronization signal blocks, the synchronization signal blocks including a primary synchronization signal, a secondary synchronization signal and a physical broadcast channel signal, and receiving the at least one transmission synchronization signal block based on the message.

[0010] Specifically, the message may also include a first synchronization signal block indicator, which indicates at least one transmission synchronization signal block included in one or more synchronization signal block groups.

[0011] When the UE operates on a frequency band exceeding a specific value, the message may be received.

[0012] If the UE operates on a frequency band equal to or less than a specific value, a bitmap in which each bit corresponds to a candidate synchronization signal block position is used to receive a second synchronization signal block indicator indicating the position of a transmitted synchronization signal block on a frequency band equal to or less than the specific value, and the synchronization signal block can be received based on the second synchronization signal block indicator.

[0013] The synchronization signal block group indicator may indicate one or more synchronization signal block groups using a bitmap.

[0014] The first synchronization signal block indicator may correspond to information about the number of at least one transmission synchronization signal blocks included in one or more synchronization signal block groups.

[0015] The first synchronization signal block indicator may indicate a position of at least one transmission synchronization signal block within one or more synchronization signal block groups.

[0016] If at least one transmission synchronization signal block is received, a signal other than the at least one transmission synchronization signal block may not be received in a resource corresponding to the at least one transmission synchronization signal block.

[0017] A second synchronization signal block indicator indicating a location at which at least one transmission synchronization signal block is to be sent is also received using a bitmap in which each bit corresponds to a candidate synchronization signal block location. If the first synchronization signal block group indicator conflicts with information of the second synchronization signal block indicator, at least one transmission synchronization signal block may be received based on the second synchronization signal block indicator.

[0018] A value obtained by multiplying the number of synchronization signal block groups that can be indicated by the first synchronization signal block group indicator by the number of transmission synchronization signal blocks that can be indicated by the first synchronization signal block indicator corresponds to the number of transmission synchronization signal blocks that can be indicated by the second synchronization signal block indicator.

[0019] In order to further achieve these and other advantages and in accordance with the purpose of the present invention, according to different embodiments, a user equipment (UE) receiving a synchronization signal in a wireless communication system includes an RF module configured to transmit and receive radio signals with a base station, and a processor configured to receive a message including a synchronization signal block group indicator in a manner connected to the RF module, the synchronization signal block group indicator indicating one or more synchronization signal block groups including at least one transmission synchronization signal block among a plurality of synchronization signal block groups that group a specified number of candidate synchronization signal block positions of the synchronization signal blocks, the synchronization signal block including a primary synchronization signal, a secondary synchronization signal and a physical broadcast channel signal, and the processor is configured to receive at least one transmission synchronization signal block based on the message.

[0020] Specifically, the message may also include a first synchronization signal block indicator, which indicates at least one transmission synchronization signal block included in one or more synchronization signal block groups.

[0021] When the UE operates on a frequency band exceeding a specific value, the message may be received.

[0022] If the UE operates on a frequency band equal to or less than a specific value, the processor is configured to use a bitmap in which each bit corresponds to a candidate synchronization signal block position to receive a second synchronization signal block indicator indicating a position at which a transmission synchronization signal block is sent on a frequency band equal to or less than the specific value, and receive a synchronization signal block based on the second synchronization signal block indicator.

[0023] The synchronization signal block group indicator may indicate one or more synchronization signal block groups using a bitmap.

[0024] To further achieve these and other advantages and in accordance with the purpose of the present invention, according to another different embodiment, a method for measuring frequency (which is measured by a user equipment (UE) in a wireless communication system) includes receiving a synchronization signal block indicator, which indicates at least one candidate synchronization signal block including a transmission synchronization signal block among candidate synchronization signal block positions of synchronization signal blocks including a primary synchronization signal, a secondary synchronization signal and a physical broadcast channel signal, and performing measurements related to the frequency of sending the transmission synchronization signal block using the transmission synchronization signal block corresponding to the at least one candidate synchronization signal block.

[0025] The synchronization signal block indicator may indicate at least one candidate synchronization signal block using a bitmap.

[0026] In order to further achieve these and other advantages and in accordance with the purpose of the present invention, according to another different embodiment, a user equipment (UE) for measuring frequency in a wireless communication system includes an RF module configured to transmit and receive radio signals with a base station in a manner connected to the RF module, and a processor configured to receive a synchronization signal block indicator, which indicates at least one candidate synchronization signal block including a transmission synchronization signal block among candidate synchronization signal block positions of synchronization signal blocks including a primary synchronization signal, a secondary synchronization signal and a physical broadcast channel signal, and the processor is configured to perform measurements related to the frequency of sending the transmission synchronization signal block using the transmission synchronization signal block corresponding to the at least one candidate synchronization signal block.

[0027] The synchronization signal block indicator may indicate at least one candidate synchronization signal block using a bitmap.

[0028] Beneficial effects

[0029] According to the present invention, although the number of synchronization signal candidates is equal to or greater than a prescribed number, the index of the transmitted synchronization signal can be indicated using a small number of bits, thereby reducing signaling overhead.

[0030] Those skilled in the art will recognize that the effects that can be achieved by the present invention are not limited to the above specific description, and other advantages of the present invention will be more clearly understood from the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a diagram of the structures of a control plane and a user plane of a radio interface protocol between a user equipment and E-UTRAN based on the 3GPP radio access network standard;

[0032] Figure 2 is a diagram for explaining physical channels used in a 3GPP system and a general signal transmission method using the physical channels;

[0033] Figure 3 is a diagram of the structure of a radio frame in an LTE system;

[0034] Figure 4 is a diagram illustrating a radio frame structure for transmitting an SS (synchronization signal) in an LTE system;

[0035] Figure 5 The structure of a downlink radio frame in an LTE system is illustrated;

[0036] Figure 6 The structure of an uplink subframe in an LTE system is illustrated;

[0037] Figure 7illustrates an example of a connection scheme between the TXRU and antenna elements;

[0038] Figure 8 An example of a self-contained subframe structure is illustrated;

[0039] Figure 9 is a diagram for explaining an embodiment of mapping a synchronization signal sequence to a resource element;

[0040] Figure 10 is a diagram for explaining an embodiment of generating a primary synchronization signal sequence;

[0041] Figures 11 to 13 is a diagram for explaining measurement results of detection performance and PAPR (Peak to Average Power Ratio) performance when a synchronization signal is transmitted according to an embodiment of the present invention;

[0042] Figures 14 and 15 is a diagram for explaining an embodiment of multiplexing PSS / SSS / PBCH in a synchronization signal;

[0043] Figures 16 to 22 is a diagram for explaining a method of configuring a synchronization signal burst and a synchronization signal burst set;

[0044] Figures 23 to 25 A diagram for explaining a method of indexing a synchronization signal and a method of indicating an index;

[0045] Figures 26 to 42 is a graph of measurement results of performance according to an embodiment of the present invention;

[0046] Figures 43 to 44 is a diagram for explaining an embodiment of configuring bandwidth for a synchronization signal and a downlink common channel;

[0047] Figure 45 is a block diagram of a communication device according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0048] The configuration, operation and other features of the present disclosure will be easily understood by using the embodiments of the present disclosure described with reference to the accompanying drawings.The embodiments of the present disclosure set forth herein are examples of applying the technical features of the present disclosure to a 3rd Generation Partnership Project (3GPP) system.

[0049] Although the embodiments of the present disclosure are described in the context of Long Term Evolution (LTE) and LTE-Advanced (LTE-A) systems, they are merely exemplary. Therefore, as long as the above definition is valid for the communication system, the embodiments of the present disclosure are applicable to any other communication system.

[0050] The term "base station (BS)" may be used to cover the meaning of terms including remote radio head (RRH), evolved Node B (eNB or eNode B), reception point (RP), relay, etc.

[0051] Figure 1 This document illustrates the control plane and user plane protocol stacks in the radio interface protocol architecture between a user equipment (UE) and an evolved UMTS terrestrial radio access network (E-UTRAN) that conforms to the 3GPP radio access network standard. The control plane is a path for the UE and E-UTRAN to transmit control messages to manage calls, and the user plane is a path for transmitting data generated by the application layer (e.g., voice data or internet packet data).

[0052] The physical (PHY) layer at Layer 1 (L1) provides information transfer services to its higher layer, the medium access control (MAC) layer. The PHY layer is connected to the MAC layer via a transport channel. The transport channel delivers data between the MAC layer and the PHY layer. Data is transmitted on the physical channel between the PHY layers of the transmitter and receiver. The physical channel uses time and frequency as radio resources. Specifically, the physical channel is modulated with orthogonal frequency division multiple access (OFDMA) for the downlink (DL) and single carrier frequency division multiple access (SC-FDMA) for the uplink (UL).

[0053] The MAC layer at Layer 2 (L2) provides services to its higher layer, the Radio Link Control (RLC) layer, via logical channels. The RLC layer at L2 supports reliable data transmission. RLC functions can be implemented in the functional blocks of the MAC layer. The Packet Data Convergence Protocol (PDCP) layer at L2 performs header compression to reduce the amount of unnecessary control information, thereby efficiently transmitting Internet Protocol (IP) packets, such as IP version 4 (IPv4) or IP version 6 (IPv6) packets, over a narrow-bandwidth air interface.

[0054] The Radio Resource Control (RRC) layer at the lowest part of Layer 3 (or L3) is defined only on the control plane. The RRC layer controls logical channels, transport channels, and physical channels related to the configuration, reconfiguration, and release of radio bearers. Radio bearers refer to services provided at L2 for data transmission between the UE and the E-UTRAN. For this purpose, the RRC layer of the UE and the E-UTRAN exchange RRC messages with each other. If an RRC connection is established between the UE and the E-UTRAN, the UE is in RRC connected mode, otherwise, the UE is in RRC idle mode. The Non-Access Stratum (NAS) layer above the RRC layer performs functions including session management and mobility management.

[0055] DL transport channels used to deliver data from the E-UTRAN to the UE include the Broadcast Channel (BCH) for carrying system information, the Paging Channel (PCH) for carrying paging messages, and the Shared Channel (SCH) for carrying user traffic or control messages. DL multicast traffic or control messages, or DL ​​broadcast traffic or control messages, can be sent on the DL SCH or a separately defined DL Multicast Channel (MCH). UL transport channels used to deliver data from the UE to the E-UTRAN include the Random Access Channel (RACH) for carrying initial control messages and the UL SCH for carrying user traffic or control messages. Logical channels defined above and mapped to the transport channels include the Broadcast Control Channel (BCCH), the Paging Control Channel (PCCH), the Common Control Channel (CCCH), the Multicast Control Channel (MCCH), the Multicast Traffic Channel (MTCH), and others.

[0056] Figure 2 Physical channels and a general method for transmitting signals on the physical channels in a 3GPP system are illustrated.

[0057] When a UE is powered on or enters a new cell, it performs an initial cell search (S201). The initial cell search involves acquiring synchronization with the eNB. Specifically, the UE synchronizes its timing to the eNB and obtains the cell identifier (ID) and other information by receiving the Primary Synchronization Channel (P-SCH) and Secondary Synchronization Channel (S-SCH) from the eNB. The UE can then obtain information broadcast in the cell by receiving the Physical Broadcast Channel (PBCH) from the eNB. During the initial cell search, the UE can monitor the DL channel status by receiving the Downlink Reference Signal (DL RS).

[0058] After the initial cell search, the UE may acquire detailed system information by receiving a physical downlink control channel (PDCCH) and receiving a physical downlink shared channel (PDSCH) based on information included in the PDCCH (S202).

[0059] If the UE initially accesses the eNB or does not have radio resources for signal transmission to the eNB, the UE may perform a random access procedure with the eNB (S203 to S206). In the random access procedure, the UE may transmit a predetermined sequence as a preamble on a physical random access channel (PRACH) (S203 and S205), and may receive a response message to the preamble on a PDCCH and a PDSCH associated with the PDCCH (S204 and S206). In the case of a contention-based RACH, the UE may additionally perform a contention resolution procedure.

[0060] After the above process, the UE can receive the PDCCH and / or PDSCH (S207) and send the Physical Uplink Shared Channel (PUSCH) and / or Physical Uplink Control Channel (PUCCH) to the eNB (S208). This is a general DL and UL signal transmission process. Specifically, the UE receives downlink control information (DCI) on the PDCCH. Here, DCI includes control information such as resource allocation information for the UE. Different DCI formats are defined according to different usages of DCI.

[0061] The control information transmitted by the UE to the eNB on the UL or received by the UE from the eNB on the DL includes DL / UL Acknowledgement / Negative Acknowledgement (ACK / NACK) signals, Channel Quality Indicator (CQI), Precoding Matrix Index (PMI), Rank Indicator (RI), etc. In the 3GPP LTE system, the UE can transmit control information such as CQI, PMI, RI, etc. on the PUSCH and / or PUCCH.

[0062] Figure 3 The structure of a radio frame used in the LTE system is illustrated.

[0063] Reference Figure 3 , the radio frame is 10ms (327200xTs) long and is divided into 10 equally sized subframes. Each subframe is 1ms long and is further divided into two time slots. Each time slot is 0.5ms (15360xTs) long. In this article, Ts represents the sampling time and Ts=1 / (15kHzx2048)=3.2552x10-8 (about 33ns). A time slot includes multiple resource blocks (RBs) in the frequency domain and multiple orthogonal frequency division multiplexing (OFDM) symbols or SC-FDMA symbols in the time domain. In the LTE system, one RB includes 12 subcarriers multiplied by 7 (or 6) OFDM symbols. The unit time for transmitting data is defined as a transmission time interval (TTI). TTI can be defined in units of one or more subframes. The above radio frame structure is merely exemplary, and thus the number of subframes in a radio frame, the number of time slots in a subframe, or the number of OFDM symbols in a time slot may vary.

[0064] Figure 4 1 is a diagram illustrating a radio frame structure for transmitting SS (synchronization signal) in an LTE system. In particular, Figure 3 A radio frame structure for transmitting a synchronization signal and a PBCH in FDD (Frequency Division Duplex) is illustrated. Figure 4 (a) shows the positions where SS and PBCH are transmitted in a radio frame configured by a normal CP (cyclic prefix), Figure 4 (b) shows the locations where SS and PBCH are transmitted in a radio frame configured by the extended CP. ..

[0065] Will refer to Figure 4 The SS is described in more detail. The SS is classified into PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal). The PSS is used to acquire time domain synchronization and / or frequency domain synchronization such as OFDM symbol synchronization, time slot synchronization, etc. In addition, the SSS is used to acquire the CP configuration of the cell (i.e., information indicating whether a normal CP or an extended CP is used), frame synchronization, and / or cell group ID. Figure 4 , PSS and SSS are sent through two OFDM symbols in each radio frame. Specifically, considering that the GSM (Global System for Mobile Communications) frame length is 4.6ms to facilitate inter-radio access technology (inter-RAT) measurement, SS is sent in the first time slot in each of subframe 0 and subframe 5. In particular, PSS is sent in the last OFDM symbol in each of the first time slot of subframe 0 and the first time slot of subframe 5. In addition, SSS is sent in the penultimate OFDM symbol in each of the first time slot of subframe 0 and the first time slot of subframe 5. The boundary of the corresponding radio frame can be detected by SSS. PSS is sent in the last OFDM symbol of the corresponding time slot, and SSS is sent in the OFDM symbol immediately before the OFDM symbol in which PSS is sent. According to the transmission diversity scheme for SS, only a single antenna port is used. However, the transmission diversity scheme of the SS standard is not separately defined in the current standard.

[0066] By detecting the PSS, the UE can determine whether the corresponding subframe is subframe 0 or subframe 5. Since the PSS is transmitted every 5 ms, the UE cannot determine whether the subframe is subframe 0 or subframe 5. Therefore, when using only the PSS, the UE cannot identify the radio frame boundary. In other words, frame synchronization cannot be achieved using only the PSS. The UE detects the radio frame boundary by detecting that the SSS is transmitted twice with different sequences within a radio frame.

[0067] By performing a cell search procedure using PSS / SSS to demodulate DL signals and determining time and frequency parameters required to perform UL signal transmission at an accurate time, the UE can communicate with the eNB only after obtaining system information necessary for system configuration of the UE from the eNB.

[0068] System information is configured with a master information block (MIB) and a system information block (SIB). Each SIB includes a set of function-related parameters and is classified into MIB, SIB type 1 (SIB1), SIB type 2 (SIB2), and SIB3 to SIB8 according to the parameters included.

[0069] The MIB includes the most frequently transmitted parameters that are essential for the UE to initially access the network served by the eNB. The UE can receive the MIB through a broadcast channel (e.g., PBCH). The MIB includes downlink system bandwidth (DL BW), PHICH configuration, and system frame number (SFN). Therefore, the UE can explicitly know information about the DL BW, SFN, and PHICH configuration by receiving the PBCH. On the other hand, the UE can implicitly know information about the number of transmission antenna ports of the eNB. The information about the number of transmission antennas of the eNB is implicitly signaled by masking (e.g., XOR operation) a sequence corresponding to the number of transmission antennas to a 16-bit CRC (cyclic redundancy check) used to detect errors in the PBCH.

[0070] SIB1 includes not only information on time domain scheduling of other SIBs, but also parameters necessary to determine whether a specific cell is suitable for cell selection. The UE receives SIB1 via broadcast signaling or dedicated signaling.

[0071] The DL carrier frequency and the corresponding system bandwidth can be obtained through the MIB carried by the PBCH. The UL carrier frequency and the corresponding system bandwidth can be obtained through the system information corresponding to the DL signal. After receiving the MIB, if there is no valid system information stored in the corresponding cell, the UE applies the DL BW value included in the MIB to the UL bandwidth until the System Information Block Type 2 (SIB2) is received. For example, if the UE obtains SIB2, the UE can identify the entire UL system bandwidth that can be used for UL transmission through the UL carrier frequency and UL bandwidth information included in SIB2.

[0072] In the frequency domain, the PSS / SSS and PBCH are transmitted regardless of the actual system bandwidth in a total of 6 RBs (i.e., 3 RBs to the left and 3 RBs to the right of the DC subcarrier in the corresponding OFDM symbol). In other words, the PSS / SSS and PBCH are transmitted in only 72 subcarriers. Therefore, the UE is configured to detect or decode the SS and PBCH regardless of the downlink transmission bandwidth configured for the UE.

[0073] After completing the initial cell search, the UE can perform a random access procedure to complete access to the eNB. To this end, the UE sends a preamble via the PRACH (Physical Random Access Channel) and can receive a response message via the PDCCH and PDSCH in response to the preamble. In the case of contention-based random access, it can send additional PRACHs and perform contention resolution procedures, such as the PDCCH and the PDSCH corresponding to the PDCCH.

[0074] After performing the above-mentioned procedures, the UE may perform PDCCH / PDSCH reception and PUSCH / PUCCH transmission as a general UL / DL signal transmission procedure.

[0075] The random access procedure is also called the random access channel (RACH) procedure. The random access procedure is used for various purposes, including initial access, UL synchronization adjustment, resource allocation, switching, etc. The random access procedure is classified into a contention-based procedure and a dedicated (i.e., non-contention-based) procedure. Generally, the contention-based random access procedure is used to perform initial access. On the other hand, the dedicated random access procedure is restrictively used to perform switching, etc. When performing a contention-based random access procedure, the UE randomly selects a RACH preamble sequence. Thus, multiple UEs can send the same RACH preamble sequence at the same time. As a result, a contention resolution procedure is required thereafter. In contrast, when performing a dedicated random access procedure, the UE uses a RACH preamble sequence specifically allocated to the UE by the eNB. Therefore, the UE can perform a random access procedure without conflicting with different UEs.

[0076] The contention-based random access procedure includes the following four steps: The messages sent in the four steps may be referred to as messages (Msg) 1 to 4 in the present invention.

[0077] - Step 1: RACH preamble (via PRACH) (UE to eNB)

[0078] - Step 2: Random Access Response (RAR) (via PDCCH and PDSCH (eNB to UE))

[0079] - Step 3: Layer 2 / Layer 3 message (via PUSCH) (UE to eNB)

[0080] -Step 4: Contention Resolution Message (eNB to UE)

[0081] On the other hand, the dedicated random access procedure includes the three steps described below. The messages sent via the three steps may be referred to as messages (Msg) 0 to 2 in this disclosure. Uplink transmission corresponding to the RAR (i.e., step 3) may also be performed as part of the random access procedure. The dedicated random access procedure may be triggered using the PDCCH (hereinafter, PDCCH command), which is used by the eNB to instruct the transmission of the RACH preamble.

[0082] - Step 0: RACH preamble assignment via dedicated signaling (eNB to UE)

[0083] - Step 1: RACH preamble (via PRACH) (UE to eNB)

[0084] - Step 2: Random Access Response (RAR) (via PDCCH and PDSCH) (eNB to UE)

[0085] After transmitting the RACH preamble, the UE attempts to receive a random access response (RAR) within a preconfigured time window. Specifically, the UE attempts to detect a PDCCH (hereinafter, RA-RNTI PDCCH) with an RA-RNTI (Random Access RNTI) within the time window (e.g., a CRC masked with the RA-RNTI in the PDCCH). If the RA-RNTI PDCCH is detected, the UE checks whether there is a RAR for the UE in the PDSCH corresponding to the RA-RNTI PDCCH. The RAR includes timing advance (TA) information indicating timing offset information for UL synchronization, UL resource allocation information (UL grant information), a temporary UE identifier (e.g., temporary cell-RNTI, TC-RNTI), etc. The UE can perform UL transmission (e.g., message 3) based on the resource allocation information and TA value included in the RAR. HARQ is applied to the UL transmission corresponding to the RAR. Specifically, the UE can receive reception response information (e.g., PHICH) corresponding to message 3 after transmitting message 3.

[0086] The random access preamble (i.e., RACH preamble) consists of a cyclic prefix of length TCP and a sequence part of length TSEQ. TCP and TSEQ depend on the frame structure and random access configuration. The preamble format is controlled by a higher layer. The RACH preamble is sent in the UL subframe. The transmission of the random access preamble is limited to specific time resources and frequency resources. The resources are called PRACH resources. In order to match index 0 to a lower number of subframes and PRBs in the radio frame, the PRACH resources are numbered in ascending order of the number of PRBs in the frequency domain and the number of subframes in the radio frame. The random access resources are defined according to the PRACH configuration index (refer to the 3GPP TS 36.211 standard document). The RACH configuration index is provided by a higher layer signal (sent by the eNB).

[0087] In the LTE / LTE-A system, the subcarrier spacing of the random access preamble (ie, RACH preamble) is adjusted by 1.25 kHz and 7.5 kHz for preamble formats 0 to 3 and preamble format 4, respectively (refer to 3GPP TS 36.211).

[0088] Figure 5 Exemplary control channels included in a control region of a subframe in a DL radio frame are illustrated.

[0089] Reference Figure 5, a subframe includes 14 OFDM symbols. Depending on the subframe configuration, the first one to three OFDM symbols of the subframe are used for the control region, and the other 13 to 11 OFDM symbols are used for the data region. Figure 5 In the figure, reference characters R1 to R4 denote RSs or pilot signals for antennas 0 to 3. RSs are allocated in a predetermined pattern in a subframe, regardless of the control region and data region. Control channels are allocated to non-RS resources in the control region, and traffic channels are also allocated to non-RS resources in the data region. Control channels allocated to the control region include the Physical Control Format Indicator Channel (PCFICH), the Physical Hybrid ARQ Indicator Channel (PHICH), the Physical Downlink Control Channel (PDCCH), and others.

[0090] PCFICH is a physical control format indicator channel that carries information about the number of OFDM symbols used for PDCCH in each subframe. PCFICH is located in the first OFDM symbol of the subframe and is configured with a higher priority than PHICH and PDCCH. PCFICH includes 4 resource element groups (REGs), each of which is distributed to the control region based on the cell identity (ID). One REG includes 4 resource elements (REs). RE is the smallest physical resource defined by one subcarrier and one OFDM symbol. PCFICH is set to 1 to 3 or 2 to 4 depending on the bandwidth. PCFICH is modulated with quadrature phase shift keying (QPSK).

[0091] The PHICH is a physical hybrid automatic repeat and request (HARQ) indicator channel that carries HARQ ACK / NACK for UL transmission. That is, the PHICH is a channel that delivers DL ACK / NACK information for UL HARQ. The PHICH includes one REG and is cell-specifically scrambled. ACK / NACK is indicated in one bit and modulated using binary phase shift keying (BPSK). The modulated ACK / NACK is spread with a spreading factor (SF) of 2 or 4. Multiple PHICHs mapped to the same resources form a PHICH group. The number of PHICHs multiplexed into the PHICH group is determined by the number of spreading codes. The PHICH (group) is repeated three times to achieve diversity gain in the frequency and / or time domains.

[0092] The PDCCH is a physical DL control channel allocated to the first n OFDM symbols of a subframe. In this document, n is an integer of 1 or greater indicated by the PCFICH. The PDCCH occupies one or more CCEs. The PDCCH carries resource allocation information about transport channels, PCH and DL-SCH, UL scheduling grants, and HARQ information to each UE or UE group. The PCH and DL-SCH are transmitted on the PDSCH. Therefore, in addition to specific control information or specific service data, the eNB and UE usually send and receive data on the PDSCH.

[0093] Information indicating that one or more UEs receive PDSCH data and information indicating how the UEs should receive and decode the PDSCH data is delivered on the PDCCH. For example, assuming that the cyclic redundancy check (CRC) of a specific PDCCH is masked by the radio network temporary identifier (RNTI) "A" and information about data sent in radio resources (e.g., in frequency position) "B" based on transport format information "C" (e.g., transport block size, modulation scheme, coding information, etc.) is sent in a specific subframe, the UEs within the cell use their RNTI information in the search space to monitor the PDCCH (i.e., blind decoding). If one or more UEs have RNTI "A", these UEs receive the PDCCH and receive the PDSCH indicated by "B" and "C" based on the information of the received PDCCH.

[0094] Figure 6 The structure of a UL subframe in the LTE system is illustrated.

[0095] Reference Figure 6 , the UL subframe can be divided into a control region and a data region. The physical uplink control channel (PUCCH) including uplink control information (UCI) is allocated to the control region, and the physical uplink shared channel (PUSCH) including user data is allocated to the data region. The middle of the subframe is allocated to PUSCH, and the data region is allocated to PUCCH on both sides in the frequency domain. The control information sent on the PUCCH may include HARQ ACK / NACK, CQI indicating the downlink channel state, RI for multiple input multiple output (MIMO), and a scheduling request (SR) requesting UL resource allocation. The PUCCH of one UE occupies one RB in each time slot of the subframe. That is, the two RBs allocated to the PUCCH hop on the time slot boundary of the subframe. Specifically, PUCCHs with m=0, m=1, and m=2 are allocated to Figure 6 subframes in .

[0096] Hereinafter, channel state information (CSI) reporting will be described. In the current LTE standard, there are two MIMO transmission schemes: open-loop MIMO, which operates without channel information, and closed-loop MIMO, which operates with channel information. Specifically, in closed-loop MIMO, each of the eNB and the UE can perform beamforming based on CSI to obtain multiplexing gain for the MIMO antennas. To obtain CSI from the UE, the eNB can instruct the UE to feedback CSI on the downlink signal by allocating a PUCCH (Physical Uplink Control Channel) or a PUSCH (Physical Uplink Shared Channel) to the UE.

[0097] CSI is mainly divided into three types of information: RI (Rank Indicator), PMI (Precoding Matrix), and CQI (Channel Quality Indicator). First, as mentioned above, RI indicates the rank information of the channel and means the number of streams that the UE can receive using the same time-frequency resources. In addition, because RI is determined by long-term channel fading, it can be fed back to the eNB over a longer period of time compared to PMI and CQI values.

[0098] Second, PMI is a value obtained by reflecting the spatial characteristics of the channel and indicates the precoding matrix index of the eNB preferred by the UE based on metrics such as signal to interference plus noise ratio (SINR). Finally, CQI is a value indicating channel strength and generally represents the received SINR that can be obtained by the eNB when using PMI.

[0099] In 3GPP LTE-A systems, the eNB can configure multiple CSI processes for a UE and report CSI for each CSI process. In this case, the CSI process includes CSI-RS resources for specifying signal quality and CSI-IM (interference measurement) resources, i.e., IMRs (interference measurement resources) for interference measurement.

[0100] Since the wavelength is shorter in the millimeter wave (mmW) field, multiple antenna elements can be installed in the same area. More specifically, the wavelength is 1 cm in the 30 GHz band, and a total of 64 (8×8) antenna elements of a 2D array can be installed in a 4×4 cm panel at intervals of 0.5λ (wavelength). Therefore, the recent trend in the mmW field attempts to increase coverage or throughput by enhancing BF (beamforming) gain using multiple antenna elements.

[0101] In this case, if a transceiver unit (TXRU) is provided to control the transmit power and phase of each antenna element, independent beamforming can be performed for each frequency resource. However, when TXRUs are provided for all 100 antenna elements, effectiveness deteriorates in consideration of cost. Therefore, a scheme is considered in which multiple antenna elements are mapped to one TXRU and the beam direction is controlled by an analog phase shifter. Since this analog beamforming scheme can generate only one beam direction in the entire frequency band, the problem of frequency selective beamforming being unavailable arises.

[0102] As an intermediate type between digital BF and analog BF, a hybrid BF with B TXRUs and fewer than Q antenna elements can be considered. In this case, although the connection scheme of the B TXRUs and Q antenna elements varies, the number of beam directions that enable simultaneous transmission is limited to B or less.

[0103] Figure 7 An example of a connection scheme between the TXRU and antenna elements is illustrated.

[0104] Figure 7 (a) illustrates the connection of a TXRU to a subarray. In this case, the antenna elements are connected to only one TXRU. Figure 7 (a) is different, Figure 6 (b) illustrates that the TXRU is connected to all antenna elements. In this case, the antenna elements are connected to all TXRUs. Figure 6 In this example, W represents the phase vector multiplied by the analog phase shifter. That is, the direction of the analog beamforming is determined by W. In this case, the mapping between CSI-RS antenna ports and TXRUs can be one-to-one or one-to-many.

[0105] As more communication devices require greater communication capacity, demand has emerged for mobile broadband communications that are more advanced than conventional RATs (Radio Access Technologies). Furthermore, large-scale MTC (Machine Type Communication) technology, which connects multiple devices and things to provide a variety of services anywhere and at any time, is one of the main considerations for next-generation communications. Furthermore, discussions have been held regarding communication system design that takes into account services and users that are susceptible to reliability and latency. Given this situation, the introduction of next-generation RATs has been discussed, and these next-generation RATs will be referred to as NewRATs in this disclosure.

[0106] Considered in the fifth generation of NewRAT Figure 8 The self-contained subframe structure shown in FIG is used to minimize the data transmission delay in the TDD system. Figure 8 An example of a self-contained subframe structure is illustrated.

[0107] exist Figure 8 In the figure, the shaded area indicates the downlink control region, and the black area indicates the uplink control region. Unmarked areas can be used for either downlink or uplink data transmission. In this structure, downlink and uplink transmissions are performed sequentially within a subframe, allowing downlink data to be sent and uplink ACK / NACK to be received within the subframe. As a result, when an error occurs during data transmission, the time required for data retransmission can be reduced, thereby minimizing the latency of the final data transmission.

[0108] In this self-contained subframe structure, the base station and the UE need a time gap for switching from transmit mode to receive mode or vice versa. To this end, some OFDM symbols (OS) in the self-contained subframe structure when downlink switches to uplink are set as a guard period.

[0109] Examples of self-contained subframe types that can be configured in a system operating based on NewRAT include the following four subframe types.

[0110] - Downlink control period + downlink data period + GP + uplink control period

[0111] - Downlink control period + downlink data period

[0112] - Downlink control period + GP + uplink data period + uplink control period

[0113] - Downlink control period + GP + uplink data period

[0114] Hereinafter, a method of generating a synchronization signal and a method of indicating a synchronization signal index are described according to an embodiment of the present invention.

[0115] 1. Parameter Set and Basic Subcarrier Spacing

[0116] The parameter set for the SS block may be defined as follows.

[0117] -Subcarrier spacing (bandwidth)

[0118] 15kHz (up to 5MHz), 30kHz (up to 10MHz), 120kHz (up to 40MHz), 240kHz (up to 80MHz)

[0119] Since 24 RBs are allocated to transmit the PBCH, a 4.32 MHz transmission bandwidth is required for a 15 kHz subcarrier, and a 34.56 MHz transmission bandwidth is required for a 120 kHz subcarrier. In addition, the minimum usable carrier bandwidth for NR is determined by 5 MHz in the frequency range up to 6 GHz. In the frequency range from 6 GHz to 52.6 GHz, the minimum usable carrier bandwidth for NR is determined by 50 MHz.

[0120] Specifically, as mentioned in the previous description, in the frequency range below 6 GHz, a subcarrier spacing of 15 kHz is determined as the default parameter set. In the frequency range above 6 GHz, a subcarrier spacing of 120 kHz can be determined as the default parameter set. More specifically, in the frequency range from 6 GHz to 52.6 GHz, a subcarrier spacing of 120 kHz can be determined as the default parameter set. However, it is necessary to accurately approach the detection performance of the 15 kHz subcarrier based on the PSS / SSS in 6 GHz.

[0121] In addition, the possibility of introducing a wider subcarrier spacing (e.g., 30 kHz or 240 kHz subcarrier spacing) to transmit NR-SS can be considered.

[0122] 2. Transmission Bandwidth and NR-SS Sequence RE Mapping

[0123] Reference Figure 9 , similar to the mapping method of PSS / SSS sequences mapped to REs in LTE, the NR-SS sequence can be mapped to REs located at the center of the transmission bandwidth. Some REs located at the edge of the transmission bandwidth can be reserved as guard subcarriers. For example, when 12 RBs are used to transmit NR-SS, 127 REs are used for the NR-SS sequence and 17 REs are reserved. In this case, the 64th element of the NR-SS sequence can be mapped to a subcarrier located at the center of the bandwidth where the NR-SS is transmitted.

[0124] Furthermore, when the NR-SS sequence is mapped to REs, in the case of 15 kHz subcarriers, it can be assumed that a 2.16 MHz transmission bandwidth is used to transmit the NR-SS. If the subcarrier spacing increases by an integer multiple, the NR-SS bandwidth also increases by the same integer multiple.

[0125] Specifically, the bandwidth for transmitting NR-SS may be defined as follows according to the subcarrier spacing.

[0126] If the subcarrier spacing corresponds to 15 kHz, the bandwidth for transmitting NR-SS may correspond to 2.16 MHz.

[0127] If the subcarrier spacing corresponds to 30 kHz, the bandwidth for transmitting NR-SS may correspond to 4.32 MHz.

[0128] If the subcarrier spacing corresponds to 120 kHz, the bandwidth for transmitting NR-SS may correspond to 17.28 MHz.

[0129] If the subcarrier spacing corresponds to 240 kHz, the bandwidth for transmitting NR-SS may correspond to 34.56 MHz.

[0130] 3. NR-PSS Sequence Design

[0131] In the NR system, in order to classify 1000 cell IDs, the number of NR-PSS sequences is defined by 3, and the number of NR-SSS hypotheses corresponding to each NR-PSS is defined by 334.

[0132] When designing an NR-PSS, considerations such as timing ambiguity, PAPR, and detection complexity must be considered. To address timing ambiguity, it may be possible to use a frequency-domain M-sequence to generate the NR-PSS. However, using an M-sequence to generate the NR-PSS may result in a relatively high PAPR. Therefore, when designing an NR-PSS, it is necessary to research frequency-domain M-sequences with low PAPR characteristics.

[0133] In addition, the modified ZC sequence can be considered as the NR-PSS sequence. Specifically, if four ZC sequences are generated in a manner that is continuously arranged in the time domain, it may be possible to resolve the timing ambiguity problem, have a low PAPR characteristic, and reduce the detection complexity. Specifically, in the NR system, when the UE intends to detect the NR-PSS with a transmission bandwidth wider than the bandwidth of multi-sequence and LTE, the detection complexity increases. Therefore, it is very important to reduce the detection complexity when it comes to NR-PSS.

[0134] Based on the foregoing discussion, two types of NR-PSS sequences can be considered.

[0135] (1) Frequency M sequence with low PAPR characteristics

[0136] - Polynomial expression: g(x) = x 7 +x 6 +x 4 +x+1 (initial polynomial shift register value: 1000000)

[0137] - Circular shift: 0, 31, 78

[0138] (2) Four ZC sequences arranged continuously in the time domain

[0139] - ZC sequence of length 31 (root indices: {1,30}, {7,24}, {4,27})

[0140] -Equation used to generate the sequence

[0141] [Equation 1]

[0142]

[0143]

[0144] n=0,1,...,31

[0145] n=0,1,...,31

[0146] n=0,1,...,31

[0147] Figure 10 This is a diagram for briefly explaining a method of generating NR-PSS using four consecutive ZC sequences in the time domain. Figure 10 When N sub-symbols correspond to S1, S2, ..., Sn, if the sequence of sub-symbols is concatenated before performing IFFT, DFT (discrete Fourier transform) expansion is performed using the length of the total sequence, and multiple sequences corresponding to the N sub-symbols are mapped according to subcarriers, and IFFT is performed. It is possible to obtain a time domain sequence of NIFFT length without the problem of out-of-band emission.

[0148] 4.NR-SSS sequence design

[0149] The NR-SSS sequence is generated from a single long sequence and a combination of two M sequences with different polynomial expressions, resulting in 334 hypotheses. For example, if the cyclic shift value of the first M sequence corresponds to 112 and the cyclic shift value of the second M sequence corresponds to 3, a total of 336 hypotheses can be obtained. In this case, the scrambling sequence of the NR-PSS can be obtained by applying the third M sequence.

[0150] If a relatively short period (e.g., 5 ms / 10 ms) NR-SS burst set is configured, the NR-SS burst set may be transmitted several times in two radio frames, each radio frame having a length of 10 ms.

[0151] Specifically, if different NR-SSS sequences are introduced for NR-SS burst sets transmitted several times, in other words, if a different NR-SSS sequence is used each time an NR-SS burst set is transmitted, the UE can identify each of the multiple NR-SS burst sets transmitted within the basic period.

[0152] For example, if an NR-SSS burst set is transmitted four times in a basic period, it can be considered that the original set of NR-SSS sequences is applied to the first NR-SSS burst set and a NR-SSS sequence different from the original set is applied to the second NR-SSS burst set, the third NR-SSS burst set, and the fourth NR-SSS burst set. If two different NR-SSS sequence sets are used, one NR-SSS sequence set is used for the first and third NR-SSS burst sets, and the other NR-SSS sequence set can be used for the second and fourth NR-SSS burst sets.

[0153] In the NR system, two M sequences are defined for the NR-SSS sequence, each of which has a length of 127, and a final sequence is generated by multiplying elements included in each M sequence.

[0154] Specifically, the NR-SSS sequence may correspond to a scrambling sequence given by the NR-SSS, the NR-SSS sequence may have a length of 127, and the NR-SSS sequence may be determined by Equation 2 described below.

[0155] [Equation 2]

[0156] For n=0, ..., 126 and z=0, 1, d(n)=s 1,m (n)s 2,k (n)c z (n)

[0157] In this case, z=0 may be used for NR-SSS transmitted in the first SS burst set of two radio frames, each of which has a length of 10 ms. In addition, z=1 may be used for NR-SSS transmitted in the second SS burst set, the third SS burst set, and the fourth SS burst set.

[0158] In this case, s 1,m (n) and s 2,k (n) can be determined by Equation 3 described below.

[0159] [Equation 3]

[0160] s 1,m (n) = S1((n+m) mod 127),

[0161] s 2,k (n) = S2((n+k) mod 127)

[0162] In this case, we can define m=N ID1 mod112, K = floor(N ID1 / 112), k=CS2(K), 0≤N ID1 ≤333, CS2∈{48,67,122}.

[0163] Finally, to calculate S1 and S2, we can define S r (i) = 1-2x(i), 0≤i≤126, r = 1, 2. In this case, the polynomial of x(i) can be defined by Equation 4 described below.

[0164] [Equation 4]

[0165] x(j+7)=(x(j+3)+x(j))mod2,r=1

[0166] x(j+7)=(x(j+3)+x(j+2)+x(j+1)+x(j))mod2,r=2

[0167] In this case, the initial conditions for x(i) can correspond to

[0168] x(0)=x(1)=x(2)=x(3)=x(4)=x(5)=0, x(6)=1, and may have a value satisfying 0≤j≤119.

[0169] In this case, as the preamble and midamble of the SSS, two scrambling sequences including C0(n) and C1(n) may be used. The two scrambling sequences depend on the PSS. As shown in Equation 5 below, the scrambling sequence can be defined by applying different cyclic shifts to C(n) corresponding to the M sequence.

[0170] [Equation 5]

[0171] c z (n) = C ((n + p) mod 127)

[0172] Where p = CS1(N ID2 +3·z), CS1∈{23,69,103,64,124,24}, N ID2 ∈{0,1,2}

[0173] In this case, it may be defined that C(i)=1-2x(i) and 0≤I≤126. In this case, the polynomial of x(i) may be defined by Equation 6 described below.

[0174] [Equation 6]

[0175] x(j+7)=(x(j+5)+x(j+4)+x(j+3)+x(j+2)+x(j+1)+x(j))mod2

[0176] In this case, the initial conditions of x(i) may correspond to x(0)=x(1)=x(2)=x(3)=x(4)=x(5)=0, x(6)=1, and may have a value satisfying 0≤j≤119.

[0177] The following describes the performance measurement results according to the aforementioned embodiments. To measure the performance of NR-PSS, three methods for designing NR-SSS were considered: 1) a frequency-domain M-sequence (traditional PSS sequence), 2) an M-sequence with low PAPR, and 3) a sequence generated by concatenating four ZC sequences in the time domain.

[0178] Furthermore, in order to measure NR-SSS, the NR-SSS sequence proposed by the present invention is used.

[0179] 5. Measurement results based on the aforementioned NR-PSS sequence design

[0180] PAPR and CM

[0181] The measurement results of PAPR and CM measured for the three types of NR-PSS sequences are shown in Table 1 below.

[0182] [Table 1]

[0183] PAPR[dB] CM[dB] Frequency domain M sequence (WA) 4.87,5.10,5.74 1.25,1.76,2.19 M sequence with low PAPR 4.16,3.99,4.15 1.10,1.42,1.50 Four ZC sequences concatenated in time 2.80,3.49,3.91 0.094,0.71,0.79

[0184] The results show that the PAPR / CM ratio of the NR-SSS, which is based on a sequence concatenated with four ZC sequences in the time domain, is lower than that of the NR-PSS, which is based on an M-sequence. Furthermore, when comparing an M-sequence with a low PAPR with a frequency-domain M-sequence, the PAPR / CM ratio of the M-sequence with a low PAPR is lower than that of the frequency-domain M-sequence. Furthermore, since PAPR / CM is a significant factor in determining the price of a power amplifier, it is important to consider designing an NR-PSS with a low PAPR / CM ratio.

[0185] Therefore, in terms of PAPR / CM, the NR-PSS based on the ZC sequence shows better performance measurement results than the NR-PSS based on the M sequence. Compared with the NR-PSS based on the frequency-domain M sequence, the NR-PSS based on the M sequence with low PAPR shows better performance measurement results.

[0186] False detection rate

[0187] Figure 11 The evaluation of the false detection rate of each of the above NR-PSS is illustrated. Figure 11 , it can be seen that the performance of each NR-PSS design has a similar level. On the other hand, referring to Figure 12, it can be seen that the sequence generated by concatenating 4 ZC sequences has the lowest detection complexity.

[0188] Specifically, refer to Figure 12 , it can be seen that the sequence generated by concatenating four ZC sequences and the frequency-domain sequence have similar detection performance. In this case, the sequence generated by concatenating four ZC sequences has the advantage of lower detection complexity. Assuming that NR-PSS sequences have similar detection complexity, the sequence generated by concatenating four ZC sequences offers superior performance compared to the M sequence.

[0189] Therefore, under the premise of the same detection complexity, the detection performance of the NR-PSS design based on the ZC sequence provides better performance compared with the detection performance of the frequency domain M sequence.

[0190] 6. Measurement results based on the aforementioned NR-SSS sequence design

[0191] Hereinafter, the detection performances according to the number of NR-SSS sequences are compared with each other. In order to measure the performance, the conventional SSS sequence is compared with the NR-SSS proposed in the present invention.

[0192] The following briefly describes the information about the NR-SSS sequence design.

[0193] 1) Single-group NR-SSS (334 hypotheses per NR-PSS sequence)

[0194] 2) Two groups of NR-SSS (668 hypotheses per NR-PSS sequence)

[0195] Reference Figure 13 ,Although the assumption of NR-SSS is doubled, no particular ,performance degradation is detected., ,Therefore, in order to detect the boundary of the SS burst set within the ,basic period, it is possible to consider introducing another set of NR-SSS.

[0196] In addition, for Figures 11 to 13 The parameters of the measurement experiments are shown in Table 2 below.

[0197] [Table 2]

[0198]

[0199] 7.SS block configuration

[0200] When the maximum payload size of PBCH corresponds to 80 bits, it can use a total of 4 OFDM symbols to transmit an SS block. In addition, the time position of NR-PSS / NR-SSS / NR-PBCH in the SS block including NR-PSS, NR-SSS and NR-PBCH needs to be considered. When performing initial access, NR-PBCH can be used as a reference signal for precise time / frequency tracking. In order to improve the estimation accuracy, the two OFDM symbols used for NR-PBCH can be positioned as far apart as possible. In particular, as Figure 14 As shown in (a), the present invention proposes to use the first and fourth OFDM symbols of the SS block to transmit the NR-PBCH. Therefore, the second OFDM symbol is allocated to the NR-SSS, and the third OFDM symbol can be used for the NR-SSS.

[0201] In addition, when NR-SSS is sent to measure or discover cells, it is not necessary to send both NR-PBCH and SS block time index indication. Figure 14 As shown in (b), the SS block includes two OFDM symbols. The first OFDM symbol is allocated to the NR-SSS, and the second OFDM symbol is allocated to the NR-SSS.

[0202] Reference Figure 15 (a), NR-PBCH is allocated within 288 REs, and these REs are configured by 24 RBs. In addition, since the length of NR-PSS / NR-SSS corresponds to 127, 12 RBs are required to send NR-PSS / NR-SSS. In particular, when configuring SS blocks, SS blocks are allocated within 24 RBs. In addition, it is preferred to allocate SS blocks within 24 RBs to align the RB grid between different parameter sets (e.g., 15kHz, 30kHz, 60kHz, etc.). In addition, since it is assumed in the NR system that a minimum bandwidth of 5MHz of 25 RBs can be defined using a 15MHz subcarrier spacing, 24 RBs are used to send SS blocks. NR-PSS / SSS is located at the center of the SS block. This may indicate that NR-PSS / SSS is allocated to the 7th to 18th RBs.

[0203] In addition, if Figure 15 If the SS block is configured as shown in (a) of FIG, problems may occur in the AGC (automatic gain control) operation of the UE with 120kHz subcarrier spacing and 240kHz subcarrier spacing. Specifically, in the case of 120kHz subcarrier spacing and 240kHz subcarrier spacing, it may not be possible to correctly perform NR-SSS detection due to the AGC operation. Therefore, as described in the following two embodiments, it is possible to consider changing the configuration of the SS block.

[0204] (Method 1) PBCH-PSS-PBCH-SSS

[0205] (Method 2)PBCH-PSS-PBCH-SSS-PBCH

[0206] Specifically, if the PBCH symbol is located at the start point of the SS block and the PBCH symbol is used as a dummy symbol for the AGC operation, it may be possible to enable the AGC operation of the UE to be completed more smoothly.

[0207] In addition, you can Figure 15 NR-PSS / NR-SSS / NR-PBCH are allocated as shown in (b). Specifically, NR-PSS is allocated to the 0th symbol, and NR-SSS may be allocated to the 2nd symbol. In addition, NR-PBCH may be allocated to the 1st to 3rd symbols. In this case, NR-PBCH may be allocated exclusively to the 1st and 3rd symbols. In other words, NR-PBCH is allocated only to the 1st and 3rd symbols, and NR-SSS and NR-PBCH may be mapped together to the 2nd symbol.

[0208] 8.SS Burst Configuration

[0209] This invention describes a method for determining which OFDM symbols are transmittable using a SS block. The CP type is semi-statically configured along with UE-specific signaling. NR-PSS / SSS can support normal CPs. This allows for solving the CP detection issue during initial access.

[0210] However, in the NR system, an extended CP may be included in each 0.5ms edge. Specifically, when the SS block is located within a slot or between slots, the center of the SS block may be located at the 0.5ms edge. In this case, CPs of different lengths may be applied to the NR-PSS and / or NR-SSS in the SS block. In this case, if the UE performs NR-SS detection assuming that a normal CP is applied to the NR-SSS and / or NR-SSS, the detection performance may deteriorate. Therefore, it is necessary to design the SS block to have an edge not exceeding 0.5ms in the NR system.

[0211] Figure 16 This section illustrates an example of configuring SS bursts in the TDD case. In NR systems, the DL control channel is located at the first OFDM symbol in a slot and / or mini-slot, and the UL control channel can be located at the last transmitted UL symbol. To avoid collisions between the SS block located in the slot and the DL / UL control channel, the SS block can be located at the center of the slot.

[0212] The maximum number of SS blocks included in the SS burst set is determined based on the frequency range. In addition, a candidate value of the number of SS blocks is determined based on the frequency range. In addition, based on Figure 16 Based on the example of configuring SS bursts shown in , the present invention proposes the total time interval required to send SS blocks in an SS burst set.

[0213] [Table 3]

[0214]

[0215] As shown in Table 3, if 30kHz and 240kHz subcarrier spacings are introduced to transmit NR-SS, it may be possible to expect that the SS block will be transmitted within a maximum of 2ms. However, since the basic subcarrier spacings for NR-SS transmission correspond to 15KHz and 120kHz, it is necessary to determine whether to introduce a wider minimum system bandwidth (e.g., 10MHz for 20kHz subcarrier spacing and 80MHz for 240kHz subcarrier spacing) to introduce 30kHz and 240kHz subcarrier spacings. If it is determined that NR supports a minimum system bandwidth of 5MHz in a frequency band equal to or narrower than 6GHz and 50MHz in a frequency band of 6GHz, it is necessary to design SS burst sets based on 15kHz and 120kHz subcarrier spacings. If the maximum number of SS blocks corresponds to 8 in a frequency band equal to or narrower than 6GHz and corresponds to 64 in a frequency band wider than 6GHz, the system overhead is considerably high because the time required to transmit the SS block corresponds to 4ms. Furthermore, since it is preferable to have a short time interval when transmitting SS blocks in terms of network energy saving and UE measurement, it is necessary to define candidate positions for transmitting SS blocks within a duration of N ms (e.g., N=0.5, 1, 2).

[0216] 9.SS burst set configuration

[0217] When configuring SS burst sets, such as Figure 17 As shown, it can be considered two types according to the SS burst period. One is Figure 17 The local type shown in (a) is as follows. According to the local type, all SS blocks are sent continuously in the SS burst set. On the other hand, the other is Figure 17 According to the distribution type, SS bursts are periodically sent within the SS burst set period.

[0218] The local type SS burst provides advantages over the distributed type SS burst in terms of energy saving for idle UEs and efficiency for measuring inter-frequency. Therefore, it is more preferred to support the local type SS burst.

[0219] In addition, if Figure 17As shown in (a), if an SS burst set is configured with a local type, no uplink signal can be transmitted during the symbol period to which the SS burst set is mapped. Specifically, as the subcarrier spacing allocated to the SS block becomes larger, the symbol size becomes smaller. Specifically, the number of symbol periods in which no uplink signal is transmitted increases. If the subcarrier spacing allocated to the SS block is equal to or larger than a specific size, it is necessary to leave symbols between SS bursts with a specified spacing to perform uplink transmission.

[0220] Figure 18 The SS burst set configuration is illustrated when the subcarrier spacing to which the SS block is allocated corresponds to 120 kHz and 240 kHz. Figure 18 When the subcarrier spacing corresponds to 120kHz and 240kHz, SS bursts are configured in units of 4 SS bursts while leaving a specified space. Specifically, SS blocks are arranged in units of 0.5ms, while the symbol period (0.125ms) used for uplink transmission is left empty.

[0221] In a frequency range equal to or wider than 6 GHz, a subcarrier spacing of 60 kHz can be used to transmit data. Figure 19 As shown, in the NR system, the subcarrier spacing used to send data (e.g., 60 kHz) and the subcarrier spacing used to send SS blocks (e.g., 120 kHz or 240 kHz) can be multiplexed.

[0222] In addition, refer to Figure 19 In the portion indicated by the box, when multiplexing SS blocks with 120 kHz subcarrier spacing and data with 60 kHz subcarrier spacing, collisions or overlaps can occur at the 120 kHz subcarrier spacing SS blocks, 60 kHz subcarrier spacing GPs, and the DL control region. Because collisions between SS blocks and the DL / UL control region are preferably avoided, the configuration of SS bursts and SS burst sets needs to be modified.

[0223] In order to modify the configuration of the SS burst, the present invention proposes two implementation methods.

[0224] like Figure 20 As shown in FIG, the first embodiment is to change the position of SS burst format 1 and the position of SS burst format 2. Specifically, if the position Figure 20 By swapping SS burst format 1 and SS burst format 2 in the box, it is possible to avoid conflicts between the SS block and the DL / UL control region. In other words, SS burst format 1 is located at the front of the 60 kHz subcarrier spacing, and SS burst format 2 is located at the back of the 60 kHz subcarrier spacing.

[0225] In summary, the aforementioned first embodiment can be expressed as follows.

[0226] 1) 120KHz subcarrier spacing

[0227] - The first OFDM symbol of the candidate SS / PBCH block has an index of {4, 8, 16, 20, 32, 36, 44, 48} + 70*n. For carrier frequencies greater than 6 GHz, n = 0, 2, 4, 6.

[0228] - The first OFDM symbol of the candidate SS / PBCH block has an index of {2, 6, 18, 22, 30, 34, 46, 50} + 70*n. For carrier frequencies greater than 6 GHz, n = 1, 3, 5, 7.

[0229] 2) 240KHz subcarrier spacing

[0230] - The first OFDM symbol of the candidate SS / PBCH block has an index of {8, 12, 16, 20, 32, 36, 40, 44, 64, 68, 72, 76, 88, 92, 96, 100} + 140*n. For carrier frequencies greater than 6 GHz, n=0, 2.

[0231] - The first OFDM symbol of the candidate SS / PBCH block has an index of {4, 8, 12, 16, 36, 40, 44, 48, 60, 64, 68, 72, 92, 96, 100, 104} + 140*n. For carrier frequencies greater than 6 GHz, n=1, 3.

[0232] like Figure 21 As shown, the second embodiment is to change the configuration of the SS burst set. Specifically, the SS burst set can be configured in a manner such that the start boundary of the SS burst set is aligned with (ie, matched with) the start boundary of the 60 kHz subcarrier spacing time slot.

[0233] Specifically, an SS burst consists of SS blocks arranged locally during a 1ms period. Specifically, during a 1ms period, an SS burst with a 120kHz subcarrier spacing has 16 SS blocks, and an SS burst with a 240kHz subcarrier spacing has 32 SS blocks. In this case, based on a 60kHz subcarrier spacing, one time slot is allocated as the gap between SS bursts.

[0234] In summary, the aforementioned second embodiment can be expressed as follows.

[0235] 1) 120KHz subcarrier spacing

[0236] - The first OFDM symbol of the candidate SS / PBCH block has an index of {4, 8, 16, 20} + 28*n. For carrier frequencies greater than 6 GHz, n = 0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18.

[0237] 2) 240KHz subcarrier spacing

[0238] - The first OFDM symbol of the candidate SS / PBCH block has an index of {8, 12, 16, 20, 32, 36, 40, 44} + 56*n. For carrier frequencies greater than 6 GHz, n = 0, 1, 2, 3, 5, 6, 7, 8.

[0239] 10. Method to indicate the SS / PBCH blocks actually transmitted within a 5ms duration

[0240] In the NR system, it is possible to specify candidate locations for sending SS blocks within an SS burst set period (e.g., 5ms) to perform the initial access procedure. In addition, the location of the SS block actually sent can be notified to the connected / idle mode UE. In this case, the network can have the flexibility to utilize resources according to the network status. However, depending on the configuration method of indicating the SS block actually used, there may be different flexibility in configuring the SS burst set. For example, if the individual location information of the SS block actually sent (e.g., a bitmap of SS blocks or SS bursts) can be set to the UE, both the localized type and the distributed type can operate according to the network status. The individual location information can be included in different SI indicating measurement-related information.

[0241] Furthermore, it may be possible to change the SS burst period based on network configuration and provide the UE with information about measurement timing / duration. When the SS burst period changes, it is necessary to determine candidate locations for transmitting SS blocks. To determine the locations for transmitting SS blocks, the present invention proposes two implementations described below.

[0242] (Method 1) The network can use hypotheses for candidate locations of the fundamental period.

[0243] (Method 2) The network may indicate the location where the SS block is actually transmitted within the measurement section.

[0244] In the NR system, the SS burst set configuration can be designed based on the basic period. When the SS burst set period and measurement duration are indicated by the network, the SS burst set configuration can be assumed by the SS burst configuration. For example, when there is no indication from the network, if the UE assumes a 5ms period as the SS burst set period for measurement, it may be possible to configure an SS burst set for a 5ms period. The SS burst set configuration can also be used for a basic period (e.g., 20ms) and a period configured by the network (e.g., 5, 10, 20, 40, 80, and 160ms).

[0245] In order to more efficiently utilize resources for SS burst set configuration, the network can indicate the location where the SS blocks are actually sent within the measurement duration. For example, in the case of a basic cycle, NR-SS and NR-PBCH should be sent within the SS burst set period. In addition, when the cycle is longer than the basic cycle, it can send NR-SS only for measurement purposes. If the network is able to configure the location where the SS blocks are actually sent, the unused resources allocated to NR-PBCH can be allocated to data / control channels. In the case of a cycle shorter than the basic cycle, the network selects some SS blocks from the SS blocks included in the SS burst set to configure the SS blocks actually used.

[0246] In addition, the number of candidates for transmitting SS blocks is limited depending on the network environment. For example, the number of candidates may vary depending on the subcarrier spacing of the allocated SS blocks. In this case, it may be possible to notify the connected / idle mode UE of the location where the SS block is actually transmitted. The actual transmitted SS / PBCH block indication indicating the location where the SS block is actually transmitted can be used to utilize the resources of the serving cell (e.g., rate matching) and can be used to perform measurements related to the resources of neighboring cells.

[0247] If the UE can accurately identify the untransmitted SS block, the UE can recognize that the UE can receive other information such as paging or data via the candidate resources of the untransmitted SS block. For resource flexibility, it is necessary to accurately indicate the SS block actually transmitted in the serving cell.

[0248] Specifically, since other information such as paging or data cannot be received in resources where SS blocks are transmitted, the UE receives different data or different signals via resources where SS blocks are not actually transmitted to improve resource utilization efficiency. Therefore, it is necessary for the UE to identify SS block candidates where SS blocks are not actually transmitted.

[0249] In order to accurately indicate the SS blocks actually transmitted in the serving cell, information regarding a complete 4-bit, 8-bit, or 64-bit bitmap is required. In this case, the bit size included in the bitmap can be determined based on the maximum number of SS blocks that can be transmitted in each frequency range. For example, to indicate the SS blocks actually transmitted within a 5 ms period, an 8-bit bitmap is required in the frequency range from 3 GHz to 6 GHz, and a 64-bit bitmap is required in the frequency range equal to or wider than 6 GHz.

[0250] The bits used to indicate the SS blocks actually transmitted in the serving cell may be defined by RMSI or OSI, and the RMSI / OSI includes configuration information for data or paging. Since the actual transmitted SS / PBCH block indication is associated with the configuration for downlink resources, the RMSI / OSI may include information about the actual transmitted SS blocks.

[0251] In addition, in order to measure neighboring cells, an indication of the SS / PBCH blocks actually sent by the neighboring cells is required. However, if there are many listed cells, the full bitmap type indicator may excessively increase the signal overhead. In order to reduce the signaling overhead, it may consider various compressed forms of indicators. In addition, in order not only to measure neighboring cells but also to reduce the signaling overhead, a compressed form of the indicator for the indicator indicating the SS blocks sent by the serving cell may be considered. In other words, the SS block indicator described below can be used to indicate the SS blocks actually sent in the neighboring cell and the serving cell. As mentioned in the foregoing description, the SS burst may correspond to a set of SS blocks included in the time slot according to each subcarrier. However, only in the following embodiments, the SS burst may correspond to a set of a specified number of SS blocks, regardless of the time slot.

[0252] Reference Figure 22 To illustrate one embodiment, assume that an SS burst includes 8 SS blocks. In this case, a total of 8 SS bursts can exist in a frequency band equal to or wider than 6 GHz, in which 64 SS blocks are placed.

[0253] In this case, SS blocks are grouped by SS burst to compress the entire 64-bit bitmap. 8-bit information indicating the SS burst including the actually transmitted SS blocks may be used instead of the 64-bit bitmap information. If the 8-bit bitmap information indicates SS burst #0, SS burst #0 may include one or more actually transmitted SS blocks.

[0254] In this case, additional information may be considered to indicate the number of SS blocks actually transmitted per SS burst. Each SS burst may locally include as many SS blocks as the number of SS blocks indicated by the additional information.

[0255] The UE combines the number of actually transmitted SS blocks per SS burst indicated by the additional information with the bitmap indicating the SS burst including the actually transmitted SS blocks to estimate the actually transmitted SS blocks.

[0256] For example, it may assume the indications shown in Table 4 below.

[0257] [Table 4]

[0258]

[0259] According to Table 4, it can be known from the 8-bit bitmap that SS blocks are included in SS bursts #0, #1, and #7, and it can be known from the additional information that each SS burst includes four SS blocks. As a result, it can be estimated that the SS blocks are transmitted via the first four candidate positions of SS bursts #0, #1, and #7.

[0260] Furthermore, unlike the above example, if the additional information is forwarded in the form of a bitmap, it may be possible to make the location where the SS block is transmitted flexible.

[0261] For example, information related to SS burst transmission is indicated by a bitmap, and SS blocks transmitted within the SS burst may be indicated by other bits.

[0262] Specifically, a total of 64 SS blocks are classified into 8 SS bursts (ie, SS block groups), and it is possible to inform the UE of the SS burst in use by sending an 8-bit bitmap to the UE. Figure 22 When defining SS bursts as shown, if the SS bursts are multiplexed with time slots having a 60 kHz subcarrier spacing, the boundary between the SS bursts and the time slots can be aligned. Specifically, if a bitmap is used to indicate the on / off status of the SS bursts, the UE can determine whether the SS blocks are transmitted in time slot units for all subcarrier spacings in a frequency band equal to or wider than 6 GHz.

[0263] In this case, unlike the previous example, a bitmap is used to notify the UE of additional information. In this case, since the bitmap information needs to be transmitted for the eight SS blocks included in each SS burst, eight bits are required. The additional information is generally applied to all SS bursts. For example, if the bitmap information for the SS burst indicates the use of SS burst #0 and SS burst #1, and the additional bitmap information for the SS block indicates that the first and fifth SS blocks are transmitted in the SS burst, the first and fifth SS blocks are transmitted in each of SS burst #0 and SS burst #1, and the number of SS blocks actually transmitted becomes four.

[0264] Furthermore, some neighboring cells may not be included in the cell list. Neighboring cells not included in the cell list use a default format for the actual transmitted SS blocks. If the default format is used, the UE may perform measurements on neighboring cells not included in the cell list. In this case, the default format may be predefined or configured by the network.

[0265] In addition, if the information about the SS block actually transmitted in the serving cell conflicts with the information about the SS block actually transmitted in the neighboring cell, the UE can obtain the information about the SS block actually transmitted by prioritizing the information about the SS block transmitted in the serving cell.

[0266] In particular, if information about an actually transmitted SS block is received in the form of a complete bitmap and in a packet form, since the information in the complete bitmap form is likely to be more accurate, the information in the complete bitmap form may be preferentially used for receiving the SS block.

[0267] 11. Signals and channels used to indicate time index

[0268] The SS block time index indication is forwarded by NR-PBCH. If the time index indication is included in a part of the NR-PBCH (such as NR-PBCH content, scrambling sequence, CRC, redundant version, etc.), the indication is securely forwarded to the UE. However, if the time index indication is included in a part of the NR-PBCH, there may be additional complexity when decoding the NR-PBCH of the neighboring cell. In addition, although decoding of the NR-PBCH of the neighboring cell can be performed, this is not mandatory when designing the system. In addition, additional discussion is necessary to determine the signals and channels that are suitable for forwarding the SS block time index indication.

[0269] Since the SS block time index information will be used as a time resource allocation reference for initial access-related channels / signals (such as system information forwarding in the target cell, PRACH preamble, etc.), the SS block time index information should be securely sent to the UE. In addition, the time index is used to measure RSRP at the SS block level to measure neighboring cells. In this case, the SS block time index information does not need to be very accurate.

[0270] The present invention proposes that the NR-PBCH DMRS be used as a signal for forwarding the SS block time index. Furthermore, the present invention proposes that the time index indication be included in a portion of the NR-PBCH. In this case, for example, the portion of the NR-PBCH may correspond to a scrambling sequence, a redundancy version, or the like of the NR-PBCH. According to the present invention, the SS block time index can be detected from the NR-PBCH DMRS, and the detected index can be checked by NR-PBCH decoding. Furthermore, in order to measure neighboring cells, the index can be obtained from the NR-PBCH DMRS of the neighboring cell.

[0271] The time index indication can be configured via two implementations described below.

[0272] (Method 1) A single index method of allocating an index to each of all SS blocks included in an SS burst set.

[0273] (Method 2) A multi-index method of allocating indexes using a combination of SS burst indexes and SS block indexes.

[0274] As described in Embodiment 1, if a single index method is supported, many bits are required to indicate the number of all SS blocks within an SS burst set period. In this case, the DMRS sequence and scrambling sequence for NR-PBCH preferably indicate an SS block indicator.

[0275] In contrast, as described in Embodiment 2, using a multi-index method provides design flexibility for indicating indices. For example, both the SS burst index and the SS block index can be included in a single channel. Furthermore, each index can be transmitted separately via a different channel / signal. For example, the SS burst index can be included in the content or scrambling sequence of the NR-PBCH. The SS block index can be forwarded via the DMRS sequence of the NR-PBCH.

[0276] 11.SS Block Time Index

[0277] The present invention proposes a method for configuring SS burst sets within a shorter duration (e.g., 2 ms) to save energy for the network and UE. In this case, all SS blocks can be located within the SS burst set period, regardless of the period (e.g., 5, 10, 20, 40, 80, 160 ms). Figure 23 The SS block index when the subcarrier spacing corresponds to 15 kHz is illustrated.

[0278] Reference Figure 23To explain the SS block index. If the maximum number of SS blocks is defined by L, the index of the SS block corresponds to 0 to L-1. In addition, the SS block index is derived from the OFDM symbol index and the time slot index. In addition, the SS burst set can be configured by 4 SS blocks located at two time slots adjacent to each other. Thus, the SS block index corresponds to 0 to 3, and the time slot index is defined by 0 and 1. In addition, the SS block includes 4 OFDM symbols, and the two OFDM symbols included in the SS block are used to transmit the PBCH. In this case, the index of the OFDM symbol used to transmit the PBCH may correspond to 0 and 2. As Figure 23 As shown in (a), the index of the SS block is derived from the index of the OFDM symbol and time slot. For example, the SS block transmitted in time slot #1 and OFDM symbol #2 is mapped to index 3.

[0279] like Figure 23 As shown in (b), the network can configure the period of the SS burst set in the NR system. In addition, it can be configured with short periods such as 5 and 10ms. By doing so, more SS blocks can be allocated for transmission. The index of the SS block can be identified within the configured period of the SS burst set. Figure 23 As shown in (c), if a 5ms period is configured, 4 SS blocks can be sent within the configured period. In addition, a total of 16 SS blocks can be sent within the basic period. In this case, the index of the SS block can be repeated within the default period, and 4 SS blocks among the 16 SS blocks can have the same index.

[0280] 12.NR-PBCH content

[0281] In NR systems, the MIB payload size is expected to be extended based on the response LS from RAN2. The following describes the expected MIB payload size and NR-PBCH content in NR systems.

[0282] 1) Payload: 64 bits (48 bits of information, 16 bits of CRC)

[0283] 2) NR-PBCH content:

[0284] - At least part of SFN / H-SFN

[0285] -Configuration information about the public search space

[0286] -NR carrier center frequency information

[0287] The UE detects the cell ID and timing information, and can then obtain information for accessing the network from the PBCH, including part of the timing information such as SFN, SS block index and half-frame timing, information about the common control channel (such as time / frequency position), information about the bandwidth part (such as bandwidth and SS block position), and information about the SS burst set (such as SS burst set period and the SS block index actually sent).

[0288] Since limited time / frequency resources (such as 576 REs) are occupied only for PBCH, essential information should be included in PBCH. In addition, if possible, auxiliary signals such as PBCH DMRS can be used to further include essential information or additional information.

[0289] (1) SFN (System Frame Number)

[0290] In the NR system, a system frame number (SFN) is defined to identify the 10ms space. In addition, similar to the LTE system, an index between 0 and 1023 can be introduced for the SFN. The index can be explicitly indicated using a bit or can be implicitly indicated.

[0291] According to the NR system, the PBCH TTI corresponds to 80ms, and the minimum SS burst period corresponds to 5ms. Therefore, the PBCH can be transmitted up to 16 times in 80ms units. A different scrambling sequence for each transmission can be applied to the PBCH encoded bits. Similar to the LTE PBCH decoding operation, the UE can detect 10ms space. In this case, the 8 SFN states are implicitly indicated by the PBCH scrambling sequence, and 7 bits used to represent the SFN can be defined in the PBCH content.

[0292] (2) Timing information in radio frames

[0293] Depending on the carrier frequency range, the SS block index can be explicitly indicated via bits included in the PBCH content and / or the PBCH DMRS sequence. For example, in frequency ranges equal to or narrower than 6 GHz, only the 3 bits of the SS block index are forwarded via the PBCH DMRS sequence. In frequency bands equal to or wider than 6 GHz, the lowest 3 bits of the SS block index are indicated by the PBCH DMRS sequence, and the highest 3 bits of the SS block index are forwarded via the PBCH content. Specifically, the maximum 3 bits of the SS block index can be defined in the PBCH content only within the frequency range from 6 GHz to 52.6 GHz.

[0294] (3) Information used to indicate that there is no RMSI corresponding to the PBCH

[0295] In NR, SS blocks can be used not only to provide information for accessing the network, but also for measurement operations. Specifically, in order to perform wideband CC operation, multiple SS blocks can be sent for measurement.

[0296] However, it is not necessary to forward RMSI via all frequency locations where SS blocks are transmitted. Specifically, for resource efficiency, RMSI can be forwarded via specific frequency locations. In this case, a UE performing an initial access procedure cannot identify whether RMSI is provided at the detected frequency location. To address the above issue, it is necessary to define a bit field for identifying the absence of RMSI corresponding to the PBCH of the detected frequency region. In addition, it is also necessary to consider a method for identifying the absence of RMSI corresponding to the PBCH without a bit field.

[0297] To this end, the SS block in which the RMSI does not exist is configured to be transmitted at a frequency position not defined as a frequency raster. In this case, since the UE performing the initial access procedure cannot detect the SS block, the above problem can be solved.

[0298] (4) SS burst set period and actual transmitted SS blocks

[0299] For measurement purposes, information about the SS burst set period and the actual transmitted SS blocks can be indicated. Specifically, this information is preferably included in the system information used for cell measurement and inter-cell / intra-cell measurement. Specifically, this information needs to be defined in the PBCH content.

[0300] (5) Payload size

[0301] As shown in Table 5, considering the decoding performance of PBCH, a maximum payload size of 64 bits can be assumed.

[0302] [Table 5]

[0303]

[0304] 13.NR-PBCH scrambling

[0305] This section describes the type and initialization of the NR-PBCH scrambling sequence. In NR, the PN sequence can be considered. However, if the Gold sequence with a length of 31 defined in the LTE system is used as the NR-PBCH sequence and no serious problems occur, it is preferred to reuse the Gold sequence as the NR-PBCH scrambling sequence.

[0306] The scrambling sequence can be initialized by the cell ID, and the 3-bit SS block index indicated by the PBCH-DMRS can be used to initialize the scrambling sequence. In addition, if the half-frame indication is indicated by the PBCH-DMRS or a different signal, the half-frame indication can also be used as a seed value for initializing the scrambling sequence.

[0307] 14. Transmission method and antenna port

[0308] In NR systems, NR-PBCH transmission is performed based on a single antenna port. When transmission is performed based on a single antenna port, the following method can be considered for transmitting NR-PBCH.

[0309] (Method 1) TD-PVS (Time Domain Precoding Vector Switching) method

[0310] (Method 2) CDD (Cyclic Delay Diversity) method

[0311] (Method 3) FD-PVS (Frequency Domain Precoding Vector Switching) Method

[0312] Depending on the transmission method, NR-PBCH can achieve transmission diversity gain and / or channel estimation performance gain. In addition, TD-PVS and CDD can be considered for transmitting NR-PBCH. On the other hand, FD-PVS is not preferred because it causes overall performance loss due to channel estimation loss.

[0313] In addition, the antenna port assumptions for NR-SS and NR-PBCH are explained. In the initial access state, it can be considered to transmit NR-SS and NR-PBCH via different antenna ports to provide network flexibility when transmitting NR-SS and NR-PBCH in the NR system. However, the UE can assume that the antenna ports for NR-SS and NR-PBCH are the same or different based on the network configuration.

[0314] 15.NR-PBCH DMRS Design

[0315] In the NR system, DMRS is introduced for the phase reference of NR-PBCH. In addition, NR-PSS / NR-SSS / NR-PBCH are present in all SS blocks, and the OFDM symbols where NR-PSS / NR-SSS / NR-PBCH are located are continuous in a single SS block. However, if the transmission scheme between NR-SSS and NR-PBCH is different, it cannot be assumed that NR-SSS will be used as a reference signal for demodulating NR-PBCH. Therefore, it is necessary to design NR-PBCH under the assumption that NR-SSS is not used as a reference signal for demodulating NR-PBCH in the NR system.

[0316] To design DMRS, DMRS overhead, time / frequency location, and scrambling sequence need to be considered.

[0317] The overall PBCH decoding performance can be determined by the channel estimation performance and the NR-PBCH code rate. The number of REs used to send DMRS has a trade-off relationship between the channel estimation performance and the NR-PBCH code rate. Therefore, it is necessary to find the number of REs suitable for DMRS. For example, if 4 REs per RB are allocated to DMRS, better performance may be achieved. If two OFDM symbols are allocated to send NR-PBCH, 192 REs are used for DMRS and 384 REs are used for MIB transmission. In this case, if the payload size corresponds to 64 bits, a coding speed of 1 / 12, which is the same as the coding speed of LTE PBCH, can be obtained.

[0318] When allocating multiple OFDM symbols to transmit the NR-PBCH, it is necessary to determine which OFDM symbols will include the DMRS. In this case, to prevent performance degradation due to residual frequency offset, it is preferable to allocate the DMRS to all OFDM symbols where the NR-PBCH is located. Specifically, all OFDM symbols used to transmit the NR-PBCH can include the DMRS.

[0319] The PBCH DMRS is used as a time / frequency tracking RS for the OFDM symbol locations used to transmit the NR-PBCH. As the distance between two OFDM symbols containing DMRS becomes longer, accurate frequency tracking becomes more advantageous. Therefore, the first and fourth OFDM symbols can be allocated to transmit the NR-PBCH.

[0320] In addition, the frequency position of the DMRS can be mapped by interleaving in the time domain that can be shifted according to the cell ID. When the DMRS pattern is uniformly distributed, the DMRS pattern can be used for DFT-based channel estimation, which provides optimized performance for 1-D channel estimation. To improve channel estimation performance, wideband RB bundling can be used.

[0321] The DMRS sequence can use a pseudo-random sequence defined by the Gold sequence type. The length of the DMRS sequence can be defined by the number of DMRS REs per SS block. Furthermore, the DMRS sequence can be generated based on the cell ID and the slot number / OFDM symbol index within the 20ms default period corresponding to the SS burst set. Furthermore, the SS block index can be determined based on the slot index and the OFDM symbol index.

[0322] Furthermore, NR-PBCH DMRS scrambling is required using 1008 cell IDs and a 3-bit SS block index. This is because, when comparing detection performance based on the number of DMRS sequence hypotheses, 3-bit detection performance is known to be optimal for that number of DMRS sequence hypotheses. However, since it was found that there is little performance loss when increasing detection performance from 4 to 5 bits, using a number of hypotheses of 4 to 5 bits is feasible.

[0323] In other words, the DMRS sequence can be initialized by the cell ID, the SS block index included in the SS burst set, and the half-frame indication. The equation for initializing the DMRS sequence is as follows.

[0324] [Equation 7]

[0325]

[0326] In this case, Corresponding to the SS block index in the SS block group, corresponds to a cell ID, and HF corresponds to a half-frame indication index having a value of {0,1}.

[0327] Similar to the LTE DMRS sequence, the NR-PBCH DMRS sequence can be generated using a Gold sequence of length 31 or a Gold sequence of length 7 or 8.

[0328] In addition, since the detection performance using a Gold sequence with a length of 31 is similar to that using a Gold sequence with a length of 7 or 8, the present invention proposes using a Gold sequence with a length of 31 similar to LTE DMRS. In a frequency range equal to or wider than 6 GHz, the use of a Gold sequence with a length greater than 31 can be considered.

[0329] BPSK and QPSK can be considered as modulation types for generating DMRS sequences. The detection performance of BPSK is similar to that of QPSK. However, since the correlation performance of QPSK is better than that of BPSK, QPSK is more suitable for generating DMRS sequences.

[0330] 15.NR-PBCH DMRS Pattern Design

[0331] Regarding the frequency position of DMRS, two types of DMRS RE mapping methods can be considered. According to the fixed RE mapping method, the RS mapping area is fixed in the frequency domain. According to the variable RE mapping method, the RS position is shifted according to the cell ID using the Vshift method. Since the variable RE mapping method randomizes the interference, it can have the advantage of being able to obtain additional performance gains. Therefore, the variable RE mapping method is preferably used.

[0332] The variable RE mapping method is explained in more detail. The complex modulation symbols a included in the half frame k,l It can be determined by the following equation 8.

[0333] [Equation 8]

[0334] k=4m'+v shift , if l∈{1,3}

[0335]

[0336] m′=0, 1, ..., 71

[0337]

[0338] In this case, k and l correspond to the subcarrier and OFDM symbol index located in the SS block, respectively. In addition, the complex modulation symbol can also be represented by Sure.

[0339] In addition, RS power boosting can be considered for performance enhancement. If RS power boosting and Vshift are used together, interference with TRP (total radiated power) can be reduced. In addition, when considering the detection performance gain of RS power boosting, the ratio of PDSCH EPRE to RS EPRE is preferably -1.25dB.

[0340] 16.NR-PBCH TTI boundary indication

[0341] The NR-PBCH TTI corresponds to 80ms, and the default period of the SS burst set corresponds to 20ms. This indicates that the NR-PBCH is transmitted four times within the NR-PBCH TTI. When the NR-PBCH is repeated within the NR-PBCH TTI, the NR-PBCH TTI boundaries need to be indicated. For example, similar to LTE PBCH, the NR-PBCH TTI boundaries can be indicated by the NR-PBCH scrambling sequence.

[0342] Reference Figure 24The scrambling sequence of the NR-PBCH can be determined by the cell ID and the TTI boundary indication. The period of the SS burst set can have multiple values. Therefore, the number of indices of the TTI boundary indication can be changed according to the period of the SS burst set. For example, 4 indices are required for the default period (i.e., 20ms), and 16 indices are required for a shorter period (i.e., 5ms).

[0343] Furthermore, the NR system supports both single-beam and multi-beam transmission. When multiple SS blocks are transmitted within an SS burst set period, an SS block index can be assigned to each of the multiple SS blocks. To perform randomization between SS blocks used for inter-cell transmission, a scrambling sequence needs to be determined using the SS block index. For example, if the SS block index is derived from the slot index and the OFDM symbol index, the NR-PBCH scrambling sequence can be determined using the slot index and the OFDM symbol index.

[0344] In addition, if the network sets a short period such as 5ms or 10ms to the SS burst set, more SS burst sets can be sent during the same time period. In this case, the UE may have ambiguity about the TTI boundary of the NR-PBCH sent within the default period. In order to indicate the NR-PBCH TTI boundary for a period shorter than the default period, different scrambling sequences of NR-PBCH can be considered for periods shorter than the default period. For example, if it is assumed that the period of the SS burst set is 5ms, 16 scrambling sequences are applied to NR-PBCH. By doing so, there is the advantage of being able to indicate the precise boundary of NR-PBCH transmission within the NR-PBCH TTI. On the contrary, the blind detection complexity for NR-PBCH decoding is increased. In order to reduce the blind decoding complexity of NR-PBCH, it can be considered to apply different NR-SSS sequences to distinguish NR-SSS with the default period from NR-SSS additionally sent within the default period.

[0345] 17. Time index indication method

[0346] Reference Figure 25 , time information includes SFN (system frame number), half-frame interval, and SS block time index. Time information can be represented by 10 bits of SFN, 1 bit of half-frame, and 6 bits of SS block time index. In this case, part of the 10 bits of SFN can be included in the PBCH content. In addition, NR-DMRS can include 3 bits of the 6 bits of SS block time index.

[0347] exist Figure 25 In the following, an implementation of the time index indication method is described.

[0348] -Method 1: S2 S1 (PBCH scrambling) + S0 C0 (PBCH content)

[0349] -Method 2: S2 S1 S0 (PBCH scrambling) + C0 (PBCH content)

[0350] -Method 3: S2 S1 (PBCH scrambling) + S0 C0 (PBCH DMRS)

[0351] -Method 4: S2 S1 S0 (PBCH scrambling) + C0 (PBCH DMRS)

[0352] If the half-frame indication is forwarded via the NR-PBCH DMRS, additional performance enhancement may be achieved by combining PBCH data every 5 ms. To this end, as shown in Methods 3 and 4, 1 bit for the half-frame indication may be forwarded via the NR-PBCH DMRS.

[0353] When comparing Method 3 and Method 4, although Method 3 reduces the decoding count, Method 3 may result in a loss of PBCH DMRS performance. If the PBCH DMRS can transmit 5 bits including S0, C0, B0, B1, and B2 with excellent performance, Method 3 can be used as an appropriate timing indication method. However, if the PBCH DMRS cannot transmit 5 bits with excellent performance, Method 4 can be used as an appropriate timing indication method.

[0354] Specifically, the highest 7 bits of the SFN may be included in the PBCH content, while the lowest 2 or 3 bits may be forwarded via PBCH scrambling. In addition, the lowest 3 bits of the SS block index are included in the PBCH DMRS, and the highest 3 bits of the SS block index may be included in the PBCH content.

[0355] In addition, a method for obtaining the SS block time index of the neighboring cell can be considered. Since decoding via the DMRS sequence shows better performance than decoding via the PBCH content, if the DMRS sequence changes within 5ms, 3 bits of the SS block index can be transmitted.

[0356] Furthermore, in frequency ranges equal to or narrower than 6 GHz, only the NR-PBCH DMRS of the neighboring cell can be used to transmit the SS block time index. Conversely, in frequency ranges equal to or wider than 6 GHz, since the 64 SS block indices are indicated separately via the PBCH-DMRS and PBCH content, the UE does not need to decode the PBCH of the neighboring cell.

[0357] However, if the PBCH-DMRS is decoded along with the PBCH content, this may result in additional NR-PBCH decoding complexity and degrade PBCH decoding performance compared to using only the PBCH-DMRS. As a result, it may be difficult to perform decoding on the PBCH to receive the SS blocks of the neighboring cell.

[0358] A method for the serving cell to provide the UE with a configuration related to the SS block index of the neighboring cell, rather than a decoding method for decoding the PBCH of the neighboring cell, can be considered. For example, the serving cell provides the UE with a configuration related to the highest 3 bits of the SS block index of the target neighboring cell, and the UE detects the lowest 3 bits via the PBCH-DMRS. The UE can then obtain the SS block index of the target neighboring cell by combining the highest 3 bits and the lowest 3 bits.

[0359] 18. Soft combination

[0360] NR systems need to support intelligent soft combining for SS burst sets for efficient resource utilization and PBCH coverage. Since the NR-PBCH is updated every 80 ms and the SS burst sets are transmitted in a default period of 20 ms, soft combining can be performed at least four times for NR-PBCH decoding. If a shorter period than the default is indicated for the SS burst set, more OFDM symbols can be used for soft combining of the PBCH.

[0361] 19. PBCH decoding for neighboring cell measurements

[0362] To measure a neighboring cell, it is necessary to determine whether the UE decodes the NR-PBCH of the neighboring cell. Since decoding of neighboring cells adds complexity to the UE, it is preferable not to add unnecessary complexity. Therefore, it is necessary for the UE to assume that when measuring a neighboring cell, the UE does not need to decode the NR-PBCH of the neighboring cell.

[0363] In contrast, if the SS block index is forwarded via a specific type of signal, the UE performs signal detection and can then obtain the SS block index of the neighboring cell. This reduces UE complexity. Furthermore, the specific type of signal may correspond to the NR-PBCH DMRS.

[0364] 20. Measurement results evaluation

[0365] Below, we explain the performance measurements based on payload size, transmission scheme, and DMRS. In this case, we assume that two OFDM symbols with 24 RBs are used to transmit the NR-PBCH. Furthermore, we assume that the SS burst sets (i.e., 10, 20, 40, 80 ms) have multiple periods and that the coded bits are transmitted within 80 ms.

[0366] (1) Payload size and NR-PBCH resources

[0367] Figure 26 Evaluation results are provided based on the MIB payload size (e.g., 64 bits, 80 bits). In this case, it is assumed that 384 REs and 192 REs of DMRS are used in two OFDM symbols and 24 RBs. In addition, it is assumed that a single antenna port-based transmission scheme (i.e., TD-PVS) is used.

[0368] Reference Figure 26 , NR-PBCH with a 20ms period shows a 1% error rate in -6dB SNR. In the case of a 64-bit payload, it can be seen that the payload has a gain of up to 0.8dB compared to an 80-bit payload. Specifically, if it is assumed that the payload size is between 64 bits and 80 bits, 24 RBs and 2 OFDM symbols can be used to meet the performance requirements of NRR-PBCH (i.e., 1% BLER in -6dB SNR).

[0369] (2) Transmission scheme

[0370] Figure 27 Evaluation results based on NR-PBCH transmission schemes such as TD-PVS and FD-PVS are provided. The precoder cycles in each PBCH transmission subframe (e.g., 20ms) for TD-PVS and in all N RBs (e.g., N corresponds to 6) for FD-PVS. Figure 27 In

[15] , soft combining of NR-PBCH is assumed to be performed in multiple periods of SS burst sets (i.e., 10, 20, 40, and 80 ms).

[0371] like Figure 27 As shown in Figure 1, the TD-PVS (time domain precoding vector switching) scheme shows better channel estimation performance than the FD-PVS (frequency domain precoding vector switching) scheme. In this case, it can be seen that in very low SNR areas, channel estimation performance is more important than transmit diversity gain.

[0372] (3)DMRS density

[0373] In low SNR regions, channel estimation performance enhancement is an important factor for improving demodulation performance. However, increasing the RS density for NR-PBCH improves channel estimation performance but reduces coding speed. To find a trade-off between channel estimation performance and channel coding gain, decoding performance is compared based on DMRS density. Figure 28 DMRS density is illustrated.

[0374] Figure 28(a) illustrates the case where 2 REs per symbol are used for DMRS. Figure 28 (b) illustrates the case where 4 REs per symbol are used for DMRS, and Figure 28 (c) illustrates the case where 6 REs per symbol are used for DMRS. In addition, it is assumed that a single-port based transmission scheme (ie, TD-PVS) is used in this evaluation.

[0375] Figure 28 An embodiment of a DMRS pattern for transmission based on a single antenna port is illustrated. Figure 28 , although the DMRS positions maintain the same distance between reference signals in the frequency domain, the RS density is changed. Figure 29 The performance results of DMRS according to the reference signal density are illustrated.

[0376] like Figure 29 As shown, Figure 28 The NR-PBCH decoding performance shown in (b) shows excellent channel estimation performance. Specifically, the NR-PBCH decoding performance is better than Figure 28 In contrast, see Figure 28 (c) of , since the impact of coding speed loss is greater than the gain of channel estimation performance enhancement, Figure 28 The performance shown in (c) is worse than Figure 28 Due to the above reasons, it is preferable to design an RS density of 4 REs per symbol.

[0377] (4) DMRS time position and CFO estimation

[0378] If the NR system supports self-contained DMRS, it can use self-contained DMRS to perform fine frequency offset tracking on NR-PBCH. Since the frequency offset estimation accuracy depends on the OFDM symbol distance, such as Figure 30 As shown, three types of NR-PBCH symbol intervals can be assumed.

[0379] according to Figure 30 CFO estimation is performed at -6dB SNR for each NR-PBCH symbol interval shown in . 10% CFO (1.5kHz) samples are applied in the subframe. Four REs are used as independent RSs per symbol, and the REs are included in the symbols transmitting the PBCH.

[0380] Figure 31 and Figure 32 The CDF of CFO estimated according to different NR-PBCH symbol intervals is shown. Figure 31 and Figure 32As shown in Figure 2, 90% of UEs can estimate the CFO of 1.5kHz within an error range of ±200Hz. If a minimum of 2 symbols is introduced as the NR-PBCH symbol interval, 95% of UEs can estimate the CFO within an error range of ±200Hz, and 90% of UEs can estimate the CFO within an error range of ±100Hz.

[0381] As the spacing increases, the phase offset caused by CFO increases. A larger spacing between PBCH symbols improves CFO estimation performance. Therefore, similar to noise suppression, it is easier to measure phase offset. Furthermore, a larger averaging window size improves CFO estimation accuracy.

[0382] The following describes the detection performance based on the number of DMRS sequence assumptions, modulation type, sequence generation, and SS block index for DMRS RE mapping. In these measurements, it is assumed that NR-PBCH is transmitted across 24 RBs using two OFDM symbols. Furthermore, multiple SS burst set periods can be considered. These periods can include 10ms, 20ms, and 40ms.

[0383] (5) Number of DMRS assumptions

[0384] Figure 33 The measurement results based on the SS block index are illustrated. In this case, 144 REs are used for DMRS within 24 RBs, and 432 REs in 2 OFDM symbols are used for information. In addition, it is assumed that a long sequence (e.g., a Gold sequence of length 31) is used as the DMRS sequence and QPSK is used.

[0385] Reference Figure 33 If the detection performance of 3 to 5 bits is measured twice by accumulating the detection performance, it shows an error rate of 1% in an SNR of -6dB. Specifically, in terms of detection performance, 3 to 5 bits of information can be used as the number of hypotheses of the DMRS sequence.

[0386] (6) Modulation type

[0387] Figure 34 and Figure 35 The performance measurement results of BPSK and QPSK are illustrated. This experiment is performed based on the assumption that the DMRS corresponds to 3 bits and a long sequence is used as the DMRS sequence. The power level of the interfering TRP is the same as the power level of the serving TRP.

[0388] Reference Figure 34 and Figure 35, the performance of BPSK is similar to that of QPSK. In particular, there is no significant difference in performance measurements regardless of the modulation type of the DMRS sequence. However, referring to Figure 36 , it can be seen that the correlation characteristics vary according to BPSK and QPSK.

[0389] Reference Figure 36 Compared to QPSK, BPSK is more distributed in the region with a correlation amplitude of 0.1. Therefore, when considering a multi-cell environment, it is preferable to use QPSK as the modulation type of DMRS. In particular, QPSK corresponds to a modulation type that is more suitable for DMRS sequences in terms of correlation characteristics.

[0390] (7) PBCH DMRS Sequence Generation

[0391] Figures 37 and 38 The measurement results generated based on the DMRS sequence are illustrated. The DMRS sequence can be generated based on a long sequence with a polynomial expression order equal to or greater than 30 or a short sequence with a polynomial expression order equal to or less than 8. In addition, it is assumed that the DMRS corresponds to 3 bits and the power level of the interfering TRP is the same as the power level of the serving TRP.

[0392] Reference Figures 37 and 38 , it can be seen that the detection performance based on short sequence generation is similar to that based on long sequence generation.

[0393] (8) DMRS RE mapping

[0394] Figure 39 The performance measurement results of the RE mapping method are illustrated. In this case, it is assumed that the DMRS corresponds to 3 bits, the DMRS sequence is based on a long sequence, and the power level of the interfering TRP is the same as the power level of the serving TRP. In addition, it is assumed that there is only one interference source.

[0395] like Figure 39 As shown, if variable RE mapping is used, it may have the effect of randomly distributing interference. In particular, the detection performance of variable RE mapping is better than that of fixed RE mapping.

[0396] Figure 40 The measurement results when RS power boost is used are illustrated. In this case, it is assumed that the RE transmission power of DMRS is up to about 1.76dB higher than the RE transmission power of PBCH data. If variable RE mapping and DMRS power boost are used together, the interference between different cells is reduced. Figure 40 As shown, if RS power boosting is applied, it can have a performance gain of up to 2-3 dB compared to the case where RS power boosting is not applied.

[0397] On the contrary, RS power boosting can reduce the RE transmit power of PBCH data. Therefore, RS power boosting may affect PBCH performance. Figures 41 to 42 The measurement results of PBCH performance when RS power boosting is applied and when RS power boosting is not applied are illustrated. In this case, it is assumed that the period of the SS burst set corresponds to 40ms and the coded bits are transmitted within 80ms.

[0398] If the transmit power of the REs for PBCH data is reduced, performance loss may occur. However, due to the increase in RS power, the channel estimation performance is enhanced, thereby improving the demodulation performance. In particular, if Figures 41 to 42 As shown, the performance in both cases is similar. Specifically, the performance loss due to the reduction in transmit power of REs used for PBCH data can be compensated by the gain in channel estimation performance.

[0399] Table 6 below shows assumed values ​​of parameters used for performance measurements.

[0400] [Table 6]

[0401]

[0402] 21. BWP (Bandwidth Part) used to send downlink common channels

[0403] The initial access procedure in LTE operates within the system bandwidth configured by the MIB. Furthermore, the PSS / SSS / PBCH are aligned with the center of the system bandwidth. Furthermore, a common search space is defined within the system bandwidth, system information is forwarded via the PDSCH allocated within the system bandwidth, and the RACH procedure for Msg 1 / 2 / 3 / 4 operates within the system bandwidth.

[0404] Furthermore, although NR systems support operation in wideband CCs, it is very difficult to implement a UE capable of performing the necessary operations in all wideband CCs in terms of cost. Therefore, it may be difficult to implement a UE that can smoothly perform the initial access procedure within the system bandwidth.

[0405] To solve this problem, Figure 42 As shown, NR can define a BWP for performing initial access operations. In the NR system, SS block transmission, system information forwarding, paging, and initial access procedures for RACH procedures can be performed within the BWP corresponding to each UE. In addition, at least one downlink BWP can include a CORESET with a common search space in at least one primary component carrier.

[0406] Therefore, downlink control information related to at least one RMSI, OSI, paging, and RACH message 2 / 4 is transmitted in a CORESET with a common search space. Downlink data channels associated with the downlink control information can be allocated within the downlink BWP. In addition, the UE can be expected to transmit SS blocks within the BWP corresponding to the UE.

[0407] Specifically, in NR, at least one or more downlink BWPs can be used to transmit downlink common channels. In this case, the signals that can be included in the downlink common channels may correspond to SS blocks, CORESET with a common search space, and RMSI, OSI, paging, PDSCH, etc. for RACH messages 2 / 4.

[0408] (1) Parameter set

[0409] In NR, subcarrier spacings such as 15, 30, 60, and 120 kHz are used to transmit data. Therefore, parameter sets for the PDCCH and PDSCH within the BWP for downlink common channels can be selected from parameter sets defined for data transmission. For example, in a frequency range equal to or narrower than 6 GHz, at least one or more subcarrier spacings can be selected from 15 kHz, 30 kHz, and 60 kHz subcarrier spacings. In a frequency range varying from 6 GHz to 52.6 GHz, at least one or more subcarrier spacings can be selected from 60 kHz and 120 kHz subcarrier spacings.

[0410] However, in a frequency range equal to or narrower than 6 GHz, a subcarrier spacing of 60 kHz has been defined for URLLC services. Therefore, a subcarrier spacing of 60 kHz is not suitable for transmitting PBCH in a frequency range equal to or narrower than 6 GHz. Therefore, in a frequency range equal to or narrower than 6 GHz, a subcarrier spacing of 15 kHz or 30 kHz can be used to transmit downlink common channels. In a frequency range equal to or wider than 6 GHz, a subcarrier spacing of 60 kHz or 120 kHz can be used.

[0411] In addition, the NR system supports subcarrier spacing of 15, 30, 120, and 240 kHz to transmit SS blocks. It can be assumed that the same subcarrier spacing is applied to SS blocks, CORESET with common search space, and RMSI for RAR, paging, and downlink channels such as PDSCH. Therefore, if this assumption is applied, it is not necessary to define parameter set information in the PBCH content.

[0412] Conversely, the subcarrier spacing of the downlink control channel can be changed. For example, when a subcarrier spacing of 240kHz is applied to send SS blocks in a frequency band equal to or wider than 6GHz, since a subcarrier spacing of 240kHz is not defined for data transmission, it is necessary to change the subcarrier spacing to send data. Specifically, the SCS can be changed to send data. A 1-bit indicator can be used in the PBCH content to indicate the change of the SCS. Depending on the carrier frequency range, the 1-bit indicator can be understood as {15, 30kHz} or {60, 120kHz}. In addition, the indicated subcarrier spacing can be regarded as a reference parameter set for the RB grid.

[0413] (2) Bandwidth of the BWP used to transmit the downlink common channel

[0414] In NR systems, the bandwidth of the downlink common channel (BWP) does not have to be the same as the system bandwidth of the network. Specifically, the bandwidth of the BWP can be narrower than the system bandwidth. Specifically, the bandwidth should be wider than the minimum bandwidth of the carrier but narrower than the minimum bandwidth of the UE.

[0415] Specifically, in the case of a BWP used to transmit downlink common channels, it is possible to define the BWP bandwidth to be wider than the SS block bandwidth and equal to or narrower than the specific downlink bandwidth of all UEs capable of operating in each frequency range. For example, in a frequency range equal to or narrower than 6 GHz, the minimum carrier bandwidth is defined as 5 MHz, and the minimum UE bandwidth can be assumed to be 20 MHz. In this case, the bandwidth of the downlink common channel can be defined within a range from 5 MHz to 20 MHz.

[0416] (3) Bandwidth configuration

[0417] Figure 44 An example of configuring bandwidth is illustrated.

[0418] While the initial synchronization process, including cell ID detection and PBCH decoding, is being performed, the UE attempts to detect a signal within the bandwidth of the SS block. Subsequently, the UE can continuously perform the next initial access process within the bandwidth used for the downlink common channel. Specifically, the UE obtains system information and can then perform the RACH process.

[0419] In addition, an indicator indicating the relative frequency position between the bandwidth of the SS block and the bandwidth of the downlink common channel can be defined in the PBCH content. To simplify the indication of the relative frequency position, the bandwidths of multiple SS blocks can correspond to candidate positions of the SS blocks within the bandwidth of the downlink common channel.

[0420] For example, assume that the bandwidth of the SS block corresponds to 5 MHz and the bandwidth of the downlink common channel corresponds to 20 MHz. In this case, in order to find the SS block within the bandwidth for the downlink common channel, 4 candidate positions may be defined.

[0421] 22.CORESET configuration

[0422] (1) CORESET information and RMSI scheduling information

[0423] For the network, it is more efficient to send CORESET information including RMSI scheduling information to the UE instead of directly indicating scheduling information about RMSI. Specifically, frequency resource related information such as CORESET, bandwidth of frequency location, etc. can be indicated in the PBCH content. In addition, time resource related information such as starting OFDM symbol duration, number of OFDM symbols, etc. can be additionally configured to flexibly use network resources.

[0424] In addition, the network can send information about the common search space monitoring period, duration and offset to the UE to reduce UE detection complexity.

[0425] In addition, the transmission type and bundling can be fixed according to the CORESET of the common search space. In this case, the transmission type can be determined according to whether the transmission signal is interleaved.

[0426] (2) The number of OFDM symbols included in a time slot

[0427] Regarding the number of OFDM symbols included in a time slot for a carrier frequency range equal to or narrower than 6 GHz, two candidates may be considered, such as a time slot including 7 OFDM symbols and a time slot including 14 OFDM symbols. If the NR system determines that two types of time slots are supported for a carrier frequency range equal to or narrower than 6 GHz, a method of indicating the time slot type must be defined to indicate the time resources of the CORESET having a common search space.

[0428] (3) Bit size of PBCH content

[0429] In order to indicate the parameter set, bandwidth, and CORESET information in the PBCH content, as shown in Table 7, it may be possible to specify approximately 14 bits.

[0430] [Table 7]

[0431]

[0432] Reference Figure 45, the communication device 4500 includes a processor 4510 , a memory 4520 , an RF module 4530 , a display module 4540 , and a user interface (UI) module 4550 .

[0433] For ease of description, the communication device 4500 is shown as having Figure 45 The configuration shown in . Some modules may be added to or omitted from the communication device 4500. In addition, the modules of the communication device 4500 may be divided into more modules. The processor 4510 is configured to perform operations according to the embodiments of the present disclosure described previously with reference to the accompanying drawings. Specifically, for detailed operations of the processor 4510, reference may be made to Figures 1 to 44 Description.

[0434] The memory 4520 is connected to the processor 4510 and stores an operating system (OS), applications, program code, data, etc. The RF module 4530 connected to the processor 4510 up-converts the baseband signal to an RF signal or down-converts the RF signal to a baseband signal. To this end, the RF module 4530 performs digital-to-analog conversion, amplification, filtering, and frequency up-conversion, or performs these processes in reverse. The display module 4540 is connected to the processor 4510 and displays various types of information. The display module 4540 can be configured as (but not limited to) known components such as a liquid crystal display (LCD), a light emitting diode (LED) display, and an organic light emitting diode (OLED) display. The UI module 4550 is connected to the processor 4510 and can be configured with a combination of known user interfaces such as a keyboard, a touch screen, etc.

[0435] The embodiments of the present invention described above are combinations of elements and features of the present invention. Unless otherwise stated, it can be considered that an element or feature is selective. Each element or feature can be practiced without being combined with other elements or features. In addition, the embodiments of the present invention can be constructed by combining parts of the elements and / or features. The order of operations described in the embodiments of the present invention can be rearranged. Some configurations of any one embodiment can be included in another embodiment and can be replaced by the corresponding configurations of another embodiment. It is obvious to those skilled in the art that claims that are not clearly referenced to each other in the appended claims can be presented in combination as embodiments of the present invention, or can be included as new claims through subsequent amendments after submitting an application.

[0436] Specific operations described as being performed by a BS may be performed by an upper node of the BS. That is, it is apparent that in a network composed of multiple network nodes including a BS, various operations for communicating with a UE may be performed by the BS or network nodes other than the BS. The term "BS" may be replaced with terms such as "fixed station," "Node B," "evolved Node B (eNode B or eNB)," and "access point (AP)."

[0437] The embodiments of the present invention can be implemented by various means (e.g., hardware, firmware, software, or a combination thereof). In a hardware configuration, the method according to the exemplary embodiment of the present invention can be implemented by 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 (FPGAs), processors, controllers, microcontrollers, microprocessors, etc.

[0438] In a firmware or software configuration, the embodiments of the present invention may be implemented in the form of modules, procedures, functions, etc. The software code may be stored in a memory unit and executed by a processor. The memory unit may be located inside or outside the processor and may send and receive data to and from the processor through various known means.

[0439] Those skilled in the art will recognize that the present invention may be implemented in other specific ways than those set forth herein without departing from the spirit and essential features of the present disclosure. Therefore, the above-described embodiments should be interpreted in all respects as illustrative and not restrictive. The scope of the present disclosure should be determined by the appended claims and their legal equivalents, not by the above description, and all changes coming within the meaning and equivalent range of the appended claims are intended to be embraced therein.

[0440] Industrial Applicability

[0441] Although the method and apparatus for receiving a synchronization signal are described centering on an example of application to a fifth-generation NewRAT system, the method and apparatus can be applied not only to the fifth-generation NewRAT system but also to various wireless communication systems.

Claims

1. A method performed by a base station BS, the method comprising the following steps: transmitting (i) first information and (ii) second information, wherein the first information notifies one or more synchronization signal and physical broadcast channel SS / PBCH block groups, each SS / PBCH block group including transmitted SS / PBCH blocks, and the second information notifies one or more transmitted SS / PBCH blocks within the SS / PBCH block group notified by the first information, The first information is in the form of a bitmap, and the bitmap includes 8 bits. wherein the 8 bits in the bitmap correspond to 8 SS / PBCH block groups, respectively, wherein each bit in the bitmap has a value of 1 indicating that the corresponding SS / PBCH block group includes the transmitted SS / PBCH block, wherein the second information is identically applied to each of the one or more SS / PBCH block groups; and SS / PBCH block transmission is performed based on (i) the first information and (ii) the second information.

2. The method according to claim 1, wherein The BS operates on a frequency band above 6 GHz.

3. The method according to claim 1, wherein The second information includes the number of the one or more transmitted SS / PBCH blocks.

4. The method according to claim 1, wherein Each of the one or more transmitted SS / PBCH blocks includes a primary synchronization signal PSS, a secondary synchronization signal SSS, and a PBCH signal.

5. A base station BS, comprising: at least one transceiver; at least one processor; as well as at least one computer memory operatively connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations comprising: transmitting, by the transceiver, (i) first information and (ii) second information, the first information notifying one or more synchronization signal and physical broadcast channel (SS) / PBCH block groups, each SS / PBCH block group including transmitted SS / PBCH blocks, and the second information notifying one or more transmitted SS / PBCH blocks within the SS / PBCH block group notified by the first information, The first information is in the form of a bitmap, and the bitmap includes 8 bits. wherein the 8 bits in the bitmap correspond to 8 SS / PBCH block groups, respectively, wherein each bit in the bitmap has a value of 1 indicating that the corresponding SS / PBCH block group includes the transmitted SS / PBCH block, wherein the second information is identically applied to each of the one or more SS / PBCH block groups; and SS / PBCH block transmission is performed by the transceiver based on (i) the first information and (ii) the second information. The BS according to claim 5 , wherein: The BS operates on a frequency band above 6 GHz.

7. The BS according to claim 5, wherein: The second information includes the number of the one or more transmitted SS / PBCH blocks.

8. The BS according to claim 5, wherein: Each of the one or more transmitted SS / PBCH blocks includes a primary synchronization signal PSS, a secondary synchronization signal SSS, and a PBCH signal.

9. A method performed by a user equipment (UE), the method comprising the following steps: receiving (i) first information and (ii) second information, the first information notifying one or more synchronization signal and physical broadcast channel (SS / PBCH) block groups, each SS / PBCH block group including transmitted SS / PBCH blocks, and the second information notifying one or more transmitted SS / PBCH blocks within the SS / PBCH block group notified by the first information, The first information is in the form of a bitmap, and the bitmap includes 8 bits. wherein the 8 bits in the bitmap correspond to 8 SS / PBCH block groups, respectively, wherein each bit in the bitmap has a value of 1 indicating that the corresponding SS / PBCH block group includes the transmitted SS / PBCH block, wherein the second information is identically applied to each of the one or more SS / PBCH block groups; and SS / PBCH block reception is performed based on (i) the first information and (ii) the second information.

10. The method according to claim 9, wherein: The UE operates on a frequency band above 6 GHz.

11. The method according to claim 9, wherein The second information includes the number of the one or more transmitted SS / PBCH blocks.

12. The method according to claim 9, wherein Each of the one or more transmitted SS / PBCH blocks includes a primary synchronization signal PSS, a secondary synchronization signal SSS, and a PBCH signal.

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