Method and apparatus for transmitting and receiving a signal, and computer readable medium

Abstract

The present application relates to a method and apparatus for transmitting and receiving a signal, and a computer readable medium. A method for transmitting a signal by a user equipment (UE) in a wireless communication system, the method comprising the steps of: receiving physical random access channel (PRACH) configuration information; and transmitting a PRACH in one of one or more PRACH occasions allocated in a PRACH slot based on the PRACH configuration information, wherein the transmission of the PRACH is performed based on a number of the one or more PRACH occasions, a preamble format, and a starting orthogonal frequency division multiplexing (OFDM) symbol for the PRACH, and wherein the starting OFDM symbol for the PRACH is contained in the PRACH slot.

Description

[0001] This application is a divisional application of the original invention patent application No. 201980000558.0 (International Application No.: PCT / KR2019 / 000078, Application Date: January 3, 2019, Invention Title: Method and Apparatus for Transmitting and Receiving Physical Random Access Channels). Technical Field

[0002] The present invention relates to a method and apparatus for transmitting and receiving a Physical Random Access Channel (PRACH), and more specifically, to a method and apparatus for obtaining information about PRACH timing and PRACH time slots through PRACH configuration and transmitting / receiving PRACH based on such information. Background Technology

[0003] Compared to traditional LTE systems, the increasing demand for larger communication services from various communication devices necessitates enhanced wireless broadband communication in future fifth-generation (5G) systems. In next-generation 5G systems, communication scenarios are categorized into enhanced mobile broadband (eMBB), ultra-reliable and low-latency communication (URLLC), and massive machine-type communication (mMTC).

[0004] Here, eMBB is a next-generation mobile communication scenario characterized by high spectral efficiency, high user experience data rate, and high peak data rate; URLLC is a next-generation mobile communication scenario characterized by ultra-high reliability, ultra-low latency, and ultra-high availability (e.g., vehicle-to-everything (V2X), emergency services, and remote control); and mMTC is a next-generation mobile communication scenario characterized by low cost, low energy consumption, short packet size, and massive connectivity (e.g., Internet of Things (IoT)). Summary of the Invention

[0005] Technical issues

[0006] The present invention, designed to solve the problem, aims to provide a method and apparatus for transmitting and receiving physical random access channels.

[0007] Those skilled in the art will understand that the purposes achievable by this disclosure are not limited to those specifically described above, and that the above and other purposes achievable by this disclosure will become clearer from the following detailed description.

[0008] Technical solution

[0009] In one aspect of the invention, a method is provided for transmitting a Physical Random Access Channel (PRACH) by a User Equipment (UE) in a wireless communication system, the method comprising the steps of: receiving information regarding PRACH resource allocation; and transmitting PRACH on any one of one or more PRACH opportunities allocated in a PRACH time slot based on the information, wherein the number of one or more PRACH opportunities is based on the preamble format and the start orthogonal frequency division multiplexing (OFDM) symbols used for PRACH.

[0010] Here, the preamble format and the start OFDM symbol can be obtained via the information provided.

[0011] In addition, one or more PRACH opportunities can be continuously allocated in the PRACH time slot starting from the initial OFDM symbol.

[0012] The maximum number of one or more PRACH opportunities can be 6.

[0013] Additionally, when the current preamble format has a duration of two OFDM symbols, the number of one or more PRACH timings can be 6.

[0014] One or more PRACH opportunities may be allocated only to the latter half of a PRACH slot.

[0015] Additionally, when the current preamble format has a duration of four OFDM symbols, the starting OFDM symbol can be 9.

[0016] In another aspect of the invention, a communication device for transmitting a Physical Random Access Channel (PRACH) in a wireless communication system is provided, the communication device comprising: a memory; and a processor connected to the memory, wherein the processor is configured to control: receiving information regarding PRACH resource allocation; and transmitting PRACH on any one of one or more PRACH opportunities allocated in a PRACH time slot based on the information, wherein the number of one or more PRACH opportunities is based on the preamble format and the start of orthogonal frequency division multiplexing (OFDM) symbols for PRACH.

[0017] Here, the preamble format and the start OFDM symbol can be obtained via the information provided.

[0018] One or more PRACH opportunities can be consecutively allocated in a PRACH time slot, starting from the initial OFDM symbol.

[0019] The maximum number of one or more PRACH opportunities can be 6.

[0020] Additionally, when the current preamble format has a duration of two OFDM symbols, the number of one or more PRACH timings can be 6.

[0021] One or more PRACH opportunities may be allocated only to the latter half of a PRACH slot.

[0022] Additionally, when the current preamble format has a duration of four OFDM symbols, the starting OFDM symbol can be 9.

[0023] In another aspect of the invention, a method is provided for a base station to receive a Physical Random Access Channel (PRACH) in a wireless communication system, the method comprising the steps of: transmitting information relating to PRACH resource allocation; and receiving PRACH on any one of one or more PRACH opportunities allocated in a PRACH time slot based on the information, wherein the number of one or more PRACH opportunities is based on the preamble format and the start of orthogonal frequency division multiplexing (OFDM) symbols for the PRACH.

[0024] Technical effect

[0025] According to the present invention, PRACH can be efficiently transmitted to the BS while ensuring the area used for transmitting and receiving downlink signals.

[0026] Those skilled in the art will understand that the effects achievable by this disclosure are not limited to those specifically described above, and that other effects of this disclosure will become clearer from the following detailed description taken in conjunction with the accompanying drawings. Attached Figure Description

[0027] Figure 1 This is a diagram illustrating the control plane and user plane architecture of the radio interface protocol between a User Equipment (UE) and the Evolved UMTS Terrestrial Radio Access Network (E-UTRAN), which conforms to the 3rd Generation Partnership Project (3GPP) radio access network standard.

[0028] Figure 2 This is a diagram illustrating the physical channel in a 3GPP system and a general signal transmission method using the physical channel.

[0029] Figure 3 The random access preamble format in LTE / LTE-A is illustrated.

[0030] Figure 4 Examples of SS block transports and RACH resources linked to SS blocks are shown.

[0031] Figure 5 The configuration / format of the random access channel (RACH) preamble and receiver functionality are illustrated.

[0032] Figures 6 to 8 This is a diagram illustrating the structure of radio frames and time slots used in an NR system.

[0033] Figure 9 This is a diagram illustrating an exemplary connection scheme between a transceiver unit (TXRU) and an antenna element.

[0034] Figure 10 This is a diagram illustrating beam sweeping used for synchronization signals and system information during downlink (DL) transmission.

[0035] Figure 11 This is a diagram illustrating an exemplary cell in an NR system.

[0036] Figures 12 to 14 An example of a process for transmitting and receiving a Physical Random Access Channel (PRACH) according to an embodiment of the present invention is illustrated.

[0037] Figure 15 and Figure 16 This is a diagram illustrating a method for determining the starting OFDM symbol for PRACH transmission.

[0038] Figure 17 and Figure 18 This is a diagram illustrating a method for determining PRACH slots that may have PRACH timing.

[0039] Figure 19 This is a diagram illustrating one implementation of configuring the timing of sending PRACH.

[0040] Figure 20 and Figure 21 This is a diagram illustrating one implementation of a method for allocating PRACH timings.

[0041] Figure 22 This is a block diagram illustrating the components of a wireless device that implements the present invention. Detailed Implementation

[0042] The configuration, operation, and other features of this disclosure will be readily understood by referring to the embodiments described herein with reference to the accompanying drawings. The embodiments of this disclosure set forth herein are examples of applying the technical features of this disclosure to a 3rd Generation Partnership Project (3GPP) system.

[0043] Although embodiments of this disclosure are described in the context of Long Term Evolution (LTE) and LTE-Advanced (LTE-A) systems, they are purely exemplary. Therefore, embodiments of this disclosure can be applied to any other communication system, provided that the foregoing definitions are valid for that system.

[0044] The term Base Station (BS) can be used to encompass the meanings of terms including Remote Radio Header (RRH), Evolved Node B (eNB or eNodeB), Transmitting Point (TP), Receiving Point (RP), and Relay.

[0045] The 3GPP communication standard defines downlink (DL) physical channels corresponding to resource elements (REs) carrying information originating from higher layers, as well as DL physical signals used in the physical layer and corresponding to REs that do not carry information originating from higher layers. For example, the Physical Downlink Shared Channel (PDSCH), Physical Broadcast Channel (PBCH), Physical Multicast Channel (PMCH), Physical Control Format Indicator Channel (PCFICH), Physical Downlink Control Channel (PDCCH), and Physical Hybrid ARQ Indicator Channel (PHICH) are defined as DL physical channels, while reference signals (RS) and synchronization signals (SS) are defined as DL physical signals. RS (also called pilot signals) are signals with predefined special waveforms known to both the gNode B (gNB) and the UE. For example, cell-specific RS, UE-specific RS (UE-RS), positioning RS (PRS), and channel state information RS (CSI-RS) are defined as DL RS. The 3GPP LTE / LTE-A standard defines uplink (UL) physical channels corresponding to REs carrying information originating from higher layers, as well as UL physical signals used in the physical layer and corresponding to REs that do not carry information originating from higher layers. For example, the Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH), and Physical Random Access Channel (PRACH) are defined as UL physical channels, while the Demodulation Reference Signal (DMRS) used for UL control / data signals and the Probe Reference Signal (SRS) used for UL channel measurements are defined as UL physical signals.

[0046] In this disclosure, PDCCH / PCFICH / PHICH / PDSCH refers to a set of time-frequency resources or a set of REs carrying downlink control information (DCI) / control format indicator (CFI) / DL positive acknowledgment / negative acknowledgment (ACK / NACK) / DL data. Furthermore, PUCCH / PUSCH / PRACH refers to a set of time-frequency resources or a set of REs carrying UL control information (UCI) / UL data / random access signals. Specifically, in this disclosure, the time-frequency resources or REs allocated to or belonging to PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH / PRACH are referred to as PDCCH RE / PCFICH RE / PHICH RE / PDSCH RE / PUCCH RE / PUSCHRE / PRACH RE or PDCCH resource / PCFICH resource / PHICH resource / PDSCH resource / PUCCH resource / PUSCH resource / PRACH resource. In the following text, if the UE transmits PUCCH / PUSCH / PRACH, it means that UCI / UL data / random access signals are transmitted on or through PUCCH / PUSCH / PRACH. Furthermore, if the gNB transmits PDCCH / PCFICH / PHICH / PDSCH, it means that DCI / control information is transmitted on or through PDCCH / PCFICH / PHICH / PDSCH.

[0047] In the following text, an orthogonal frequency division multiplexing (OFDM) symbol / carrier / subcarrier / RE that is assigned to CRS / DMRS / CSI-RS / SRS / UE-RS or configured with CRS / DMRS / CSI-RS / SRS / UE-RS is referred to as a CRS / DMRS / CSI-RS / SRS / UE-RS symbol / carrier / subcarrier / RE. For example, an OFDM symbol assigned to a tracking RS (TRS) or configured with a TRS is referred to as a TRS symbol, a subcarrier assigned to a TRS or configured with a TRS is referred to as a TRS subcarrier, and an RE assigned to a TRS or configured with a TRS is referred to as a TRS RE. Furthermore, a subframe configured to transmit a TRS is referred to as a TRS subframe. In addition, a subframe carrying a broadcast signal is referred to as a broadcast subframe or PBCH subframe, while a subframe carrying a synchronization signal (SS) (e.g., a primary synchronization signal (PSS) and / or a secondary synchronization signal (SSS)) is referred to as an SS subframe or a PSS / SSS subframe. OFDM symbols / subcarriers / REs that have been assigned PSS / SSS or configured with PSS / SSS are referred to as PSS / SSS symbols / subcarriers / REs.

[0048] In this disclosure, CRS port, UE-RS port, CSI-RS port, and TRS port refer to antenna ports configured to transmit CRS, UE-RS, CSI-RS, and TRS, respectively. Antenna ports configured to transmit CRS can be distinguished from each other by the location of the RE occupied by CRS according to the CRS port; antenna ports configured to transmit UE-RS can be distinguished from each other by the location of the RE occupied by UE-RS according to the UE-RS port; and antenna ports configured to transmit CSI-RS can be distinguished from each other by the location of the RE occupied by CSI-RS according to the CSI-RS port. Therefore, the term CRS / UE-RS / CSI-RS / TRS port is also used to refer to the pattern of REs occupied by CRS / UE-RS / CSI-RS / TRS in a predetermined resource area.

[0049] Figure 1 This illustrates the control plane and user plane protocol stacks in the 3GPP radio interface protocol architecture between a User Equipment (UE) and an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN). The control plane is the path through which the UE and E-UTRAN send control messages to manage calls, while the user plane is the path through which data generated from the application layer (e.g., voice data or Internet packet data) is sent.

[0050] The Physical (PHY) layer at Layer 1 (L1) provides information delivery services to its higher layers (Media Access Control (MAC) layer). The PHY layer connects to the MAC layer via a transport channel. The transport channel transmits data between the MAC and PHY layers. 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 using Orthogonal Frequency Division Multiple Access (OFDMA) for the downlink (DL) and Single Carrier Frequency Division Multiple Access (SC-FDMA) for the uplink (UL).

[0051] The Layer 2 (L2) MAC layer provides services to its higher layers (Radio Link Control (RLC) layer) via logical channels. The RLC layer at L2 supports reliable data transmission. RLC functionality can be implemented within the function blocks of the MAC layer. The Packet Data Convergence Protocol (PDCP) layer at L2 performs header compression to reduce unnecessary control information, thereby efficiently transmitting Internet Protocol (IP) packets such as IP version 4 (IPv4) or IP version 6 (IPv6) packets over the narrow-bandwidth air interface.

[0052] The Radio Resource Control (RRC) layer, located at the lowest part of Layer 3 (or L3), is defined only on the control plane. The RRC layer controls the logical, transport, and physical channels related to the configuration, reconfiguration, and release of radio bearers. Radio bearers refer to the services provided at L2 for data transmission between the UE and the E-UTRAN. For this purpose, the RRC layers of the UE and E-UTRAN exchange RRC messages. 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.

[0053] The DL transport channels used to transmit data from E-UTRAN to UE include the Broadcast Channel (BCH) carrying system information, the Paging Channel (PCH) carrying paging messages, and the Shared Channel (SCH) carrying user service or control messages. DL multicast service or control messages, or DL ​​broadcast service or control messages, can be transmitted on the DLSCH or a separately defined DL multicast channel (MCH). The UL transport channels used to transmit data from UE to E-UTRAN include the Random Access Channel (RACH) carrying initial control messages and the UL SCH carrying user service or control messages. Logical channels defined above and mapped to transport channels include the Broadcast Control Channel (BCCH), Paging Control Channel (PCCH), Common Control Channel (CCCH), Multicast Control Channel (MCCH), and Multicast Service Channel (MTCH), etc.

[0054] Figure 2 The physical channel in a 3GPP system and a general method for transmitting signals on the physical channel are illustrated.

[0055] Reference Figure 2 When the UE is powered on or enters a new cell, the UE performs an initial cell search (S201). The initial cell search includes obtaining synchronization with the eNB. Specifically, the UE synchronizes with the eNB at regular intervals 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. Then, the UE can 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).

[0056] After the initial cell search, the UE can obtain detailed system information by receiving the Physical Downlink Control Channel (PDCCH) and the Physical Downlink Shared Channel (PDSCH) based on the information included in the PDCCH (S202).

[0057] If the UE is initially accessing the eNB or there are no radio resources available for signal transmission to the eNB, the UE may perform a random access procedure with the eNB (S203 to S206). During the random access procedure, the UE may transmit a predetermined sequence as a preamble on the Physical Random Access Channel (PRACH) (S203 and S205), and may receive response messages to the preamble on the PDCCH and the 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.

[0058] Following the above process, the UE can receive PDCCH and / or PDSCH from the eNB (S207) and send the Physical Uplink Shared Channel (PUSCH) and / or Physical Uplink Control Channel (PUCCH) to the eNB (S208), which is the general DL and UL signal transmission process. Specifically, the UE receives Downlink Control Information (DCI) on the PDCCH. Here, DCI includes control information for the UE, such as resource allocation information. Different DCI formats are defined according to different uses of DCI.

[0059] Control information sent by the UE to the eNB on the UL or received from the eNB on the DL includes DL / UL positive / negative acknowledgment (ACK / NACK) signals, channel quality indicator (CQI), precoding matrix index (PMI), rank indicator (RI), etc. In 3GPP LTE systems, the UE can send control information such as CQI, PMI, and RI on the PUSCH and / or PUCCH.

[0060] Figure 3 The random access preamble format in a traditional LTE / LTE-A system is illustrated.

[0061] In traditional LTE / LTE-A systems, the random access preamble (i.e., RACH preamble) includes a physical layer code of length T. CP The cyclic prefix sum with length T SEQ The sequence portion. Parameter value T CP and T SEQ Listed in the table below, and depending on the frame structure and random access configuration. Higher-layer control preamble format. In 3GPP LTE / LTE-A systems, PRACH configuration information is signaled via cell system information and mobility control information. The PRACH configuration information indicates the root sequence index, the cyclic shift unit N of the Zadoff-Chu sequence used in the RACH procedure, and other parameters to be used within the cell. CSThe length of the root sequence and the preamble format. In 3GPP LTE / LTE-A systems, the PRACH opportunity, which determines the timing of the transmittable preamble format and RACH preamble, is indicated by the PRACH configuration index, which is part of the RACH configuration information (refer to Section 5.7 of 3GPP TS 36.211 and “PRACH-Config” of 3GPP TS 36.331). The length of the Zadoff-Chu sequence used for the RACH preamble is determined according to the preamble format (see Table 4).

[0062] [Table 1]

[0063] Preamble format <![CDATA[T CP ]]> <![CDATA[T SEQ ]]> 0 3168·Ts 24576·Ts 1 21024·Ts 24576·Ts 2 6240·Ts 2·24576·Ts 3 21024·Ts 2·24576·Ts 4 448·Ts 4096·Ts

[0064] In LTE / LTE-A systems, the RACH preamble is transmitted in the UL subframe. The transmission of the random access preamble is limited to specific time and frequency resources. These resources are called PRACH resources and are listed in ascending order of subframe number within the radio frame and PRB in the frequency domain, such that index 0 corresponds to the lowest-numbered PRB and subframe within the radio frame. Random access resources are defined according to the PRACH configuration index (refer to the 3GPP TS 36.211 standard document). The PRACH configuration index is given by higher-layer signals (transmitted by the eNB). The sequence portion of the RACH preamble (hereinafter, the preamble sequence) uses the Zadoff-Chu sequence. The preamble sequence used for RACH is generated from a Zadoff-Chu sequence with a zero correlation region, generated from one or more root Zadoff-Chu sequences. The network configuration allows the UE to use a set of preamble sequences. In legacy LTE / LTE-A systems, there are 64 available preambles per cell. The set of 64 preamble sequences in the cell is found by first including all available cyclic shifts of the root Zadoff-Chu sequence with logical index RACH_ROOT_SEQUENCE in ascending order of cyclic shifts, where RACH_ROOT_SEQUENCE is broadcast as part of the system information. If a single root Zadoff-Chu sequence cannot generate 64 preambles, additional preamble sequences are obtained from root sequences with consecutive logical indices until all 64 sequences are found. The logical root sequence order is cyclic: logical indices 0 to 837 are consecutive. The relationship between the logical root sequence indices and the physical root sequence indices u is given in Tables 2 and 3 for preamble formats 0–3 and 4, respectively.

[0065] [Table 2]

[0066]

[0067]

[0068]

[0069] [Table 3]

[0070]

[0071] The u-th root Zadoff-Chu sequence is defined by the following formula.

[0072] [Formula 1]

[0073]

[0074] The length N of the Zadoff-Chu sequence ZC The following table provides the information.

[0075] [Table 4]

[0076] Preamble format <![CDATA[N ZC ]]> 0～3 839 4 139

[0077] Starting from the u-th root Zadoff-Chu sequence, with a length of N ZC -1 random access preamble with zero correlation zone according to x u,v (n)=x u ((n+C v )mod N ZC Defined by cyclic shift, where cyclic shift is given by the following formula.

[0078] [Equation 2]

[0079]

[0080] For preamble formats 0 to 3, N is given in Table 5. CS For preamble format 4, N is given in Table 6. CS .

[0081] [Table 5]

[0082]

[0083] [Table 6]

[0084] zeroCorrelationZoneConfig <![CDATA[N CS Value 0 2 1 4 2 6 3 8 4 10 5 12 6 15 7 N / A 8 N / A 9 N / A 10 N / A 11 N / A 12 N / A 13 N / A 14 N / A 15 N / A

[0085] The parameter `zeroCorrelationzoneConfig` is provided by a higher layer. The high-speed flag, also provided by the higher layer, determines whether an unrestricted or restricted set should be used. The variable `d`... u It is related to the amplitude 1 / T SEQ The cyclic shift corresponding to the Doppler frequency shift is given by the following formula.

[0086] [Formula 3]

[0087]

[0088] p satisfies (pu) mod N ZC The smallest non-negative integer equal to 1. The parameters of the restricted set used for cyclic shifts depend on d. u For N ZC ≤d u <N ZC / 3, the parameter is given by the following formula.

[0089] [Formula 4]

[0090]

[0091]

[0092]

[0093]

[0094] For N ZC / 3≤d u <(N ZC -N CS ) / 2, the parameter is given by the following formula.

[0095] [Formula 5]

[0096]

[0097]

[0098]

[0099]

[0100] For d u All other values ​​of have no cyclic shift in the restricted set.

[0101] The time-continuous random access signal s(t), which serves as the baseband signal of RACH, is defined by the following equation.

[0102] [Formula 6]

[0103]

[0104] Where 0≤t <T SEQ -T CP ,β PRACH This is the amplitude scaling factor to comply with the transmit power specified in 3GPP TS 36.211, where k0 = n RA PRB NRB sc -N UL RB N RB sc / 2. N RB sc This represents the number of subcarriers that make up a resource block (RB). N UL RB This indicates the number of RBs in the UL time slot and depends on the UL transmission bandwidth. The position in the frequency domain is determined by the parameter n. RA PRB Control, derived from section 5.7.1 of 3GPP TS 36.211. Factor K = Δf / Δf RA The difference in subcarrier spacing between the random access preamble and uplink data transmission is considered. The variable Δf is used as the subcarrier spacing for the random access preamble. RA And a variable serving as a fixed offset for determining the frequency domain position of the random access preamble within the physical resource block. All are given in the table below.

[0105] [Table 7]

[0106]

[0107] In LTE / LTE-A systems, the subcarrier spacing Δf is 15 kHz or 7.5 kHz. However, as shown in Table 7, the subcarrier spacing Δf for the random access preamble... RA It is 1.25kHz or 0.75kHz. Figure 4 The transmission of SS blocks and RACH resources linked to SS blocks is illustrated.

[0108] In order to communicate with a UE, the gNB should acquire the optimal beam direction between the gNB and the UE. Since the optimal beam direction changes as the UE moves, it should be continuously tracked. The process of acquiring the optimal beam direction between the gNB and the UE is called the beam acquisition process, and the process of continuously tracking the optimal beam direction is called the beam tracking process. The beam acquisition process requires 1) the UE's initial attempt to access the gNB, 2) a handover of the UE from one gNB to another, or 3) beam recovery for recovery from a state where the UE and gNB cannot maintain optimal communication or enter a state of non-communication (i.e., beam failure) due to the loss of the optimal beam while performing beam tracking to search for the optimal beam between the UE and the gNB.

[0109] In the context of an NR system under development, a multi-stage beam acquisition process is being discussed for beam acquisition in environments using multiple beams. During this process, the gNB and UE perform connection establishment using a wide beam in the initial access stage, and after connection establishment, the gNB and UE use a narrowband beam for communication with optimal quality. While various methods for beam acquisition in NR systems are primarily discussed in this invention, the most actively discussed method is as follows.

[0110] 1) The gNB transmits an SS block for each wide beam to enable the UE to search for the gNB during the initial access process, i.e., perform cell search or cell acquisition, and search for the optimal wide beam to be used in the first-level beam acquisition by measuring the channel quality of each wide beam. 2) The UE performs a cell search for each beam against the SS block and performs DL beam acquisition using the cell detection results for each beam. 3) The UE performs a RACH procedure to notify the gNB that it will access the gNB it has discovered. 4) The gNB connects or associates the SS blocks transmitted for each beam with the RACH resources to be used for RACH transmission, so that the UE informs the gNB of the results of the RACH procedure and simultaneously informs it of the results of the DL beam acquisition (e.g., beam indexing) at the wide beam level. If the UE performs the RACH procedure using RACH resources connected to the optimal beam direction discovered by the UE, the gNB obtains information about the DL beam suitable for the UE during the reception of the RACH preamble.

[0111] <Beam Correspondence (BC)>

[0112] In a multi-beam environment, the challenge lies in whether the UE and / or TRP can accurately determine the transmit (Tx) or receive (Rx) beam direction between the UE and the TRP. In a multi-beam environment, beam sweeping or signal transmission repetition for signal reception can be considered based on the Tx / Rx interoperability of the TRP (e.g., eNB) or the UE. Tx / Rx interoperability is also known as Tx / Rx beam correspondence (BC) in the TRP and UE. In a multi-beam environment, if Tx / Rx interoperability in the TRP or UE cannot be maintained, the UE may not transmit UL signals in the beam direction in which the UE has already received DL signals, because the optimal path for UL can differ from the optimal path for DL. The Tx / Rx BC in the TRP is maintained if the TRP can determine the TRP Rx beam for UL reception based on DL measurements of the UE for one or more Tx beams of the TRP and / or if the TRP can determine the TRP Tx beam for DL ​​transmission based on UL measurements of one or more Rx beams of the TRP. If the UE can determine the UE Rx beam for UL transmission based on UE DL measurements of one or more Rx beams for the UE and / or if the UE can determine the UE Tx beam for DL ​​reception based on UL measurements of one or more Tx beams for the UE according to the instructions of the TRP, then the Tx / Rx BC in the UE is maintained.

[0113] In LTE and NR systems, the following elements can be used to configure the RACH signal for initial access to the gNB (i.e., initial access to the gNB via the cell used by the gNB).

[0114] *Cyclic Prefix (CP): This element is used to prevent interference from preceding (OFDM) symbols and group RACH preamble signals arriving at the gNB with various delays within a time zone. In other words, if the CP is configured to match the maximum radius of the cell, RACH preambles already transmitted by the UE in the same resource within the cell are included in the RACH receive window corresponding to the length of the RACH preamble configured by the gNB for RACH reception. The CP length is typically set to be equal to or greater than the maximum round-trip delay.

[0115] *Preamble: Defines the sequence that the gNB uses to detect signal transmission, and the preamble is used to carry this sequence.

[0116] *Guard Time (GT): This element is defined such that a RACH signal arriving at the gNB with the delay at the furthest distance from the gNB within the RACH coverage area will not interfere with signals arriving after the duration of the RACH symbol. During this GT, the UE does not transmit signals, so the GT may not be defined as a RACH signal.

[0117] Figure 5 The configuration / format of the RACH preamble and the receiver functionality are illustrated.

[0118] The UE transmits RACH signals through the designated RACH resource at the system timer obtained from the gNB via the SS. The gNB receives signals from multiple UEs. Typically, the gNB performs... Figure 5 The process shown is for RACH signal reception. Since the CP used for the RACH signal is set to the maximum round-trip delay or more, the gNB can configure any point between the maximum round-trip delay and the CP length as a boundary for signal reception. If the boundary is determined as the starting point for signal reception and if a correlation is applied from the starting point to the signal with a length corresponding to the sequence length, the gNB can obtain information about the presence of a RACH signal and information about the CP.

[0119] If the communication environment in which the gNB operates uses multiple beams, such as in the millimeter wave band, the RACH signal arrives at the eNB from multiple directions, and the gNB needs to detect the RACH preamble (i.e., PRACH) while sweeping the beam directions to receive the RACH signals arriving from multiple directions. As mentioned above, when using an analog BF (Browser Filter), the gNB performs RACH reception in only one direction at a given timing. Therefore, it is necessary to design the RACH preamble and RACH procedure so that the gNB can correctly detect the RACH preamble. This invention takes into account both cases where the gNB maintains its BC (Browser Filter) and cases where the BC cannot be maintained, and proposes a high-frequency band RACH preamble and / or RACH procedure applicable to NR systems (especially BF).

[0120] Figure 6 The structure of a radio frame used in NR is illustrated.

[0121] In NR, UL and DL transmissions are configured in frames. A radio frame is 10 ms long and is defined as two 5 ms half-frames (HF). A half-frame is defined as five 1 ms subframes (SF). Subframes are divided into one or more time slots, and the number of time slots in a subframe depends on the subcarrier spacing (SCS). Each time slot includes 12 or 14 OFDM(A) symbols depending on the cyclic prefix (CP). When using normal CP, each time slot includes 14 symbols. When using extended CP, each time slot includes 12 symbols. Here, symbols can include OFDM symbols (or CP-OFDM symbols) and SC-FDMA symbols (or DFT-s-OFDM symbols).

[0122] Table 8 shows how the number of symbols in each slot, the number of slots in each frame, and the number of slots in each subframe vary according to SCS when using normal CP.

[0123] [Table 8]

[0124] SCS(15*2^u) <![CDATA[N slot symb ]]> <![CDATA[N frame，u slot ]]> <![CDATA[N subframc，u slot ]]> 15kHz (u=0) 14 10 1 30kHz (u=1) 14 20 2 60kHz (u=2) 14 40 4 120kHz (u=3) 14 80 8 240kHz (u=4) 14 160 16

[0125] *N slot symb : Number of symbols in a time slot, *N frame，u slot : Number of time slots in a frame, *N subframe，u slot Number of time slots in a subframe.

[0126] Table 9 shows how the number of symbols per slot, the number of slots per frame, and the number of slots per subframe vary according to SCS when using extended CP.

[0127] [Table 9]

[0128] SCS(15*2^u) <![CDATA[N slot symb ]]> <![CDATA[N framc，u slot ]]> <![CDATA[N subframe，u slot ]]> 60kHz (u=2) 12 40 4

[0129] In NR systems, OFDM(A) parameter sets (e.g., SCS, CP length, etc.) can be configured differently across multiple cells merged for a single UE. Therefore, the (absolute time) duration of time resources (e.g., SF, time slots, or TTI) (referred to as time units (TU)) consisting of the same number of symbols can be set differently across merged cells. Figure 7 The time slot structure of an NR frame is illustrated. A time slot comprises multiple symbols in the time domain. For example, in the case of normal CP, a time slot comprises seven symbols. On the other hand, in the case of extended CP, a time slot comprises six symbols. A carrier comprises multiple subcarriers in the frequency domain. A resource block (RB) is defined as multiple consecutive subcarriers in the frequency domain (e.g., 12 consecutive subcarriers). A bandwidth portion (BWP) is defined as multiple consecutive (P)RBs in the frequency domain and may correspond to a set of parameters (e.g., SCS, CP length, etc.). A carrier may include up to N (e.g., 5) BWPs. Data communication is performed through active BWPs, and only one BWP can be activated for a UE. In the resource grid, each element is called a resource element (RE), and a complex symbol can be mapped within it. Figure 8The structure of a self-contained time slot is illustrated. In an NR system, frames have a self-contained structure in which the DL control channel, DL or UL data, and UL control channel can all be contained within a single time slot. For example, the first N symbols in a time slot (hereinafter, the DL control region) can be used to transmit the DL control channel, while the last M symbols in the time slot (hereinafter, the UL control region) can be used to transmit the UL control channel. N and M are integers greater than or equal to 0. The resource region between the DL control region and the UL control region (hereinafter, the data region) can be used for either DL data transmission or UL data transmission. For example, the following configuration can be considered. The parts are listed in chronological order.

[0130] 1. DL configuration only

[0131] 2. UL only

[0132] 3. Hybrid UL-DL configuration

[0133] -DL area + Protection Period (GP) + UL Control Area

[0134] -DL control area + GP + UL area

[0135] *DL area: (i) DL data area, (ii) DL control area + DL data area

[0136] *UL Area: (i) UL Data Area, (ii) UL Data Area + UL Control Area

[0137] PDCCH can be transmitted in the DL control area, and PDSCH can be transmitted in the DL data area. PUCCH can be transmitted in the UL control area, and PUSCH can be transmitted in the UL data area. Downlink control information (DCI), such as DL data scheduling information and UL data scheduling information, can be transmitted on the PDCCH. Uplink control information (UCI), such as ACK / NACK information, channel state information (CSI), and scheduling requests (SR) regarding DL data, can be transmitted on the PUCCH. GP provides a time interval during the UE's switch from transmit mode to receive mode or vice versa. Some symbols during the switch from DL to UL within a subframe can be configured as GP.

[0138] For the 5G mobile communication system under discussion, the use of ultra-high frequency band (i.e., millimeter band above 6 GHz) technology is considered to transmit data to multiple users at high transmission rates over a wide bandwidth. 3GPP refers to this technology as NR, therefore, the 5G mobile communication system is referred to as an NR system in this disclosure. However, the millimeter band has frequency characteristics where the signal attenuates too quickly with distance due to the use of such a high frequency band. Therefore, NR systems using a frequency band equal to or higher than at least 6 GHz employ the following narrow beam transmission scheme: where energy is concentrated to transmit the signal in a specific direction rather than omnidirectionally, thereby compensating for rapid propagation attenuation and overcoming the reduction in coverage caused by rapid propagation attenuation. However, if service is provided by using only one narrow beam, the service coverage of a gNB becomes narrow; therefore, the gNB provides broadband service by collecting multiple narrow beams.

[0139] When wavelengths shorten in the millimeter band (i.e., the millimeter-wave (mmW) band), multiple antenna elements can be installed in the same area. For example, a total of 100 antenna elements in the 30-GHz band with wavelengths of approximately 1 cm can be installed in a two-dimensional (2D) array with a (wavelength) spacing of 0.5λ on a 5×5 cm panel. Therefore, it is possible to increase coverage or throughput by using multiple antenna elements in mmW to increase beamforming gain.

[0140] To form narrow beams in the millimeter-wave band, beamforming schemes are primarily considered, where a gNB or UE transmits the same signal with appropriate phase differences through multiple antennas, thereby increasing energy only in a specific direction. Such beamforming schemes include digital beamforming for generating phase differences between digital baseband signals, analog beamforming for generating phase differences between modulated analog signals using time delays (i.e., cyclic shifts), and hybrid beamforming using both digital and analog beamforming. Independent beamforming per frequency resource is feasible if TXRUs are provided per antenna element to control the transmit power and phase of each antenna. However, installing TXRUs for approximately 100 antenna elements is not cost-effective. That is, multiple antennas must be used to compensate for the rapid propagation attenuation in the millimeter band, and digital beamforming requires as many RF components (e.g., digital-to-analog converters (DACs), mixers, power amplifiers, and linear amplifiers) as there are antennas. Therefore, the implementation of digital beamforming in the millimeter band faces the problem of increased communication equipment costs. Therefore, in millimeter-band applications requiring a large number of antennas, analog beamforming or hybrid beamforming should be considered. In analog beamforming, multiple antenna elements are mapped to a single TXRU, and the beam direction is controlled by an analog phase shifter. A drawback of this analog beamforming scheme is that it cannot provide frequency-selective beamforming (BF) because only one beam direction can be generated in the total band. Hybrid BF lies between digital and analog BF, using B TXRUs (fewer than Q antenna elements). In hybrid BF, although the number of beam directions varies depending on the connection between the B TXRUs and Q antenna elements, the number of beam directions that can be transmitted simultaneously is limited to B or less.

[0141] As described above, a digital beamforming (BF) performs signal processing on the digital baseband signal to be transmitted or received, thus allowing it to transmit or receive signals simultaneously in multiple directions using multiple beams. Conversely, an analog BF performs beamforming in a modulated state using the received analog signal or the analog signal to be transmitted, therefore it cannot transmit or receive signals simultaneously in multiple directions beyond the coverage of a single beam. Typically, a gNB uses broadband transmission or multi-antenna characteristics to communicate with multiple users simultaneously. When a gNB uses an analog or hybrid BF and forms an analog beam in one beam direction, the characteristics of the analog BF limit communication to users only those included in the same analog beam direction. Considering the constraints imposed by the characteristics of analog or hybrid BFs, a RACH resource allocation scheme and resource utilization scheme in a gNB according to the present invention, described later, are proposed.

[0142] Figure 9 An abstract illustration of a hybrid beamforming structure in terms of TXRU and physical antenna.

[0143] For scenarios using multiple antennas, hybrid baseband arrays (BFs) combining digital and analog baseband arrays (BFs) have emerged. Analog BFs (or RFBFs) are pre-coding (or combining) operations performed within the RF units. Due to the pre-coding (combining) in each of the baseband and RF units, hybrid BFs offer performance advantages approaching those of digital BFs while reducing the number of RF chains and DACs (or analog-to-digital converters (ADCs)). For convenience, a hybrid BF structure can be represented by N TXRUs and M physical antennas. The digital BF to be transmitted for L data layers can be represented as an N×N matrix. Then, the N converted digital signals are converted to analog signals via TXRUs and subjected to an analog BF represented as an M×N matrix. Figure 9 In this context, the number of digital beams is L, while the number of analog beams is N. Furthermore, in NR systems, configuring the gNB as a symbol-based analog beamforming (BF) is considered to more effectively support BF for UEs located in specific areas. Additionally, when an antenna panel is defined by N TXRUs and M RF antennas, the introduction of multiple antenna panels that can be applied to independent hybrid BFs is also considered. Thus, when the gNB uses multiple analog beams, different analog beams can be preferentially selected for signal reception at each UE. Therefore, beam sweeping operations are being considered, where, for at least SS, system information, and paging, the gNB changes multiple analog beams based on symbols in a specific time slot or SF to allow all UEs to have reception opportunities.

[0144] Figure 10 This is a diagram illustrating beam sweeping for SS and system information during DL transmission. Figure 10 In this context, the physical resource or physical channel for broadcasting system information of a new RAT system is called xPBCH. Analog beams from different antenna panels can be transmitted simultaneously within a single symbol, and the introduction of features for such systems is under discussion. Figure 10 The diagram shows a beam reference signal (BRS) transmitted for a single analog beam corresponding to a specific antenna panel, used to measure the channel of each analog beam. A BRS can be defined for multiple antenna ports, and each antenna port of the BRS can correspond to a single analog beam. Unlike the BRS, an SS or xPBCH can be transmitted for all analog beams included in a group of analog beams, allowing any UE to successfully receive the SS or xPBCH.

[0145] Figure 11 This is a diagram illustrating an exemplary cell in an NR system.

[0146] Reference Figure 11In contrast to traditional LTE wireless communication systems where a single eNB forms a cell, NR systems are discussing configuring a cell using multiple TRPs. If multiple TRPs form a cell, seamless communication can be advantageously maintained even if the TRP serving the UE changes, thus facilitating UE mobility management.

[0147] Compared to LTE / LTE-A systems that transmit PSS / SSS in all directions, a method is considered for transmitting signals such as PSS / SSS / PBCH by performing a beam sweep (BF) that sequentially switches the beam direction in all directions by a gNB using millimeter waves. Signal transmission / reception performed by switching beam directions is called beam sweeping or beam scanning. In this disclosure, "beam sweeping" is an action on the transmitting side, and "beam scanning" is an action on the receiving side. For example, if the gNB can utilize up to N beam directions, the gNB transmits signals such as PSS / SSS / PBCH in N beam directions. That is, the gNB transmits SS such as PSS / SSS / PBCH in each direction by sweeping the beam in the directions available or supported by the gNB. Alternatively, if the gNB is able to form N beams, the beams can be grouped, and PSS / SSS / PBCH can be transmitted / received based on the groups. A beam group includes one or more beams. Signals such as PSS / SSS / PBCH transmitted in the same direction can be defined as an SS block (SSB), and multiple SSBs can exist in a cell. If multiple SSBs exist, an SSB index can be used to identify each SSB. For example, if PSS / SSS / PBCH are transmitted in 10 beam directions in a system, then PSS / SSS / PBCH transmitted in the same direction can form an SSB, and it can be understood that there are 10 SSBs in the system. In this disclosure, the beam index can be interpreted as the SSB index.

[0148] The method according to the present invention for determining the initial orthogonal frequency division multiplexing (OFDM) symbol, PRACH timing, and PRACH time slot for PRACH transmission / reception will be described in detail below.

[0149] Before proceeding with a detailed description, please refer to Figures 12 to 14 The operation of the UE and base station according to the present invention is illustrated schematically.

[0150] Reference Figure 12The UE receives information about PRACH resources, namely, PRACH configuration information (S1201), and obtains information about the starting OFDM symbol for PRACH, PRACH time slots, and the number of PRACH opportunities included in the PRACH time slots based on the information about PRACH resources (S1203). Here, the method for obtaining information about the starting OFDM symbol for PRACH, PRACH time slots, and the number of PRACH opportunities included in the PRACH time slots based on the information about PRACH resources in operation S1203 can be configured according to the specific implementation described below.

[0151] Subsequently, the UE, referring to the received SS block, etc., sends a PRACH at one of the PRACH timings based on the acquired information (S1205).

[0152] Reference Figure 13 Regarding UE according to Figure 12 In this operation, the BS sends information about PRACH resources, namely PRACH configuration information, to the UE (S1301), and receives PRACH through one of the PRACH timings configured based on the information about the PRACH resources (S1303). In this regard, the method for determining the PRACH timing configured based on the information about the PRACH resources can be based on a specific implementation described below.

[0153] Reference Figure 14 An illustrative operation according to an embodiment of the present invention is described. The BS sends information about PRACH resources to the UE, namely, PRACH configuration information (S1401). Based on the received information about PRACH resources, the UE obtains information about the starting OFDM symbol for PRACH, the PRACH time slot, and the number of PRACH opportunities included in the PRACH time slot (S1403). Here, the method for obtaining information about the starting OFDM symbol for PRACH, the PRACH time slot, and the number of PRACH opportunities included in the PRACH time slot based on the information about PRACH resources in operation S1403 can be configured according to a specific embodiment described below.

[0154] Subsequently, the UE, referring to the received SS block, etc., sends a PRACH at one of the PRACH timings based on the acquired information (S1405).

[0155] The following sections will describe in detail the PRACH process and PRACH configuration used in operations S1203 and S1403 for determining the PRACH timing, etc.

[0156] The Residual Minimum System Information (RMSI) described in the embodiments disclosed below is system information obtained based on the Master Information Block (MIB) acquired on the PBCH, and may be referred to as System Information Block 1 (SIB1). On the other hand, Other System Information (OSI) refers to system information other than the MIB and RMSI, which are minimum system information.

[0157] Additionally, CORESET refers to the area that includes the monitoring opportunities when the UE can monitor PDCCH candidates. In other words, it represents one or more search spaces or sets of search spaces used for monitoring PDCCH.

[0158] 1. Number of starting OFDM symbols and time-domain PRACH timings

[0159] (1) Initial OFDM symbol

[0160] When the RMSI indicates a semi-static UL / DL configuration, the PRACH timing exists in the uplink portion.

[0161] In other words, when a PRACH timing is configured in a UL / DL configuration indicated by RMSI, and in a time slot indicated as DL / UL / unknown / flexible, the PRACH timing assigned to the time slot indicated as UL is valid.

[0162] Among the PRACH opportunities assigned to flexible time slots, those assigned to OFDM symbols following a specific gap after receiving an SS / PBCH block or downlink can be valid.

[0163] When OSI indicates a semi-static UL / DL configuration, the symbol index of the unpaired spectrum indicated by the semi-static UL / DL configuration is the physical symbol index. Information regarding cell-specific UL / DL configurations is defined in RMSI according to NR standard specification 38.321.

[0164] In the table used for PRACH configuration, the index of the starting OFDM symbol can be greater than 2, while the index of the starting OFDM symbol for short sequences can be 0 or 2. In NR, cell-specific semi-static UL / DL configurations can consist of time slots and OFDM symbols. That is, some OFDM symbols in a time slot can be configured as OFDM symbols for uplink. When any time slot is designated as a PRACH time slot, the UE can transmit the PRACH preamble in that PRACH time slot.

[0165] For example, from Figure 15As can be seen, when using a parameter set different from that of PRACH, or when an SS / PBCH block transmitted in a portion of a time slot or a PDSCH for RMSI transmitted in an earlier portion of a time slot, the PRACH preamble can be transmitted starting from the OFDM symbol at index #7. Therefore, to prevent PRACH timing from conflicting with DL configuration and SS / PBCH blocks, the starting OFDM symbol for PRACH should be "7".

[0166] Additionally, if the number of available uplink OFDM symbols in a time slot is less than 12, PRACH can be transmitted in the latter half of the time slot configured for uplink transmission. If the number of available uplink OFDM symbols in a time slot is less than 7, PRACH transmission is not allowed in that time slot.

[0167] (2) The number of time-domain PRACH opportunities in the PRACH slot

[0168] The number of time-domain PRACH opportunities in the PRACH slots used for the PRACH preamble format "C0" is 4. However, since the PRACH preamble format "C0" has a duration of two OFDM symbols, the number of time-domain PRACH opportunities used for the PRACH preamble format "C0" should be changed to 6. Furthermore, the number of PRACH preamble formats B1 and A1 / B1 should be configured by a value that can be 6.

[0169] In other words, for preamble formats B1, A1 / B1, or C0, the maximum number of time-domain PRACH opportunities per PRACH slot can be 6.

[0170] In NR, similar PRACH preamble formats have been introduced, such as formats A1, A1 / B1, and B1, and different PRACH preamble formats can be used depending on the starting OFDM symbol. For example, ... Figure 16 As shown in (a), when the index of the starting OFDM symbol is '0', PRACH preamble formats A1, A2, and A3, which provide wider coverage than PRACH preamble formats A1 / B1, A2 / B2, and A3 / B3, should be applied. Additionally, one of the last two OFDM symbols can be used as a guard period, while the other OFDM symbol can be used for uplink signal transmission such as PUCCH and SRS.

[0171] In other words, when the index of the starting OFDM symbol is "0", the PRACH preamble formats A1, A2, A3, B4, C0, and C2 can be applied.

[0172] Reference Figure 16(b) When the index of the starting OFDM symbol is "2", the PRACH preamble formats A1 / B1, A2 / B2, and A3 / B3 should be used because the guard OFDM symbol cannot be allocated to the last part of the PRACH time slot. That is, when the index of the starting OFDM symbol is "2", 12 OFDM symbols can be used for PRACH transmission.

[0173] In other words, when the index of the starting OFDM symbol is "2", the PRACH preamble formats A1 / B1, B1, A2 / B2, A3 / B3, B4, C0, and C2 can be used.

[0174] Similarly, refer to Figure 16 (c) When the index of the starting OFDM symbol is "7", the PRACH preamble formats A1, A2, and A3 can be applied. That is, when the index of the starting OFDM symbol is "7", six OFDM symbols can be used for PRACH transmission, and the remaining symbol can be used for SRS or PUCCH transmission.

[0175] In other words, when the starting OFDM symbol index is "7", the PRACH preamble formats A1, A3, C0, and C4 can be used.

[0176] 2. PRACH configuration and paired spectrum for FR1

[0177] (1) PRACH preamble format based on long sequence

[0178] The PRACH configuration period can be any of 10ms, 20ms, 40ms, 80ms, and 160ms. PRACH configuration tables need to be defined for periods of 40ms, 80ms, and 160ms. The simplest way to define the period is to modify the value of x based on the subframe number.

[0179] For example, the following values ​​can be defined for each PRACH preamble format.

[0180] 1) PRACH preamble format 0, 1 and 3

[0181] -x=16, y=1, subframe={{1}, {4}, {7}, {9}}

[0182] -x=8, y=1, subframe={{1}, {4}, {7}, {9}}

[0183] -x=4, y=1, subframe={{1}, {4}, {7}, {9}}

[0184] 2) PRACH preamble format 2

[0185] -x=16, y=1, subframe={1}

[0186] -x=8, y=1, subframe={1}

[0187] For PRACH configurations with a density of less than 1, for handover purposes, the UE may assume that the absolute value of the time difference between radio frames I of the current cell and the target cell is less than 153600Ts.

[0188] (2) PRACH preamble format based on short sequences

[0189] For FDD applications, a short-sequence-based PRACH preamble format should provide wider coverage than other short-sequence-based PRACH preamble formats. That is, PRACH preamble formats A1, A2, A3, B4, C0, and C2 should be used for FDD applications. Furthermore, for FDD, the PRACH preamble can be transmitted on the first OFDM symbol. Therefore, for FDD, the starting OFDM symbol can be defined as a single value "0".

[0190] In the PRACH configuration, the short-sequence PRACH preamble has a duration of 1ms, and therefore can have the same time position as defined for PRACH preamble format 0.

[0191] For PRACH configurations based on short sequence PRACH preamble formats, the following values ​​can be applied.

[0192] -x=16, y=1, subframe={{1}, {4}, {7}, {9}};

[0193] -x=8, y=1, subframe={{1}, {4}, {7}, {9}};

[0194] -x=4, y=1, subframe={{1}, {4}, {7}, {9}};

[0195] -x=2, y=1, subframe={{1}, {4}, {7}, {9}};

[0196] -x=1, y=1, subframe={{1}, {4}, {7}, {1,6}, {2,7}, {3,8}, {1,4,7}, {2,5,8}, {3,6,9}, {0,2,4,6,8}, {1,3,5,7,9}, {0,1,2,3,4,5,6,7,8,9}, {9}}.

[0197] Furthermore, for short-sequence-based PRACH preamble formats, the number of PRACH timings in a PRACH slot can vary depending on the specific PRACH preamble format as follows:

[0198] -PRACH preamble format A1, C0: 6;

[0199] -PRACH preamble format A2, C2:3;

[0200] -PRACH preamble format A3:2;

[0201] -PRACH preamble format B4:1.

[0202] There is a PRACH slot in the subframe.

[0203] 3. PRACH preamble format with unpaired spectrum

[0204] For unpaired spectrum, all PRACH preamble formats can be applied, namely PRACH preamble formats A1, A1 / B1, B1, A2, A2 / B2, A3, A3 / B3, B4, C0, and C2. In the case of unpaired spectrum, the starting OFDM symbol can be indicated to operate under conditions such as cell-specific UL / DL configurations and PDCCH resource reservations. In other words, for unpaired spectrum, the starting OFDM symbol can be defined according to the PRACH preamble format.

[0205] Specifically, the PRACH preamble format based on the starting OFDM symbol can be determined as follows.

[0206] - For the starting OFDM symbol index "0", the PRACH preamble formats A1, A2, A3, B4, C0, and C2 can be used.

[0207] - For the starting OFDM symbol index "2", the PRACH preamble formats A1 / B1, B1, A2 / B2, A3 / B3, B4, C0 and C2 can be used.

[0208] - If the number of available PRACH OFDM symbols in a time slot is less than or equal to 12 and the starting OFDM symbol index is "7", then the PRACH preamble formats A1, A3, C0, and C2 can be used.

[0209] In addition, the maximum number of PRACH opportunities that can be allocated to PRACH slots can be determined based on the PRACH preamble format and the starting OFDM symbol.

[0210] Specifically, when the starting OFDM symbol index is "0" or "2", the number of PRACH timings can be given according to the format of each PRACH preamble as follows:

[0211] -PRACH preamble formats A1, A1 / B1, and C0: 6;

[0212] -PRACH preamble format B1, A2, C2:3;

[0213] -PRACH preamble format A2 / B2, A3, A3 / B3: 2;

[0214] -PRACH preamble format B4:1.

[0215] When the starting OFDM symbol index is "7", the number of PRACH timings can be given according to the following PRACH preamble format:

[0216] -PRACH preamble format A1:3;

[0217] -PRACH preamble format A3: 1;

[0218] -PRACH preamble format C0, C2:2.

[0219] The number of PRACH slots in a subframe in FR1 is 1, while the number of PRACH slots in a slot in FR2 is 1.

[0220] In NR systems, cell-specific semi-static DL / UL configurations include the number of time slots and the number of OFDM symbols within a time period. The NR system also defines various values ​​for DL / UL configuration time periods. Therefore, the location of UL time slots is determined based on the cell-specific semi-static DL / UL configuration and the time period. Furthermore, the number of UL time slots is variable. Therefore, it is important to correctly define the subframe index and time slot index for PRACH timing. As one approach, PRACH timing can be defined starting from the last point of the DL / UL configuration time period, since UL time slots are located from the last point of that time period.

[0221] 4. Unpaired spectrum and PRACH configuration in FR1

[0222] Considering the SS / PBCH block transfer and RMSI search space, such as Figure 17 As shown in (a), at least two subframes preceding the time slot can be assigned as DL and "Unknown". In this case, when DL / UL is configured within a 5ms time period, up to six subframes (e.g., subframe indices #2, #3, #4, #7, #8, and #9) can be used for the PRACH timing. That is, candidate subframes for UL transmission can be used to establish the PRACH configuration.

[0223] For the PRACH configuration in FR1, the following values ​​can be used:

[0224] -x=16, y=1, subframe={{3}, {4}, {8}, {9}};

[0225] -x=8, y=1, subframe={{3}, {4}, {8}, {9}};

[0226] -x=4, y=1, subframe={{3}, {4}, {8}, {9}};

[0227] -x=2, y=1, subframe={{3}, {4}, {8}, {9}};

[0228] -x=1, y=1, subframe={{3}, {4}, {8}, {9}, {3,4}, {8,9}, {2,3,4}, {7,8,9}, {3,4,8,9}, {5,6,7,8,9}, {4,5,6,7,8,9}}.

[0229] (1) Based on long sequence PRACH preamble

[0230] Random access configurations for FR 1 and unpaired spectrum are currently defined as shown in Table 10 below.

[0231] [Table 10]

[0232]

[0233] Referring to Table 10, a total of 71 (=30+6+6+29) entries are allocated to the long-sequence-based PRACH preamble. The configuration for the short-sequence-based PRACH preamble for FR1 and unpaired spectra needs to be defined based on Table 10. For the configuration of the short-sequence-based PRACH preamble for FR1 and paired spectra, approximately 20 entries are used per PRACH preamble format.

[0234] Similarly, assuming each short-sequence-based PRACH preamble format uses 20 entries, then a short-sequence-based PRACH preamble requires at least 200 entries (= 10 PRACH preamble formats × 20 entries), but the number of other entries besides those used for long-sequence-based PRACH preamble formats is 185 (= 256 - 71), which is insufficient to serve as entries for short-sequence-based PRACH preambles.

[0235] Specifically, considering the ability to set various values ​​for the initial OFDM symbols of unpaired spectra, short-sequence-based RPACH preambles require more than 200 entries. Therefore, the number of entries used to configure long-sequence-based PRACH preambles should be reduced. Assuming approximately 200 entries for short-sequence-based PRACH preambles, approximately 54 entries can be allocated for long-sequence-based PRACH preamble configurations. For PRACH preamble formats 0, 1, 2, and 3, we can assume 22, 6, 6, and 22 entries respectively.

[0236] Based on the description given above, refer to Figure 17 (b) When DL / UL configuration is configured in FR1 during the 5ms and 10ms time periods, five subframes with indices #3, #4, #7, #8, and #9 can be allocated for the PRACH timing. Additionally, in the case of the 2.5ms time period of DL / UL configuration, two subframes with indices #1 and #6 can be allocated for the PRACH timing.

[0237] According to Table 10, for the SSB transmission area and RMSI search space of unpaired spectrum, the subframe located at the beginning of the DL / UL configuration period can be assigned as DL and "Unknown". Additionally, the middle or last subframe can be assigned as the PRACH timing.

[0238] For example, when the DL / UL configuration period is 10ms, the last two subframes within that 10ms duration (i.e., subframes indexed 8 and 9) can be used for the PRACH timing. When the DL / UL configuration period is 2ms, the five subframes within that 10ms duration (i.e., subframes indexed 1, 3, 5, 7, and 9) can be used for the PRACH timing. Therefore, referring to Table 10, which serves as a PRACH configuration table for long sequences, it can be seen that some entries are not suitable for DL / UL configuration. Specifically, the following entries are not suitable for DL / UL configuration:

[0239] -x=1, y=0, subframe={{1}, {2}, {5}, {6}, {7}, {1,6}, {1,6}, {2,7}, {3,8}, {3,4,8}, {1,4,6,9}}.

[0240] The PRACH configurations shown in Table 10 can help avoid conflicts between PRACH timings in cells. However, in the serving cell, when the gNB transmits SSB and RSMI PDCCH / PDSCH at the beginning of the DL / UL configuration period, the probability of conflicts between the downlink channels used for transmitting SSB and RSMI PDCCH / PDSCH and the PRACH timings is higher. As a result, the number of PRACH timings in the PRACH period can be reduced. Therefore, it is recommended to remove at least some entries in Table 10.

[0241] In other words, it is recommended to modify the parameters of formats 0 and 3 in Table 10 as follows:

[0242] -x=1, y=0, subframe={{3}, {4}, {8}, {9}, {4,9}, {3,4}, {8,9}, {3,4,9}, {4,8,9}, {7,8,9}, {3,4,8,9}, {1,3,5,7,9}}.

[0243] exist Figure 19 The result of the above modifications is shown in the figure. Figure 19 The subframe index and unpaired spectrum used for PRACH timing in FR1 are shown. (Refer to...) Figure 19 It can be seen that the modified subframe index is aligned at 2ms, 2.5ms, 5ms and 10ms, which are the end of the DL / UL configuration period.

[0244] Reference Figure 19 When the DL / UL configuration period is 5ms, the subframe with index {3,4} (which consists of two consecutive subframes) is useful. Similarly, considering a DL / UL configuration period of 2.5ms, a subframe with index {1,6} may be required. Therefore, the starting OFDM symbol of the subframe with index {1,6} could be the OFDM symbol with index #7.

[0245] (2) PRACH preamble based on short sequences

[0246] For PRACH preambles based on short sequences, the subframe index of the PRACH timing defined for PRACH preambles based on long sequences should be considered. Therefore, the subframe index of the PRACH timing can be modified at the top of the PRACH configuration according to the PRACH format.

[0247] For the PRACH configuration of the short sequence-based PRACH preamble, the configuration parameters in the short sequence-based PRACH preamble can be given as follows:

[0248] -x=16, y=1, subframe={{9}};

[0249] -x=8, y=1, subframe={{9}};

[0250] -x=4, y=1, subframe={{9}};

[0251] -x=2, y=0, subframe={{4}, {9}};

[0252] -x=2, y=1, subframe={{4}, {9}};

[0253] -x=1, y=0, subframe={{3}, {4}, {8}, {9}, {1,6}, {4,9}, {3,4}, {8,9}, {3,4,9}, {4,8,9}, {7,8,9}, {1,4,6,9}, {3,4,8,9}, {1,3,5,7,9}}.

[0254] Specifically, the configuration for short-sequence-based PRACH is configured to support various time intervals. However, since there are no entries for long time intervals in Table 10, configurations for long time intervals (such as 160ms, 80ms, and 40ms) for some PRACH preamble formats such as formats A1, A2, A3, B1, B4, C0, and C4 are defined.

[0255] Furthermore, although more entries were allocated for longer time slots, two entries defined for other formats in the case of a 20ms time slot (i.e., the slot index sets {2,3,4,7,8,9} and {7,9}) were not included in the entries used for format A2. To align the configurations of the various formats, more entries can be used as shown below.

[0256] 1) Entries used for PRACH preamble formats A2, B4, A1 / B1, A2 / B2, and A3 / B4:

[0257] -Entries for format A2 among entries defined for other formats

[0258] [Table 11]

[0259] A2 2 1 2,3,4,7,8,9 0 1 3 4 A2 2 1 7,9 0 1 3 4

[0260] -Entries for format B4 among the entries defined for other formats.

[0261] [Table 12]

[0262] B4 2 1 9 0 1 1 12 B4 1 0 9 0 1 1 12

[0263] -Entries for format A1 / B1 in configurations for long time periods such as 160ms, 80ms, and 40ms, and other format-defined entries.

[0264] [Table 13]

[0265] A1 / B1 16 1 9 2 2 6 2 A1 / B1 8 1 9 2 2 6 2 A1 / B1 4 1 9 2 1 6 2 A1 / B1 2 1 2,3,4,7,8,9 2 1 6 2 A1 / B1 1 0 3,4,8,9 2 1 6 2

[0266] -Entries for format A2 / B2 in configurations for long time periods such as 160ms, 80ms, and 40ms, and other format definitions.

[0267] [Table 14]

[0268] A2 / B2 16 1 9 2 2 3 4 A2 / B2 8 1 9 2 2 3 4 A2 / B2 4 1 9 2 1 3 4 A2 / B2 2 1 2,3,4,7,8,9 2 1 3 4 A2 / B2 2 1 7,9 2 1 3 4

[0269] -Entries for format A3 / B3 in configurations for long time periods such as 160ms, 80ms, and 40ms, and other format definitions.

[0270] [Table 15]

[0271] A3 / B3 16 1 9 0 2 2 6 A3 / B3 8 1 9 0 2 2 6 A3 / B3 4 1 9 0 2 2 6 A3 / B3 2 1 2,3,4,7,8,9 0 2 2 6 A3 / B3 1 0 3,4,8,9 0 1 2 6

[0272] 5. Unpaired spectrum and PRACH configuration in FR2

[0273] Reference Figure 18 In the FR2 case, a shorter time period of 1.25ms is defined for the 120kHz subcarrier spacing, and the last slot of this period can be allocated for the uplink. Additionally, in the 2.5ms time period, the last slot can be a candidate for the PRACH timing. Therefore, four slots with at least indices #9, #19, #29, and #39 can be allocated as PRACH timings. Furthermore, in FR2, the maximum number of SS / PBCH blocks is L=64, which is a considerable number, and the RMSI search window timing can be relatively wide. Therefore, the uplink slots used for PRACH timings can be allocated to the last part of a 5ms or 10ms time period.

[0274] Specifically, the following provides the PRACH timing for different time periods based on the cell-specific UL / DL configuration.

[0275] - In the case of a 1.25ms time slot, the latter half of the eight time slots indexed as #4, #9, #14, #19, #24, #29, #34 and #39 can be the PRACH timing available for PRACH transmission, and the eight time slots can have a subcarrier spacing of 120kHz.

[0276] - In the case of a 2.5ms time period, the latter half of the eight time slots indexed as #8, #9, #18, #19, #28, #29, #38, and #39 can be the PRACH timing available for PRACH transmission, and the eight time slots can have a subcarrier spacing of 120kHz.

[0277] - In the case of a 5ms time period, some time slots with indices #16, #17, #18, #19, #36, #37, #38, and #39 in the last part of that time period can be used as PRACH timings.

[0278] - In the case of a 10ms time period, some time slots with indices #32 to #39 in the last part of that time period can be used as PRACH timings.

[0279] In FR2, the values ​​used for PRACH configuration can be given as follows:

[0280] -x=16, y=1, subframe={{9}, {19}, {29}, {39}};

[0281] -x=8, y=1, subframe={{9}, {19}, {28}, {39}};

[0282] -x=4, y=1, subframe={{9}, {19}, {28}, {39}};

[0283] -x=2, y=1, subframe={{9}, {19}, {29}, {39}};

[0284] -x=1, y=1, subframe={{9}, {19}, {29}, {39}, {9,29}, {19,39}, {9,28,29}, {19,38,39}, {8,18,28,38}, {9,19,29,39}, {35,36,37,38,39}, {18,19,36,37,38,39}}.

[0285] 6. OFDM symbol gap following the last symbol of the SSB and / or the DL section.

[0286] As discussed above, in FR1 and FR2, only PRACH timings allocated to the UL and X portions of the PRACH slot and that precede or do not conflict with the SSB are valid. In other words, a valid PRACH timing is located at least N symbols after the last symbol and / or DL ​​portion of the SSB. That is, a valid PRACH timing is located at least N gaps after the last symbol and / or DL ​​portion of the SSB.

[0287] Here, the number of OFDM symbols required as the gap between DL and UL will be discussed. The gap is determined based on the subcarrier spacing of Msg.1 (i.e., the PRACH preamble). When the subcarrier spacing of Msg.1 is 15 / 30 / 60kHz, N = 2. When the subcarrier spacing of Msg.1 is 120kHz, considering the multiplexing between OFDM symbols with different parameter sets, an even number of OFDM symbols can be used as the DL / UL switching gap. Therefore, when the subcarrier spacing of Msg.1 is 120kHz, N can be N = 2.

[0288] When two OFDM symbols are required as a switching gap, the index of the starting OFDM symbol in the PRACH slot needs to be configured according to this gap. For example, refer to... Figure 20In (a), when the subcarrier spacing is 15 kHz, the last symbol index of the first SSB is 5. Therefore, when two OFDM symbols are needed as the DL / UL gap, the UE can transmit the PRACH preamble from the OFDM symbol with index 8. (See reference...) Figure 20 In (b), it can be seen that in the case of FR2 (i.e., when the subcarrier spacing is 120kHz), the configuration is similar to that when the subcarrier spacing is 15kHz.

[0289] Therefore, the starting OFDM symbol index for PRACH timing should be defined as an even index. In the PRACH configuration table for FR1 and TDD, the index for the starting OFDM symbol for formats A1, A2, and A3 can be defined as "8". In the PRACH configuration table for FR2 and TDD, the index for the starting OFDM symbol for formats A1, A2, A3, and C2 can also be defined as "8". Furthermore, in the PRACH configuration table for FR1 and TDD, the index for the starting OFDM symbol for formats A2 / B2 can be defined as "2".

[0290] 7. Superframe Number (SFN) information and frame boundaries for the target cell

[0291] In NR, since the minimum PRACH configuration period is 10ms, the UE should acquire frame boundary information during handover. In frequency ranges below 3GHz, NR UEs can obtain frame boundary information from the PBCH DMRS sequence. On the other hand, in frequency bands above 3GHz, a method needs to be defined to indicate the frame boundary information of the target cell without PBCH decoding. Furthermore, in NR, even if a PRACH entry with a 10ms period is configured, if the associated pattern period between the SSB and the PRACH timing is longer than 10ms, the target cell's SFN information may be required.

[0292] In TDD, it can be assumed that the gNB is tightly synchronized within 2.5ms and applies the same SFN to the target cell. However, in FDD, it is difficult to assume tight synchronization. Therefore, the gNB can provide the UE with SFN information such as the SFN offset between the serving cell and the target cell through handover commands.

[0293] 8. Total number of PRACH opportunities in the PRACH configuration period

[0294] The total number of PRACH opportunities can be calculated by multiplying the number of PRACH slots in the subframes included in the PRACH configuration, the number of PRACH opportunities in the PRACH slots, the number of subframes for each PRACH configuration index, the number of FDM-transmitted PRACH opportunities in the time instance indicated by the 2-bit value, and the PRACH configuration period.

[0295] In addition, the UE can obtain the total number of PRACH opportunities in the two-dimensional time / frequency domain based on the above information.

[0296] 9. Rules for mapping valid PRACH resources or valid PRACH timings to SS / PBCH blocks.

[0297] Once the total number of PRACH opportunities that can be allocated within the PRACH configuration period is determined, the method for mapping each SS / PBCH block to a PRACH opportunity should be determined. If the number of PRACH opportunities for each SS / PBCH block is 1, that is, a one-to-one mapping is performed between SS / PBCH blocks and PRACH opportunities, the method for mapping each SS / PBCH block to a PRACH opportunity can be easily determined. This is because it is only necessary to map the SS / PBCH blocks to PRACH opportunities sequentially. Similarly, if there are FDM-based PRACH opportunities, SS / PBCH blocks can be mapped to time-domain PRACH opportunities after being mapped to FDM-based PRACH opportunities. In this case, the time period of the PRACH opportunity should be configured according to the PRACH configuration period. That is, the first actually transmitted SS / PBCH block included in the SSB burst set within each time period is mapped to the first PRACH opportunity.

[0298] To create more general mapping rules, the following parameters can be assumed:

[0299] -X: Total number of RACH opportunities;

[0300] -N SSB_per_RO The number of SS blocks per RACH timing;

[0301] -N seq_per_SSB_per_RO The number of CBRA preambles for each SS block used for RACH transmission timing;

[0302] -M: The number of RACH opportunities per SS block, where M is determined by N. seq_per_SSB / N seq_per_SSB_per_RO Obtain; and

[0303] -Fd: The number of RACH moments that can be mapped to a single SS block simultaneously.

[0304] 1) When M≥1:

[0305] If the SS block has a one-to-many mapping relationship with multiple RACH occasions mapped to it, then M is an integer satisfying M>1, and Fd = 1. The M TDM'd RACH occasions can be sequentially mapped to one SS block.

[0306] In other words, if 1 / M, which is the number of SS blocks for each RACH occasion, is less than 1, then the SS block can be mapped to M RACH occasions. In this case, the RACH occasions mapped to one SS block can be consecutive RACH occasions.

[0307] If Fd>1, then the M RACH occasions are mapped to the SS block in frequency-time order. If M is a multiple of Fd, then a single SS block can be mapped to the FDM'd RACH occasions within a specific time. If multiple SS blocks are mapped to one RACH occasion within the same time, it should be ensured that the beam direction is the direction in which the network can receive the beams corresponding to multiple SS blocks simultaneously.

[0308] The above description is summarized in Table 16 below.

[0309] [Table 16]

[0310]

[0311] 2) When M<1:

[0312] Hereinafter, the case where multiple SS blocks are mapped to one RACH occasion (i.e., one-to-many mapping is performed) will be described. When 0<M<1, 1 / M = N, where N is defined as the number of SS blocks mapped to one RACH occasion. Assume that multiple SS blocks are CDM'd (Code Division Multiple Access) to one RACH occasion, and the beam directions corresponding to the SS blocks are the directions in which the network can receive the beams simultaneously.

[0313] If the maximum number of RACH preamble indices (such as 64 RACH preamble indices) is assigned to the RACH occasion, and it is assumed that the RACH preambles are received in a space division multiple access (SDMA) manner, then a comb-type mapping of the RACH preambles to each SS block can be performed to improve the RACH reception performance. In other words, when two SS blocks are mapped to one RACH occasion, the other RACH preamble indices are mapped to these two SS blocks. In this case, the actual cyclic shift assigned to each SS block is defined as N×Ncs, thereby improving the reception performance of the RACH preambles.

[0314] When multiple SS blocks are associated with a single RACH timing, the preamble index of the CBRA can be non-contiguously mapped to the corresponding SS blocks to improve RACH performance. Mapping multiple SS blocks to multiple RACH timings could also be considered, but this mapping method introduces implementation complexity, so it is best to exclude it from the mapping types.

[0315] 10. CORESET and search space used in the PRACH procedure

[0316] The CORESET and search space used for the PRACH procedure are unclear, but the CORESET used for the PRACH procedure (i.e., the CORESET used for msg.2 / 3 / 4 reception) should be the same as the RMSI CORESET. The search space for msg.2 / 3 / 4 should be all time slots within the configured duration. That is, the search space should include both the Random Access Response (RAR) window for msg.2 and the duration configured for msg.3 / 4.

[0317] 11. PRACH Mask Index

[0318] The PRACH mask is 4 bits and is used on both RRC and PDCCH. The PRACH mask index is shown in Table 17 below.

[0319] [Table 17]

[0320] PRACH Mask Index Permitted RACH timing 0 all 1 RACH Timing Index 1 2 RACH Timing Index 2 3 RACH Timing Index 3 4 RACH Timing Index 4 5 RACH Timing Index 5 6 RACH Timing Index 6 7 RACH Timing Index 7 8 RACH Timing Index 8 9 Every even-numbered RACH timing 10 Every odd-numbered RACH timing 11 reserve 12 reserve 13 reserve 14 reserve 15 reserve

[0321] In a PRACH timing group, it can be assumed that the 3 bits used to indicate the relevant PRACH timing index corresponding to the indicated SSB index are mapped to PRACH timings with specific consecutive SSB indices. That is, it can be assumed that the SSB of each PRACH timing is 1 / N. The 3 bits can be used to indicate one of eight logically consecutive PRACH timings. Based on the above description, the three states shown in Table 17 (i.e., all, every even-numbered PRACH timing, and every odd-numbered PRACH timing) can be defined.

[0322] The definition of the relevant PRACH timing index is unclear here, so it is necessary to clarify how to index the PRACH timing. Figure 17 An example of an index for the PRACH timing corresponding to the indicated SSB index is shown.

[0323] Reference Figure 21 The PRACH timing index of the PRACH mask is defined as follows:

[0324] - Calculate the number of available PRACH opportunities for the SSB index within the associated pattern period (up to 160ms) between the SSB and PRACH opportunities.

[0325] - PRACH timing indices #0 to #7 are periodically mapped from the first PRACH timing to the last PRACH timing.

[0326] - The PRACH timing group consists of eight logically consecutive PRACH timings.

[0327] - The indicated PRACH timing index applies to all PRACH timing groups.

[0328] 12. CORESET / Search Space for the PRACH Procedure

[0329] (1) CORESET (control resource set) used in the PRACH process

[0330] After the UE sends the PRACH preamble at the PRACH timing, the UE monitors the RAR within the configured RAR window. Since the RAR is transmitted on the PDSCH, the UE can use the RA-RNTI to monitor the corresponding PDCCH and obtain time-frequency information about the PDSCH transmissions used for RAR through the Downlink Control Indicator (DCI) used for scheduling the RAR. Therefore, the CORESET, as the potential symbol and slot location of the DCI used for scheduling the RAR, can be indicated by the network through the PRACH configuration information. Specifically, information about the CORESET used for the PRACH procedure can be sent through the PRACH configuration included in the RMSI.

[0331] If no CORESET configuration is configured for the PRACH procedure, the CORESET used for RMSI reception is used for the PRACH procedure. That is, all messages related to PDCCH transmission (such as msg.2 / msg.3 retransmission / msg.4 scheduling) share the same CORESET during the PRACH procedure.

[0332] (2) Monitoring window for the PRACH process

[0333] After sending the PRACH preamble, the UE monitors the RAR within a configured window. Furthermore, due to multi-beam operation, it monitors not only the DCI used for RAR but also the DCI used for msg.3 retransmission / msg.4 scheduling within the configured window.

[0334] Specifically, since the window sizes for each message do not need to be different, the window for RAR reception configuration, the window for DCI configuration for msg.3 retransmission, and the window for DCI configuration for msg.4 scheduled reception can have the same size. The monitoring window for RAR reception begins in the first "valid" downlink slot, taking into account the minimum timing gap after the UE sends the PRACH preamble. Similarly, the monitoring window for msg.3 retransmission / msg.4 scheduling begins in the first valid downlink slot after the UE sends msg.3.

[0335] (3) Timing for monitoring the PRACH process

[0336] The UE can monitor all time slots within the monitoring window to receive PRACH messages. Therefore, it is necessary to specify which symbols to monitor in each time slot (i.e., the monitoring timing) the UE should monitor. Unlike broadcast system information transmitted in association with the SSB index, messages used for the PRACH procedure do not need to be associated with the SSB index.

[0337] The candidate monitoring opportunities allocated for RAR reception in a time slot can be known to the UE, and DCIs about PRACH messages can be sent at the monitoring opportunities indicated in each time slot of the monitoring window.

[0338] If the number of times the monitored RMSI is received is indicated as 1 in a time slot via PBCH, then all UEs in the system monitor the PDCCH monitoring timing starting from the first symbol of each time slot during the monitoring window.

[0339] If the monitoring timing indicated in a time slot is 2, the UE needs to determine the monitoring timing within the time slot, i.e., whether to start monitoring at the first symbol of the time slot or in the middle of the time slot (such as symbols #2, #3, or #7). Since the monitoring timing is associated with the SSB index and the SSB index is already associated with RA-RNTI generation, it is simpler to associate the RA-RNTI value with the monitoring timing.

[0340] For example, if the RA-RNTI value is even, the UE can attempt to detect the PDCCH at a monitoring opportunity starting from the first symbol of each time slot within the monitoring window. If the RA-RNTI value is odd, the UE attempts to detect the PDCCH at a monitoring opportunity in the middle of each time slot within the monitoring window.

[0341] Figure 22 This is a block diagram illustrating an example of communication between wireless device 10 and network node 20. Here, network node 20 can be... Figure 22 Replace with wireless devices or UEs.

[0342] In this specification, wireless device 10 or network node 20 includes transceivers 11, 21 for communicating with one or more other wireless devices, network nodes, and / or other components of the network. Transceivers 11 and 21 may include one or more transmitters, one or more receivers, and / or one or more communication interfaces.

[0343] Additionally, transceivers 11 and 21 may include one or more antennas. According to one embodiment of the invention, the antennas are used to transmit signals processed by transceivers 11 and 21 to the outside under the control of processing chips 12 and 22, or to receive wireless signals from the outside and transmit those signals to processing chips 12 and 22. The antennas are also referred to as antenna ports. Each antenna may correspond to a single physical antenna, or may be configured as a combination of more than one physical antenna element. Signals transmitted from each antenna may not be further divided by the wireless device 10 or network node 20. From the perspective of the wireless device 10 or network node 20, the reference signal (RS) transmitted from the corresponding antenna defines the antenna and enables the wireless device 10 or network node 20 to perform channel estimation for the antenna, regardless of whether the channel is a single wireless channel from a single physical antenna or a composite channel from multiple physical antenna elements including the antenna. That is, an antenna is defined such that the channel used to transmit symbols on the antenna can be obtained from the channel through which another symbol transmitted on the same antenna passes. Transceivers supporting multiple-input multiple-output (MIMO) functionality for transmitting and receiving data using multiple antennas can be connected to two or more antennas.

[0344] In this invention, transceivers 11 and 21 can support receive beamforming and transmit beamforming. For example, in this invention, transceivers 11 and 21 can be configured to perform... Figures 9 to 11 The functions shown are as follows.

[0345] In addition, the wireless device 10 or network node 20 includes processing chips 12 and 22. Processing chips 12 and 22 may include at least one processor such as processor 13 and 23 and at least one memory device such as memory 14 and 24.

[0346] Processing chips 12 and 22 can control at least one of the methods and / or processes described herein. In other words, processing chips 12 and 22 can be configured to implement at least one of the embodiments described herein.

[0347] Processors 13 and 23 include at least one processor for performing the functions of the wireless device 10 or network node 20 described herein.

[0348] For example, one or more processors can control Figure 22 One or more transceivers 11 and 21 are used to send and receive information.

[0349] Processors 13 and 23 included in processing chips 12 and 22 perform predetermined encoding and modulation on signals and / or data to be transmitted to the outside of wireless device 10 or network node 20, and then transmit the signals and / or data to transceivers 11 and 21. For example, processors 13 and 23 convert the data sequence to be transmitted into a K-layer through demultiplexing, channel coding, scrambling, and modulation processes. The encoded data sequence is also called a codeword and is equivalent to a transport block (TB) provided as a data block by the MAC layer. A TB is encoded into a codeword, and each codeword is transmitted to the receiving device in the form of one or more layers. To perform frequency up-conversion, transceivers 11 and 21 may include an oscillator. Transceivers 11 and 21 may include N-layer oscillators. t There are N transmitting antennas (of which N) t (It is a positive integer greater than or equal to 1).

[0350] Additionally, processing chips 12 and 22 include memories 14 and 24 configured to store data, programmable software code, and / or other information for implementing the embodiments described herein.

[0351] In other words, in an embodiment according to the invention, when memories 14 and 24 are executed by at least one processor, such as processors 13 and 23, the memories allow processors 13 and 23 to execute commands... Figure 22 Some or all of the processes controlled by processors 13 and 23, or the storage including the means for implementing based Figures 1 to 21 Software codes 15 and 25 are the instructions for the implementation methods described herein.

[0352] Specifically, the processing chip 12 of the wireless device 10 according to an embodiment of the present invention can control the transceiver 11 to receive information about PRACH resource allocation from the BS, and based on the information, control the transceiver 11 to send PRACH to the BS on one of the multiple PRACH opportunities allocated in the PRACH time slot.

[0353] Here, the number of PRACH opportunities allocated in the PRACH slot can be based on the PRACH preamble format and the starting orthogonal frequency division multiplexing (OFDM) symbol.

[0354] Additionally, the processing chip 12 can obtain the preamble format and the starting OFDM symbol through information about PRACH resource allocation. Here, multiple PRACH opportunities can be continuously allocated in the PRACH time slot starting from the starting OFDM symbol. Furthermore, the maximum number of PRACH opportunities can be 6. The number of PRACH opportunities is 6 when the current preamble format has a duration corresponding to two OFDM symbols.

[0355] Multiple PRACH opportunities can be allocated only to the latter half of the PRACH slot. If the preamble format has a duration corresponding to four OFDM symbols, the index of the starting OFDM symbol can be 9.

[0356] Furthermore, according to an embodiment of the present invention, the processing chip 22 of the network node 20 can control the transceiver 21 to send information about PRACH resource allocation to the UE, and based on this information, control the transceiver 21 to receive PRACH on one of the multiple PRACH opportunities allocated in the PRACH time slot. Here, the number of PRACH opportunities allocated in the PRACH time slot can be based on the PRACH preamble format and the start OFDM symbol.

[0357] In this case, multiple PRACH opportunities can be consecutively allocated within a PRACH slot, starting from the initial OFDM symbol. Furthermore, the maximum number of PRACH opportunities can be 6. If the preamble format has a duration corresponding to two OFDM symbols, then the number of PRACH opportunities is 6.

[0358] Multiple PRACH opportunities can be allocated only to the latter half of the PRACH slot. If the preamble format has a duration corresponding to four OFDM symbols, the index of the starting OFDM symbol can be 9.

[0359] The embodiments of the present invention described above are combinations of elements and features of the present invention. Unless otherwise stated, elements or features are to be considered optional. Individual elements or features may be practiced without combination with other elements or features. Furthermore, embodiments of the present invention may be constructed by combining portions of elements and / or features. The order of operations described in the embodiments of the present invention may be rearranged. Some structures of any embodiment may be included in another embodiment and may be replaced by corresponding structures of another embodiment. It will be apparent to those skilled in the art that claims not expressly referenced in the appended claims may be presented as combinations of embodiments of the present invention, or may be included as new claims by subsequent amendments after filing the application.

[0360] Specific operations described as being performed by the BS can also be performed by upper-layer nodes of the BS. That is, it is evident that in a network consisting of multiple network nodes, including the BS, various operations performed for communicating with the UE can be performed by the BS or network nodes other than the BS. The term "BS" can be replaced by terms such as "fixed station," "node B," "evolved node B (eNode B or eNB)," and "access point (AP)."

[0361] Embodiments of the present invention can be implemented by various means, such as hardware, firmware, software, or combinations thereof. In a hardware configuration, the method according to an 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.

[0362] In firmware or software configuration, embodiments of the present invention can be implemented in the form of modules, processes, functions, etc. Software code can be stored in memory units and executed by a processor. The memory units are located inside or outside the processor and can send data to and receive data from the processor via various known means.

[0363] Those skilled in the art will understand that the invention can be practiced in other specific ways besides those set forth herein without departing from the spirit and essential characteristics of this disclosure. Therefore, the above embodiments should be interpreted in all respects as illustrative rather than restrictive. The scope of this disclosure should be determined by the appended claims and their legal equivalents, not by the foregoing description, and all changes falling within the meaning and scope of the appended claims are intended to be included herein.

[0364] Industrial applicability

[0365] Although the method and apparatus for transmitting and receiving physical random access channels have been described based on an example applied to the fifth-generation new RAT system, the method and apparatus can also be applied to various wireless communication systems other than the fifth-generation new RAT system.

Claims

1. A method performed by a user equipment (UE), the method comprising the following steps: Receive Physical Random Access Channel (PRACH) configuration information, which includes information related to the preamble format and the initial orthogonal frequency division multiplexing (OFDM) symbol; as well as Based on the PRACH configuration information, PRACH is transmitted in the PRACH time slots that include the PRACH timing. The number of PRACH opportunities in the PRACH slot is determined based on the information related to the preamble format and the start OFDM symbol, and Wherein, the starting OFDM symbol in the PRACH time slot has OFDM symbol index 7, and the number of PRACH times is greater than 1.

2. The method according to claim 1, wherein, The PRACH timing is continuously allocated in the PRACH time slot starting from the initial OFDM symbol.

3. The method according to claim 1, wherein, The maximum number of PRACH opportunities is 6.

4. The method according to claim 3, wherein, The preamble format has a duration of two OFDM symbols, and the number of PRACH timings is 6.

5. The method according to claim 1, wherein, The preamble format has a duration of four OFDM symbols.

6. A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform the method according to claim 1.

7. An apparatus for wireless communication, the apparatus comprising: A memory configured to store instructions; as well as A processor configured to perform operations by executing the instructions, the operations including: Receive Physical Random Access Channel (PRACH) configuration information, which includes information related to the preamble format and the initial Orthogonal Frequency Division Multiplexing (OFDM) symbol; and Based on the PRACH configuration information, PRACH is transmitted in the PRACH time slots that include the PRACH timing. The number of PRACH opportunities in the PRACH slot is determined based on the information related to the preamble format and the start OFDM symbol, and Wherein, the starting OFDM symbol in the PRACH time slot has OFDM symbol index 7, and the number of PRACH times is greater than 1.

8. The apparatus according to claim 7, further comprising: transceiver The device in question is a User Equipment (UE).

9. A method performed by a base station (BS), the method comprising the following steps: Send Physical Random Access Channel (PRACH) configuration information, which includes information related to the preamble format and the initial Orthogonal Frequency Division Multiplexing (OFDM) symbol. as well as Based on the PRACH configuration information, PRACH is received in the PRACH time slot that includes the PRACH timing. The number of PRACH opportunities in the PRACH slot is determined based on the information related to the preamble format and the start OFDM symbol, and Wherein, the starting OFDM symbol in the PRACH time slot has OFDM symbol index 7, and the number of PRACH times is greater than 1.

10. An apparatus for wireless communication, the apparatus comprising: A memory configured to store instructions; as well as A processor configured to perform operations by executing the instructions, the operations including: Transmit Physical Random Access Channel (PRACH) configuration information, which includes information related to the preamble format and the initial Orthogonal Frequency Division Multiplexing (OFDM) symbol; and Based on the PRACH configuration information, PRACH is received in the PRACH time slot that includes the PRACH timing. The number of PRACH opportunities in the PRACH slot is determined based on the information related to the preamble format and the start OFDM symbol, and Wherein, the starting OFDM symbol in the PRACH time slot has OFDM symbol index 7, and the number of PRACH times is greater than 1.

11. The apparatus of claim 10, further comprising: transceiver The device in question is a base station (BS).

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