Method and apparatus for transmitting and receiving a random access channel

Abstract

The present invention provides a method and apparatus for transmitting and receiving a random access channel. The present disclosure provides a method for a user equipment to transmit a random access channel (RACH) in a wireless communication system. Specifically, the method includes: receiving information about an actually transmitted synchronization signal block (SSB) and RACH configuration information about a RACH resource; and transmitting a RACH in at least one RACH resource among the RACH resources mapped to the actually transmitted SSB based on the information about the actually transmitted SSB and the RACH configuration information, wherein, based on the RACH configuration information, within a RACH configuration period, the actually transmitted SSB is repeatedly mapped to the RACH resource multiple times, and the number of repeated mappings is the number of actually transmitted SSBs multiplied by a positive integer.

Description

[0001] This application is a divisional application of the patent application with application number 201880028305.X (PCT / KR2018 / 005119), application date May 3, 2018, and title "Method and apparatus for transmitting and receiving a random access channel", which was filed on October 29, 2019. Technical Field

[0002] The present disclosure relates to a method and apparatus for transmitting and receiving a random access channel, and more particularly, to a method and apparatus for transmitting and receiving a random access channel by mapping a synchronization signal block to a resource for a random access channel and through a resource for a random access channel corresponding to the synchronization signal block. Background Art

[0003] As more and more communication devices require greater communication traffic with the current trend, a next-generation fifth-generation (5G) system is needed to provide enhanced wireless broadband communication compared to traditional LTE systems. In the next-generation 5G system, communication scenarios are divided into enhanced mobile broadband (eMBB), ultra-reliable and low-latency communication (URLLC), massive machine-type communication (mMTC), and the like.

[0004] Here, eMBB is a new-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 power consumption, short packets, and large-scale connection (e.g., Internet of Things (IoT)). Summary of the Invention

[0005] Technical Problem

[0006] An object of the present disclosure is to provide a method and apparatus for transmitting and receiving a random access channel.

[0007] Those skilled in the art will understand that the objects that can be achieved by the present disclosure are not limited to those specifically described above, and the above and other objects that can be achieved by the present disclosure will be clearly understood from the following detailed description.

[0008] Technical Solution

[0009] A method for a UE to transmit a random access channel (RACH) in a wireless communication system according to an embodiment of the present disclosure includes: receiving information on an actually transmitted synchronization signal block (SSB) and RACH configuration information on RACH resources; and transmitting a RACH in at least one of the RACH resources mapped to the actually transmitted SSB based on the information on the actually transmitted SSB and the RACH configuration information, wherein, based on the RACH configuration information, in a RACH configuration period, the actually transmitted SSB is repeatedly mapped to the RACH resources by a positive integer multiple of the number of actually transmitted SSBs.

[0010] Here, the RACH resources remaining after the repeated mapping by a positive integer multiple of the number of actually transmitted SSBs may not be mapped to the actually transmitted SSB.

[0011] In addition, in the RACH resources not mapped to the actually transmitted SSB, an uplink signal other than the RACH may be transmitted, or a downlink signal may be received.

[0012] In addition, when the number of SSBs that each RACH resource can map is less than 1, one SSB may be mapped to as many consecutive RACH resources as the reciprocal of the number of SSBs that each RACH resource can map.

[0013] A UE for transmitting a random access channel (RACH) in a wireless communication system according to the present disclosure includes: a transceiver configured to transmit radio signals to / from a base station; and a processor connected to the transceiver and configured to control the transceiver, wherein the processor controls the transceiver to receive information on an actually transmitted synchronization signal block (SSB) and RACH configuration information on RACH resources, and controls the transceiver to transmit a RACH in at least one of the RACH resources mapped to the actually transmitted SSB based on the information on the actually transmitted SSB and the RACH configuration information, wherein, based on the RACH configuration information, in a RACH configuration period, the actually transmitted SSB is repeatedly mapped to the RACH resources by a positive integer multiple of the number of actually transmitted SSBs.

[0014] Here, the RACH resources remaining after the repeated mapping by a positive integer multiple of the number of actually transmitted SSBs may not be mapped to the actually transmitted SSB.

[0015] In addition, in the RACH resources not mapped to the actually transmitted SSB, an uplink signal other than the RACH may be transmitted, or a downlink signal may be received.

[0016] In addition, when the number of SSBs that each RACH resource can map is less than 1, one SSB can be mapped to as many consecutive RACH resources as the reciprocal of the number of SSBs that each RACH resource can map.

[0017] A method for a base station to receive a random access channel (RACH) in a wireless communication system according to an embodiment of the present disclosure includes: transmitting information about an actually transmitted synchronization signal block (SBB) and RACH configuration information about RACH resources; and performing RACH reception in RACH resources mapped to the actually transmitted SSB based on the information about the actually transmitted SSB and the RACH configuration information, wherein, based on the RACH configuration information, in a RACH configuration period, the actually transmitted SSBs are repeatedly mapped to the RACH resources by a positive integer multiple of the number of actually transmitted SSBs.

[0018] Here, information about the actually transmitted SSB can be obtained based on the RACH resource in which the RACH has been received, and the information about the actually transmitted SSB corresponds to the synchronization that the UE that has transmitted the RACH intends to obtain.

[0019] A base station for receiving a random access channel (RACH) in a wireless communication system according to the present disclosure includes: a transceiver configured to transmit radio signals to / from a UE; and a processor connected to the transceiver and configured to control the transceiver, wherein the processor controls the transceiver to transmit information about an actually transmitted synchronization signal block (SBB) and RACH configuration information about RACH resources, and controls the transceiver to perform RACH reception in RACH resources mapped to the actually transmitted SSB based on the information about the actually transmitted SSB and the RACH configuration information, wherein, based on the RACH configuration information, in a RACH configuration period, the actually transmitted SSBs are repeatedly mapped to the RACH resources by a positive integer multiple of the number of actually transmitted SSBs.

[0020] Beneficial Effects

[0021] According to the present disclosure, resources for a random access channel can be mapped to synchronization signal blocks and other signals can be transmitted / received through resources for the random access channel that are not mapped to synchronization signal blocks to perform an efficient initial access process.

[0022] Those skilled in the art will understand that the effects that can be achieved using the present disclosure are not limited to the effects specifically described above, and other advantages of the present disclosure will be more clearly understood from the following detailed description in conjunction with the accompanying drawings. Description of the Drawings

[0023] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the present disclosure, and together with the specification are used to explain the principles of the present disclosure.

[0024] Figure 1 Illustrates the random access preamble formats in LTE / LTE-A.

[0025] Figure 2 Illustrates the time slot structure available in the new radio access technology (NR).

[0026] Figure 3 Abstractly illustrates the hybrid beamforming structure from the perspective of a transceiver unit (TXRU) and a physical antenna.

[0027] Figure 4 Illustrates a cell of the new radio access technology (NR).

[0028] Figure 5 Illustrates the SS block transmission and the RACH resources linked to the SS block.

[0029] Figure 6 Illustrates the configuration / formats of a random access channel (RACH) preamble and a receiver function.

[0030] Figure 7 Illustrates the receive (Rx) beam formed in a gNB for receiving a RACH preamble.

[0031] Figure 8 Is a diagram for describing the terms related to RACH signals and RACH resources used in the description of the present disclosure.

[0032] Figure 9 Illustrates a RACH resource set.

[0033] Figure 10 Is a diagram for describing the RACH resource boundary alignment regarding the present disclosure.

[0034] Figure 11 Illustrates the method of configuring a mini slot in the time slot SLOT for RACH when BC is valid RACH among them.

[0035] Figure 12 Illustrates the method of configuring a mini slot in the time slot SLOT for RACH when BC is valid RACH among them.

[0036] Figure 13 Illustrates the method of configuring a mini slot in the time slot SLOT for RACH when BC is invalid RACH among them.

[0037] Figure 14 The figure shows a method of configuring micro - slots using a protection time.

[0038] Figure 15 The figure shows an example of cascading micro - slots into the same length as a normal slot with a valid BC to transmit data.

[0039] Figures 16 to 28 The figure shows embodiments of a method for configuring RACH resources and a method for allocating RACH resources.

[0040] Figure 29 It is a block diagram showing the components of transmitter 10 and receiver 20 that implement the present disclosure. Detailed Description

[0041] Now, reference will be made in detail to the exemplary embodiments of the present invention, which are illustrated in the accompanying drawings. The following detailed description with reference to the accompanying drawings is intended to explain the exemplary embodiments of the present invention, and not to show the only embodiments that can be implemented according to the present invention. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced without these specific details.

[0042] In some cases, known structures and devices are omitted or shown in block diagram form, focusing on the important features of the structures and devices so as not to obscure the concepts of the present invention. The same reference numerals will be used throughout the specification to represent the same or similar parts.

[0043] The following techniques, apparatuses, and systems can be applied to various wireless multi-access systems. Examples of multi-access systems include Code Division Multiple Access (CDMA) systems, Frequency Division Multiple Access (FDMA) systems, Time Division Multiple Access (TDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, and Multi-Carrier Frequency Division Multiple Access (MC-FDMA) systems. CDMA can be implemented via radio technologies such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can be implemented via radio technologies such as Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), or Enhanced Data rates for GSM Evolution (EDGE). OFDMA can be implemented via radio technologies such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is part of the evolved UMTS (E-UMTS) that uses E-UTRA. 3GPP LTE uses OFDMA in the DL and SC-FDMA in the UL. Long Term Evolution-Advanced (LTE-A) is an evolved version of 3GPP LTE. For ease of description, it is assumed that the present invention is applied to a 3GPP-based communication system such as LTE / LTE-A, NR. However, the technical features of the present invention are not limited thereto. For example, although the following detailed description is given based on a mobile communication system corresponding to the 3GPP LTE / LTE-A / NR system, aspects of the present invention that are not specific to 3GPP LTE / LTE-A / NR can be applied to other mobile communication systems.

[0044] For example, the present invention can be applied to contention-based communications such as Wi-Fi and non-contention-based communications such as in 3GPP LTE / LTE-A systems, where the eNB allocates DL / UL time / frequency resources to the UE and the UE receives DL signals and transmits UL signals according to the resource allocation of the eNB. In a non-contention-based communication scheme, an access point (AP) or a control node for controlling the AP allocates resources for communication between the UE and the AP, while in a contention-based communication scheme, communication resources are occupied through contention among UEs that wish to access the AP. A contention-based communication scheme will now be briefly described. One type of contention-based communication scheme is Carrier Sense Multiple Access (CSMA). CSMA refers to a probabilistic media access control (MAC) protocol that is used to confirm the absence of other traffic on the same shared transmission medium (also referred to as a shared channel) such as a frequency band before a node or communication device transmits traffic. In CSMA, the transmitting device determines whether another transmission is being performed before attempting to send traffic to the receiving device. In other words, the transmitting device attempts to detect the presence of a carrier from another transmitting device before attempting to perform a transmission. After detecting the carrier, the transmitting device waits for another transmitting device that is performing a transmission to complete the transmission before performing its own transmission. Therefore, CSMA can act as a communication scheme based on the principle of "sense before transmit" or "listen before talk". Schemes for avoiding conflicts between transmitting devices in a contention-based communication system using CSMA include Carrier Sense Multiple Access with Collision Detection (CSMA / CD) and / or Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). CSMA / CD is a collision detection scheme in a wired local area network (LAN) environment. In CSMA / CD, a personal computer (PC) or server that wishes to perform communication in an Ethernet environment first confirms whether communication is occurring on the network, and if another device is transmitting data on the network, the PC or server waits and then transmits data. That is, when two or more users (e.g., PCs, UEs, etc.) transmit data simultaneously, a conflict occurs between the simultaneous transmissions, and CSMA / CD is a scheme for flexibly transmitting data by monitoring for conflicts. The transmitting device using CSMA / CD adjusts its data transmission by listening to data transmissions performed by another device using specific rules. CSMA / CA is a MAC protocol specified in the IEEE 802.11 standard. A wireless local area network (WLAN) system compliant with the IEEE 802.11 standard does not use CSMA / CD that has already been used in the IEEE 802.3 standard but uses CA, i.e., a collision avoidance scheme.The transmission device always listens to the carrier of the network, and if the network is empty, the transmission device waits for a determined time according to its position registered in the list and then sends data. Various methods are used to determine the priority of the transmission devices in the list and reconfigure the priority. In a system according to certain versions of the IEEE 802.11 standard, collisions may occur, and in such a case, a collision listening process is performed. The sending device using CSMA / CA uses specific rules to avoid collisions between its data transmission and the data transmission of another transmission device.

[0045] In the embodiments of the present invention described below, the term "assume" may mean that the subject of the sending channel sends the channel according to the corresponding "assumption". This may also mean that, in the case where it is assumed that the channel has been sent according to the "assumption", the subject of the receiving channel receives or decodes the channel in a form conforming to the "assumption".

[0046] In the present invention, puncturing a channel on a specific resource means mapping the signal of the channel to a specific resource during the resource mapping process of the channel, but a part of the signal mapped to the punctured resource is excluded in the sending channel. In other words, the specific resource punctured during the resource mapping process of the channel is not counted as a resource for the channel, and actually the signal mapped to the specific resource among the signals of the channel that are not sent. Assuming that the signal mapped to the specific resource is not sent, the receiver of the channel receives, demodulates, or decodes the channel. On the other hand, rate matching of the channel on a specific resource means that the channel is never mapped to a specific resource during the resource mapping process of the channel, and thus the specific resource is not used for the transmission of the channel. In other words, the resource with rate matching during the resource mapping process of the channel is not counted as a resource for the channel. Assuming that the specific rate-matching resource is not used for the mapping and transmission of the channel, the receiver of the channel receives, demodulates, or decodes the channel.

[0047] In the present invention, a user equipment (UE) can be a fixed or mobile device. Examples of the UE include various devices that send and receive user data and / or various types of control information to and from a base station (BS). The UE can be referred to as a terminal equipment (TE), a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, a personal digital assistant (PDA), a wireless modem, a handheld device, etc. Additionally, in the present invention, the BS generally refers to a fixed station that performs communication with the UE and / or another BS and exchanges various data and control information with the UE and another BS. The BS can be referred to as an advanced base station (ABS), a node B (NB), an evolved node B (eNB), a base transceiver system (BTS), an access point (AP), a processing server (PS), etc. Specifically, the BS of the UTRAN is called a Node-B, the BS of the E-UTRAN is called an eNB, and the BS of the new radio access technology network is called a gNB. When describing the present invention, the BS will be referred to as a gNB.

[0048] In the present invention, a node refers to a fixed point that can send / receive radio signals through communication with the UE. Regardless of its terminology, various types of gNBs can be used as nodes. For example, a BS, a Node B (NB), an eNode B (eNB), a pico cell eNB (PeNB), a home eNB (HeNB), a gNB, a relay, a repeater, etc. can be nodes. Additionally, the node can not be a gNB. For example, the node can be a radio remote head (RRH) or a radio remote unit (RRU). The RRH or RRU generally has a lower power level than that of the gNB. Since the RRH or RRU (hereinafter referred to as RRH / RRU) is generally connected to the gNB through a dedicated line such as an optical cable, the cooperative communication between the RRH / RRU and the gNB can be smoothly performed compared to the cooperative communication between the gNBs connected through radio lines. At least one antenna is installed per node. The antenna can mean a physical antenna or an antenna port or a virtual antenna.

[0049] In the present invention, a cell refers to a defined geographical area to which one or more nodes provide communication services. Thus, in the present invention, communicating with a specific cell may mean communicating with a gNB or node that provides communication services to the specific cell. Additionally, the DL / UL signals of a specific cell refer to the DL / UL signals from / to the gNB or node that provides communication services to the specific cell. A node that provides UL / DL communication services to a UE is called a serving node, and the cell to which the serving node provides UL / DL communication services is specifically called a serving cell. Furthermore, the channel state / quality of a specific cell refers to the channel state / quality of the channel or communication link formed between the gNB or node that provides communication services to the specific cell and the UE. In a 3GPP-based communication system, a UE can use the cell CRS transmitted on a specific reference signal (CRS) resource assigned to a specific node through the antenna port of the specific node and / or the CSI-RS transmitted on a channel state information reference signal (CSI-RS) resource to measure the DL channel state received from the specific node.

[0050] Meanwhile, a 3GPP-based communication system uses the concept of a cell to manage radio resources, and the cell associated with radio resources is distinguished from the cell of the geographical area.

[0051] The "cell" of the geographical area can be understood as the coverage area where a node can provide services using a carrier, and the "cell" of radio resources is associated with the bandwidth (BW) that is the frequency range configured by the carrier. Since the DL coverage area, which is the range where a node can transmit an effective signal, and the UL coverage area, which is the range where a node can receive an effective signal from a UE, depend on the carrier carrying the signal, the coverage area of the node can be associated with the coverage area of the "cell" of the radio resources used by the node. Therefore, sometimes the term "cell" can be used to indicate the service coverage area of a node, the radio resources at other times, or the range where signals using the radio resources can reach with an effective intensity at other times.

[0052] Meanwhile, the communication standards of 3GPP use the concept of a cell to manage radio resources. A "cell" associated with radio resources is defined by a combination of downlink resources and uplink resources, that is, a combination of DL CC and UL CC. A cell can be configured by only downlink resources or can be configured by both downlink resources and uplink resources. If carrier aggregation is supported, the link between the carrier frequency (or DL CC) of the downlink resources and the carrier frequency (or UL CC) of the uplink resources can be indicated by system information. For example, the combination of DL resources and UL resources can be indicated by a link in System Information Block Type 2 (SIB2). Carrier frequency means the center frequency of each cell or CC. A cell operating on the primary frequency can be called the primary cell (Pcell) or PCC, and a cell operating on the secondary frequency can be called the secondary cell (Scell) or SCC. The carrier corresponding to the Pcell on the downlink will be called the downlink primary CC (DL PCC), and the carrier corresponding to the Pcell on the uplink will be called the uplink primary CC (UL PCC). Scell means a cell that can be configured after radio resource control (RRC) connection establishment and is used to provide additional radio resources. Scell can form a set of serving cells for the UE together with the Pcell according to the UE's capabilities. The carrier corresponding to the Scell on the downlink will be called the downlink secondary CC (DL SCC), and the carrier corresponding to the Scell on the uplink will be called the uplink secondary CC (UL SCC). While the UE is in the RRC-CONNECTED state, if the UE is not configured by carrier aggregation or does not support carrier aggregation, there is only a single serving cell configured by the Pcell.

[0053] The 3GPP-based communication standard defines a DL physical channel corresponding to a resource element carrying information derived from a higher layer and a DL physical signal corresponding to a resource element used by the physical layer but not carrying information derived from a higher layer. 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, and reference signals and synchronization signals are defined as DL physical signals. A reference signal (RS), also known as a pilot, refers to a special waveform of a predefined signal that is known to both the BS and the UE. For example, a cell-specific RS (CRS), UE-specific RS (UE-RS), positioning RS (PRS), and Channel State Information RS (CSI-RS) can be defined as DL RSs. Meanwhile, the 3GPP LTE / LTE-A standard defines a UL physical channel corresponding to a resource element carrying information derived from a higher layer and a UL physical signal corresponding to a resource element used by the physical layer but not carrying information derived from a higher layer. 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, and a Demodulation Reference Signal (DMRS) for UL control / data signal demodulation and a Sounding Reference Signal (SRS) for UL channel measurement are defined as UL physical signals.

[0054] In the present invention, the Physical Downlink Control Channel (PDCCH), Physical Control Format Indicator Channel (PCFICH), Physical Hybrid Automatic Repeat reQuest Indicator Channel (PHICH), and Physical Downlink Shared Channel (PDSCH) respectively refer to a set of time-frequency resources or resource elements (REs) carrying downlink control information (DCI), a set of time-frequency resources or REs carrying a control format indicator (CFI), a set of time-frequency resources or REs carrying downlink positive acknowledgment (ACK) / negative ACK (NACK), and a set of time-frequency resources or REs carrying downlink data. Additionally, the Physical Uplink Control Channel (PUCCH), Physical Uplink Shared Channel (PUSCH), and Physical Random Access Channel (PRACH) respectively refer to a set of time-frequency resources or REs carrying uplink control information (UCI), a set of time-frequency resources or REs carrying uplink data, and a set of time-frequency resources or REs carrying a random access signal. In the present invention, specifically, the time-frequency resources or REs allocated to or belonging to PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH / PRACH are respectively referred to as PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH / PRACH REs or PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH / PRACH time-frequency resources. Therefore, in the present invention, the PUCCH / PUSCH / PRACH transmissions of the UE are conceptually the same as the UCI / uplink data / random access signal transmissions on the PUSCH / PUCCH / PRACH respectively. Additionally, the PDCCH / PCFICH / PHICH / PDSCH transmissions of the gNB are conceptually the same as the downlink data / DCI transmissions on the PDCCH / PCFICH / PHICH / PDSCH respectively.

[0055] Hereinafter, the OFDM symbol / subcarrier / RE to which or for which CRS / DMRS / CSI-RS / SRS / UE-RS / TRS is assigned or configured will be referred to as CRS / DMRS / CSI-RS / SRS / UE-RS / TRS symbol / carrier / subcarrier / RE. For example, the OFDM symbol to which or for which Tracking RS (TRS) is assigned or configured is called a TRS symbol, the subcarrier to which or for which TRS is assigned or configured is called a TRS subcarrier, and the RE to which or for which TRS is assigned or configured is called a TRS RE. Additionally, the subframe configured for TRS transmission is called a TRS subframe. Furthermore, the subframe in which a broadcast signal is transmitted is called a broadcast subframe or a PBCH subframe, and the subframe in which a synchronization signal (e.g., PSS and / or SSS) is transmitted is called a synchronization signal subframe or a PSS / SSS subframe. The OFDM symbol / subcarrier / RE to which or for which PSS / SSS is assigned or configured is called a PSS / SSS symbol / subcarrier / RE, respectively.

[0056] In the present invention, a CRS port, a UE-RS port, a CSI-RS port, and a TRS port refer to an antenna port configured to transmit CRS, an antenna port configured to transmit UE-RS, an antenna port configured to transmit CSI-RS, and an antenna port configured to transmit TRS, respectively. The antenna ports configured to transmit CRS can be distinguished from each other according to the CRS port by the positions of the REs occupied by CRS, the antenna ports configured to transmit UE-RS can be distinguished from each other according to the UE-RS port by the positions of the REs occupied by UE-RS, and the antenna ports configured to transmit CSI-RS can be distinguished from each other according to the CSI-RS port by the positions of the REs occupied by CSI-RS. Thus, the terms CRS / UE-RS / CSI-RS / TRS port can also be used to indicate the pattern of the REs occupied by CRS / UE-RS / CSI-RS / TRS in a predetermined resource region. In the present invention, DMRS and UE-RS refer to RSs for demodulation, and thus, the terms DMRS and UE-RS are used to refer to RSs for demodulation.

[0057] For terms and technologies not described in detail in the present invention, reference may be made to the standard documents of 3GPP LTE / LTE-A, such as 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213, 3GPP TS 36.321, and 3GPP TS 36.331, as well as the standard documents of 3GPP NR, such as 3GPP TS 38.211, 3GPP TS 38.212, 3GPP 38.213, 3GPP 38.214, 3GPP 38.215, 3GPP TS 38.321, and 3GPP TS 36.331.

[0058] In the LTE / LTE-A system, when the UE is powered on or wishes to access a new cell, the UE performs an initial cell search process, which includes obtaining time and frequency synchronization with the cell and detecting the physical layer cell identity N. cell ID To this end, the UE can receive synchronization signals from the eNB, such as the primary synchronization signal (PSS) and the secondary synchronization signal (SSS), so as to establish synchronization with the eNB and obtain information such as the cell identity (ID). After the initial cell search process, the UE can perform a random access process to complete the access to the eNB. To this end, the UE can send a preamble through the physical random access channel (PRACH) and receive a response message to the preamble through the PDCCH and PDSCH. As a normal UL / DL transmission process, after performing the above processes, the UE can perform PDCCH / PDSCH reception and PUSCH / PUCCH transmission. The random access process is also referred to as the random access channel (RACH) process. The random access process is used for various purposes, including initial access, adjustment of UL synchronization, resource allocation, and handover.

[0059] After transmitting a RACH preamble, the UE attempts to receive a random access response (RAR) within a preset time window. Specifically, the UE attempts to detect a PDCCH with a random access radio network temporary identifier (RA-RNTI) (hereinafter, RA-RNTI PDCCH) in the time window (e.g., masking the CRC on the PDCCH with the RA-RNTI). When detecting the RA-RNTI PDCCH, the UE checks whether there is a RAR pointing to it in the PDSCH corresponding to the RA-RNTI PDCCH. The RAR includes timing advance (TA) information indicating timing offset information for UL synchronization, UL resource allocation information (UL grant information), and a temporary UE identifier (e.g., temporary cell-RNTI (TC-RNTI)). The UE can perform (e.g., Msg3) UL transmission according to the resource allocation information and TA value in the RAR. HARQ is applied to the UL transmission corresponding to the RAR. Therefore, after transmitting Msg3, the UE can receive response information (e.g., PHICH) corresponding to Msg3.

[0060] Figure 1 FIG. illustrates the random access preamble format in a conventional LTE / LTE-A system.

[0061] In a conventional LTE / LTE-A system, a random access preamble, i.e., a RACH preamble, includes a cyclic prefix with length T in the physical layer and a sequence part with length T CP and has a length of T SEQ The parameter values T CP and T SEQ are listed in the following table and depend on the frame structure and random access configuration. The higher layer controls the preamble format. In the 3GPP LTE / LTE-A system, the PRACH configuration information is signaled through the system information and mobility control information of the cell. The PRACH configuration information indicates the root sequence index to be used for the RACH procedure in the cell, the cyclic shift unit N CS of the Zadoff-Chu sequence, the length of the root sequence, and the preamble format. In the 3GPP LTE / LTE-A system, the PRACH occasion, which can be the timing for transmitting the preamble format and the RACH preamble, is indicated by a PRACH configuration index, which is part of the RACH configuration information (refer to Section 5.7 of 3GPP TS 36.211 and "PRACH-Config" in 3GPP TS 36.331). The length of the Zadoff-Chu sequence for the RACH preamble is determined according to the preamble format (refer to Table 4).

[0062] Table 1

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

[0064] In the LTE / LTE-A system, RACH preambles are transmitted in UL subframes. The transmission of random access preambles is restricted to certain time and frequency resources. These resources are referred to as PRACH resources and are enumerated in ascending order of subframe numbers within a radio frame and PRBs in the frequency domain, such that index 0 corresponds to the lowest numbered PRB and subframe within a radio frame. The random access resources are defined according to the PRACH configuration index (refer to the standard document of 3GPP TS 36.211). The PRACH configuration index is given by a higher layer signal (sent by the eNB).

[0065] The sequence part of the RACH preamble (hereinafter, the preamble sequence) uses Zadoff-Chu sequences. The preamble sequences for RACH are generated from Zadoff-Chu sequences with zero correlation zones, from one or more root Zadoff-Chu sequences. The network configures the set of preamble sequences that the UE is allowed to use. In a traditional LTE / LTE-A system, 64 preambles are available in each cell. The set of 64 preamble sequences in a cell is found by first including all available cyclic shifts of the root Zadoff-Chu sequence with the logical index RACH_ROOT_SEQUENCE in ascending order of cyclic shift, where RACH_ROOT_SEQUENCE is broadcast as part of the system information. In cases where 64 preambles cannot be generated from a single root Zadoff-Chu sequence, 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 index 0 continues to 837. For preamble formats 0 to 3 and 4, the relationship between the logical root sequence index and the physical root sequence index u is given by Tables 2 and 3 respectively.

[0066] Table 2

[0067]

[0068]

[0069]

[0070] Table 3

[0071]

[0072] The u-th root Zadoff-Chu sequence is defined by the following formula.

[0073] Formula 1

[0074]

[0075] Table 4

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

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

[0078] Formula 2

[0079]

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

[0081] Table 5

[0082]

[0083] Table 6

[0084]

[0085]

[0086] The parameter zeroCorrelationZoneConfig is provided by the higher layer. The parameter High-speed-flag provided by the higher layer determines whether an unrestricted set or a restricted set should be used.

[0087] The variable d u is the cyclic shift corresponding to the Doppler shift with amplitude 1 / T SEQ , and is given by the following formula.

[0088] Formula 3

[0089]

[0090] p is the smallest non-negative integer that satisfies (pu) mod N ZC = 1. The parameters for the restricted set used for cyclic shift depend on d u . For N ZC ≤ d u < N ZC / 3, the parameters are given by the following formula.

[0091] Formula 4

[0092]

[0093]

[0094]

[0095]

[0096] For N ZC / 3 ≤ d u < (N ZC - N CS ) / 2, the parameter is given by the following formula.

[0097] Formula 5

[0098]

[0099]

[0100]

[0101]

[0102] For all other values of d u there is no cyclic shift in the constellation.

[0103] The time - continuous random access signal s(t) as the baseband signal of RACH is defined by the following formula.

[0104] Formula 6

[0105]

[0106] where 0 ≤ t < T SEQ - T CP when, β PRACH is the amplitude scaling factor to meet the transmit power specified in 3GPP TS36.211, and k 0 = n RA PRB N RB sc - N UL RB N RB sc / 2. N RB sc represents the number of sub - carriers that make up a resource block (RB). N UL RB represents the number of RBs in the UL time slot and depends on the UL transmission bandwidth. The position in the frequency domain is controlled by the parameter n RA PRB which parameter n RA PRBDerived from Section 5.7.1 of 3GPP TS 36.211. The factor K = △f / △f RA The difference in subcarrier spacing between the random access preamble and the uplink data transmission is considered. The variables △f are all given in the following table RA (subcarrier spacing for the random access preamble) and the variable (fixed offset that determines the frequency domain position of the random access preamble within the physical resource block).

[0107] Table 7

[0108]

[0109] In the LTE / LTE-A system, the subcarrier spacing △f is 15 kHz or 7.5 kHz. However, as shown in Table 7, the subcarrier spacing △f for the random access preamble RA is 1.25 kHz or 0.75 kHz.

[0110] As more and more communication devices require higher communication capacity, there is a need for enhanced mobile broadband relative to traditional radio access technologies (RATs). Additionally, massive machine type communication that provides various services anytime and anywhere by connecting multiple devices and objects to each other is a major issue to be considered in next-generation communication. Furthermore, the design of communication systems considering services / UEs that are sensitive to reliability and latency is being discussed. The introduction of next-generation RATs has been discussed by considering enhanced mobile broadband communication, massive MTC, ultra-reliable and low-latency communication (URLLC), etc. In the current 3GPP, research on the next-generation mobile communication system after the EPC is underway. In the present invention, for convenience, the corresponding technology is referred to as new RAT (NR) or 5G RAT.

[0111] The NR communication system is required to support much better performance than the traditional fourth-generation (4G) system in terms of data rate, capacity, latency, energy consumption, and cost. Therefore, the NR system needs to make progress in terms of bandwidth, spectrum, energy, signaling efficiency, and cost per bit.

[0112] <OFDM parameter set>

[0113] The new RAT system uses an OFDM transmission scheme or a similar transmission scheme. The new RAT system can follow OFDM parameters different from those of the LTE system. Alternatively, the new RAT system can conform to the parameter sets of the traditional LTE / LTE-A system, but can have a system bandwidth wider than that of the traditional LTE / LTE-A system (e.g., 100 MHz). A cell can support multiple parameter sets. That is, UEs operating with different parameter sets can coexist within a cell.

[0114] <Subframe Structure>

[0115] In the 3GPP LTE / LTE-A system, the duration of a radio frame is 10 ms (307,200 T s ). The radio frame is divided into 10 subframes of the same size. Subframe numbers can be assigned to the 10 subframes within a radio frame respectively. Here, T s represents the sampling time, where T s = 1 / (2048 * 15 kHz). The basic time unit of LTE is T s . Each subframe is 1 ms long and is further divided into two time slots. In a radio frame, 20 time slots are numbered sequentially from 0 to 19. The duration of each time slot is 0.5 ms. The time interval for transmitting a subframe is defined as the transmission time interval (TTI). Time resources can be distinguished by the radio frame number (or radio frame index), subframe number (or subframe index), time slot number (or time slot index), etc. TTI refers to the interval during which data can be scheduled. For example, in the current LTE / LTE-A system, a UL grant or DL grant transmission opportunity occurs every 1 ms, and there is no transmission opportunity for multiple UL / DL grants within a time shorter than 1 ms. Therefore, the TTI in the traditional LTE / LTE-A system is 1 ms.

[0116] Figure 2 The figure shows the time slot structure available in the new radio access technology (NR).

[0117] To minimize data transmission latency, in the 5G new RAT, a time slot structure is considered in which the control channel and the data channel are time-division multiplexed.

[0118] In Figure 2 , the shaded area represents the transmission area of the DL control channel (e.g., PDCCH) carrying DCI, and the black area represents the transmission area of the UL control channel (e.g., PUCCH) carrying UCI. Here, DCI is the control information sent by the gNB to the UE. DCI can include information about cell configuration that the UE should know, such as DL-specific information for DL scheduling, and UL-specific information such as UL grants. UCI is the control information sent by the UE to the gNB. UCI can include HARQ ACK / NACK reports for DL data, CSI reports for DL channel status, and scheduling requests (SR).

[0119] In Figure 2 , the symbol regions from symbol index 1 to symbol index 12 can be used to transmit the physical channel (e.g., PDSCH) carrying downlink data, or can be used to transmit the physical channel (e.g., PUSCH) carrying uplink data. According toFigure 2 The time slot structure can sequentially perform DL transmission and UL transmission in one time slot. Therefore, it is possible to perform the transmission / reception of DL data and the reception / transmission of UL ACK / NACK for DL data in one time slot. As a result, the time taken to retransmit data when a data transmission error occurs can be reduced, thereby minimizing the latency of the final data transmission.

[0120] In this time slot structure, a time gap is required for the process of switching from the transmission mode to the reception mode or from the reception mode to the transmission mode of the gNB and the UE. For the process of switching between the transmission mode and the reception mode, some OFDM symbols when switching from DL to UL in the time slot structure are set as a guard period (GP).

[0121] In the traditional LTE / LTE-A system, the DL control channel is time-division multiplexed with the data channel, and the PDCCH, which is a control channel, is transmitted across the entire system bandwidth. However, in the new RAT, it is expected that the bandwidth of a system reaches approximately at least 100 MHz, and it is difficult to allocate the control channel across the entire bandwidth for the transmission of the control channel. For the data transmission / reception of the UE, if the entire bandwidth is monitored to receive the DL control channel, this may result in increased battery consumption and reduced efficiency of the UE. Therefore, in the present invention, the DL control channel can be centrally transmitted or distributedly transmitted in a partial bandwidth within the system bandwidth (i.e., the channel bandwidth).

[0122] In the NR system, the basic transmission unit is a time slot. The time slot duration can be composed of 14 symbols with a normal cyclic prefix (CP) or 12 symbols with an extended CP. The time slot is scaled in time according to the subcarrier spacing used. That is, if the subcarrier spacing increases, the length of the time slot shortens. For example, when the number of symbols per time slot is 14, the number of time slots in a 10-ms frame is 10 at a subcarrier spacing of 15 kHz, 20 at a subcarrier spacing of 30 kHz, and 40 at a subcarrier spacing of 60 kHz. If the subcarrier spacing increases, the length of the OFDM symbol shortens. The number of OFDM symbols in a time slot depends on whether the OFDM symbol has a normal CP or an extended CP and does not change according to the subcarrier spacing. Considering the basic subcarrier spacing of 15 kHz and the maximum TFT size of 2048 in the LTE system, the basic time unit T used in the LTE system s is defined as T s= 1 / (15000 * 2048) seconds and corresponds to the sampling time for a subcarrier spacing of 15 kHz. In the NR system, various subcarrier lengths can be used in addition to the 15 kHz subcarrier spacing. Since the subcarrier spacing and the corresponding time length are inversely proportional, the actual sampling time corresponding to a subcarrier spacing greater than 15 kHz is shorter than T s = 1 / (15000 * 2048) seconds. For example, the actual sampling times for subcarrier spacings of 30 kHz, 60 kHz, and 120 kHz will be 1 / (2 * 15000 * 2048) seconds, 1 / (4 * 15000 * 2048) seconds, and 1 / (8 * 15000 * 2048) seconds, respectively.

[0123] <Analog Beamforming>

[0124] The recently discussed fifth-generation (5G) mobile communication system is considering using the super high-frequency band, i.e., the millimeter frequency band equal to or higher than 6 GHz, to send data to multiple users in a wide frequency band while maintaining a high transmission rate. In 3GPP, this system is used as NR, and in the present invention, this system will be referred to as the NR system. Since the millimeter frequency band uses a too-high frequency band, its frequency characteristics exhibit very strong signal attenuation according to the distance. Therefore, in order to correct the strong propagation attenuation characteristics, the NR system using a frequency band of at least 6 GHz or higher uses a narrow beam transmission scheme to solve the problem of reduced coverage caused by strong propagation attenuation by sending signals in a specific direction rather than in all directions to focus the energy. However, if only one narrow beam is used to provide signal transmission services, since the range served by one BS becomes narrow, the BS provides broadband services by aggregating multiple narrow beams.

[0125] In the millimeter frequency band (i.e., the millimeter wave (mmW) band), the wavelength is shortened, so multiple antenna elements can be installed in the same area. For example, a total of 100 antenna elements can be installed in a 5 cm × 5 cm panel in a two-dimensional array at an interval of 0.5λ (wavelength) in a 30 GHz band with a wavelength of about 1 cm. Therefore, in mmW, by considering using multiple antenna elements to increase the beamforming (BF) gain, the coverage or throughput can be increased.

[0126] As a method for forming a narrow beam in the millimeter band, beamforming schemes are mainly considered, in which the BS or UE transmits the same signal with an appropriate phase difference through a large number of antennas, so that the energy increases only in a specific direction. Such beamforming schemes include digital beamforming for imparting a phase difference to a digital baseband signal, analog beamforming for imparting a phase difference to a modulated analog signal using a time delay (i.e., cyclic shift), and hybrid beamforming using both digital beamforming and analog beamforming. If a transceiver unit (TXRU) is provided for each antenna element so that the transmission power and phase can be adjusted, independent beamforming can be performed for each frequency resource. However, it is not very feasible in terms of cost to install TXRUs in all approximately 100 antenna elements. That is, the millimeter band requires the use of a large number of antennas to correct the strong propagation attenuation characteristics. Digital beamforming requires as many radio frequency (RF) components (e.g., digital-to-analog converters (DACs), mixers, power amplifiers, linear amplifiers, etc.) as the number of antennas. Therefore, if digital beamforming is desired in the millimeter band, the cost of the communication device increases. Therefore, when a large number of antennas are required in the millimeter band, analog beamforming or hybrid beamforming is considered. In the analog beamforming method, multiple antenna elements are mapped to one TXRU, and an analog phase shifter is used to adjust the beam direction. This analog beamforming method can form only one beam direction in the entire frequency band, and thus may not be able to perform frequency-selective beamforming (BF), which is disadvantageous. The hybrid BF method is an intermediate type between digital BF and analog BF, and uses B TXRUs with fewer than Q antenna elements in number. In the case of hybrid BF, the number of directions in which the beam can be transmitted simultaneously is limited to B or less, depending on the set method of the B TXRUs and the Q antenna elements.

[0127] As described above, digital BF can transmit or receive signals in multiple directions simultaneously using multiple beams by processing the digital baseband signal to be transmitted or received, while analog BF cannot transmit or receive signals in multiple directions simultaneously beyond the coverage range of one beam by performing BF in the state where the analog signal to be transmitted or received is modulated. Generally, the BS uses broadband transmission or multi-antenna characteristics to communicate with multiple users simultaneously. If the BS uses analog or hybrid BF and forms an analog beam in one beam direction, due to the analog BF characteristics, the eNB communicates only with the users included in the same analog beam direction. Considering the limitations caused by the analog BF or hybrid BF characteristics, a method for allocating RACH resources and a method for using resources of a BS according to the present invention are proposed, which will be described later.

[0128] <Hybrid analog beamforming>

[0129] Figure 3The TXRU and hybrid BF structures are abstractly illustrated in terms of physical antennas.

[0130] When multiple antennas are used, a hybrid BF method is considered in which digital BF and analog BF are combined. Analog BF (or RFBF) refers to an operation in which the RF unit performs precoding (or combining). In hybrid BF, each of the baseband unit and the RF unit (also referred to as a transceiver) performs precoding (or combining), so that performance close to that of digital BF can be obtained while reducing the number of RF chains and the number of digital-to-analog (D / A) (or analog-to-digital (A / D)) converters. For convenience, the hybrid BF structure can be represented as N TXRUs and M physical antennas. The digital BF for L data layers to be sent by the transmitter can be represented as an N×L matrix. Next, the N converted digital signals are converted into analog signals by the TXRU, and the analog BF represented as an M×N matrix is ​​applied to the analog signals. In Figure 3 In the NR system, the number of digital beams is L and the number of analog beams is N. In the NR system, the BS is designed to change the analog BF in units of symbols, and efficient BF support for UEs located in a specific area is considered. If N TXRUs and M RF antennas are defined as one antenna panel, the NR system even considers introducing a method that can be applied to multiple antenna panels for independent hybrid BF. In this way, when the BS uses multiple analog beams, since which analog beam is beneficial to signal reception may be different for each UE, a beam scanning operation is considered so that at least for synchronization signals, system information, and paging, all UEs can have a reception opportunity by changing the multiple analog beams to be applied by the BS according to the symbols in a specific time slot or subframe.

[0131] Recently, the 3GPP standardization organization is considering network slicing to implement multiple logical networks in a single physical network in a new RAT system (ie, an NR system, which is a 5G wireless communication system). The logical network should be able to support various services with various requirements (e.g., eMBB, mMTC, URLLC, etc.). The physical layer system of the NR system considers a method of supporting an orthogonal frequency division multiplexing (OFDM) scheme using a variable parameter set according to various services. In other words, the NR system can consider an OFDM scheme (or multiple access scheme) using independent parameter sets in each time and frequency resource area.

[0132] Recently, with the emergence of smart phone devices, data services have increased significantly, and the NR system needs to support higher communication capacity (e.g., data throughput). One method considered for increasing communication capacity is to transmit data using multiple transmit (or receive) antennas. If digital BF is to be applied to multiple antennas, each antenna requires an RF chain (e.g., a chain composed of RF components such as power amplifiers and downconverters) and a D / A or A / D converter. This structure increases hardware complexity and consumes high power, which may be impractical. Therefore, when using multiple antennas, the NR system considers the above-mentioned hybrid BF method that combines digital BF and analog BF.

[0133] Figure 4 The figure shows a cell of a New Radio (NR) access technology system.

[0134] Reference Figure 4 , in the NR system, a method in which multiple transmit and receive points (TRPs) form a cell is being discussed, which is different from the traditional LTE wireless communication system in which one base station (BS) forms a cell. If multiple TRPs form a cell, seamless communication can be provided even when the TRP serving the UE changes, which is beneficial for UE mobility management.

[0135] In the LTE / LTE-A system, PSS / SSS are transmitted omnidirectionally. At the same time, consider such a method in which a gNB using millimeter wave (mmWave) transmits signals such as PSS / SSS / PBCH through BF while scanning the beam direction in all directions. The transmission / reception of signals during the scanning of the beam direction is called beam sweeping or beamscanning. In the present invention, "beam sweeping" represents the behavior of a transmitter, and "beam scanning" represents the behavior of a receiver. For example, assume that a gNB can have at most N beam directions, and the gNB transmits signals such as PSS / SSS / PBCH in each of the N beam directions. That is, the gNB transmits synchronization signals such as PSS / SSS / PBCH in each direction when scanning the directions that the gNB can have or the directions that the gNB expects to support. Alternatively, when the gNB can form N beams, a beam group can be configured by grouping a small number of beams, and PSS / SSS / PBCH can be transmitted / received for each beam group. In this case, a beam group includes one or more beams. Signals such as PSS / SSS / PBCH transmitted in the same direction can be defined as a synchronization (SS) block, and multiple SS blocks can exist in a cell. When there are multiple SS blocks, the SS block index can be used to distinguish between SS blocks. For example, if PSS / SSS / PBCH are transmitted in 10 beam directions in a system, the PSS / SSS / PBCH transmitted in the same direction can constitute an SS block, and it can be understood that there are 10 SS blocks in the system. In the present invention, the beam index can be interpreted as the SS block index.

[0136] Figure 5 Illustrate the transmission of an SS block and the RACH resources linked to the SS block.

[0137] In order to communicate with a UE, the gNB should obtain the optimal beam direction between the gNB and the UE, and since the optimal beam direction is changed as the UE moves, the optimal beam direction should be continuously tracked. The process of obtaining 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 is required for 1) the initial access in which the UE first attempts to access the gNB, 2) the handover in which the UE switches from one gNB to another gNB, or 3) the beam recovery for recovery from the following state, which refers to: when performing beam tracking for searching for the optimal beam between the UE and the gNB, as a result of losing the optimal beam, the UE and the gNB cannot maintain the optimal communication state or enter a communication impossible state, that is, beam failure.

[0138] In the case of the NR system under development, a multi-level beam acquisition process is being discussed for beam acquisition in an environment using multiple beams. In the multi-level beam acquisition process, the gNB and the UE perform connection establishment using a wide beam in the initial access phase, and after the connection establishment ends, the gNB and the UE perform communication with the best quality using a narrow band. In the present invention, although various methods for beam acquisition for the NR system are mainly discussed, the methods most actively discussed at present are as follows.

[0139] 1) The gNB transmits an SS block per wide beam so that the UE searches for the gNB during the initial access process, that is, performs cell search or cell acquisition, and searches for the best wide beam to be used in the beam acquisition in the first stage by measuring the channel quality of each wide beam. 2) The UE performs cell search for the SS block per beam and performs DL beam acquisition using the cell detection result of each beam. 3) The UE performs a RACH process to notify the gNB that the UE will access the gNB discovered by the UE. 4) The gNB connects or associates the SS block transmitted per beam and the RACH resource to be used for RACH transmission so that the UE notifies the gNB of the result of the RACH process and at the same time notifies the result of the DL beam acquisition at the wide beam level (for example, beam index). If the UE performs the RACH process using the RACH resource connected to the best beam direction discovered by the UE, the gNB obtains information on the DL beam suitable for the UE during the process of receiving the RACH preamble.

[0140] <Beam Correspondence (BC)>

[0141] In a multi-beam environment, it is problematic whether the UE and / or the TRP can accurately determine the transmit (Tx) or receive (Rx) beam directions between the UE and the TRP. In a multi-beam environment, signal transmission repetition or beam scanning for signal reception can be considered based on the Tx / Rx reciprocity capabilities of the TRP (e.g., eNB) or the UE. The Tx / Rx reciprocity capability is also referred to as Tx / Rx beam correspondence (BC) in the TRP and the UE. In a multi-beam environment, since the optimal path for the UL can be different from the optimal path for the DL, if the Tx / Rx reciprocity capability in the TRP or the UE is not maintained, the UE may not transmit the UL signal in the beam direction in which the UE has received the DL signal. The Tx / Rx BC in the TRP is maintained if the TRP can determine the TRP Rx beam for UL reception based on the UE's DL measurements 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 the UL measurements for one or more Rx beams of the TRP. The Tx / Rx BC in the UE is maintained if the UE can determine the UE Rx beam for UL transmission based on the UE's DL measurements for one or more Rx beams of the UE and / or if the UE can determine the UE Tx beam for DL reception based on the indication of the TRP based on the UL measurements for one or more Tx beams of the UE.

[0142] In the LTE system and the NR system, the following elements can be used to configure the RACH signal for the initial access to the gNB (i.e., the initial access to the gNB through the cell used by the gNB).

[0143] * Cyclic Prefix (CP): This element is used to prevent interference generated from the previous / earlier (OFDM) symbol and group RACH preambles arriving at the gNB with different time delays from entering one time zone. That is, if the CP is configured to match the maximum radius of the cell, the RACH preambles already transmitted by the UEs in the cell are included in the RACH reception window, which corresponds to the length of the RACH preamble configured by the gNB for RACH reception. The CP length is usually set to be equal to or greater than the maximum round-trip delay.

[0144] * Preamble: Defines the sequence used by the gNB for detecting signal transmission, and the preamble is used to carry this sequence.

[0145] * Guard Time (GT): This element is defined to ensure that the RACH signal arriving at the gNB with a delay from the farthest distance on the RACH coverage from the gNB does not interfere with the signals arriving after the RACH symbol duration. During this GT period, the UE does not transmit a signal, so the GT may not be defined as a RACH signal.

[0146] Figure 6 Configuration / format showing RACH preambles and receiver functions.

[0147] The UE sends a RACH signal through the specified RACH resources at the system timing of the gNB obtained through the SS. The gNB receives signals from multiple UEs. Generally, the gNB performs Figure 5 the process shown in for RACH signal reception. Since the CP 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 the boundary for signal reception. If the boundary is determined as the starting point for signal reception and if correlation is applied to a signal of a length corresponding to the sequence length starting from the starting point, the gNB can obtain information on whether there is a RACH signal and information on the CP.

[0148] If the communication environment (e.g., millimeter wave band) operated by the gNB uses multiple beams, the RACH signal arrives at the eNB from multiple directions, and the gNB needs to detect the RACH preamble (i.e., PRACH) while scanning the beam directions to receive the RACH signals arriving from multiple directions. As described above, when using analog BF, the gNB performs RACH reception in one direction at only one timing. For this reason, it is necessary to design the RACH preamble and the RACH process such that the gNB can correctly detect the RACH preamble. Considering the case where the BC of the gNB is maintained and the case where the BC is not maintained, the present invention proposes a RACH preamble and / or a RACH process for a high-frequency band to which the NR system (especially BF) can be applied.

[0149] Figure 7 Illustration of the receive (Rx) beam formed at the gNB for receiving the RACH preamble.

[0150] If the BC is not maintained, even when the gNB forms an Rx beam in the Tx beam direction of the SS block in a state where the RACH resources are linked to the SS block, the beam directions may not match. Therefore, the RACH preamble can be configured in the format shown in (a) of Figure 7 such that the gNB can perform beam scanning to perform / attempt to perform RACH preamble detection in multiple directions while scanning the Rx beam. At the same time, if the BC is maintained, since the RACH resources are linked to the SS block, the gNB can form an Rx beam in the direction of the transmitted SS block for one RACH resource and detect the RACH preamble only in that direction. Therefore, the RACH preamble can be configured in the format shown in (b) of Figure 7

[0151] As described above, considering the DL beam acquisition report and DL preferred beam report of the UE and the two purposes of beam scanning of the gNB according to the BC, the RACH signal and RACH resources should be configured.

[0152] Figure 8 The figure illustrates the RACH signal and RACH resources for explaining the terms used to describe the present invention. In the present invention, the RACH signal can be configured as follows.

[0153] *RACH resource element: The RACH resource element is the basic unit used when the UE transmits the RACH signal. Since different RACH resource elements can be respectively used for RACH signal transmissions of different UEs, a CP is inserted into the RACH signal in each RACH resource element. By the CP, the protection of the signal between UEs has been maintained, so there is no need for a GT between the RACH resource elements.

[0154] *RACH resource: The RACH resource is defined as a set of cascaded RACH resource elements connected to an SS block. If the RACH resources are allocated continuously, two consecutive RACH resources can be respectively used for signal transmissions of different UEs, like the RACH resource elements. Therefore, a CP can be inserted into the RACH signal in each RACH resource. Because the CP prevents signal detection distortion caused by time delay, there is no need for a GT between the RACH resources. However, if only one RACH resource is configured, that is, the RACH resources are not configured discontinuously, since the PUSCH / PUCCH can be allocated after the RACH resource, a GT can be inserted before the PUSCH / PUCCH.

[0155] *RACH resource set: The RACH resource set is a set of cascaded RACH resources. If there are multiple SS blocks in the cell and the cascaded RACH resources respectively connected to multiple SS blocks, the cascaded RACH resources can be defined as a RACH resource set. A GT is inserted into the last one of the RACH resource sets, which is the part of the RACH resource set where a RACH resource and another signal such as PUSCH / PUCCH may be encountered. As described above, since the GT is the duration when no signal is transmitted, the GT may not be defined as a signal. The GT is not shown in Figure 8 shown.

[0156] *RACH preamble repetition: When configuring RACH preambles for Rx beam scanning of a gNB, i.e., when the gNB configures the RACH preamble format such that the gNB can perform Rx beam scanning, if the same signal (i.e., the same sequence) is repeated within the RACH preamble, no CP is required between the repeated signals because the repeated signals serve as CP. However, when using different signals to repeat the preamble within the RACH preamble, CP is required between the preambles. GT is not required between RACH preambles. Hereinafter, the present invention is described under the assumption of repeating the same signal. For example, if the RACH preamble is configured in the form of "CP + preamble + preamble", the present invention is described under the assumption that the preambles within the RACH preamble are configured with the same sequence.

[0157] Figure 8 The figure shows the RACH resources for multiple SS blocks regarding a gNB and the RACH preambles in each RACH resource. The gNB attempts to receive RACH preambles in each RACH resource in the time region where the RACH resources are configured. The UE sends its RACH preamble through the RACH resource linked to a specific SS block (e.g., the SS block with better Rx quality), rather than sending RACH preambles in each of the RACH resources for all SS blocks of the cell. As described above, different RACH resource elements or different RACH resources can be used for different UEs to send RACH preambles.

[0158] Figure 9 The figure shows a RACH resource set. Figure 9 (a) of shows the case where two RACH resource elements per RACH resource are configured in the cell of the gNB where BC is maintained. Figure 9 (b) of shows the case where one RACH resource element per RACH resource is configured in the cell of the gNB where BC is maintained. Refer to Figure 9 (a), two RACH preambles can be sent in the RACH resource linked to the SS block. Refer to Figure 9 (b), one RACH preamble can be sent in the RACH resource linked to the SS block.

[0159] It can be configured as shown in Figure 9 so that the efficiency of the RACH resources is maximized using the RACH signal configuration characteristics described in Figure 8 . As shown in Figure 9 , in order to improve the usage / assignment efficiency of the RACH resources, the RACH resources or RACH resource elements can be configured to be fully cascaded without allocating blank durations between the RACH resources in the RACH resource set.

[0160] However, if as shown in Figure 9With the RACH resources configured as shown, the following problems may occur. 1) When BC is maintained and the gNB receives the RACH resources corresponding to SS block #N by forming a beam in the direction of SS block #N, since the Rx beam changes at the middle of the OFDM symbol (OS) defined for the data or control channel, the gNB only partially uses the resources other than the frequency resources allocated as RACH resources. That is, as shown in (a) of Figure 9 , if the gNB forms an Rx beam to receive SS block #1, OS #4 cannot be used for the data channel or the control channel. 2) When BC is not maintained and the gNB performs Rx beam scanning within the RACH resource element, for the RACH resources corresponding to SS block #1, the gNB can perform RACH preamble detection while receiving the data / control signal by forming an Rx beam on each of the OSs at the boundary of OS #1 / OS #2 / OS #3. However, when the gNB performs beam scanning on the RACH resources corresponding to SS block #2, the beam direction for receiving the data / control signal and the beam direction for receiving the RACH preamble do not match during the duration corresponding to OS #4, resulting in problems in detecting the RACH preamble.

[0161] In summary, if the gNB performs beam scanning while changing the direction of the Rx beam for RACH signal reception and the timing of the Rx beam change does not match the OFDM symbol boundary defined for the data or control channel, there is a problem of reducing the resource utilization / assignment efficiency of the data or control channel services in the frequency region other than the frequency resources allocated as RACH resources. To solve this problem, the present invention proposes to allocate the RACH resources in a structure aligned with the OFDM symbol boundary so that the gNB can perform RACH preamble detection while changing the beam direction in a multi-beam scenario, and at the same time the gNB uses all radio resources other than the RACH resources for the data and control channels. When BC is maintained, for example, two methods can be used to align the RACH resources or the RACH preambles transmitted through the RACH resources with the OFDM symbol boundary, as shown in Figure 10 .

[0162] Figure 10 FIG. illustrates the boundary alignment of the RACH resources according to the present invention. Figure 10 The example illustrated in corresponds to the case where BC is maintained and two RACH resource elements can be transmitted on one RACH resource. When BC is not maintained, one RACH preamble can be configured by one CP and multiple consecutive preambles, as shown in (a) of Figure 7 or Figure 8As shown in (a) of. Even in this case, the present invention can be applied. One RACH resource element can be transmitted on one RACH resource, and the present invention can be applied thereto.

[0163] 1) One of the methods for aligning the OFDM symbol boundary and the RACH resource boundary (hereinafter, Method 1) determines the CP length and the preamble length of the RACH preamble by considering the RACH preamble detection capability of the gNB, the coverage area of the gNB, and the subcarrier spacing of the RACH preamble. Then, the CP length and the preamble length are used to configure the RACH resource element, as Figure 10 shown in (a) of. The gNB can configure the RACH resource by determining the number of RACH resource elements of each RACH resource in consideration of the capacity of the RACH resource. The gNB configures the RACH resource such that the boundary of each of the RACH resources to be continuously used is aligned with the boundary of the OFDM symbol to be used for the data and control channels. In this case, a blank duration may occur between the RACH resources. The blank duration can be configured as a duration during which no signal is transmitted. Alternatively, a signal can be additionally transmitted only as a post-fix to the last RACH resource element in the RACH resource. That is, a UE that transmits the RACH preamble using the last RACH resource element in the time domain among the RACH resource elements in the RACH resource can add a suffix signal to its RACH preamble and then transmit the RACH preamble. A UE that transmits the RACH preamble using a RACH resource element other than the last RACH resource element can transmit the RACH preamble without adding a suffix signal.

[0164] 2) Another method among the methods for aligning the OFDM symbol boundary and the RACH resource boundary (hereinafter, Method 2) configures the CP length and the preamble length so as to align the RACH resource boundary with the OFDM symbol boundary, as Figure 10As shown in (b) of. However, since the number of RACH resource elements in each RACH resource can vary, if the length of the RACH preamble is changed to match the OFDM symbol boundary, there is a risk of changing the characteristics of the preamble sequence in the RACH preamble. That is, according to the preamble format shown in Table 4, the length of the Zadoff-Chu (ZC) sequence used to generate the preamble is determined to be 839 or 130. If the length of the preamble is changed to align the length of the RACH preamble with the OFDM symbol boundary, the characteristics of the ZC sequence as the preamble sequence may be changed. Therefore, if the RACH preamble format is determined and the RACH resource elements per RACH resource are determined, the length of the RACH preamble can be fixed, but the CP length can become greater than the length determined in the configured RACH preamble format, so that the RACH resource is aligned with the OFDM symbol boundary. That is, this method is used to align the RACH resource boundary (i.e., the RACH preamble boundary sent through the RACH resource) with the OFDM symbol (i.e., the normal OFDM symbol) for sending data / control channels by fixing the length of each preamble in the RACH preamble and increasing the CP length to match the OFDM symbol boundary in order to maintain the characteristics of the preamble sequence. In this case, the CP length of only some RACH resource elements can be configured to increase (i.e., the CP length of only some RACH preambles is configured to increase), or the CP length of all RACH resource elements can be configured to increase appropriately (i.e., the CP length of each RACH preamble is configured to increase appropriately). For example, if the gNB configures RACH resources in the time domain configured by OFDM symbols, the gNB configures a preamble format indicating the CP length and the sequence part length, so that the sequence part length is a positive integer multiple of the preamble length obtained from a specific length (e.g., the length of the ZC sequence for RACH) according to the number of preambles to be included in the corresponding RACH preamble, and the CP length is equal to the value obtained by subtracting the sequence part length from the total length of the normal OFDM symbol. If the lengths of all OFDM symbols are the same, the RACH preamble format according to the present invention will be defined such that the sum of a positive integer multiple of the predefined preamble length (e.g., the preamble length obtained from the predefined length of the ZC sequence) and the CP length is a multiple of the OFDM symbol length. When the UE detects the SS block of the cell and generates a RACH preamble to be sent on the RACH resource connected to the SS block, the UE generates a RACH preamble by using a sequence of a specific length (e.g., the ZC sequence) according to the preamble format configured by the gNB to generate each preamble to be included in the RACH preamble and adding the CP to the front of the preamble or the repetition of the preamble.

[0165] Since BC is not maintained, Method 1 and Method 2 can be equally applied even when the gNB performs Rx beam scanning. When BC is maintained for Method 1 and Method 2, it is very likely to configure the RACH preamble in a format including one preamble. At the same time, except that when BC is not maintained, the RACH preamble is very likely to be configured to include preamble repetition. Since BC is not maintained, the Method 1 and Method 2 described in the reference Figure 10 can be equally applicable to the case where the gNB wishes to perform Rx beam scanning. For example, when BC is not maintained such that the gNB expects to perform Rx beam scanning, the gNB configures and signals the preamble format in a form including preamble repetition (e.g., refer to Figure 7 (a) of Figure 8 (a)). Here, the RACH resources can be configured in the form of Method 1 to monitor the RACH preamble by considering the duration from the end of one RACH resource to just before the start of the next RACH resource as the blank duration or the suffix duration. Alternatively, the RACH resources can be configured in the form of Method 2 to monitor the RACH preamble in each RACH resource configured by the gNB under the assumption that the RACH preamble boundary is equal to the OFDM symbol boundary.

[0166] The RACH resource allocation method proposed in the present invention is used to efficiently use the frequency resources other than the frequency resources occupied by the RACH resources as data resources or control channel resources in one time slot or multiple time slots for the RACH resources. Therefore, in order to efficiently use the data / control channel resources considering the RACH resources, the gNB needs to use the information about which unit is used to form a beam for the time slot to which the RACH resources are allocated to schedule the data or the control channel. When the gNB performs scheduling and transmits the data or the control channel based on this information, the UE can receive the information about which OFDM symbol unit is used. For this purpose, two methods can be considered such that the gNB can schedule the data or the control channel in the time region to which the RACH resources are allocated.

[0167] * Mini-slot allocation

[0168] When scheduling a channel in the time region to which the RACH resources are allocated, since the scheduled channel should be included in one beam region, the time length of the resources to which the channel is allocated should be shorter than the time length of the RACH resources and can include multiple short-length time slots for one RACH resource.

[0169] If the gNB operates by configuring the beam direction for each RACH resource, and the time unit in which the gNB allocates resources to the UE does not match in the time region where the RACH resource is allocated and in the time region where the RACH resource is not allocated, the gNB shall define a time slot for scheduling in the time region occupied by the RACH resource, and notify the UE of the information related to the time slot. Hereinafter, the time slot used for scheduling in the time region occupied by the RACH resource will be referred to as a mini-slot. In this structure, there are some considerations for transmitting data or control channels through the mini-slot. For example, the following considerations are given.

[0170] 1) For the case of defining a mini-slot for the time slot to which the RACH resource is allocated:

[0171] Figure 11 Illustrates the method of configuring a mini-slot in the RACH time slot SLOT when BC is maintained. RACH inside.

[0172] The UE knows all the information about the RACH resources used by the gNB through the system information. Therefore, the set of the minimum OFDM symbols including the entire RACH resource allocated for each SS block can be defined as a mini-slot. When the gNB performs scheduling at the time when the RACH resource is allocated, the UE interprets the mini-slot as a TTI and transmits data or control channels in the TTI. If there are multiple mini-slots included in a normal time slot, the UE needs to determine through which mini-slot the UE will transmit data / control channels. The methods for the UE to determine the mini-slot to be used for transmitting data / control channels can generally include the following two schemes.

[0173] >A. If the gNB schedules the transmission of UL data / control channels, the gNB can specify for the UE through DCI which mini-slot within the time slot the UE should use for transmission.

[0174] >B. In a multi-beam scenario, the UE continuously performs beam tracking. If the UE has previously received information from the gNB about the SS block to which the serving beam from which the UE is currently receiving service is connected, the UE interprets the same time region as the time region in which the RACH resource connected to the SS block associated with the serving beam is allocated as the time region in which the UE should perform transmission. If the RACH resource connected to the SS block associated with the UE's serving beam does not exist in the time slot scheduled for the UE, the UE can determine that a beam mismatch has occurred.

[0175] 2) For the case of defining multiple mini-slots in the time slot to which the RACH resource is allocated:

[0176] Figure 12 Illustrates when BC is maintained in the RACH time slot SLOTRACH Another method of configuring micro-slots internally.

[0177] When multiple micro-slots are defined in the time slot to which the RACH resource is allocated, this is basically similar to the case where multiple micro-slots are defined in the time slot to which the RACH resource is allocated except that multiple micro-slots exist in the time slot to which the RACH resource is allocated. Perform the same operations as the method proposed in Figure 11 . However, as shown in Figure 12 , the minimum OFDM symbol set including the entire RACH resource is divided into several subsets, and each subset is defined as a micro-slot. In this case, the gNB should first notify the UE how to divide the minimum OFDM symbol set including the RACH resource to use the micro-slots. For example, the gNB can indicate to the UE in the form of a bitmap how to divide the minimum OFDM symbol including the RACH resource. Alternatively, when the minimum OFDM symbol including the RACH resource can be divided into multiple equal subsets, the gNB can notify the UE of the number of allocated micro-slots. In addition, the gNB should indicate to the scheduled UE which micro-slot among the multiple micro-slots the UE should use to send data / control channels. The gNB can directly indicate through DCI the micro-slot through which data / control channels should be sent. Alternatively, when scheduling the UE in the time region to which the RACH resource is allocated, the gNB can notify the UE in advance (e.g., during connection establishment) of the micro-slots to be used. Alternatively, the micro-slots to be used can be determined through a predetermined rule using information shared between the UE and the gNB (such as the UE ID).

[0178] 3) Case where the BC does not remain during preamble repetition and thus beam scanning is performed:

[0179] Figure 13 Illustration of the method of configuring micro-slots in RACH time slot SLOT when the BC does not remain RACH Method of micro-slots within.

[0180] When the BC does not remain, as described above, the gNB performs beam scanning while scanning the beam direction of the receiver in the time slot to which a RACH resource is allocated. Therefore, this case can operate similarly to the scenario where the BC remains and there are multiple micro-slots in the time slot to which the RACH resource is allocated. To this end, similar to the method described in Figure 12 , the gNB sends information to the UE about how to perform beam scanning for the set of minimum OFDM symbols including the RACH resource and information about which SS block each beam is connected to. This information can be used as information about which micro-slots can be scheduled for the UE. In this case, similar to Figure 12In the method described, the UE can receive, via DCI, information on which of the multiple micro-slots that can be scheduled for the UE is scheduled to transmit data / control channels. Alternatively, the scheduling information can be pre-scheduled via an RRC signal, or the information can be defined via predefined rules using information shared between the gNB and the UE.

[0181] 4) Case of license-free scheduling:

[0182] >A. When the time resource of the data / control channel transmitted by the UE on license-free resources overlaps with the RACH resource, the data / control channel can be transmitted in the micro-slots defined in the time region of the RACH resource. However, when license-free scheduling is used and the signal format of the data / control channel that the UE will transmit via license-free scheduling (i.e., via license-free resources) is a normal time slot or a time slot shorter than a normal time slot but longer than the micro-slots defined in the RACH resource region, and when the length of the micro-slot is too short such that the code rate of the transmission of the data / control channel via the micro-slot is too high relative to the specified code rate, the UE can i) discard the transmission, ii) change the transmission block size, or iii) use multiple micro-slots to transmit the data / control channel when multiple micro-slots are available. On the other hand, when the code rate of the transmission of the data / control channel is still lower than the specified code rate even when the data / control channel is transmitted with the length of the micro-slot, the UE can also transmit the data / control channel with the specified transmission block size.

[0183] >B. When license-free scheduling is used and the signal format of the data / control channel that the UE will transmit via license-free scheduling (i.e., via license-free resources) is shorter than a micro-slot, the data / control channel can be normally transmitted at the micro-slot position determined in the above scheme. That is, if the data / control channel via license-free scheduling requires a resource shorter than a micro-slot in the time domain, the UE transmits the data / control channel in the micro-slot corresponding to the same gNB Rx beam as the data / control channel among the micro-slots configured to match the length of the RACH resource (i.e., RACH preamble). In this case, compared with the pre-configured signal format, the transmission block size can be increased in proportion to the micro-slot length according to a predetermined rule. For example, if the signal format for transmitting the data / control channel via license-free scheduling is defined to use two OFDM symbols and the length of the micro-slot in the RACH time slot corresponds to three OFDM symbols, the transmission block size capable of carrying the data / control channel via license-free scheduling can be increased by 1.5 times.

[0184] 5) Allocating micro-slots to guard time or blank duration:

[0185] Figure 14 The figure shows a method of configuring micro-slots using guard time.

[0186] The gNB can freely configure the Rx beam for a part of the duration configured as the guard time, or the gNB can freely configure the Rx beam for the blank duration in the remaining time slots after configuring the RACH resources in one time slot, even if the blank duration is not for the guard time. Therefore, the gNB can notify the UE of information about the mini-slots that can be used independently of the beam for receiving the RACH resources and information related to the RACH resources, and the UE can expect dynamic scheduling to be performed for the mini-slots configured in the guard time. The position of the allocated mini-slots can be determined by the above method (e.g., the method of indicating the length, position, and beam direction of the mini-slots configured in the RACH time slot).

[0187] 6) Allocation of short PUCCH resources:

[0188] In a TDD system, the control channel can be sent during a partial duration of one time slot by configuring the control channel with a short length. In the NR system, a scheme of sending the DL control channel in the first part of one time slot and the UL control channel in the last part of one time slot is being discussed. In particular, the UL control channel sent in this way is called short PUCCH. Since the short PUCCH is configured to be sent on the last one or two symbols, the short PUCCH can be sent in the above-mentioned mini-slots. However, as described above, since the beam direction may change within one time slot, the short PUCCH cannot always be located in the last part of the time slot. Therefore, when the short PUCCH is scheduled in the time slot area where the RACH resources are allocated, the UE sends the short PUCCH in the mini-slot in which the beam in the same direction as the beam from which the UE receives service (i.e., the gNB Rx beam, or the UE Tx beam corresponding to the gNB Rx beam) or the beam formed by the gNB in advance for the short PUCCH link (i.e., the gNB Rx beam, or the UE Tx beam corresponding to the gNB Rx beam) exists. In this case, the PUCCH can be sent at the last symbol position in the mini-slot, the symbol position specified by the gNB through signaling, or the symbol position determined by the rule. However, when the beam in the same direction as the beam from which the UE receives service or the beam formed by the gNB in advance for the short PUCCH link does not exist, the UE can discard the transmission of the short PUCCH.

[0189] * Mini-slot concatenation

[0190] In the process of forming the Rx beam for the RACH resource set, if the Rx beam directions of the respective RACH resources are not very different, data or the control channel can be sent through a long time slot to perform transmission throughout the duration of the RACH resource set. This can be called mini-slot concatenation, where the above-mentioned mini-slots are used by concatenation as described above.

[0191] Figure 15 FIG. illustrates an example of transmitting data by cascading micro-slots of the same length as a normal time slot while BC is maintained. In particular, Figure 15 FIG. illustrates the transmission of cascaded micro-slots and the insertion of reference signals during the RACH resource duration while BC is maintained. For example, a data packet can be transmitted in a long time slot obtained by cascading micro-slots, such that the long time slot can have the same length as a normal time slot. In this case, a data packet is transmitted separately in the micro-slots within the long time slot.

[0192] Therefore, in the case of data transmission using cascaded micro-slots, since the gNB forms the Rx beam of each RACH resource using the information on the SS block transmission direction, the UE is expected to transmit a signal in the direction where each SS block can be received with the best quality. Therefore, the gNB notifies the UE of information related to Rx beamforming for each OFDM symbol (when BC is not maintained) or for each RACH resource (when BC is maintained) in the RACH resource time region (e.g., information associated with the SS block). In this case, smooth reception of the data channel may not be possible because the Rx beam of the gNB changes during signal transmission, while the UE performs signal transmission through cascaded micro-slots and transmits reference signals in the format defined for normal time slots. Therefore, considering the change in the Rx beam direction of the gNB, it is necessary to insert the reference signal in the unit where the Rx beam direction of the gNB changes. For this purpose, it is desirable to define a reference signal structure for the cascaded micro-slots allocated in the RACH resource duration. The UE to which a data channel or a control channel in the format of cascaded micro-slots is allocated in the RACH resource duration should transmit a reference signal in the format of cascaded micro-slots.

[0193] During the transmission of PUSCH or PUCCH, if there is no stable gNB Rx beam for the UE Tx beam direction of PUSCH or PUCCH or multiple beams have similar quality, PUSCH or a long PUCCH can be transmitted through cascaded micro-slots to use the beam diversity characteristic for stable reception. In this case, the gNB can efficiently use the time resource to which the RACH resource is allocated by transmitting PUSCH or PUCCH in the RACH resource region.

[0194] In addition, the gNB performs beam tracking on the Tx beam or Rx beam so that the beam with the best quality is maintained as the serving beam in order to stably maintain the service in a multi-beam environment. Therefore, the gNB can use the characteristics in which the gNB changes the Rx beam during the time duration of the slot to which the RACH resource is allocated, by having the UE perform repeated transmissions of PUSCH, long PUCCH, or short PUCCH in each RACH resource region, or by transmitting the RS defined for beam tracking through multiple mini-slots, to measure the quality of the gNB Rx beam or the UE Tx beam and perform beam tracking. That is, in order to efficiently use the resources for beam tracking, the gNB can cause the UE to transmit a physical channel suitable for the characteristics of the time region to which the RACH resource is allocated, and the gNB can use this physical channel as a resource for beam tracking. In other words, in order to efficiently use the resources for beam tracking, the gNB can instruct the UE that the UE should transmit a physical channel through the UE Tx beam suitable for each of the mini-slots configured in the time region to which the RACH resource is allocated, and the gNB can use this physical channel for beam tracking in each mini-slot. In order to cause the UE to efficiently transmit the signal for beam tracking, the gNB notifies the UE of the information about the change in the beam direction as described above, and the UE inserts a reference signal into each Rx beam of the gNB according to this information and a predefined rule, and transmits the reference signal. The gNB can use this reference signal as a signal for channel estimation during the Rx beam duration or as a signal for signal quality measurement for beam tracking.

[0195] When transmitting the PUSCH or long PUCCH received in the gNB through beam diversity, since the gNB attempts to receive the signal during each Rx beam duration, the antenna gain can have different characteristics. Therefore, the UE can configure the transmission power of the PUSCH / PUCCH differently for each Rx beam direction (e.g., each RACH resource region). To this end, the gNB can notify the UE that the reference channel / signal information for path loss calculation for open-loop power control and the power control parameters should be configured separately for each RACH resource region. The UE uses this information to configure and transmit different transmission powers in the RACH resource time region.

[0196] In contrast, during signal transmission for beam tracking (or beam management) in multiple RACH resource regions, each RACH resource region should maintain the same transmission power so that the gNB can measure the quality of the signals received by the gNB. In this case, only one reference channel / signal is needed to control one power. If the gNB notifies the UE of information about the reference channel / signal or the information is predefined by rules, the UE can use the reference channel / signal to determine the magnitude of the transmission power and send the PUSCH / PUCCH by applying the transmission power equally to all regions.

[0197] The gNB can notify the UE that the UL data or control channel transmitted in the RACH resource transmission time region (i.e., the time region in which the RACH resources are configured in the corresponding cell) is for beam diversity or for beam tracking for each UL channel, and cause the UE to perform a power control operation according to the above usage.

[0198] <PRACH Configuration>

[0199] The PRACH configuration includes the time / frequency information of the RACH resources and can be included in the remaining minimum system information (RMSI). The RMSI can be interpreted as system information block 1 (SIB1) and represents the system information that the UE should obtain after receiving the master system information block (MIB) through the physical broadcast channel (PBCH). When receiving the PRACH configuration information, the UE can use one preamble in the preamble set included in the PRACH configuration to send the PRACH message 1 (Msg1) on the specified time and frequency resources. The preamble format in the PRACH configuration information can also provide the CP length, the number of repetitions, the subcarrier spacing, the sequence length, etc.

[0200] Hereinafter, the PRACH configuration will be described in detail.

[0201] 1. RACH resource allocation in the time domain

[0202] Reference will be made to Figure 16 and Figure 17 to describe the RACH resource configuration in the time domain. Here, the RACH resources refer to the time / frequency resources through which the PRACH message 1 can be sent. Describe the RACH preamble index configuration in the RACH resources. The RACH resources are associated with the SS blocks to identify the preferred downlink Tx beam directions. That is, each RACH resource in the time domain is associated with an SS block index.

[0203] In addition, a set of RACH resources in the time domain can be defined with respect to the default period of the SS blocks in the cell. Multiple RACH resources associated with a single SS block can be within the set of RACH resources in the time domain. Reference will be made to Figure 16, the SS block period and the RACH resource set period can be set, as shown in Figure 16 . The RACH resource set period can be determined based on the SS block period, and multiple RACH resources can be configured in the RACH resource set period. As described above, the RACH resource set period can be set according to the PRACH configuration information. In this case, the RACH resource set period can be the same as the PRACH configuration period. In the present disclosure, the PRACH configuration period, i.e., the RACH configuration period, can refer to the time period in which a set of RACH resources appears according to the corresponding RACH configuration.

[0204] In Figure 16 , the time instance to which a RACH resource is allocated is called a RACH opportunity. That is, when only considering the time domain and the frequency domain without a sequence field, a RACH resource can be called a RACH opportunity. If the RACH resource set period is determined based on the SS block period, the correct timing instance can be indicated as an offset from the transmission timing of the SS block associated with the corresponding RACH resource. The correct position of the RACH opportunity in the RACH resource set is also provided to the UE.

[0205] Figure 17 FIG. illustrates a method of indicating the association between the SS block and the RACH resource. Each RACH resource set is set using the SS block period. Since the correct starting point of the RACH resource set corresponding to the SS block in the time domain may be different, the timing offset between each SS block and the RACH resource set corresponding to it can be signaled.

[0206] The RACH resource duration is determined by the PRACH preamble format. The length of the RACH preamble including the guard time (e.g., the preamble format) is set according to the cell coverage. In addition, the repetition number of the preamble determines the RACH resource duration. Therefore, in addition to the RACH preamble format for the CP length, the RACH resource configuration also includes the repetition number of the RACH sequence for indicating the preamble length.

[0207] As described above, the initial downlink beam acquisition process in the NR system using multiple beams is preferably performed by detecting the SS block with the highest received quality. Therefore, information about the UE-preferred downlink beam is signaled to the gNB through the initial RACH process. Therefore, information about the beam index corresponding to the SS block detected by the UE can be indirectly signaled through the position of the resource for RACH preamble transmission in the NR system. For example, the RACH resources are linked to each SS block, and the UE signals information about the beam index to the gNB in the form of the RACH resources linked to each SS block, as referred to above in Figure 5As described above. That is, the UE can signal the preferred downlink beam, i.e., the SS block, to the gNB by transmitting a PRACH using the RACH resource associated with the SS block detected by the UE.

[0208] As described above, the time / frequency resources of the RACH resource are basically linked to the SS block, and thus it is desirable to allocate the RACH resource based on the default SS block transmission period used in the initial access phase. However, when the number of UEs in the cell of the gNB is small, the RACH resource can be allocated intermittently compared to the default transmission period. Therefore, the present disclosure proposes to define the time slot to which the RACH resource is allocated as a RACH time slot and to allocate the RACH time slot period as a multiple of the default SS block transmission period. Although the above description is based on a multi-beam environment, in order to maintain the same structure, it may be effective to allocate the RACH resource in the same way in a single-beam environment. In addition, the RACH time slot period can be associated with the RACH configuration period set by the foregoing PRACH configuration information, and the period between RACH time slots at the same position or having the same index within the RACH configuration period can be the same as the RACH configuration period. The information about the RACH time resource among the RACH resource allocation information sent from the network / gNB to the UE can include the following.

[0209] 1) Associated SS block index

[0210] 2) Position of the RACH time slot relative to the SS block

[0211] 3) RACH time slot period represented by a multiple of the SS block period or a function of the SS block period

[0212] 4) Offset value for indicating the correct position unambiguously when the RACH time slot period relative to the SS block period is greater than 1. Here, the offset value is set based on subframe number 0.

[0213] When the time / frequency resources to which the RACH resource is allocated are linked to the SS block, the number of RACH resources for which the UE can perform RACH transmission can be the same as the number of SS blocks. Although the RACH resource generally includes time, frequency, and code domain resources capable of carrying a RACH preamble, for the sake of convenience of description, in the present disclosure, the RACH resource is used as a time / frequency resource block capable of carrying a RACH preamble. However, the mentioned RACH resource together with the preamble sequence can be used as a concept including a sequence domain, i.e., a code domain. For example, when the RACH resource is represented as sharing the same time / frequency resource, when the sequence domain is also considered, the RACH resource can correspond to multiple RACH resources, although from the perspective of time / frequency resources they are one RACH resource.

[0214] However, in an environment where the number of UEs located in the gNB is small, it may be inefficient to allocate different RACH resources to SS blocks. Therefore, if the gNB can receive RACH preambles through the same Rx beam or receive RACH preambles simultaneously through multiple beams, the same time / frequency resources can be allocated to the RACH resources linked to multiple SS blocks. That is to say, multiple SS blocks can be associated with a single RACH time-frequency resource. In this case, the SS blocks regarding the RACH resources can be distinguished by the preamble index or set of preamble indices used in the RACH resources. That is to say, the number of RACH resources can be allocated to be less than or equal to the number of SS blocks.

[0215] The gNB determines the time / frequency domain to which the RACH resources will be allocated and signals information about it to the UE through system information. In the case of LTE, depending on the preamble format, one or two subframes constitute a RACH time slot, and thus, if the gNB specifies a specific subframe position through the PRACH configuration information, the UE can know the position of the RACH resources in the time domain. On the other hand, the NR system depends on different types of information according to the gNB configuration and environmental requirements. Specifically, the RACH preamble is set in such a way that short basic sequences are defined for robustness against high Doppler frequencies, Rx beam scanning, TDD / FDD-compliant design, etc., and the short basic sequences are repeated for beam scanning and ensuring coverage. Therefore, the position of the RACH time resources can vary greatly depending on the gNB or the environment. In addition, the NR system can consist of multiple very small cells. In this case, the RACH preamble may become quite short, and thus, a RACH time slot in which multiple RACH preambles can be transmitted can be configured in the time domain. For example, the RACH time resource information can be provided to the UE as Figure 18 illustrated.

[0216] Figure 18 Illustrate the RACH time resource information. The information about the time resources of the RACH resources, that is, the PRACH time resource information, can include the following information.

[0217] 1) The relative position of the RACH resources / slots with respect to the SS block position or the position of the RACH time slot with respect to the SS period

[0218] 2) The position of the OFDM symbol at which the RACH resources start in the RACH time slot

[0219] 3) Regarding the preamble format (i.e., CP length, sequence length) of the RACH resources and the number of repetitions of the sequence and / or

[0220] 4) Information on how much of the RACH resources defined above are allocated to the timeline. Information corresponding to the position of each of the plurality of RACH resources (e.g., the relative or absolute position of each RACH resource when the RACH resources are allocated and the RACH resources are not contiguous on the timeline).

[0221] Meanwhile, even when the RACH resources linked to multiple SS blocks share the same time / frequency resources, the UE needs to distinguish and transmit RACH preambles for each of the RACH resources linked to the SS blocks for the same time / frequency resources in order to transmit beam acquisition information to the gNB. To this end, the preamble sequences available in a single RACH resource need to be partitioned for and allocated to the SS blocks. The preamble sequences in the LTE and NR systems consist of root sequences that determine the basic sequences and combinations of cyclic shift sequences and orthogonal cover sequences having zero correlation within each root sequence. Here, in order to improve resource efficiency, multiple root sequences can be allocated to facilitate protecting a large number of preamble sequences within the RACH resources. Generally, the cross-correlation between root sequences is greater than the cross-correlation between sequences having different cyclic shift versions or sequences having different orthogonal cover sequences. In addition, due to the beam characteristics, the signals received through beams different from the beam suitable for the UE are weaker, and thus, even if the cross-correlation is slightly larger in the beam direction different from the beam direction for the UE, the cross-correlation between the corresponding sequences does not significantly affect the RACH reception performance. Therefore, when multiple RACH resources share the same time / frequency resources, it is desirable that each RACH resource consists of preamble sequences having a small cross-correlation. If the RACH preamble sequences consist of a combination of a root sequence and sequences having different cyclic shift versions or orthogonal cover sequences within the root sequence, as in the above embodiments, the preamble sequences having different cyclic shift versions within the same root sequence or the preamble sequences having different orthogonal cover sequences within the same root sequence can be preferentially allocated to the same beam, i.e., the RACH resources linked to a single SS block, and then different root sequence indices can be allocated. For example, the preamble sequences can be allocated to the RACH time / frequency resources as Figure 19 illustrated.

[0222] Figure 19 An example of RACH preamble sequence allocation is illustrated.

[0223] Refer to Figure 19, the root sequence {15, 27, 127, 138} is assigned to a single time / frequency resource, and the orthogonal cover {0, 1} and cyclic shift versions {0, 1, 2, 3} are assigned to each root sequence. Here, when two RACH resources are assigned to the time / frequency resource, the ZC index and OCC index composed of cyclic shift versions are preferentially assigned to the RACH resource linked to the Nth SS block, and the RACH preamble sequence set composed of two root sequences {15, 27} is assigned. The RACH preamble sequence set is assigned to the RACH resource linked to the (N + 1)th SS block in the same order. To signal the RACH resources to the UE, the gNB signals the information of the RACH preamble sequence set for configuring each RACH resource, and determines the order of the RACH preamble sequences in the RACH preamble sequence set according to a predefined rule. Here, the predefined rule preferentially increases the RACH preamble sequence index for {OCC index, cyclic shift version}, and then increases the next RACH preamble sequence index based on the root sequence index. That is, the RACH preamble sequence index preferentially increases in ascending order of the cross-correlation between sequences.

[0224] 2. RACH Resource Configuration in the Frequency Domain

[0225] The PRACH configuration can provide information about the frequency domain of the RACH resources. When the UE attempts PRACH transmission when the UE is not yet connected to the cell, the UE may not be able to identify the system bandwidth or resource block index.

[0226] In LTE, the UE can easily obtain the correct position of the RACH resources because the synchronization signal is transmitted at the center of the system bandwidth and the PBCH provides the system bandwidth. However, NR does not guarantee transmission synchronization at the center of the system bandwidth. Therefore, it may not be easy for the UE to obtain the resource block index for PRACH transmission in NR. Therefore, a method for providing the RACH resource position in the frequency domain is needed.

[0227] Since the UE in the idle mode obtains frequency synchronization based on the SS block, it is desirable to provide information about the frequency position of the RACH resources for the SS block bandwidth. That is, the RACH resources in the frequency domain need to be located within the SS block bandwidth in which the UE detects the SS block. The RACH preamble transmission bandwidth has a fixed value with a default subcarrier spacing of 15 kHz for PSS / SSS / PBCH. For example, the RACH preamble transmission bandwidth can be fixed to 1.08 MHz with a default subcarrier spacing of 15 kHz. Additionally, when the RACH preamble transmission bandwidth is 1.08 MHz, it is assumed that the SS block transmission bandwidth with a subcarrier spacing of 15 kHz is four times the RACH transmission bandwidth. The network needs to provide the correct RACH resource position in the frequency domain within the SS block.

[0228] If RACH resources are configured outside the SS block in which the network transmits PSS / SSS / PBCH, information about the RACH resources needs to be signaled based on the bandwidth of the SS block and the bandwidth of the RACH. Here, the system bandwidth is indexed in terms of the SS block bandwidth.

[0229] 3. Number of Resources in the Time Domain

[0230] Short ZC sequences are used as NR PRACH preambles. Short ZC sequences may result in a lack of sequences in the time resources defined as the temporary CP and RACH preambles. To solve this problem, multiple time and frequency resources can be allocated to the RACH resources in a RACH time slot, and in addition to the frequency resource information, the gNB also needs to signal to the UE the number of time resources used in the RACH time slot.

[0231] 4. Sequence Information

[0232] In LTE, 64 sequences are allocated to the RACH resources, and when a root code (i.e., root sequence) is allocated, due to the zero cross - correlation property, before using other root codes, the cyclic shift versions of the root code are first mapped to the preamble index.

[0233] The same property can be reused in NR - PRACH. Sequences with zero cross - correlation can be preferentially allocated to the RACH preambles. Here, zero cross - correlation is provided according to the cyclic shift version and the defined orthogonal cover (when defined). When a root code is allocated, the orthogonal cover is allocated according to a predetermined rule or setting, and the cyclic shift version with the root code and the orthogonal cover is mapped to the preamble index.

[0234] In summary, the PRACH configuration signaled by the gNB to the UE can include the following parameters.

[0235] - RACH resource allocation in the time domain / frequency domain: preamble format (CP duration and repetition count of the ZC sequence)

[0236] - Sequence information: root code index, orthogonal cover index (if defined), and cyclic shift length

[0237] 5. RACH Time Slot Mode

[0238] Multiple time slot patterns within a specific time interval that can include RACH resources can be determined based on the RACH message 1 sub - carrier spacing.

[0239] (1) RACH Time Slot Mode Configuration Method 1

[0240] When the SS block transmission period is 5 ms, all the first time slots within the 5 ms period are reserved for SS block transmission. If the SS block transmission period is 10 ms, the first time slot of the first half-frame with a 10 ms period is reserved for SS block transmission.

[0241] Although NR defines the time slot positions for SS block transmission, i.e., the SS block candidate time slot positions where SS block transmission is possible, the SS block is not always transmitted at the candidate time slot positions. That is, the candidate time slot positions are not always reserved for SS block transmission.

[0242] Meanwhile, the RACH time slot pattern for RACH resources depends considerably on the candidate time slot positions for SS block transmission. However, it is inefficient to define the RACH time slot pattern only based on the candidate time slot positions for SS block transmission in terms of resource flexibility, and thus it is necessary to consider the time slots where the SS block is actually transmitted to define the RACH time slot pattern. Therefore, the present disclosure defines the rules for RACH time slot allocation for RACH resources as follows.

[0243] - Time slots capable of transmitting SS blocks can be reserved for RACH resources according to the actually transmitted SS block. Here, information about the actually transmitted SS block is signaled by RMSI.

[0244] - Even if a RACH time slot is reserved as a RACH resource according to the PRACH configuration, the RACH time slot may not be used as a RACH resource according to the SS block transmission period.

[0245] - Even if a RACH time slot is reserved as a RACH resource according to the PRACH configuration, the RACH time slot signaled as the time slot where the SS block is actually transmitted by RMSI may not be used as a RACH resource.

[0246] Since the position of the actually transmitted SS block is determined according to the network's selection, the corresponding information is signaled to the UE by RMSI, but it is difficult to define a single fixed RACH time slot pattern for RACH resources according to the actually transmitted SS block pattern and different SS block transmission periods. Therefore, rules for defining the RACH time slot pattern can be defined such that the information about the actually transmitted SS block takes precedence over the RACH resource configuration.

[0247] The duration of the RACH time slot configuration for RACH resources can be 10 ms / 20 ms and is determined considering network operation and load. Additionally, to support the RACH time slot pattern configuration for RACH resources with longer periods such as 80 ms or 160 ms, the network needs to provide the RACH time slot pattern period based on a basic time slot pattern such as a 20 ms time slot pattern.

[0248] Specifically, a time slot pattern that may include RACH resources can be configured regardless of the candidate time slot positions where an SS block can be transmitted or configured at the candidate time slot positions where an SS block can be transmitted.

[0249] Figure 20 The figure shows candidate time slot positions where an SS block can be transmitted within a 10 ms window in a frequency band of 6 GHz or less. The subcarrier spacings available for SS block transmission at 6 GHz or lower are 15 kHz and 30 kHz, and the maximum number of time slot positions where an SS block can be transmitted is 8.

[0250] If a long sequence with a subcarrier spacing of 1.25 kHz or 5 kHz is used for RACH preamble transmission at 6 GHz, the RACH time slot pattern configuration that can be reserved as RACH resources can be set based on time slots with a length of 1 ms. Table 8 shows an example of the RACH time slot pattern configuration set based on time slots with a length of 1 ms, as described above.

[0251] Meanwhile, the exact information about the RACH preamble format used in Table 8 can be signaled separately.

[0252] [Table 8]

[0253]

[0254]

[0255]

[0256] Considering the alignment with the PUSCH time slot boundary of the RACH preamble with subcarrier spacings such as 15 / 30 / 60 / 120 kHz, it is necessary to determine the RACH time slot pattern in the case of a short sequence based on the subcarrier spacing of Msg 1. Determining the RACH time slot pattern based on the subcarrier spacing of Msg 1 means using the time slot length determined with the subcarrier spacing of Msg 1 as the basic unit to determine the RACH time slot pattern information and signaling it to the UE. The subcarrier spacing of Msg 1 is 15 / 30 kHz when it is 60 GHz or lower, and 60 / 120 kHz when it is 6 GHz or higher.

[0257] The subcarrier spacing of the SS block can be different from that of Msg 1. For example, in a bandwidth of 6 GHz or less, the subcarrier spacing of the SS block can be 15 kHz and the subcarrier spacing of Msg 1 is 30 kHz, or the subcarrier spacing of the SS block can be 30 kHz and the subcarrier spacing of Msg 1 is 15 kHz. Similarly, the subcarrier spacing of the SS block can be 120 kHz and the subcarrier spacing of Msg 1 is 60 kHz, or the subcarrier spacing of the SS block can be 240 kHz and the subcarrier spacing of Msg 1 is 120 kHz.

[0258] Meanwhile, the RACH time slot mode involves uplink time slot configuration information and thus requires at least the resolution of the Msg 1 parameter set. Therefore, considering the time slot / duration in which the SS block can be transmitted regardless of the subcarrier spacing of the SS block, the RACH time slot mode of the RACH resource needs to be determined based on the subcarrier spacing of Msg 1. Additionally, as described above, the principle of RACH resource allocation considering SS block allocation can be defined such that information about the actually transmitted SS block takes precedence over the RACH resource configuration discussed above regarding the RACH preamble based on the long sequence.

[0259] Furthermore, in the case of the RACH preamble format with a subcarrier spacing of 15 kHz, the RACH time slot duration is determined based on the 15 kHz subcarrier spacing. That is, in this case, the RACH time slot duration is 1 ms, and thus the RACH preamble with a subcarrier spacing of 15 kHz can have a RACH time slot mode arranged in at least one symbol (preferably, two or more symbols) in a 1 ms time slot. Additionally, since the RACH time slot duration based on the 15 kHz subcarrier spacing is 1 ms, the RACH time slot mode based on the 15 kHz subcarrier spacing can be used as the RACH time slot mode of the long sequence, which is defined for a 1 ms time slot.

[0260] That is, the time slot mode of the RACH preamble format with a subcarrier spacing of 15 kHz can use the same mode as the RACH preamble format with the long sequence, as shown in Table 8.

[0261] In addition, in the case of a RACH preamble format with a subcarrier spacing of 30 kHz, the RACH slot duration is determined based on the 30 kHz subcarrier spacing. That is, the RACH slot duration is 0.5 ms, and each radio frame includes 20 slots. Similarly, in the case of a RACH preamble format with a subcarrier spacing of 60 kHz, the RACH slot pattern includes 0.25 ms slots, i.e., 40 slots per radio frame. In the case of a RACH preamble format with a subcarrier spacing of 120 kHz, the RACH slot pattern is determined based on 80 slots per radio frame. Therefore, the RACH slot pattern can be specified according to the subcarrier spacing of the RACH preamble. In other words, it is necessary to specify M states according to the subcarrier spacing of the RACH preamble, and the RACH slot frequency (the number of RACH slots in a specific time period) and / or period are different according to the state of the subcarrier spacing.

[0262] Alternatively, by repeating in the time domain, a basic slot pattern such as the RACH slot pattern for a subcarrier spacing of 15 kHz can be used for a wider subcarrier spacing.

[0263] This method reuses the above RACH slot pattern based on a 1 ms slot, and configures the pattern by reducing the micro-slot length according to the subcarrier spacing through a scaling method. For example, when the subcarrier spacing is 30 kHz, the slot length is reduced to 0.5 ms, and 20 slots are included in the radio frame. That is, in the case of RACH slot pattern configuration index 0 in Table 8, slot index 0 is reserved for RACH resources in frames with even numbers. That is, it is assumed that the RACH slot pattern basis includes 10 slots in a 10 ms radio frame. When scaled to slots with a subcarrier spacing of 30 kHz, there are two sets of 10 slots in a 10 ms radio frame. That is, there are two slot patterns with 10 slots as the RACH slot pattern basis in the corresponding duration (10 ms). Here, the slots actually allocated to the RACH resources can be signaled in units of the RACH slot pattern basis. For example, the slots allocated to the RACH resources can be specified as follows by signaling a bitmap for each even system frame number.

[0264] - "11": The pattern of 10 slots in two groups repeated in a 10 ms radio frame is valid as the RACH slot pattern for RACH resources.

[0265] - "10": Only the first pattern of the pattern of 10 slots in two groups repeated in a 10 ms radio frame is valid as the RACH slot pattern for RACH resources.

[0266] - "01": The second mode of the pattern of 10 time slots in two sets that repeats only in a 10-ms radio frame is valid as the RACH time slot pattern for RACH resources.

[0267] Similarly, when the foregoing RACH time slot pattern basis is scaled to time slots with a subcarrier spacing of 60 kHz, there are four sets of 10 time slots in a 10-ms radio frame. There are four RACH time slot patterns with 10 time slots as the RACH time slot pattern window in the corresponding duration (10 ms). In the case of time slots with a subcarrier spacing of 120 kHz, there are eight RACH time slot patterns.

[0268] That is, first, the RACH time slot pattern configuration is configured based on a subcarrier spacing of 15 kHz. When the subcarrier spacing of the time slot length of the RACH time slot pattern is increased, multiple time slot patterns can be repeated within a basic time (e.g., 10 ms), and any one of the N repeated time slot groups actually used for RACH resources can be signaled in the form of a bitmap or the like.

[0269] (2) RACH Time Slot Pattern Configuration Method 2

[0270] Since the RACH preamble for the long sequence has a length of at least 1 ms, it is necessary to configure the RACH time slot pattern for time slots with a length of 1 ms. Figure 20 Shows the positions of the time slots capable of transmitting SS blocks within a 10-ms window of 6 GHz or lower. Refer to Figure 20 , however, defines the positions of the candidate time slots capable of transmitting SS blocks, but the candidate time slots are not always reserved for SS blocks. In addition, the RACH time slot pattern of the RACH resources depends quite a lot on the time slot positions for SS block transmission. Therefore, it is actually difficult to define the RACH time slot pattern considering the time slots in which SS blocks are transmitted. Therefore, considering the maximum number of SS blocks that can be transmitted according to the bandwidth, the present disclosure proposes a time slot allocation for RACH resources.

[0271] [Table 9]

[0272]

[0273] Table 9 shows the RACH time slot indices of the RACH resources in a radio frame of 6 GHz or lower. A method of supporting the maximum number of RACH resources corresponding to the maximum number of SS blocks is described with reference to Table 9. CDM / FDM is mainly used at frequencies of 6 GHz or lower, and therefore, a 5-ms SS block transmission period can be considered to discuss the RACH resources and the RACH resource pattern can be configured in a duration of 10 ms / 20 ms.

[0274] Meanwhile, to support RACH resource allocation within an 80 ms / 160 ms window, an offset value relative to the starting position of the RACH resources can be determined based on a basic duration such as 10 ms or 20 ms.

[0275] In the case of short sequences, considering alignment with the boundaries of PUSCH time slots having a subcarrier spacing of RACH preambles such as 15 / 30 / 60 / 120 kHz, it is necessary to determine the RACH time slot pattern based on the subcarrier spacing of Msg 1. In the case of the subcarrier spacing of Msg 1, a subcarrier spacing of 15 / 30 kHz is used at 6 GHz or lower frequencies, and a subcarrier spacing of 60 / 120 kHz is used at 6 GHz or higher frequencies.

[0276] The subcarrier spacing of the SS block can be different from the subcarrier spacing of Msg 1. For example, the subcarrier spacing of the SS block can be 15 kHz, and the subcarrier spacing of Msg 1 can be 30 kHz, or the subcarrier spacing of the SS block can be 30 kHz, and the subcarrier spacing of Msg 1 can be 15 kHz in a bandwidth of 6 GHz or lower. Similarly, an SS block with a subcarrier spacing of 120 kHz and a Msg 1 with a subcarrier spacing of 60 kHz can be sent, or an SS block with a subcarrier spacing of 240 kHz and a Msg 1 with a subcarrier spacing of 120 kHz can be sent at a bandwidth of 6 GHz or higher. Meanwhile, the RACH time slot pattern involves uplink time slot configuration information and therefore needs to be configured based on the resolution of the Msg 1 parameter set. Therefore, regardless of the subcarrier spacing of the SS block, considering the time slots / durations in which the SS block can be sent, it is necessary to determine the RACH time slot pattern of the RACH resources based on the subcarrier spacing of Msg 1. Here, determining the RACH time slot pattern based on the subcarrier spacing of Msg 1 means using the time slot length determined by the subcarrier spacing of Msg 1 as a basic unit to determine the RACH time slot pattern information and signaling it to the UE.

[0277] In addition, in the case of a RACH preamble format with a 15 kHz subcarrier spacing, the length of the RACH time slot is determined based on the 15 kHz subcarrier spacing. In this case, the length of the RACH time slot is 1 ms, and thus the RACH preamble with a 15 kHz subcarrier spacing can have a RACH time slot pattern arranged with at least one symbol (preferably, two or more symbols) within a 1 ms time slot. Furthermore, since the length of the RACH time slot based on a 15 kHz subcarrier spacing is 1 ms, the RACH time slot pattern based on a 15 kHz subcarrier spacing can be used as the RACH time slot pattern for a long sequence, for which the RACH time slot pattern is defined for a time slot with a length of 1 ms.

[0278] In addition, in the case of the RACH preamble format with a 30 kHz subcarrier spacing, the RACH slot length is determined based on the 30 kHz subcarrier spacing. That is, the RACH slot length is 0.5 ms, and each radio frame includes 20 slots. Figure 21 Shows the positions of the slots capable of transmitting SS blocks in a bandwidth of 6 GHz or lower. The positions of the slots for the RACH resources in the radio frame can be determined based on the subcarrier spacing of the SS block and the subcarrier spacing of Msg 1, as shown in Table 10.

[0279] Table 10

[0280]

[0281] The RACH slot pattern is based on slots with a length of 0.25 ms and each radio frame includes 40 slots when using a 60 kHz subcarrier spacing, and based on slots with a length of 0.125 ms and each radio frame includes 80 slots when using a 120 kHz subcarrier spacing. Therefore, the RACH slot pattern varies according to the subcarrier spacing of the RACH preamble. Figure 22 Shows the positions of the slots capable of transmitting SS blocks based on the subcarrier spacing of the SS block and the subcarrier spacing of Msg 1. The positions of the slots for the RACH resources can be determined based on the subcarrier spacing of the SS block and the subcarrier spacing of Msg 1, as shown in Table 11.

[0282] [Table 11]

[0283]

[0284] In summary, it is necessary to specify M states for each subcarrier spacing for the RACH preamble, and different RACH slot frequencies and / or periods can be had according to the respective states of the subcarrier spacing.

[0285] 6. Priority between the ATSS (Actually Transmitted Synchronization Signal) and the RACH resources

[0286] Hereinafter, a method for solving the problems in the following two cases is proposed, that is, the case where an SS block is actually transmitted (hereinafter, the actually transmitted SS block is referred to as "ATSS") in a specific slot included in the RACH slot pattern for RACH resource configuration, or the case where an ATSS is generated for the duration corresponding to a specific RACH slot pattern within the PRACH configuration window or the PRACH configuration period.

[0287] Conflicts between RACH resources and ATSSs may occur in the above-mentioned RACH time slot mode configuration methods 1 and 2. The difference between the two methods is that the conflict with the ATSS occurs in units of time slots in method 1, while in method 2 the conflict occurs according to the SS block transmission period.

[0288] To solve such problems more efficiently, m specific time slots, for example, 10 or 20 time slots, can be used as basic units to configure the aforementioned RACH time slot mode configuration table, which is different from Table 8 for configuring the RACH time slot mode, in which the RACH time slot configuration index changes according to whether the system frame number corresponding to the third column is even.

[0289] Here, the basis for RACH time slot mode configuration can vary according to the RACH preamble format, the subcarrier spacing of Msg 1, and the length of the time slots that make up the RACH time slot mode. For example, the basis for RACH time slot mode configuration can be 10 time slots in the case of a 1 ms time slot, and 20 time slots in the case of a 0.25 ms time slot. Hereinafter, the unit length for determining the RACH time slot mode is referred to as the RACH time slot mode basis, and the RACH time slot mode basis is specified as the number of time slots rather than an absolute time unit, i.e., ms.

[0290] When the RACH time slot mode basis for RACH resource configuration is configured similarly to Table 8, Table 12 is obtained.

[0291] [Table 12]

[0292]

[0293]

[0294] The difference between Table 8 and Table 12 is that the RACH time slot mode configuration table is configured in units of the RACH time slot mode basic length. That is to say, one or more RACH time slot mode bases can be repeated in the actual RACH resource configuration window. The RACH resource configuration window specifies the duration during which the RACH resources are configured and the RACH resource configuration is repeated for each window. For example, if the RACH resource configuration window consists of 40 time slots and the RACH time slot mode basis is 10 time slots, the 10-time-slot RACH time slot mode basis is repeated four times during the 40 time slots. Here, all four repeated RACH time slot mode bases can be allocated to the RACH resources, or only some of them can be allocated to the RACH resources. That is to say, the number of RACH time slot mode bases among the four RACH time slot mode bases #0, #1, #2, and #3 that are allocated to the RACH resources can be signaled. For example,

[0295] - When all RACH time slot pattern bases are allocated: 1111

[0296] - When only some RACH time slot pattern bases are allocated to RACH resources: Signaling directly the number of RACH time slot pattern bases actually allocated to RACH resources (e.g., when RACH time slot pattern bases #1 and #3 are allocated to RACH resources: 0101)

[0297] When determining whether to allocate a specific RACH time slot pattern base to RACH resources and signaling the specific RACH time slot pattern base, the SS block transmission period also needs to be considered. For example, when the RACH time slot length is 1 ms and the SS block transmission period is 20 ms in the above embodiment, RACH resources may not be configured during the duration corresponding to the frame in which the SS block is transmitted. More specifically, RACH time slot pattern bases #0, #1, #2, and #3 can be mapped to the zeroth frame, the first frame, the second frame, and the third frame, each frame having a length of 10 ms. When the SS block is transmitted in frames #0 and #2, RACH time slot pattern bases #0 and #2 are excluded from the RACH resource configuration, and the RACH time slot pattern for RACH resources is applied to frames #1 and #3. However, when the SS block transmission period is 40 ms, the zeroth frame is excluded from the RACH resource configuration, and the first frame, the second frame, and the third frame can be configured as RACH resources. For frames not configured as RACH resources, additional signaling is required.

[0298] When the PRACH configuration window has a length that is an integer multiple greater than 1 of the RACH time slot pattern base, if the number of RACH time slot pattern bases effective for RACH resources among the repeated RACH time slot pattern bases is signaled, the UE recognizes that RACH resources are configured only during the duration in which the RACH time slot pattern base is applied, and does not recognize other durations as RACH resources.

[0299] In other words, when a part of the basic duration of the RACH time slot pattern effective for using RACH resources overlaps with the ATSS,

[0300] 1) The entire RACH time slot pattern base duration is not used as a RACH resource. However, even in this case, when there is additionally an effective RACH time slot pattern base that does not overlap with the ATSS in the PRACH configuration window, this RACH time slot pattern base can be used.

[0301] 2) In the corresponding RACH time slot pattern basic duration, the half-frame or frame including the ATSS is not used as a RACH resource, and the half-frame or frame not including the ATSS is used as a RACH resource. In particular, when there are multiple RACH time slot pattern bases within the PRACH configuration window and the SS block transmission period is longer than the RACH time slot pattern basic length, this method can be applied.

[0302] 3) In the corresponding RACH time slot pattern base station duration, the time slot including the ATSS is not used as a RACH resource, and the time slot not including the ATSS can be used as a RACH resource. In particular, when there is only one RACH time slot pattern base within the PRACH configuration window and the SS block transmission period is equal to the RACH time slot pattern basic length, this method must be used.

[0303] 4) Which one of the above methods 1), 2) and 3) will be adopted to use the RACH resource while avoiding conflicts with the ATSS needs to be signaled or specified separately, and these three methods can be combined / selected according to conditions / environments.

[0304] In the case of a short sequence, the RACH time slot pattern for RACH resource configuration is signaled based on the subcarrier spacing of Msg 1, and a method of signaling the RACH time slot pattern based on the length (1 ms) of the time slot configured based on a 15 kHz subcarrier spacing in the case of a long sequence is proposed. Additionally, in the case of Msg 1 based on a short sequence, to align the time slot boundary for PUSCH transmission, Msg 1 is used to configure the RACH time slot pattern. This can be interpreted to mean that the transmission of PUSCH such as Msg3 needs to conform to the subcarrier spacing of Msg 1. For various reasons, the subcarrier spacing of Msg 1 can become different from that of Msg 3. Furthermore, the network can set default parameter sets or reference parameter sets, such as subcarrier spacing or time slot length, for operations such as fallback mode. In this case, it is necessary to determine the RACH time slot pattern for RACH resource configuration based on the default parameter set or reference parameter set. The default parameter set or reference parameter set can be signaled by the network to the UE as PRACH configuration or system information. Additionally, the default parameter set or reference parameter set can be directly specified as a specific value, or can be connected to the parameter set of the RACH time slot, which determines the time slot pattern for RACH resource configuration for each subcarrier spacing of Msg1.

[0305] 7. Association between RACH resource and SS block index

[0306] In the following, a method for signaling the Tx beam direction of the gNB and connection information regarding RACH resources to a UE in the initial access state will be described in detail. As described above, the Tx beam direction of the gNB refers to the beam direction of the SS block, as described above. Additionally, when the UE can observe / measure a specific RS other than the SS block in the initial access state, the Tx beam direction can refer to the RS. For example, the specific RS can be the CSI-RS.

[0307] In NR, multiple SS blocks can be formed and transmitted according to the number of beams of the gNB. Additionally, each SS block can have a unique index, and the UE can infer the index of the SS block including the PSS / SSS / PBCH by detecting the PSS / SSS and decoding the PBCH. The system information transmitted by the gNB includes RACH configuration information. The RACH configuration information can include a list regarding multiple RACH resources, information for identifying the multiple RACH resources, and connection information regarding each RACH resource and SS block.

[0308] Similar to the above description where the RACH resources are limited to the time / frequency resources where the UE can send PRACH preambles, in the following description, the RACH resources are limited to time / frequency resources. A method for indicating the RACH position on the frequency axis and the RACH position on the time axis will be described below. In the above description, one RACH resource is linked to one or more SS blocks, and the RACH resources that are consecutive on the time axis are defined as a RACH resource set. Multiple RACH resource sets that are consecutive on both the frequency axis and the time axis are defined as a RACH resource block.

[0309] Figure 23 Illustrate the RACH resource block.

[0310] As Figure 23 illustrated, the RACH resource block can be defined as the time / frequency block of the RACH resources, and each RACH resource in the RACH resource block has a unique index determined by the time / frequency position.

[0311] Map the RACH resource indices in the RACH resource block according to specific rules. For example, the RACH resource indices can be assigned according to frequency-time sorting or time-frequency sorting. For example, referring to Figure 21 , in the case of frequency-time sorting, the RACH resources in the RACH resource block can be indexed as follows.

[0312] -RACH resource #0 (time, frequency): (0,0)

[0313] -RACH resource #1: (1,0)

[0314] - RACH Resource #2: (2,0)

[0315] -......

[0316] Here, the unit of the time - axis length in the RACH resource block can be determined by the RACH preamble format, and the unit of the frequency - axis length can be determined by the RACH resource bandwidth (e.g., 1.08 MHz) or the resource block group (RBG) unit.

[0317] When the UE requests system information transmission by sending a specific RAH preamble, multiple RACH resource blocks can be specified to send information about the number of SS blocks or system information in the system / cell. In particular, when there are a large number of SS blocks, if all the RACH resources corresponding to each SS block are configured to be continuous, as described above, it may impose a significant restriction on the uplink / downlink data service. Therefore, the network can configure the RACH resources that are continuous on the time / frequency axis into RACH resource blocks and arrange the configured RACH resource blocks discontinuously. Thus, multiple RACH resource blocks can be configured, and each RACH resource block can also have a unique index.

[0318] In other words, the duration of configuring the RACH resource block (hereinafter referred to as the RACH configuration duration) can be specified in the system / cell, and there can be one or more RACH blocks in the RACH configuration duration. Figure 22 The figure shows the RACH configuration duration according to the present disclosure. The information that needs to be signaled by the network / gNB to the UE can include the length of the RACH configuration duration, the number of RACH resource blocks (i.e., RACH blocks), the position of each RACH block, etc. As Figure 24 illustrated, the interval of the RACH blocks can be signaled to the UE in the RACH configuration duration (i.e., the RACH configuration period). For example, the network / gNB can signal the number of time slots or the relative position such as offset information as the RACH block position information in absolute time units starting from RACH block #0, or directly signal the starting time - slot index of the RACH block in the RACH configuration duration for each RACH block.

[0319] Each RACH resource in the RACH resource block can have a unique configuration. In this case, the RACH resources can have different generation frequencies and periods, and each RACH resource can be connected to a specific SS - block CSI - RS or downlink beam direction. When there is such a connection relationship, information about the connection is also provided to the UE. Figure 22Illustrate the configuration of each RACH resource in the RACH resource block. The slot index that can be reserved for the RACH resources in a specific RACH resource period can be defined in the standard document, and different configuration numbers can be allocated according to the RACH resource generation frequency as illustrated in Figure 25 . The network / gNB can signal the generation frequency / period of a specific RACH resource to the UE by signaling a specific configuration number using the system information.

[0320] The network can signal the number and starting point (e.g., slot index) of the RACH resource block (i.e., RACH block) of each RACH resource to the UE. Additionally, when signaling information about each RACH resource block to the UE, the network signals the number Nt of RACH resources on the time axis and the number Nf of RACH resources on the frequency axis. For the RACH resource block, Nt and Nf can be different. The network / gNB maps the RACH resource index according to the time / frequency position of the RACH resources in the RACH resource block, and signals information indicating the period / generation frequency of each RACH resource (e.g., configuration number) and information such as the connected SS block or CSI-RS index. Here, the network / gNB can signal the period / generation frequency of each RACH resource by indicating a specific configuration number set according to the RACH resource generation frequency, as described above.

[0321] Additionally, the RACH preamble format can be set for each RACH resource. Although all RACH preamble formats can be configured to be the same in the system, the subcarrier spacing and the number of repetitions are kept the same in the RACH resource block, and different RACH preamble formats can be set for each RACH resource block. However, the number of repetitions of the RACH preamble is fixed in the same RACH resource block, but each RACH resource included in the RACH resource block can be configured to use different preamble sequences. For example, different root indexes or different cyclic shift (CS) versions can be set for each RACH resource included in the RACH resource block.

[0322] The signaling for RACH configuration is summarized as follows. The network performs a process of identifying time / frequency resources (i.e., RACH resources for RACH preamble transmission). For this, the RACH resource index can be determined by the RACH resource block index and the RACH resource index in the RACH resource block, and the RACH resource generation frequency / cycle for each RACH resource index can correspond to each of the multiple RACH configuration numbers in the present disclosure. In addition, the network sends the RACH preamble information that each RACH resource can use to the UE, and sends the connected SS block index or CSI-RS index information. Therefore, the UE can obtain information about the RACH time / frequency resources and preamble resources to be used when the UE intends to perform RACH in a specific downlink beam direction, and use the corresponding resources to perform RACH.

[0323] Meanwhile, when determining the RACH time slot pattern for RACH resource configuration, as described above, a RACH time slot pattern capable of including RACH resources can be configured regardless of the time slots in which SS blocks can be sent, or a RACH time slot pattern capable of including RACH resources can be configured for the time slots in which SS blocks can be sent.

[0324] (1) RACH resource multiplexing (TDM / FDM / CDM)

[0325] Up to 8 SS blocks can be sent in a band of 6 GHz or lower. For the case where up to 8 SS blocks are sent, it may be necessary to have 8 time slots in the RACH time slot pattern window in which RACH resources can be reserved, or it may not be necessary to reserve 8 time slots. This is because the limitation that the gNB needs to send / receive signals in only one direction at a time is eliminated, because reserving 8 time slots with a length of 1 ms for RACH resources corresponding to the number of SS blocks results in a considerable overhead for the system, and since the band is 6 GHz or lower, digital beamforming can be applied to mmWave.

[0326] Therefore, code division multiplexing or frequency division multiplexing can be performed on the RACH resources in a band of 6 GHz or lower in the configured time slots. That is, as the number of SS blocks sent increases, it is necessary to increase the number of frequency axis resources or divide and use the RACH preamble resources according to the SS blocks.

[0327] It is possible to transmit up to 64 or 128 SS blocks in a frequency band of 6 GHz or higher. For the transmission of 128 SS blocks, 128 RACH resources may not always be configured according to TDM. When a large subcarrier spacing is used, the slot length on the time axis decreases, but the configuration of 128 RACH resources according to TDM always acts as a burden on the network, different from the case where a small subcarrier spacing is used. Therefore, although beamforming is performed only in one direction for SS block transmission, when it is possible to receive RACH preambles in multiple directions simultaneously or when it is possible to transmit signals in multiple directions simultaneously according to the gNB capability, as in the system of 6 GHz or lower described above, it is necessary to consider CDM / FDM of RACH resources in addition to TDM of RACH resources.

[0328] For this purpose, it is necessary to signal the number of frequency division multiplexing resources in the indicated RACH slot mode configuration. The frequency axis information for RACH preamble transmission, i.e., the start frequency information, the number of frequency bands allocated to RACH resources, and whether frequency allocation is performed in the direction of increasing frequency from the start frequency or in the direction of decreasing frequency from the start frequency when RACH resources are frequency division multiplexed, needs to be signaled or specified for a specific direction between the UE and the gNB. When multiple resources are frequency division multiplexed on the frequency axis, the frequency division multiplexed resources or frequency bands can be indexed at a specific time or in a specific slot, and the frequency resource index information mapped to each SS block needs to be signaled or specified in a specific manner between the UE and the gNB.

[0329] In addition, in the case of using CDM of RACH preambles, it is necessary to signal the information about the number of RACH preambles allocated to each SS block. Also, considering the case where CDM / FDM is performed, it is necessary to signal the number of RACH preambles allocated to each SS block.

[0330] (2) ATSS blocks in RMSI (SIB 1 / 2)

[0331] Although it is possible to transmit up to 8 or 128 SS blocks, in an actual system, it is possible to transmit 8 or 128 or fewer SS blocks. If the gNB does not otherwise signal the information about the number of SS blocks transmitted, the gNB needs to signal this information through RMSI (Remaining Minimum System Information) because the UE needs to accurately know this information. This information is called the actually transmitted SS block (ATSS).

[0332] It is desirable to allocate RACH resources based on the actually transmitted SS blocks, rather than based on the assumed maximum number of SS blocks implemented in the standard, to prevent system waste. As shown in Table 9, when configuring the RACH time slot pattern for RACH resource allocation, SS blocks can be transmitted or not transmitted in the time slots indicated in the RACH time slot pattern configuration. Such information can be detected through the ATSS included in the RMSI. Although the RACH time slot pattern for RACH resources is configured except for the time slots in which SS blocks can be transmitted even in RACH time slot pattern configuration method 2, the mapping to the actual RACH resources is based on the ATSS. When the RACH time slot pattern configuration conflicts with some ATSS information, that is, when the RMSI indicates the ATSS transmission of SS blocks in the time slots indicated by the RACH time slot pattern, the UE recognizes that the SS blocks are transmitted in the time slots and thus cannot use the time slots. That is, the UE does not attempt RACH preamble transmission in the time slots and excludes the time slots from the mapping for the association between the SS blocks and the RACH resources.

[0333] The UE checks the number and location of available RACH time slots by combining the PRACH configuration and the ATSS information. The number of available time slots on the time axis, the number of RACH resources in the RACH time slots according to the RACH preamble format, the number of resources on the frequency axis, and / or the number of RACH preambles available for each SS block are combined to determine the association between the SS blocks and the RACH resources. That is, the association between the SS blocks and the RACH resources is not preset according to the RACH time slot pattern for RACH resource allocation and the maximum number of SS blocks, but is determined according to the provided signaling, and the mapping between the SS blocks and the RACH resources is performed.

[0334] If time division multiplexing is performed on the RACH resources and then frequency division multiplexing is performed on the RACH resources, the position of the frequency axis resources, the number of frequency axis resources, the information on the number of frequency resources allocated to one SS block, and the information on the number of RACH preambles allocated to each frequency resource need to be signaled. If time division multiplexing is performed on the RACH resources and then code division multiplexing is performed on the RACH resources, the information on the number of RACH preambles that can be used for each SS block needs to be signaled.

[0335] In other words, when Ns is the number of SS blocks, the following information needs to be signaled.

[0336] - Nf: The number of RACH resources for each frequency division multiplexing.

[0337] - Nfc: The number of RACH preambles that can be used in one frequency resource

[0338] -Nfs: The number of frequency resources that can be associated with an SS block

[0339] -Nc: The number of RACH preambles allocated to each SS block

[0340] The UE detects the number and location of time slots that can be used as available RACH resources on the timeline by combining the RACH time slot pattern configuration and the ATSS information, and calculates the number of RACH resources on the timeline using the signaled RACH preamble format.

[0341] Then, the UE calculates the time / frequency / code information that can be used as RACH resources by combining the signaled frequency and code domain information, indexes the corresponding RACH resources, and then performs the mapping between the SS block and the corresponding RACH resource index. At the same time, the method by which the UE calculates the RACH resource index needs to be performed by a method previously specified between the UE and the network, and the actually transmitted SS blocks are mapped to the RACH resource index / associated with the RACH resource index in ascending order of the SS block index.

[0342] That is, when the SS block index is signaled as 2, 5, 5, and 7 and the RACH resource index is 0, 1, 2, and 3 by the RMSI indicating the ATSS, SS blocks #2, #4, #5, and #7 are mapped to RACH resources #0, #1, #2, and #3 respectively.

[0343] The RACH resource indexing is performed in such a way that the RACH resources are indexed in the order of code resources in the basic time / frequency domain of the index, while indexing the code resources, and then indexing in ascending order of frequency resources and indexing in the order of code resources. Alternatively, the frequency resources are indexed simultaneously and then the time resources are indexed.

[0344] After indexing the RACH resources in a given order, the number of RACH resources may not always correspond to the number of SS blocks. In this case, the number of RACH resources is generally equal to or greater than the number of SS blocks. When there are RACH resources remaining after association with all ATSSs and thus there are RACH resources not associated with any SS block in the RACH resource configuration window or the RACH time slot pattern configuration window, the corresponding RACH time / frequency resources are not reserved for RACH resources. The UE does not assume that RACH is transmitted in the corresponding resources and always transmits uplink. If there are no RACH resources associated with a specific ATSS, i.e., the RACH resources are insufficient for the number of SS blocks, the network can send signaling for allowing a time slot adjacent to a specific time slot included in the RACH time slot pattern configuration of the RACH resources as RACH resources for the UE.

[0345] Here, a specific slot index and the number of slots can be specified by signaling, and the first slot that does not transmit an SS block among the slots adjacent to the last slot of the slot implicitly indicated in the RACH slot pattern configuration or the specified specific slot can be used as the RACH resource.

[0346] Alternatively, the UE can additionally use the RACH resources corresponding to the number of slots in which the RACH slot pattern configuration conflicts with the ATSS information. When two slots are used for SS block transmission, the UE can use the slots adjacent to the two slots used for SS block transmission among the slots indicated by the corresponding RACH slot pattern configuration as the slots for RACH. The corresponding slots must be the slots not used for SS block transmission. When the SS block is transmitted in an adjacent slot, the slot immediately following that slot is selected. The processing of the remaining RACH resources is performed in the same manner as described above.

[0347] As another method for the case where there are RACH resources not associated with any SS block, the remaining RACH resources are mapped sequentially from the first ATSS again. That is, the number of RACH resources can be greater than the number of ATSSs, and preferably, each ATSS will be mapped to the RACH resources k times. In other words, the ATSSs are cyclically associated with the RACH resources k times. Referring to Figure 26 , when there are 3 ATSSs and 8 RACH resources, the 3 ATSSs are mapped to 3 RACH resources and then mapped again to the next 3 RACH resources, and the remaining 2 RACH resources are not associated with the ATSSs. The number of ATSSs is related to the number of RACH resources such that each ATSS needs to be mapped to at least one RACH resource in the PRACH configuration window, and the ATSS-RACH resource mapping pattern can be repeated k times according to the freedom of the network. If there are still remaining RACH resources even after mapping the ATSSs to the RACH resources k times, the remaining RACH resources are not reserved for the RACH resources. When the remaining RACH resources have a slot / micro-slot length, the UE performs DCI monitoring in the corresponding slot. Here, k is a positive integer and can be the maximum number of times the ATSSs are mapped to the RACH resources. That is, k can be floor(number of RACH resources / number of ATSSs). In other words, the ATSSs are repeatedly mapped to the RACH resources k times, which is a positive integer in the PRACH configuration window, and the remaining RACH resources are invalid as RACH resources.

[0348] In addition, the pattern in which each of the ATSSs is mapped to at least one RACH resource can be repeated in the PRACH configuration window. This is described in detail by the above example. When mapping 3 ATSSs to 8 RACH resources twice and leaving 2 RACH resources remaining in the PRACH configuration window of a specific duration, in the PRACH configuration window of the next duration, map the 3 ATSSs to the 8 RACH resources twice in the same pattern, and the 2 remaining RACH resources are invalid RACH resources and thus may not be reserved for RACH resources.

[0349] Unless there are special cases such as setting the PRACH configuration window through additional signaling, the PRACH configuration window can have the same duration as the PRACH configuration period. That is, unless otherwise specified, the PRACH configuration window can be the same as the PRACH configuration period.

[0350] (3) Indicate the ATSS through RRC signaling

[0351] The aforementioned ATSS is information sent simultaneously with the time of performing the PRACH configuration and is sent through the RMSI (i.e., SIB1 / 2) that carries the most basic information of the system after PBCH transmission. However, this information needs to be broadcast to all UEs in the cell and results in a considerable signaling overhead to indicate whether up to 128 SS blocks are sent.

[0352] Therefore, the information about the ATSS is sent in the form of a compressed bitmap rather than a full bitmap in the RMSI. The system provides accurate ATSS information for serving cell measurement after the random access procedure and sends the ATSS information through RRC. The ATSS information received through the RMSI may be different from the ATSS information received through RRC. In this case, the ATSS information sent through RRC signaling takes precedence over the ATSS information sent through the RMSI. In this case, additional factors for UE operation regarding RACH resources need to be considered.

[0353] The UE does not assume to send / receive PUSCH / PUCCH and downlink channels in the time / frequency resources allocated to the RACH resources. The resources reserved for RACH have a higher resource allocation priority than the resources immediately following the resources in which the SS block is sent. However, when the UE learns that some of the SS blocks in the ATSS received through the RMSI are not actually sent by using the ATSS information sent through RRC, the UE releases all RACH resources associated with the SS blocks that have not actually been sent. That is, it is assumed that no RACH preambles are sent in the released resources. In addition, the released resources can be used as downlink resources. That is, the UE performs DCI monitoring in the released resources / time slots.

[0354] 8. Resource Allocation in RACH Time Slots

[0355] When information about RACH time slots is correctly provided, RACH resources in each RACH time slot can be obtained based on the combination of the RACH preamble format and the subcarrier spacing indicated by Msg 1.

[0356] In addition, in order to signal the correct position of RACH resources in a time slot, the network needs to signal RACH time slot type information, such as the starting symbol index of RACH resources, as Figure 27 shown. Here, the starting symbol index can be 0, 1, or 2. Although RACH time slot type information signaling can be performed for each RACH time slot, it is more desirable to perform RACH time slot type information signaling for all RACH time slots in order to reduce signaling overhead.

[0357] (1) Frequency Domain Configuration

[0358] The frequency position of RACH resources is signaled based on the initial bandwidth part (BWP) of the uplink in the bandwidth part and the resource allocation information for RACH transmission.

[0359] (2) RACH Resource Allocation in RACH Time Slots

[0360] When using a short-sequence-based RACH preamble, multiple RACH resources can be included in a single RACH time slot. In this case, RACH resources can be allocated continuously or discontinuously. Although discontinuous allocation of RACH resources may be advantageous in terms of flexibility and latency reduction, the network needs to indicate which symbols are reserved for RACH. Therefore, considering resource efficiency and signaling overhead, it is desirable to allocate RACH resources continuously in a RACH time slot. That is, when multiple RACH resources are included in a RACH time slot, it is desirable to arrange the RACH resources continuously even if not all the resources included in the RACH time slot are used as RACH resources.

[0361] When the RACH resources are continuous, RACH preamble format B is applied to the last RACH resource in the continuous RACH resources in the RACH time slot, and RACH preamble format A / B is applied to the remaining RACH resources.

[0362] In addition, in order to support URLLC in NR, the RACH time slot can be configured as follows.

[0363] - Option 1: Allocate RACH resources in the RACH time slot based on a micro-slot configuration, and determine the length of the micro-slot according to the transmission of RMSI in the idle mode or other system information.

[0364] - Option 2: Determine the RACH time slot pattern based on micro time slots, and the system in the idle mode supports micro time slots.

[0365] - Option 3: Dynamic or semi-static signaling takes precedence over RACH resource configuration.

[0366] In the cases of Option 1 and Option 2, the RACH resources are continuously allocated in the micro time slots within the RACH time slot, and the RACH resources are not allocated to the micro time slots following the micro time slots where the RACH resources have been continuously allocated. Additionally, in the cases of Option 1 and Option 2, the starting symbol index of the RACH resources included in the micro time slot where the RACH resources are allocated can be signaled, or the micro time slots can have the same RACH resource allocation pattern within the RACH time slot.

[0367] However, in the case of Option 2, as the number of micro time slots included in the RACH time slot increases, the number of RACH time slot patterns increases, and thus the overhead for specifying the RACH time slot pattern may increase. Therefore, network signaling can take precedence over RACH resource configuration for dynamic utilization and resource flexibility. However, since the RACH resources are reserved in the idle mode with high priority, the above method is not desirable.

[0368] <RACH Resource Association>

[0369] When obtaining RACH resource information, it is necessary to obtain the SS block index associated with each RACH resource. The simplest method is to signal the SS block index associated with each RACH resource. However, a predefined rule is needed to map the SS blocks to the RACH resources to reduce signaling overhead. For example, the predefined rule can be regarded as a method of sequentially mapping the SS blocks to the RACH resource groups in the time domain and mapping the actually transmitted SS blocks to the RACH resource groups again.

[0370] (1) Derive the valid RACH time slot and the valid RACH symbol

[0371] Since the RACH resources are mapped to the RACH time slot according to the PRACH configuration, regardless of the time position of the SS blocks actually transmitted in TDD / FDD, the UE needs to be able to derive the valid RACH time slot by combining the information included in the PRACH configuration and the information about the SS blocks actually transmitted through RMSI. Additionally, the candidate time slot positions for SS block transmission are not always reserved for SS block transmission. That is, as described above, the information indicating whether each SS block is actually transmitted, i.e., the actually transmitted SS block information, is indicated through RMSI.

[0372] In other words, the UE needs to be able to combine the information on the SS blocks actually transmitted via RMSI and the PRACH configuration information, and derive a valid RACH time slot considering the predefined rules.

[0373] In addition, when the UE derives a valid RACH time slot, the UE needs to be able to derive valid RACH symbols based on the signaled RACH preamble format and the starting symbol index of the RACH time slot specified for all cells. Moreover, the symbols indicated as uplink via slot format indication (SFI) can be valid RACH symbols, and thus the UE needs to consider the SFI to derive valid RACH symbols. Here, the valid RACH symbols need to satisfy the number of consecutive symbols defined by the RACH preamble format. In addition, a single set of valid RACH symbols can be defined as a single RACH occasion.

[0374] Furthermore, since it is necessary to determine whether the RACH resources are always allocated continuously in the RACH time slot and whether the number of RACH occasions per RACH time slot is the same for all RACH time slots, explicit signaling is required when the number of RACH occasions per RACH time slot is different for a cell. In addition, in order to calculate the total number of RACH occasions of the UE, the network needs to signal the number of frequency-division multiplexed RACH resources via the RACH-Config index in the two-dimensional time / frequency resource region.

[0375] (2) Rules for mapping valid RACH resources or valid RACH occasions to SS blocks

[0376] If the total number of RACH occasions that can be allocated within the PRACH configuration period is determined, then the method of mapping the SS blocks to the RACH occasions needs to be determined. If the number of RACH occasions per SS block is 1, i.e., if the SS blocks are mapped to the RACH occasions one-to-one, then the method of mapping the SS blocks to the RACH occasions can be easily determined because the SS blocks can be mapped to the RACH occasions sequentially. Similarly, when there are frequency-division multiplexed RACH occasions, it is desirable to first map the SS blocks to the frequency-division multiplexed RACH occasions and then map the SS blocks to the RACH occasions in the time domain. Here, the time period of the RACH occasions needs to be set according to the PRACH configuration period.

[0377] Figure 28 Illustrate the case assuming a RACH preamble format with a length of 4 symbols, 4 RACH occasions in the time slot, and a starting symbol index of 2. Refer to Figure 28 Describe the mapping relationship between the SS blocks and the RACH occasions. When there are frequency-division multiplexed RACH occasions, the method of mapping the SS blocks to the frequency axis and then mapping the SS blocks to the time axis can be used.

[0378] Determine the RACH resource mapping pattern period based on the actually transmitted SS block and the rule for mapping the SS block to a valid RACH occasion, and thus the RACH resource mapping pattern period can be different from the PRACH configuration period.

[0379] To create a more general mapping rule, the following parameters can be assumed.

[0380] - X: The total number of RACH occasions

[0381] - N SSB_per_RO : The number of SS blocks per RACH occasion

[0382] - N seq_per_SSB_per_RO : The number of CBRA preambles per SS block for the RACH transmission occasion

[0383] - M: The number of RACH occasions per SS block. M is obtained by N seq_per_SSB / N seq_per_SSB_per_RO obtained.

[0384] - Fd: The number of RACH occasions that can be mapped to one SS block simultaneously

[0385] 1) When M ≥ 1

[0386] When one SS block is mapped to multiple RACH occasions, that is, when one-to-many mapping is performed, the value of M is an integer corresponding to M > 1, and Fd = 1. M time-division multiplexed RACH occasions can be sequentially mapped to one SS block.

[0387] In other words, when 1 / M, which is the number of SS blocks per RACH occasion, is less than 1, the SS block can be mapped to M RACH occasions. Here, the RACH occasions mapped to one SS block can be consecutive RACH occasions.

[0388] If Fd > 1, map M RACH occasions to the SS block in the order of frequency first and time second. Preferably, when M is a multiple of Fd, a single SS block can be mapped to frequency-division multiplexed RACH occasions within a predetermined time. If multiple SS blocks are mapped to one RACH occasion at the same time, it is necessary to ensure that the network can receive the directions of the beams corresponding to the multiple SS blocks simultaneously.

[0389] The above description is summarized as shown in Table 13.

[0390] [Table 13]

[0391]

[0392] 2) When M < 1

[0393] Describe the case where multiple SS blocks are mapped to one RACH occasion, i.e., the case of performing many-to-one mapping. If 0 < M < 1 and 1 / M = N, where N is defined as the number of SS blocks mapped to one RACH occasion, and it is assumed that multiple SS blocks are code-division multiplexed to one RACH occasion and the beam directions corresponding to the multiple SS blocks are the directions in which the network can simultaneously receive the beams corresponding to the SS blocks.

[0394] If the maximum number of RACH preamble indices, such as 64, is allocated to the RACH occasion, the RACH preambles mapped to the SS blocks can be mapped in a comb pattern to facilitate increasing the RACH reception performance under the assumption of receiving RACH preambles according to spatial division multiple access (SDM). In other words, if 2 SS blocks are mapped to one RACH occasion, the other RACH preamble indices are mapped to the 2 SS blocks. Here, to improve the RACH preamble reception performance, the actual cyclic shift allocated to each SS block is defined as N * Ncs.

[0395] Meanwhile, when multiple SS blocks are associated with one RACH occasion, the CBRA preamble indices for each SS block can be mapped discontinuously for RACH performance improvement. Additionally, mapping multiple SS blocks to multiple RACH occasions can be considered, but this mapping method leads to implementation complexity and is therefore preferably excluded from the mapping types.

[0396] (4) Rules for mapping RACH resources to RACH preambles

[0397] Since the maximum number of RACH preambles for each RACH resource and RACH resource group is limited, it is necessary to allocate RACH preambles to the RACH resource / RACH resource group in the direction of increasing root index cyclic shift, where the root index increases and the time domain increases. Here, it is necessary to signal the starting root index mapped to the first RACH resource.

[0398] The common RACH preamble format needs to be applied to all RACH resources by the same number of repetitions because there is no reason to use different RACH preamble formats for RACH resources considering the target coverage of the cell for at least the RACH procedure in the idle state.

[0399] 1) Example 1: Number of RACH preambles for each RACH occasion or SS block

[0400] Information about the RACH preambles and a series of supported RACH preamble values that the UE needs to know in order to map RACH preambles to RACH opportunities is shown in Table 14. In addition, the UE can calculate the number of RACH preambles for each RACH opportunity based on the number of RACH preambles per SS block for contention-based random access (CBRA) and the number of RACH opportunities per SS block and signal the number of RACH opportunities per SS block.

[0401] [Table 14]

[0402]

[0403]

[0404] When M ≥ 1, the number of RACH preambles for CBRA for each RACH opportunity is calculated as the value obtained by dividing the number of RACH preambles for CBRA per SS block by M. Here, if there is a non-zero remainder, the RACH preambles not mapped to RACH opportunities are assigned to the RACH opportunity with the maximum or minimum index associated with the SS block. Alternatively, the RACH preambles can be mapped to RACH opportunities by a cyclic method. For example, when the number of RACH preambles per SS block is 48 and the number of RACH opportunities mapped to the SS block is 4, the number of preambles for each RACH opportunity is 12. If the number of RACH preambles per SS block is 48 and the number of RACH opportunities mapped to the SS block is 5, then each RACH opportunity can use at least 9 RACH preambles. For each RACH opportunity mapped to the SS block, the remaining 3 RACH preambles can be sequentially mapped to the RACH opportunity index in a frequency-first and time-second manner.

[0405] When M < 1, if multiple SS blocks are mapped to one RACH occasion and the multiple SS blocks share the same RA-RNTI, the maximum number of RACH preambles for each RACH occasion is 64 RAPIDs. If the sum of the RACH preambles for multiple SS blocks is not greater than 64, the UE can use the number of RACH preambles for each SS block for the RACH occasion signaled. However, if the sum of the RACH preambles for multiple SS blocks is greater than 64, the number of RACH preambles that the UE can use can be recalculated so that the number of RACH preambles for each SSB in the RACH occasion does not exceed 64. For example, when M is 1 / 4 and the number of RACH preambles for each SS block is 16, the sum of the RACH preambles for each of the 4 SS blocks does not exceed 64, and thus 16 preambles for each RACH occasion are used. That is, if M is 1 / 4 and the number of RACH preambles for each SS block is 32, the number of RACH preambles for each SS block in the RACH occasion needs to be limited to 16.

[0406] When multiple SS blocks are mapped to one RACH occasion, i.e., M < 1, the RA-RNTI can be allocated for each SS block at the same time / frequency position. In other words, when M is 1 / 4 and the number of RACH preambles for each SS block is 32, 32 * 4 RACH preambles can be used for the RACH occasion with the RA-RNTI unique to the SS block, and thus different RARs are generated for the SS blocks regarding the RACH occasion. This involves a method of calculating the RA-RNTI regardless of whether the virtual SS block index is calculated.

[0407] 2) Example 2: Method for mapping SS blocks and RACH occasions to RACH preamble indices

[0408] Determine the number of RACH preambles for each SS block and the number of RACH preambles for each RACH occasion according to the RACH preamble index mapping rule. The RACH preamble index is mapped in the RACH resource group. If a single SS block is associated with one RACH resource group, the RACH preamble index is mapped to the RACH occasion associated with the SS block.

[0409] When M ≥ 1, if the number of RACH preambles for each RACH occasion is Npreamble_occasion and each RACH occasion has an index #n (n = 0, 1,..., M - 1), the nth RACH occasion has RACH preamble indices {0 to (Npreamble_occasion - 1)+(n * Npreamble_occasion)}.

[0410] Conversely, when M < 1, if the SS blocks in the RACH occasion share the RA-RNTI and the number of RACH preambles calculated for each SS block is Npreamble_SSB, the RACH preamble indices {0 to (Npreamble_SSB - 1)+(m * Npreamble_SSB)} are assigned to the m-th SS block. Here, m is the SS block index reordered based on the actually transmitted SS blocks. Additionally, the RACH occasion can have values from 0 to Npreamble_occasion as the RACH preamble indices of Npreamble_occasion. Here, Npreamble_occasion can be 64.

[0411] Meanwhile, each SS block is assigned the RA-RNTI, and each SS block is assigned the RACH preamble indices {0 to (Npreamble_SSB - 1)}. The number of RACH preambles that can be associated with the RACH occasion can be m * Npreamble_SSB. Here, m is the number of SS blocks mapped to the RACH occasion, and Npreamble_SSB is the number of RACH preambles for each SS block and can be obtained by signaling.

[0412] 3) Example 3: Method for mapping RACH occasions / SS blocks to RACH preambles

[0413] Basically, the RACH preambles are assigned to the RACH occasion in the directions of root index cyclic shift increase, root index increase. If the RACH resource group consists of time-division multiplexed RACH occasions with Fd = 1, the RACH preambles can be assigned to the RACH resource group in the directions of root index cyclic shift increase, root index increase, and time domain increase, i.e., the direction of RACH occasion index increase.

[0414] Additionally, if the RACH resource group consists of time-division multiplexed RACH occasions with Fd > 1, the RACH preambles can be assigned to the RACH resource group in the directions of root index cyclic shift increase, root index increase, frequency domain increase, and time domain increase.

[0415] If the RACH preamble sequences can be different for different RACH resource groups, the RACH preambles can generally be assigned in the directions of root index cyclic shift increase, root index increase, and when Fd > 1, frequency domain increase and time domain increase.

[0416] (5) Total number of RACH occasions in the PRACH configuration period

[0417] The total number of RACH opportunities can be calculated by multiplying the number of RACH time slots in a subframe in a time instance indicated by a 2-bit value included in the PRACH configuration, the number of RACH opportunities in an RACH time slot, the number of subframes for each PRACH configuration index, the number of frequency-division multiplexed RACH opportunities, and the PRACH configuration period.

[0418] In addition, the UE can derive the total number of RACH opportunities in the two-dimensional time domain / frequency domain based on the foregoing information.

[0419] Meanwhile, the total number of RACH opportunities may not be exactly the same as the number of RACH opportunities that need to be associated with the actually transmitted SS block in the PRACH configuration period. When the total number of RACH opportunities is greater than the required number of RACH opportunities, the remaining RACH opportunities are not used for RACH opportunities and are used for uplink data transmission. When the total number of RACH opportunities is less than the required number of RACH opportunities, this needs to be recognized by the network as a configuration error, and this type of configuration needs to be avoided.

[0420] Figure 29 FIG. is a block diagram showing components of a transmitting device 10 and a receiving device 20 that implement the present disclosure.

[0421] The transmitting device 10 and the receiving device 20 each include a radio frequency (RF) unit 13 and 23 that transmit or receive radio signals carrying information and / or data, signals, and messages; memories 12 and 22 that store various types of information related to communication in a wireless communication system; and processors 11 and 21 that are operably coupled to components such as the RF units 13 and 23 and the memories 12 and 22, and control the memories 12 and 22 and / or the RF units 13 and 23 to perform at least one of the foregoing embodiments of the present disclosure.

[0422] The memories 12 and 22 can store programs for processing and controlling the processors 11 and 21, and temporarily store input / output information. The memories 12 and 22 can be used as buffers.

[0423] Processors 11 and 21 generally provide overall control over the operations of various modules in the transmitting device or the receiving device. Specifically, processors 11 and 21 may perform various control functions to implement the present disclosure. Processors 11 and 21 may be referred to as a controller, a microcontroller, a microprocessor, a microcomputer, etc. Processors 11 and 21 may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In a hardware configuration, processors 11 and 21 may be provided with an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), and so on. In a firmware or software configuration, the firmware or software may be configured to include modules, procedures, functions, etc. The firmware or software configured to implement the present disclosure may be provided in processors 11 and 21, or may be stored in memories 12 and 22 and executed by processors 11 and 21.

[0424] The processor 11 of the transmitting device 10 performs predetermined encoding and modulation on signals and / or data scheduled by the processor 11 or a scheduler connected to the processor 11, and transmits the same to the outside, and then transmits the encoded and modulated signals and / or data to the RF unit 13. For example, the processor 11 converts the transmission data stream into K layers after demultiplexing, channel coding, scrambling, modulation, etc. The encoded data stream is referred to as a codeword, which is equivalent to the data block provided by the MAC layer, that is, the transport block (TB). One TB is encoded into one codeword, and each codeword is transmitted to the receiving device in the form of one or more layers. For upconversion, the RF unit 13 may include an oscillator. The RF unit 13 may include N t transmitting antennas (N t is a positive integer equal to or greater than 1).

[0425] The signal processing of the receiving device 20 is configured to be opposite to that of the transmitting device 10. The RF unit 23 of the receiving device 20 receives a radio signal from the transmitting device 10 under the control of a processor. The RF unit 23 may include N r receiving antennas, and restores the signals received through each receiving antenna to baseband signals through downconversion. For downconversion, the RF unit 23 may include an oscillator. The processor 21 may restore the original data intended to be transmitted by the transmitting device 10 by decoding and demodulating the radio signals received through the receiving antennas.

[0426] Each of the RF units 13 and 23 may include one or more antennas. According to an embodiment of the present disclosure, the antennas transmit the signals processed by the RF units 13 and 23 to the outside, or receive radio signals from the outside, and provide the received radio signals to the RF units 13 and 23 under the control of the processors 11 and 21. The antennas may also be referred to as antenna ports. Each antenna may correspond to a physical antenna, or may be configured as a combination of two or more physical antenna units. The signals transmitted from each antenna may not be further decomposed by the receiving device 20. The RS transmitted corresponding to the respective antennas defines the antennas as viewed from the receiving device 20 side, and enables the receiving device 20 to perform channel estimation of the antennas, whether the channel is a single radio channel from one physical antenna or a composite channel from a plurality of physical antenna elements including the antenna. That is, the antennas are defined such that the channel carrying the symbols on the antenna can be derived from the channel carrying another symbol on the same antenna. In the case of an RF unit supporting MIMO in which data is transmitted and received through a plurality of antennas, the RF unit may be connected to two or more antennas.

[0427] In the present disclosure, the RF units 13 and 23 may support receive BF and transmit BF. For example, the RF units 13 and 23 may be configured to perform the reference in the present disclosure Figures 5 to 8 In the example functions described above. In addition, the RF units 13 and 23 may be referred to as transceivers.

[0428] In an embodiment of the present disclosure, the UE operates as the transmitting device 10 on the UL and as the receiving device 20 on the DL. In an embodiment of the present disclosure, the gNB operates as the receiving device 20 on the UL and as the transmitting device 10 on the DL. Hereinafter, the processor, RF unit, and memory in the UE are respectively referred to as the UE processor, UE RF unit, and UE memory, and the processor, RF unit, and memory in the gNB are respectively referred to as the gNB processor, gNB RF unit, and gNB memory.

[0429] The gNB processor of the present disclosure may send information about the ATSS and RACH configuration information about the RACH resources to the UE. When the RACH is received in the RACH resources, the gNB may obtain information about the SSB corresponding to the synchronization that the UE wants to obtain based on the RACH resources on which the RACH has been sent. That is, the gNB processor can know information about the SSB corresponding to the beam selected by the ATSS having the highest RSRP value in the ATSS measured by the UE based on the RACH resources on which the RACH has been sent. Therefore, the gNB processor cannot receive the RACH through the RACH resources not mapped to the ATSS.

[0430] The UE processor of the present disclosure maps the ATSS to the RACH resource based on the ATSS information and the information on the RACH resource received from the gNB, and transmits the RACH in the RACH resource mapped to the SSB with the highest RSRP value selected from the received SSBs based on the ATSS information. Therefore, the UE does not transmit the RACH in the RACH resource not mapped to the ATSS.

[0431] In the RACH resource not mapped to the ATSS, an uplink transmission other than the RACH resource transmission may occur, or downlink reception may be performed.

[0432] Here, the UE processor repeatedly maps the ATSS to the RACH resource during the RACH configuration period, the number of repeated mappings is a positive integer multiple of the number of ATSSs, and does not transmit the RACH through the remaining RACH resources after the mapping. In addition, the number of times of repeatedly mapping the ATSS may be the same as the largest integer among the integers less than the value obtained by dividing the number of RACH resources by the number of ATSSs. In addition, when the number of SSBs that can be mapped to the RACH resource is less than 1, one SSB is mapped to as many consecutive RACH resources as the reciprocal of the number.

[0433] The gNB processor or UE processor of the present disclosure may be configured to implement the present disclosure in a cell operating in a high frequency of 6 GHz or above, where analog BF or hybrid BF is used.

[0434] As described above, a detailed description of the preferred embodiments of the present disclosure has been given so that those skilled in the art can implement and execute the present disclosure. Although the above has referred to the preferred embodiments of the present disclosure, those skilled in the art will understand that various modifications and changes can be made to the present disclosure within the scope of the present disclosure. For example, those skilled in the art can use the components described in the foregoing embodiments in combination. Therefore, the above embodiments should be construed as illustrative in all aspects and not restrictive. The scope of the present disclosure should be determined by the appended claims and their legal equivalents, rather than by the above description, and all changes falling within the meaning and scope of the appended claims are intended to be included therein.

[0435] Industrial Applicability

[0436] Although the method and apparatus for transmitting and receiving a random access channel have been described by focusing on examples applied to 5G NewRAT, the method and apparatus can be applied to various wireless communication systems other than 5G NewRAT.

Claims

1. A method for a UE to transmit a Random Access Channel (RACH) in a wireless communication system, the method comprises: receiving information related to a Synchronization Signal Block (SSB) actually transmitted, and RACH configuration information related to resources for transmitting RACH preambles; and transmitting the RACH preamble in RACH resources based on the information related to the actually transmitted SSB and the RACH configuration information, wherein the UE obtains the RACH resources based on the mapping of the actually transmitted SSB to the RACH resources within the RACH configuration window, wherein, within the RACH configuration window, the actually transmitted SSB is repeatedly mapped to the RACH resources through a positive integer number of mapping cycles, and any remaining RACH resources within the RACH configuration window after the repeated mapping are not mapped to the actually transmitted SSB and are not used as RACH resources.

2. The method according to claim 1, further comprises: transmitting an uplink signal other than the RACH preamble or receiving a downlink signal in RACH resources not mapped to the actually transmitted SSB.

3. The method according to claim 1, wherein, each RACH resource mapped to the actually transmitted SSB maps the number of actually transmitted SSBs.

4. The method according to claim 3, wherein, the number of actually transmitted SSBs mapped to each RACH resource is less than 1, and one actually transmitted SSB is mapped to as many consecutive RACH resources as the reciprocal of the number of actually transmitted SSBs mapped to each RACH resource.

5. A processor for a User Equipment (UE), the processor being configured to be coupled to a Radio Frequency (RF) transceiver of the UE and execute the method according to any one of claims 1 to 4.

6. A User Equipment (UE) in a wireless communication system, comprises: a Radio Frequency (RF) transceiver configured to transmit and receive radio signals; and a processor according to claim 5, the processor being coupled to the RF transceiver.

7. A computer program product comprising computer program code tangibly embodied in a computer-readable medium, the computer program code comprising instructions that, when provided to a User Equipment (UE) and executed on a processor of the UE, cause the UE to execute the method according to any one of claims 1 to 4.

Images