Method and apparatus for performing multi-beam based random access procedure in wireless communication

Abstract

This disclosure provides a method and apparatus for performing a multi-beam-based random access procedure in wireless communication. A method for a base station to perform a contention-free multi-beam-based random access procedure in wireless communication includes: transmitting information about one or more random access channel (RACH) resources to a user equipment via Radio Resource Control (RRC) signaling, said one or more RACH resources including information for beam direction acquisition, different RACH resources being mapped to each beam, and one or more multi-RACH preambles being mapped to said one or more RACH resources based on Frequency Division Multiplexing (FDM); receiving one or more assigned multi-RACH preambles from the user equipment using the one or more RACH resources across multiple beams; and transmitting a random access response to the user equipment.

Description

[0001] This application is a divisional application of Chinese patent application No. 201780067632.1, filed on October 27, 2017, entitled “Method and apparatus for performing a multi-beam-based random access procedure in wireless communication”. Technical Field

[0002] This disclosure relates to methods and apparatus for performing a multi-beam-based random access procedure in a next-generation / 5G radio access network (hereinafter referred to as "New Radio (NR)"). Background Technology

[0003] Recently, 3GPP approved a research project, "Study on New Radio Access Technology," for researching next-generation / 5G radio access technologies. Building upon this research, Radio Access Network Working Group 1 (RAN WG1) has discussed frame structure, channel coding and modulation, waveforms, and multiple access methods for New Radio (NR). The requirement is that NR be designed to not only provide improved data rates compared to LTE / LTE-Advanced, but also meet various requirements in specific and particular use cases.

[0004] In particular, enhanced mobile broadband (eMBB), massive machine-type communication (mMTC), and ultra-reliable low-latency communication (URLLC) have been proposed as representative use cases for NR. To meet the requirements of each scenario, NR needs to be designed with a more flexible frame structure compared to LTE / LTE-Advanced.

[0005] Furthermore, as a method to address delay spread caused by multiple paths, a cyclic prefix is ​​included at the beginning of OFDM symbols in OFDM-based wireless communication systems. A cyclic prefix is ​​also included at the beginning of each OFDM symbol in LTE / LTE-Advanced systems.

[0006] Specifically, in LTE / LTE-Advanced systems, OFDM-based resource elements with identical subcarrier spacing and symbol spacing are configured, and the base station configures the cyclic prefix length, etc., based on the cell size and corresponding delay spread characteristics. User equipment detects the length of the cyclic prefix configured in the corresponding cell by receiving a synchronization signal and achieving time / frequency synchronization with the cell.

[0007] In this regard, NR systems have been developed to support multiple parameter sets (numerology) to support various use cases, and therefore there is a need to provide a method for configuring the length of the cyclic prefix for parameter sets other than the parameter set used to transmit synchronization signals. Summary of the Invention

[0008] Technical issues

[0009] The purpose of this disclosure is to provide a specific method for RACH operation required when operating a multi-beam-based uplink in an environment where Tx / Rx channel reciprocity is unavailable.

[0010] Technical solution

[0011] According to one aspect of this disclosure, a method is provided for a base station to perform a multi-beam-based random access procedure in wireless communication. The method includes: transmitting information about one or more random access channel (RACH) resources to a user equipment; receiving one or more multi-RACH preambles from the user equipment using multiple beams; and transmitting a random access response to the user equipment.

[0012] According to another aspect of this disclosure, a method is provided for a user equipment to perform a multi-beam-based random access procedure in wireless communication. The method includes: receiving information from a base station regarding one or more RACH resources; transmitting one or more multi-RACH preambles to the base station using multiple beams; and receiving a random access response from the base station.

[0013] According to another aspect of this disclosure, a user equipment is provided for performing a multi-beam-based random access procedure in wireless communication. The user equipment includes: a receiver configured to receive information about one or more RACH resources from a base station and to receive a random access response from the base station; and a transmitter configured to transmit one or more multi-RACH preambles to the base station using multiple beams.

[0014] Invention Effects

[0015] According to embodiments of this disclosure, RACH operations required when operating a multi-beam-based uplink in an environment where Tx / Rx channel reciprocity is unavailable can be performed. Attached Figure Description

[0016] Figure 1 This is a diagram illustrating a contention-based random access process.

[0017] Figure 2 This is a diagram showing the timing of the Random Access Response (RAR) window.

[0018] Figure 3 This is a diagram showing the timing of the random access response.

[0019] Figure 4 This is a diagram illustrating a contention-free random access procedure.

[0020] Figure 5 This is a diagram illustrating the resource block (RB) structure in a hybrid parameter set based on TMD.

[0021] Figure 6 This is a diagram illustrating a method for transmitting a sector-based RACH preamble according to an embodiment of the present disclosure.

[0022] Figure 7 This is a flowchart illustrating a method for a base station to perform a multi-beam-based random access procedure in wireless communication, according to another embodiment of the present disclosure.

[0023] Figure 8 This is a flowchart illustrating a method for a user equipment to perform a multi-beam-based random access procedure in wireless communication, according to another embodiment of the present disclosure.

[0024] Figure 9 This is a block diagram illustrating a base station according to another embodiment of the present disclosure.

[0025] Figure 10 This is a block diagram illustrating a user equipment according to another embodiment of the present disclosure. Detailed Implementation

[0026] In the following description, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. When adding reference numerals to elements in each drawing, the same elements will be designated by the same reference numerals, even if they are shown in different drawings, where possible. Furthermore, in the following description of the present disclosure, detailed descriptions of known functions and configurations contained herein will be omitted where it is determined that the description may instead obscure the subject matter of the disclosure.

[0027] In this disclosure, an MTC terminal can refer to a terminal that supports low cost (or low complexity), a terminal that supports enhanced coverage, etc. Additionally, in this disclosure, an MTC terminal can refer to a terminal classified as belonging to a specific category for supporting low cost (or low complexity) and / or enhanced coverage.

[0028] In other words, an MTC terminal can refer to a low-cost (or low-complexity) user equipment category / type that is newly defined in 3GPP Release 13 and performs LTE-based MTC-related operations. An MTC terminal can also refer to a user equipment category / type defined in or before 3GPP Release 12 that supports enhanced coverage compared to typical LTE coverage or supports low power consumption. Alternatively, an MTC device can refer to a low-cost (or low-complexity) user equipment category / type newly defined in Release 13.

[0029] In this disclosure, wireless communication systems are widely deployed to provide various communication services, such as voice communication services and packet data services. Wireless communication systems include user equipment (UE) and base stations (BS, eNB, gNB, or xNB). In this disclosure, UE is defined as a general term referring to a terminal used in wireless communication. For example, UE can refer to, but is not limited to, UEs supporting Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE), High Speed ​​Packet Access (HSPA), International Mobile Telecommunications (IMT)-2020 (5G or New Radio), etc.; mobile stations (MS) supporting Global System for Mobile Communications (GSM); user terminals (UT); subscriber stations (SS); wireless equipment, etc.

[0030] A base station or cell typically refers to a station that communicates with a UE. The term "base station or cell" is a general term encompassing, but not limited to, all various communication service areas and devices, such as Node-B, evolved Node-B (eNB), g-Node-B (gNB), low-power node (LPN), sector, site, various types of antennas, base transceiver system (BTS), access point, point (e.g., transmit point, receive point, or transceiver point), relay node, megacell, macrocell, microcell, picocell, femtocell, remote radio terminal (RRH), radio unit (RU), and small cell.

[0031] In other words, in this disclosure, base station or cell is collectively defined as a general term, which also includes: some communication service areas or functions covered by the base station controller (BSC) in CDMA, node-B in WCDMA, evolved node B (eNB) or sector (site) in LTE; all kinds of coverage areas, such as megacells, macrocells, microcells, picocells, femtocells and relay nodes, RRH, RU, small cell communication range, etc.

[0032] Each cell is controlled by a base station. Therefore, base stations can be divided into two categories. A base station can refer to: 1) an apparatus that forms and provides a corresponding communication service area such as a megacell, macrocell, microcell, picocell, femtocell, or small cell, or 2) a communication service area. In case 1), a base station can refer to: i) an apparatus that forms and provides a corresponding communication service area and is controlled by the same entity, or ii) apparatuses that interact and cooperate with each other to form and provide a corresponding communication service area. Depending on the communication scheme adopted by the base station, a base station can refer to an eNB, RRH, antenna, RU, low-power node (LPN), point, transmit / receive point, transmit point, receive point, etc. In case 2), a base station can be the communication service area itself, where the UE can receive signals from or transmit signals to other UEs and neighboring base stations.

[0033] Therefore, base stations are collectively defined as general terms, including megacells, macrocells, microcells, picocells, femtocells or small cells, RRH, antennas, RUs, LPNs, points, eNBs, transmit / receive points, transmit points or receive points.

[0034] In this disclosure, UE and base station are two entities used to perform transmission / reception in accordance with the techniques and spirit of the art described herein. UE and base station are defined as general terms and are not limited to specific terms or words. UE and base station are two entities used to perform uplink or downlink transmission / reception in accordance with the techniques and spirit of the art described herein. UE and base station are defined as general terms and are not limited to specific terms or words. In this document, uplink (hereinafter referred to as "UL") refers to data transmission / reception from / to the base station by the UE, and downlink (hereinafter referred to as "DL") refers to data transmission / reception from / to the UE by the base station.

[0035] Any of the multiple access technologies can be applied to a wireless communication system. For example, a wireless communication system can employ various multiple access technologies, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-TDMA, OFDM-FDMA, OFDM-CDMA, etc. Embodiments of this disclosure can be applied to resource allocation in the following scenarios: i) asynchronous wireless communication, evolving from GSM, WCDMA, and HSPA to LTE / LTE-Advanced and IMT-2020; ii) synchronous wireless communication, evolving to CDMA, CDMA-2000, and UMB. This disclosure is not limited to or construed as being limited to a particular field of wireless communication, but is intended to include all technical fields to which the spirit of this disclosure can be applied.

[0036] UL and DL transmissions can be performed based on: i) Time Division Duplex (TDD) technology that performs transmission through different time slots or ii) Frequency Division Duplex (FDD) technology that performs transmission through different frequencies.

[0037] Furthermore, in systems such as LTE or LTE-Advanced, relevant standards define UL and DL channels established on a single carrier or a pair of carriers for transmitting / receiving control information. UL and DL can be configured with one or more control channels, such as the Physical DL Control Channel (PDCCH), Physical Control Format Indication Channel (PCFICH), Physical Hybrid ARQ Indication Channel (PITCH), Physical UP Control Channel (PUCCH), Enhanced Physical DL Control Channel (EPDCCH), etc. For transmitting / receiving data, UL and DL can be configured with one or more data channels, such as the Physical DL Shared Channel (PDSCH), Physical UL Shared Channel (PUSCH), etc.

[0038] At the same time, control information can be transmitted via EPDCCH (enhanced PDCCH or extended PDCCH).

[0039] In this disclosure, a cell may refer to the coverage area of ​​a signal transmitted from a transmitting point or a transmitting / receiving point, a component carrier having the coverage area of ​​a signal transmitted from a transmitting point or a transmitting / receiving point, or the transmitting / receiving point itself.

[0040] A wireless communication system that applies at least one embodiment thereto can be: i) a coordinated multipoint transmit / receive system (CoMP system), wherein two or more transmit / receive points cooperate to transmit signals, ii) a coordinated multi-antenna transmission system, or iii) a coordinated multi-cell communication system. A CoMP system may include at least two transmit / receive points and a UE.

[0041] Multiple transmit / receive points can be at least one RRH, which is connected to the BS or macrocell (hereinafter referred to as "eNB") via optical cable or fiber and is therefore controlled in a wired manner, and has high or low transmission power in the macrocell area.

[0042] In the following text, DL refers to communication or a communication path from a multitransmitter / receiver point to the UE, or UL refers to communication or a communication path from the UE to the multitransmitter / receiver point. In DL, the transmitter can be part of the multitransmitter / receiver point, and the receiver can be part of the UE. In UL, the transmitter can be part of the UE, and the receiver can be part of the multitransmitter / receiver point.

[0043] In the following text, the transmission and reception of signals through channels such as PUCCH, PUSCH, PDCCH, EPDCCH, or PDSCH can be described as the transmission and reception of PUCCH, PUSCH, PDCCH, EPDCCH, or PDSCH.

[0044] Additionally, the description of transmitting or receiving PDCCH or the description of transmitting or receiving signals via PDCCH can be used to mean transmitting or receiving EPDCCH / MPDCCH or transmitting or receiving signals via EPDCCH / MPDCCH.

[0045] In other words, the physical DL control channel described below can refer to PDCCH or EPDCCH, or it can be used to mean both PDCCH and EPDCCH / MPDCCH.

[0046] Furthermore, for ease of description, EPDCCH / MPDCCH can be applied to embodiments of this disclosure that include PDCCH, and PDCCH can also be applied to embodiments of this disclosure that include EPDCCH / MPDCCH.

[0047] Meanwhile, the higher-level signaling described below includes Radio Resource Control (RRC) signaling that transmits RRC information containing RRC parameters.

[0048] The base station performs DL transmissions to the UE. The base station may transmit a Physical DL Shared Channel (PDSCH) as the primary physical channel for unicast transmission, and a Physical DL Control Channel (PDCCH), which transmits i) DL control information such as scheduling required for receiving the PDSCH, and ii) scheduling approval information for transmission via UL data channels (e.g., the Physical UL Shared Channel (PUSCH)). Hereinafter, the transmission / reception of signals through each channel can be described in such a manner that the corresponding channel is used for transmission / reception.

[0049] [Typical random access]

[0050] UEs that have not yet achieved or maintained UL synchronization use the Random Access Channel (RACH) to achieve UL synchronization. When UE UL synchronization is achieved, the base station can schedule UL transmission resources under orthogonal conditions. RACH-based synchronization can be triggered by the following events.

[0051] 1. If the UE is in the RRC_CONNECTED state but has not established UL synchronization, then when the UE is asked to transmit new UL data.

[0052] 2. If the UE is in the RRC_CONNECTED state but has not established UL synchronization, then when the UE is required to transmit ACK / NACK in response to newly received DL data.

[0053] 3. If the UE is in the RRC_CONNECTED state, then when the UE hands over from the current cell to the target cell.

[0054] 4. When the UE transitions from the RRC_IDLE state to the RRC_CONNECTED state (e.g., initial access or tracking area update).

[0055] 5. If the UE enters a connected state to recover from a radio link failure, an exception may be made, even if UL synchronization is achieved, if no additional UL resources are allocated for transmitting a scheduling request (SR) to the UE.

[0056] NR defines two types of random access procedures: contention-based random access procedures and contention-free random access procedures. In contention-based random access procedures, since the UE randomly selects and transmits the preamble, a collision occurs when one or more UEs transmit the same preamble simultaneously. Therefore, it is necessary to provide a procedure to overcome this situation.

[0057] In a contention-free random access procedure, no conflict occurs because a dedicated preamble is assigned to the UE, and the random access procedure is executed at a much higher speed compared to a contention-based random access procedure. Normally, the UE uses a contention-based random access procedure. However, a contention-free random access procedure is permitted when the UE is required to perform the random access procedure at a high speed.

[0058] Figure 1 This is a diagram illustrating a contention-based random access procedure.

[0059] refer to Figure 1 The contention-based random access process is as follows.

[0060] Step 1: Preamble Transmission

[0061] Of the 64 preambles, one or more are reserved for use by the base station in a contention-free RACH. The remaining preambles can be used in a contention-based random access procedure and are divided into two subgroups. Broadcast system information instructs the UE to select one of the two subgroups. The UE selects a preamble from the corresponding subgroup based on the required transmission resource size.

[0062] The initial value of the preamble transmission power is set considering path loss. The UE estimates the path loss by measuring the average of the reference received power (RSRP) of the DL and sets the power offset based on the following: the desired signal-to-interference-plus-noise ratio (SINR), the UL interference and noise levels measured in the time-frequency slot allocated to the RACH preamble, and the preamble type.

[0063] Step 2: Random Access Response (RAR)

[0064] The base station uses the PDSCH to transmit the Random Access Response (RAR), and the RAR is indicated by the Random Access Radio Network Temporary Identifier (RA-RNTI) transmitted via the PDCCH. The RA-RNTI enables the identification of the time-frequency slot used to detect the preamble transmitted by the UE.

[0065] RAR transmission information may include, for example, the identifier of the detected preamble, a timing alignment indication for UL transmission to synchronize the UE, an initial UL resource acknowledgment for transmitting the message in step 3, or the allocation of a cell radio network temporary identifier (temporary C-RNTI). The RAR message may include information such as a 'backoff indicator', which may indicate a retry of the random access procedure after a predetermined time delay.

[0066] Figure 2 This is a diagram showing the timing of the Random Access Response (RAR) window.

[0067] refer to Figure 2 The UE is expected to receive the RAR within the time window. The start and end points of the window are indicated by the base station and broadcast as part of the cell-specific system information. In relevant standards, the earliest subframe is allowed to be 2ms after the end of the preamble subframe. However, the normal delay time (the interval between the end of the preamble subframe and the start of the first subframe of the RAR window) is typically 4ms. The RAR consists of the message from step 2 and the DL transmission resource allocation message 'G'. The message from step 2 is transmitted using PDSCH, and 'G' is transmitted using PDCCH.

[0068] If the RAR is not received within the set time window, the UE performs a preamble retransmission. The minimum delay for preamble retransmission after the end of the RAR window is 3ms (even if the UE receives the PDCCH carrying the DL resources used in the RAR, if the UE has not successfully demodulated the RAR message, the minimum delay before preamble retransmission increases to 4ms, taking into account the time spent by the UE attempting to demodulate the RAR).

[0069] Base stations can be configured with 'preamble power ramping', allowing transmission power to increase at constant intervals with each retransmitted preamble. In WCDMA, initial preamble power needs to be reduced to control interference; however, preamble power control in LTE is less sensitive than in WCDMA because LTE random access preambles are typically orthogonal to other UL transmissions. Therefore, the success rate of the first preamble transmission during random access is higher than in WCDMA, and the need for power ramping tends to decrease.

[0070] Step 3: Layer 2 / L3 messages

[0071] This message is the first UL transmission scheduled on the PUSCH and uses Hybrid Automatic Repeat Request (HARQ). The UE uses this message to transmit random access procedure messages, such as RRC access requests, tracking area updates, and scheduling requests.

[0072] The message includes the temporary C-RNTI assigned via RAR in step 2, and includes either the C-RNTI or a 48-bit UE identifier (ID).

[0073] If a preamble collision occurs in step 1, the UEs involved in the collision will receive the same temporary C-RNTI via RAR, and therefore will collide on the same UL time-frequency resources when transmitting L2 / L3 messages. If all UEs fail to demodulate due to the collision, each UE restarts the random access procedure after performing the maximum number of HARQ retransmissions. However, demodulation can be successfully performed even if a preamble collision occurs. Therefore, in this case, the contention can be resolved through the procedure in step 4.

[0074] Figure 3 This is a diagram showing the timing of the random access response (message 3 transmission).

[0075] refer to Figure 3 When the UE has successfully received the RAR, the minimum processing delay time of the UE is obtained by subtracting the round-trip transmission time (TA) from 5ms before transmitting message 3.

[0076] Step 4: Contention Resolution Message

[0077] When multiple UEs transmit the same preamble, this step is used to distinguish which UE is actually identified by the preamble.

[0078] The base station generates a contention resolution message that includes the 48-bit UE identifier (C-RNTI or temporary C-RNTI) included in the L2 / L3 message in step 3, and transmits the generated message to the UE.

[0079] When a conflict occurs among multiple UEs, if the L2 / L3 message is successfully demodulated, only the UE that has detected its own UE ID (or C-RNTI) will perform HARQ feedback. Other UEs will leave the random access procedure and begin a new random access procedure.

[0080] After receiving the contention resolution message, the UE responds to the following three possible scenarios.

[0081] - When the UE has successfully demodulated and identified its own UE ID, the UE sends 'ACK'.

[0082] - When the UE has successfully demodulated and is aware that the message includes another UE ID, the UE does not transmit any content, which is called 'DTX'.

[0083] - When the UE fails to demodulate the message or loses the DL confirmation, the UE does not transmit any content.

[0084] Figure 4 This is a diagram illustrating a contention-free random access procedure.

[0085] refer to Figure 4 The contention-free random access process is as follows.

[0086] The base station assigns a preamble to each UE, and the UE transmits the assigned preamble, thus preventing conflicts between UEs. This method is applied when the access procedure should be completed within a short time (such as when restoring DL traffic to the UE or performing a handover). The procedure is performed through the following steps.

[0087] Step 1: The base station assigns the preamble to the UE.

[0088] Step 2: The UE transmits the assigned preamble.

[0089] Step 3: The base station transmits a random access response.

[0090] Next-generation / 5G radio access network (5G New Radio (NR))

[0091] Recently, 3GPP approved a research project titled "Study on New Radio Access Technologies" for researching next-generation / 5G radio access technologies. Based on this research, discussions have been held regarding frame structure, channel coding and modulation, waveforms, and multiple access schemes for NR.

[0092] NR is required to be designed to not only provide improved data transmission rates compared to Long Term Evolution (LTE) / LTE-Advanced, but also meet various requirements in specific and particular usage scenarios. In particular, enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable low latency communication (URLLC) are proposed as representative usage scenarios for NR. To meet the requirements of each scenario, a more flexible frame structure compared to LTE / LTE-Advanced is required to be designed.

[0093] Specifically, eMBB, mMTC, and URLLC are considered by 3GPP as representative usage scenarios for NR. Since each usage scenario poses different requirements for data rate, latency, coverage, etc., a method for efficiently multiplexing radio resource units that are different from each other based on parameter sets (e.g., subcarrier spacing (SCS), subframe, transmission time interval (TTI), etc.) is needed as a solution for efficiently meeting the requirements according to the usage scenario through the frequency band provided to any NR system.

[0094] For example, similar to typical LTE / LTE-Advanced, there is an increasing need to support, through one NR frequency band, a 1 ms subframe (or 0.5 ms time slot) structure based on a 15 kHz subcarrier spacing, a 0.5 ms subframe (or 0.25 ms time slot) structure based on a 30 kHz subcarrier spacing, and a 0.25 ms subframe (or 0.125 ms time slot) structure based on a 60 kHz subcarrier spacing.

[0095] In addition, discussions are underway for the following technologies: i) configuring a subframe formed by X OFDM symbols (e.g., X = 14 or 7, or any other natural number) or a symbol formed by Y OFDM symbols (e.g., Y = 14 or 7, or any other natural number) as a resource allocation unit (e.g., a scheduling unit in the time domain) in the time domain within a parameter set (e.g., subcarrier spacing structure), or ii) defining a mini-slot formed by Z OFDM symbols having a smaller granularity than a subframe or a time slot (i.e., any natural number satisfying Z < Y and Z < X).

[0096] RB structure based on TDM hybrid parameter set

[0097] As described above, when multiple parameter sets are supported through an NR carrier and the subcarrier spacing of each parameter set has a value of 2 n *15 kHz (n is 0 or a natural number greater than 0), the subcarriers of each parameter set are defined to be mapped in a nested manner in the frequency domain onto a subset / superset with a subcarrier spacing of 15 kHz.

[0098] Figure 5This is a diagram illustrating the resource block (RB) structure in a hybrid parameter set based on TMD.

[0099] Furthermore, when configuring the frame structure by multiplexing the corresponding parameter set in a TDM manner, the RBs used as resource allocation units in the frequency axis by the corresponding NR carrier are defined in a nested manner as subsets / supersets of RBs based on the 15kHz RB grid, such as... Figure 5 As shown.

[0100] In this case, the number of subcarriers forming an RB in each parameter set is determined to have a specific number, such as one of 12 or 16, regardless of the corresponding parameter set.

[0101] In NR, research has been conducted on multi-beam multiple-input multiple-output (MIMO) transmission technology, and its application in UL and RACH transmissions has also been discussed.

[0102] This disclosure provides a method for RACH transmission based on multi-beams. In particular, this document provides RACH beam control techniques that can be employed when Tx / Rx channel reciprocity is unavailable, and a random access procedure (or a portion thereof) for maintaining this.

[0103] In 5G NR, multi-beam-based initial access techniques have been discussed. The following is the protocol for RACH operation, a fundamental access step, presented at the RAN1 86bis meeting.

[0104] Protocols in RAN1 86bis meeting

[0105] • When Tx / Rx reciprocity is available at the gNB at least for multi-beam operation, the following RACH procedure shall be considered at least for UEs in idle mode.

[0106] The association between one or more instances of the -DL broadcast channel / signal and a subset of RACH resources is communicated to the UE via broadcast system information or is known to the UE.

[0107] • FFS: "Unrelated" signaling

[0108] Further research is needed on the detailed design of the RACH preamble.

[0109] - Based on DL measurements and corresponding associations, the UE selects a subset of RACH resources.

[0110] • FFS: Tx beam selection for RACH preamble transmission

[0111] - At the gNB, the UE's DL Tx beam can be obtained based on the detected RACH preamble and will also be applied to message 2.

[0112] • The UL authorization in message 2 can indicate the timing of message 3's transmission.

[0113] • For cases with and without Tx / Rx reciprocity, a common random access procedure should be strived for.

[0114] • When Tx / Rx reciprocity is unavailable, the following should be further considered, at least for UEs in idle mode.

[0115] - Whether or how to report DL Tx beams to gNB, for example

[0116] ·RACH preamble / resources

[0117] ·Msg.3

[0118] - Whether or how to indicate the UL Tx beam to the UE, for example

[0119] ·RAR

[0120] As specified in the basic protocol for RACH operation, in the case of NR RACH discussed at the standardization meeting, an agreement was reached on the method of using multiple beams for RACH when Tx / Rx channel reciprocity is available.

[0121] However, when Tx / Rx channel reciprocity is unavailable, specific methods such as beam control methods and methods for indicating beam information to the UE have not been discussed.

[0122] Therefore, this paper provides a specific method for operating the RACH operation required when using a multi-beam UL in environments where Tx / Rx channel reciprocity is unavailable.

[0123] The embodiments and / or examples described below are not limited to situations where Tx / Rx channel reciprocity is unavailable, and therefore can also be applied to multi-beam-based RACH transmissions using Tx / Rx channels.

[0124] Example 1. Performing RACH preamble transmission based on sector beams

[0125] Since Example 1 is based on an environment where the UE cannot obtain information about its UL transmission (Tx) beam, i.e., 'Tx / Rx reciprocity is not present', the technique of transmitting the RACH preamble using a wide beam is discussed below. Furthermore, the sector beam described below is used to refer to the term wide beam and can be described by various terms such as grouped beams, multi-beam sets, etc.

[0126] According to Example 1, the method for transmitting the RACH preamble begins by configuring the basic RACH resources through RRC resource configuration.

[0127] First, the following configuration information related to RACH must be transmitted to the UE. This system information can be configured in a manner similar to the RACH configuration included in typical SIB2, or it can be configured by defining additional messages.

[0128] - Basically, for the pre-configured period T RACH Allocate a single RACH resource

[0129] -in T RACH Repeated transmission of RACH signal N within a cycle REP Second-rate

[0130] - Use a single resource or N for repeating RACH sequences RACH Individual resources

[0131] Here, the RACH preamble can be mapped to the RACH sequence for the following two purposes.

[0132] - Use a single RACH sequence when only a simple RACH search is required.

[0133] When it is not necessary to obtain the beam direction information of the base station, the use of a single RACH sequence is performed.

[0134] It should be noted that, considering the possibility of differences in the upward beam caused by UE movement, only grouped beams can be used. Therefore, when the RACH preamble is received from the UE, the base station can simply identify that the RACH preamble has been received, and can avoid performing candidate detection, specific refinement, etc. for the upward beam.

[0135] - When RACH search requires consideration of beam directivity, use one or more multi-RACH sequences.

[0136] When it is necessary to obtain the beam direction information of the base station, the use of multi-RACH sequences is performed.

[0137] It should be noted that, considering the possibility of differences in the upward beam caused by UE movement, only grouped beams can be used, and different RACH sequences or RACH resources can be mapped to each beam. Therefore, when one or more RACH preambles are received from the UE, the base station can obtain the directional information of one or more upward beams or appropriate procedural encoding and beam directivity information based on the reception of one or more RACH preambles.

[0138] Figure 6 This is a diagram illustrating a method for transmitting a sector-based RACH preamble according to an embodiment of the present disclosure.

[0139] -General: Sector beam scanning within a given time period (see...) Figure 6 )

[0140] Basically, one or more RACH preambles are transmitted in the form of grouped beams or sector beams in a specific range or all directions formed by scanning or rotating in a specific direction with a specific orientation.

[0141] Example 1-1

[0142] In Example 1-1, within a given time period, at different N... RACH One or more RACH preambles are transmitted sequentially in each direction. That is, in Example 1-1, when performing beam scanning for transmitting RACH preambles, in N... RACH One or more preambles are transmitted in each direction.

[0143] For example, such as Figure 6 As shown, due to N RACH The value is 3, therefore the RACH preamble is transmitted in three directions. Basically, one or more RACH preambles are transmitted in the form of group-type sector beams (including subsets of beams).

[0144] At this point, on the timeline at N RACH One or more RACH preambles are transmitted sequentially in each direction. When the transmission unit of the RACH preamble is a subframe, it is transmitted through N... RACH Each subframe transmits one or more RACH preambles. When the transmission unit of the RACH preamble is a time slot, it is transmitted through N... RACH One or more RACH preambles are transmitted in each time slot. When the transmission unit of the RACH preamble is a symbol, it is transmitted through N. RACH Each symbol transmits one or more RACH preambles.

[0145] Examples 1-2

[0146] In Examples 1-2, N is transmitted simultaneously in a single time. RACH One sector beam, one or more RACH preambles in T RACH N are repeatedly transmitted within a period REP This means that, in other words, Embodiments 1-2 are similar to Embodiments 1-1, except that when performing beam scanning for transmitting one or more RACH preambles, in N... RACH One or more preambles are transmitted in each direction. At this time, in N... RACH One or more preambles are transmitted simultaneously in each direction.

[0147] Therefore, one or more RACH preambles can be transmitted by multiplexing on the same time-frequency resources, or by mapping them to orthogonal N based on FDM. RACHA RACH resource is generated, and then one or more preambles mapped are transmitted.

[0148] One or more RACH preambles can be transmitted repeatedly, and the number of repetitions can be defined as N. REP N can be REP Set to be equal to or different from sector beam N RACH The total value.

[0149] Example 2

[0150] In Example 2, when sector beam information is received via one or more RACH preambles of the UE, the base station then uses a multi-beam set belonging to the corresponding sector beam X to perform the RACH process.

[0151] In Example 2, a method is proposed for defining one or more beam subsets for at least one RACH preamble transmitted in a grouped beam configuration. When the UE transmits one or more RACH preambles via sector beams, as... Figure 6 As shown, the base station can detect the UE's best beam or preferred beam candidate by detecting one or more RACH preambles.

[0152] Therefore, it is necessary to define beamgroups.

[0153] As a first method, as shown in Table 1, beamgrouping can be performed orthogonally to each other. That is, subsets of beams in each sector do not overlap. In this case, the base station can identify the sector mapping of the UE on a one-to-one basis using one or more received RACH preambles.

[0154] Table 1

[0155] Orthogonal beam grouping

[0156]

[0157] As a second method, beamgrouping can be performed in an overlapping manner as shown in Table 2. That is, at least one subset of beams in each sector beam can overlap with another, or two or more sector beams can be transmitted via a single RACH preamble.

[0158] For example, as shown in Table 2, when the RACH preamble P is detected... 1' At that time, the base station can identify the best beam in one or more upper beams of the UE that is included in sector beam P. 扇区,1 and sector beam P 扇区,2 Similarly, when the RACH preamble P is detected... 2'At that time, the base station can identify the best beam in one or more upper beams of the UE that is included in sector beam P. 扇区,3 and sector beam P 扇区,4 middle.

[0159] The second method provides less accurate information about the best beam candidates for the UE, but has the advantage of reducing RACH transmission time.

[0160] Table 2

[0161] Overlapping beam grouping

[0162]

[0163] As described above, embodiments 1, 1-1, 1-2, and 2 have been provided in this disclosure as specific methods for RACH operations required when operating a multi-beam-based UL in an environment where Tx / Rx channel reciprocity is unavailable. Hereinafter, methods for performing multi-beam-based random access procedures using specific methods for RACH operations required when operating a multi-beam-based UL in an environment where Tx / Rx channel reciprocity is unavailable are discussed.

[0164] Figure 7 This is a flowchart illustrating a method for a base station to perform a multi-beam-based random access procedure in wireless communication, according to another embodiment of the present disclosure.

[0165] refer to Figure 7 A method for a base station to perform a multi-beam-based random access procedure in wireless communication includes: at step S710, transmitting information about one or more RACH resources to the UE; at step S720, receiving one or more multi-RACH preambles from the UE using multiple beams; and at step S730, transmitting a random access response to the UE.

[0166] The information about one or more RACH resources in step S710 can be transmitted to the UE via RRC configuration. The information about one or more RACH resources in step S710 may include basic RACH resource configuration information as described in Example 1, such as a pre-configured period T. RACH For period T RACH Repeating N REP The number of transmissions, the type of RACH sequence, etc. In this case, as described in Example 1, a single RACH sequence can be used when a simple RACH search is required, and one or more multi-RACH sequences can be used when a RACH search considering beam directionality is required.

[0167] When it is necessary to obtain beam direction information from the base station, one or more multi-RACH sequences are used. In this case, considering the possibility of differences in the upward beam caused by UE movement, only grouped beams can be used, and different RACH sequences or RACH resources can be mapped to each beam. Therefore, when receiving one or more RACH preambles from the UE, the base station can obtain the direction information of one or more upward beams or appropriate procedural coding and beam directivity information based on the reception of one or more RACH preambles.

[0168] Basically, one or more RACH preambles are transmitted in the form of grouped beams or sector beams in a specific range or all directions formed by scanning or rotating in a specific direction with a specific orientation.

[0169] Receiving one or more multi-RACH preambles from the UE in step S720 can be performed by sequentially receiving one or more multi-RACH preambles. The transmission unit for the multiple RACH preambles can be one of a time slot, a subframe, or a symbol. Receiving one or more multi-RACH preambles from the UE in step S720 can be performed by one of the number of time slots, subframes, or symbols (corresponding to the number of multi-RACH preambles).

[0170] As described in Example 1-1, N can be different from each other within a given time period. RACH One or more RACH preambles are received sequentially in N directions. That is, during beam scanning for transmitting one or more RACH preambles, beams can be received from N... RACH Each direction receives one or more preambles.

[0171] For example, such as Figure 6 As shown, due to N RACH The value is 3, therefore the RACH preamble is received in three directions. Essentially, the RACH preamble is received in group-type sector beams (including subsets of beams).

[0172] At this point, on the timeline at N RACH One or more RACH preambles are received sequentially in each direction. When the transmission unit of the RACH preamble is a subframe, it is transmitted through N... RACH Each subframe receives one or more RACH preambles. When the transmission unit of the RACH preamble is a time slot, it is transmitted through N... RACH Each time slot receives one or more RACH preambles. When the transmission unit of the RACH preamble is a symbol, it is transmitted through N. RACH Each symbol receives one or more RACH preambles.

[0173] As described in Examples 1-2, N is transmitted simultaneously in a single time.RACH One sector beam, one or more RACH preambles in T RACH N are repeatedly transmitted within a period REP Second-rate.

[0174] At this point, a multi-RACH preamble can be used, employing a multi-RACH sequence. As described in Example 1, when a RACH search considering beam directivity is required, one or more multi-RACH sequences can be used.

[0175] Meanwhile, the aforementioned random access procedure can be a contention-free random access procedure.

[0176] Each of the multiple beams may include one or more subsets. In this case, a subset of the multiple beams corresponding to the RACH resource can be used to perform the transmission of the random access response to the UE in step S730.

[0177] One or more beams for transmitting a random access response to the UE can be determined using a subset of multiple beams corresponding to the RACH resource, and then the random access response can be performed through the determined one or more beams.

[0178] As described in Example 2, when sector beam information is received via one or more RACH preambles of the UE, the base station then uses a multi-beam set belonging to the corresponding sector beam X to perform the RACH process.

[0179] When the UE transmits one or more RACH preambles through a sector beam, such as Figure 6 As shown, the base station can detect the UE's best beam or preferred beam candidate by detecting one or more RACH preambles.

[0180] As a first method, as shown in Table 1, beamgrouping can be performed orthogonally to each other. That is, subsets of beams in each sector do not overlap. In this case, the base station can identify the sector mapping of the UE on a one-to-one basis using one or more received RACH preambles.

[0181] As a second method, beamgrouping can be performed in an overlapping manner, as shown in Table 2. That is, at least one subset of beams in each sector beam can overlap with another, or two or more sector beams can be transmitted using a single RACH preamble.

[0182] For example, as shown in Table 2, when the RACH preamble P is detected... 1' At that time, the base station can identify the best beam in one or more upper beams of the UE that is included in sector beam P. 扇区,1 and sector beam P 扇区,2 Similarly, when the RACH preamble P is detected...2' At that time, the base station can identify the best beam in one or more upper beams of the UE that is included in sector beam P. 扇区,3 and sector beam P 扇区,4 middle.

[0183] As mentioned above, wireless communication can exist in environments where channel reciprocity between UL and DL beams is unavailable. That is, there may be environments where the UE cannot obtain information about its UL transmission (Tx) beam, i.e., 'Tx / Rx reciprocity is not present'. The unavailability of channel reciprocity between UL and DL beams in such environments could mean that Tx / Rx beam correspondence information will not exist in next-generation wireless communication.

[0184] Figure 8 This is a flowchart illustrating a method for a UE to perform a multi-beam-based random access procedure in wireless communication according to another embodiment of the present disclosure.

[0185] refer to Figure 8 A method 800 for a UE to perform a multi-beam-based random access procedure in wireless communication includes: at step S810, receiving information from a base station about one or more RACH resources; at step S820, transmitting one or more multi-RACH preambles to the base station using multiple beams; and at step S830, receiving a random access response from the base station.

[0186] Information about one or more RACH resources in step S810 can be received from the base station via RRC configuration. This information may include basic RACH resource configuration information as described in Example 1, such as a pre-configured period T. RACH For period T RACH Repeat N REP The number of transmissions, the type of RACH sequence, etc. In this case, as described in Example 1, a single RACH sequence can be used when a simple RACH search is required, and one or more multi-RACH sequences can be used when a RACH search considering beam directionality is required. When it is necessary to obtain the beam directionality information of the base station, the use of one or more multi-RACH sequences is performed.

[0187] The transmission of one or more multi-RACH preambles to the base station in step S820 can be performed by sequentially transmitting one or more multi-RACH preambles. The transmission unit for the multiple RACH preambles can be one of a time slot, a subframe, or a symbol. The transmission of one or more multi-RACH preambles to the base station in step S820 can be performed using one of the following quantities (corresponding to the number of multi-RACH preambles): time slot, subframe, or symbol.

[0188] As described in Example 1-1, N can be different from each other within a given time period. RACH One or more RACH preambles are transmitted sequentially in each direction. That is, during a beam scan for transmitting one or more RACH preambles, one or more preambles can be transmitted to N. RACH One direction.

[0189] For example, such as Figure 6 As shown, due to N RACH The value is 3, therefore the RACH preamble is transmitted in three directions. Basically, one or more RACH preambles are transmitted in the form of group-type sector beams (including subsets of beams).

[0190] At this point, on the timeline at N RACH One or more RACH preambles are transmitted sequentially in each direction. When the transmission unit of the RACH preamble is a subframe, it is transmitted through N... RACH Each subframe transmits one or more RACH preambles. When the transmission unit of the RACH preamble is a time slot, it is transmitted through N... RACH One or more RACH preambles are transmitted in each time slot. When the transmission unit of the RACH preamble is a symbol, it is transmitted through N. RACH Each symbol transmits one or more RACH preambles.

[0191] As described in Examples 1-2, N is transmitted simultaneously in a single time. RACH One sector beam, one or more RACH preambles in T RACH N are repeatedly transmitted within a period REP Second-rate.

[0192] At this time, as described in Example 1, when a RACH search that takes beam directionality into account is required, one or more multi-RACH sequences can be used for one or more multi-RACH preambles.

[0193] Meanwhile, the aforementioned random access procedure can be a contention-free random access procedure.

[0194] like Figure 6 As shown, multiple beams (P) 扇区,1 P 扇区,2 P 扇区,3 Each of the following can include one or more subsets (e.g., for P) 扇区,2 P 2.1 P 2.2 P 2.3 A subset of multiple beams corresponding to RACH resources can be used to perform the receiving of a random access response from the base station in step S830.

[0195] Random access responses can be received from the base station using a beam determined by a subset of multiple beams corresponding to RACH resources.

[0196] As described in Example 2, when sector beam information is received via one or more RACH preambles of the UE, the base station subsequently performs the RACH procedure using a multi-beam set belonging to the corresponding sector beam X. As described above, as a first method, beam grouping can be performed orthogonally to each other as shown in Table 1, or as shown in Table 2, beam grouping can be performed in an overlapping manner.

[0197] As mentioned above, wireless communication can exist in environments where channel reciprocity between the UL beam and the DL beam is unavailable. That is, there may be environments where the UE cannot obtain information about its UL transmission (Tx) beam, i.e., 'Tx / Rx reciprocity is not present'.

[0198] According to embodiments of this disclosure, a multi-beam-based RACH transmission method and random access procedure have been provided for next-generation / 5G radio access networks. In particular, this document provides RACH beam control techniques that can be employed when Tx / Rx channel reciprocity is unavailable, and random access procedures (or portions thereof) for maintaining these.

[0199] Figure 9 This is a block diagram illustrating a base station according to another embodiment of the present disclosure.

[0200] refer to Figure 9 The base station 900 includes a controller 910, a transmitter 920, and a receiver 930.

[0201] Controller 910 is configured to control the operation of base station 900 for transmitting multi-beam-based RACH in next-generation wireless communication. Controller 910 is configured to control the overall operation of base station 900 for use in reference... Figure 7 The described wireless communication performs a multi-beam-based RACH process.

[0202] Transmitter 920 and receiver 930 are respectively configured to send signals, messages and data to and from the UE necessary for performing some of the embodiments described above.

[0203] Specifically, the transmitter 920 can be configured to transmit information about one or more RACH resources to the UE and to transmit a random access response to the UE.

[0204] Receiver 930 can be configured to receive one or more multi-RACH preambles from the UE using multiple beams. Receiver 930 can be configured to receive one or more multi-RACH preambles sequentially. Receiver 930 can be configured to receive one or more multi-RACH preambles by one of a number of time slots, subframes, or symbols (corresponding to the number of multi-RACH preambles).

[0205] Transmitter 920 can be configured to transmit random access responses using a subset of multiple beams corresponding to RACH resources.

[0206] The controller 910 can be configured to determine one or more beams for transmitting a random access response using a subset of multiple beams corresponding to RACH resources. The transmitter 920 can be configured to transmit the random access response to the UE through the determined one or more beams.

[0207] Figure 10 This is a block diagram illustrating a user equipment according to another embodiment of the present disclosure.

[0208] refer to Figure 10 The UE 1000 includes a receiver 1010, a controller 1020, and a transmitter 1030.

[0209] Receiver 1010 can be configured to receive DL control information, data and messages from the base station through the corresponding channel.

[0210] Controller 1020 is configured to control the operation of UE 1000 for transmitting multi-beam-based RACH in next-generation wireless communication. Controller 1020 is configured to control the overall operation of UE 1000 for use in reference... Figure 8 The described wireless communication performs a multi-beam-based RACH process.

[0211] Transmitter 1030 is configured to transmit UL control information, data and messages to the base station via the corresponding channel.

[0212] Receiver 1010 can be configured to receive information about one or more RACH resources from a base station and to receive random access responses from the base station. Transmitter 1130 can be configured to transmit one or more multi-RACH preambles to the base station using multiple beams.

[0213] Transmitter 1130 can be configured to sequentially transmit one or more multi-RACH preambles using one or more multi-RACH sequences.

[0214] Each of the multiple beams may include one or more subsets. Receiver 1010 may be configured to receive random access responses from the base station using subsets of the multiple beams corresponding to the RACH resources.

[0215] Receiver 1010 can be configured to receive random access responses from a base station using a beam determined by using a subset of multiple beams corresponding to RACH resources.

[0216] Standardization specifications or standard documents related to the above embodiments form part of this disclosure. Therefore, it should be understood that the contents of standardization specifications and parts of standard documents incorporated into the detailed description and claims are also included within the scope of this disclosure.

[0217] While preferred embodiments of this disclosure have been described for illustrative purposes, those skilled in the art will understand that various modifications, additions, and substitutions can be made without departing from the scope and spirit of the invention as disclosed in the appended claims. Therefore, exemplary aspects of this disclosure have not been described for limiting purposes, but rather for describing embodiments; thus, the scope of this disclosure should not be limited to such embodiments. The scope of this disclosure should be interpreted based on the following claims, and all technical concepts within the scope of their equivalents should be construed as including within the scope of this disclosure.

[0218] Cross-references to related applications

[0219] Where applicable, this application claims priority under 35 USC § 119(a) to Korean Patent Application No. 10-2016-0146950, filed November 4, 2016, and Korean Patent Application No. 10-2017-0135198, filed October 18, 2017, the entire contents of which are incorporated herein by reference. Furthermore, this non-provisional application claims priority in countries other than the United States based on the same grounds of the Korean patent application, the entire contents of which are incorporated herein by reference.

Claims

1. A method for a base station to perform a contention-free random access procedure based on a multi-beam wireless communication, the method comprising: The configuration information regarding the transmission resources of multiple random access channels (RACH) is transmitted to the user equipment via Radio Resource Control (RRC) signaling. One or more multi-RACH preambles are received from the user equipment via multiple beams, and beam direction information is obtained based on the reception of the one or more multi-RACH preambles. The one or more multi-RACH preambles are mapped by the user equipment to the multiple RACH transmission resources based on frequency division multiplexing (FDM) and the number of multiple RACH transmission resources multiplexed by frequency division multiplexing. Different RACH transmission resources are mapped by the user equipment to each beam. as well as The random access response is transmitted to the user equipment.

2. The method of claim 1, wherein, The one or more multi-RACH preambles are received sequentially from the user equipment.

3. The method of claim 1, wherein, The receiving unit of the one or more multi-RACH preambles is one of a time slot, a subframe, or a symbol.

4. The method of claim 1, wherein, The wireless communication is conducted in an environment where channel reciprocity is unavailable between one or more uplink UL beams and one or more downlink DL beams.

5. A method for a user equipment to perform a contention-free random access procedure based on a multi-beam wireless communication, the method comprising: The configuration information for the transmission resources of multiple random access channels (RACH) is received from the base station via Radio Resource Control (RRC) signaling. One or more multi-RACH preambles are mapped to the multiple RACH transport resources based on frequency division multiplexing (FDM) and the number of multiple RACH transport resources being frequency divided multiplexed, and different RACH transport resources are assigned to each beam, and the one or more multi-RACH preambles are transmitted to the base station through multiple beams; as well as Receive a random access response from the base station.

6. The method according to claim 5, wherein, The one or more multi-RACH preambles are sequentially transmitted to the base station.

7. The method of claim 5, wherein, The unit for transmitting the one or more multi-RACH preambles is one of a time slot, a subframe, or a symbol.

8. The method according to claim 5, wherein, The wireless communication is conducted in an environment where channel reciprocity is unavailable between one or more uplink UL beams and one or more downlink DL beams.

9. A user equipment for performing a multi-beam-based contention-free random access procedure in wireless communication, the user equipment comprising: Memory; and A processor operatively coupled to the memory, The processor is configured as follows: This causes the user equipment to receive configuration information about the transmission resources of multiple random access channels (RACH) from the base station via Radio Resource Control (RRC) signaling; This causes the user equipment to map one or more multi-RACH preambles onto the multiple RACH transmission resources based on frequency division multiplexing (FDM) and the number of multiple RACH transmission resources being frequency divided multiplexed, and to assign different RACH transmission resources to each beam, and to transmit the one or more multi-RACH preambles to the base station through multiple beams; as well as This causes the user equipment to receive a random access response from the base station.

10. The user equipment of claim 9, wherein, The one or more multi-RACH preambles are sequentially transmitted to the base station.

11. The user equipment of claim 9, wherein, The unit that transmits the one or more multi-RACH preambles to the base station is one of a time slot, a subframe, or a symbol.

12. The user equipment of claim 9, wherein, The wireless communication is conducted in an environment where channel reciprocity is unavailable between one or more uplink UL beams and one or more downlink DL beams.

13. A base station for performing a multi-beam-based contention-free random access procedure in wireless communication, the base station comprising: Memory; and A processor operatively coupled to the memory; The processor is configured as follows: This causes the base station to transmit configuration information about the transmission resources of multiple random access channels (RACH) to the user equipment via Radio Resource Control (RRC) signaling. This causes the base station to receive one or more multi-RACH preambles from the user equipment via multiple beams and to obtain beam direction information based on the reception of the one or more multi-RACH preambles. The one or more multi-RACH preambles are mapped by the user equipment onto the multiple RACH transmission resources based on Frequency Division Multiplexing (FDM) and the number of frequency-division multiplexed RACH transmission resources, and different RACH transmission resources are mapped by the user equipment to each beam; and This causes the base station to transmit a random access response to the user equipment.

14. The base station of claim 13, wherein, The one or more multi-RACH preambles are received sequentially from the user equipment.

15. The base station of claim 13, wherein, The receiving unit of the one or more multi-RACH preambles is one of a time slot, a subframe, or a symbol.

16. The base station of claim 13, wherein, The wireless communication is conducted in an environment where channel reciprocity is unavailable between one or more uplink UL beams and one or more downlink DL beams.

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