Terminal, wireless communication method, and system

Abstract

To provide a terminal and a wireless communication method for the terminal that can appropriately control a random access procedure even when transmission / reception points of different types are set.SOLUTION: A receiving unit receives downlink control information (DCI) transmitted from a first transmission / reception point. A transmitting unit transmits UL signals to at least one of the first transmission / reception point and a second transmission / reception point. A control unit determines to transmit a random access preamble to the second transmission / reception point if the DCI includes information indicating the presence of the second transmission / reception point, and determines to transmit the random access preamble to the first transmission / reception point if the DCI does not include the information indicating the presence of the second transmission / reception point.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a terminal, a wireless communication method and a system in a next-generation mobile communication system. [Background technology]

[0002] In Universal Mobile Telecommunications System (UMTS) networks, Long Term Evolution (LTE) was specified with the aim of achieving higher data rates and lower latency (Non-Patent Document 1). Also, LTE-Advanced (3GPP Rel. 10-14) was specified with the aim of achieving higher capacity and more advanced features than LTE (Third Generation Partnership Project (3GPP) Release (Rel.) 8, 9).

[0003] Successor systems to LTE (e.g., 5th generation mobile communication system (5G), 5G+ (plus), New Radio (NR), 3GPP Rel. 15 or later) are also being considered.

[0004] In existing LTE systems (e.g., LTE Rel. 8-13), a user equipment (UE: User Equipment) controls reception of a downlink shared channel (e.g., Physical Downlink Shared Channel (PDSCH)) based on downlink control information (Downlink Control Information (DCI), also referred to as DL assignment, etc.) from a radio base station. Also, the UE controls transmission of an uplink shared channel (e.g., Physical Uplink Shared Channel (PUSCH)) based on DCI (also referred to as UL grant, etc.).

[0005] In addition, in existing LTE systems, when UL synchronization is established between a radio base station and a user terminal, UL data transmission from the user terminal is possible. For this reason, existing LTE systems support a random access procedure (RACH procedure: Random Access Channel Procedure, also called an access procedure) for establishing UL synchronization.

[0006] The random access procedure of existing LTE systems supports four steps (messages 1 to 4). For example, in the random access procedure, a user terminal transmits a random access preamble (PRACH) corresponding to message 1 to a base station, and acquires information about UL transmission timing from a response signal (random access response, or message 2) from the radio base station in response to the PRACH. Thereafter, the user terminal transmits a message (message 3) on an uplink shared channel based on the information acquired in message 2, and then receives message 4 (also called contention-resolution) transmitted from the base station. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] 3GPP TS 36.300 V8.12.0 “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 8)”, April 2010 Summary of the Invention [Problem to be solved by the invention]

[0008] In future wireless communication systems (e.g., NR Rel. 16, Rel. 17, or later), in order to expand the coverage of uplink (UL) transmissions of PUSCH, PUSCH, etc., it is being considered to provide reception points (RPs, Rx points) that mainly handle reception from terminals (e.g., UEs) in addition to transmission / reception points (TRPs, central TRPs).

[0009] In addition, NR supports a random access procedure, which requires the terminal to transmit a PRACH or the like.

[0010] However, there has been insufficient consideration as to how to control the transmission destination of the PRACH, etc. If the PRACH transmission operation is not controlled appropriately, there is a risk of communication degradation occurring.

[0011] Therefore, the present disclosure has been made in consideration of such points, and one of its objectives is to appropriately control the random access procedure even when transmission and reception points of different types are set. [Means for solving the problem]

[0012] A terminal according to one embodiment of the present disclosure includes a receiving unit that receives downlink control information (DCI) transmitted from a first transmission / reception point, a transmitting unit that transmits an UL signal to at least one of the first transmission / reception point and a second transmission / reception point, and a control unit that, if the DCI includes information indicating the existence of the second transmission / reception point, decides to transmit a random access preamble to the second transmission / reception point, and, if the DCI does not include information indicating the existence of the second transmission / reception point, decides to transmit the random access preamble to the first transmission / reception point. [Effects of the Invention]

[0013] According to one aspect of the present disclosure, even when transmission and reception points of different types are set, it is possible to appropriately control the random access procedure. [Brief explanation of the drawings]

[0014] [Figure 1] 1A and 1B are diagrams illustrating an example of DL reception and UL transmission of a UE to a transmitting / receiving point and a receiving point. [Figure 2] 2A and 2B are diagrams illustrating an example of a random access procedure. [Figure 3] FIG. 3 is an example of a table showing the correspondence between NID Rxpoint and reception point ID. [Figure 4] FIG. 4 is a diagram showing an example of a method for setting a reception point ID. [Figure 5] FIG. 5 illustrates an example of SSB reception and PRACH transmission to a central TRP and reception point of a UE. [Figure 6] FIG. 6 illustrates an example of SSB reception and PRACH transmission to a central TRP and reception point of a UE. [Figure 7] FIG. 7 illustrates an example of SSB reception and PRACH transmission to a central TRP and reception point of a UE. [Figure 8] FIG. 8 illustrates an example of SSB reception and PRACH transmission to a central TRP and reception point of a UE. [Figure 9] FIG. 9 illustrates an example of SSB reception and PRACH transmission to a central TRP and reception point of a UE. [Figure 10] FIG. 10 illustrates an example of SSB reception and PRACH transmission to a central TRP and reception point of a UE. [Figure 11] FIG. 11 is a diagram illustrating an example of the relationship between the type of random access preamble and the received power. [Figure 12] FIG. 12 is a diagram illustrating an example of a schematic configuration of a wireless communication system according to an embodiment. [Figure 13] FIG. 13 is a diagram illustrating an example of the configuration of a base station according to an embodiment. [Figure 14] FIG. 14 is a diagram illustrating an example of the configuration of a user terminal according to an embodiment. [Figure 15] FIG. 15 is a diagram illustrating an example of the hardware configuration of a base station and a user terminal according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] (UL coverage) In Rel. 15 NR, the coverage (reaching distance) of PUSCH, PUCCH, PRACH, PDSCH, PDCCH, and PBCH is not uniform. The coverage of PUSCH is limited, especially in the coverage at higher frequencies. Future wireless communication systems (e.g., Rel. 16, Rel. 17, or later) are expected to improve at least one of UL coverage and UL throughput.

[0016] To expand UL coverage, reception points (RP, Rx point) as shown in FIG. 1B may be provided in addition to conventional transmission / reception points (TRP, central TRP) as shown in FIG. 1A. In the present disclosure, the terms transmission / reception point, transmission / reception point (TRP), central TRP, transmission and reception point, main TRP, transmission / reception (Tx and Rx) cell, transmission / reception component carrier (CC), transmission / reception bandwidth part (BWP), first point, first transmission / reception point, primary point, and first base station may be interchangeable. In the present disclosure, the terms reception point, reception point (RP), reception (Rx) point, distributed TRP, additional TRP, restrictive TRP, reception cell, reception CC, reception BWP, second point, second transmission / reception point, secondary point, and second base station may be interchangeable.

[0017] The reception points may be connected to a TRP (e.g., a base station) or a core network via wired or wireless connections. The reception points may be treated as a network or a base station.

[0018] The receiving point may not include some of the configurations (capabilities, functions, etc.) of the central TRP. At least one function of DL data transmission, SS / PBCH block transmission, and DL transmission may be omitted in the receiving point. At least one of antennas, panels, antenna elements, and radio frequency (RF) units (RF chains, RF circuits) may be fewer in number in the receiving point than in the central TRP. The maximum transmission power of the receiving point may be lower than that of the central TRP. The UE may receive DL signals (e.g., PDCCH, PDSCH, SSB, PBCH, etc.) from the central TRP and transmit UL signals (e.g., PUCCH, PUSCH, PRACH, etc.) to the receiving point based on the DL signals.

[0019] The reception point may be a transmission / reception point that has limited DL transmission compared to the central TRP, or a transmission / reception point of a different type than the central TRP.

[0020] (Random Access Procedure) Existing LTE systems (e.g., LTE Rel. 8-14) support random access procedures for establishing uplink (UL) synchronization. Random access procedures include contention-based random access (also called contention-based random access (CBRA)) and non-contention-based random access (non-CBRA, also called contention-free random access (CFRA)).

[0021] In contention-based random access (CBRA), a UE transmits a preamble randomly selected from multiple preambles (also called random access preambles, random access channel (Physical Random Access Channel (PRACH)), RACH preambles, etc.) defined for each cell. Contention-based random access is a UE-initiated random access procedure and can be used, for example, at the time of initial access, the start or restart of UL transmission, etc.

[0022] On the other hand, in contention-free random access (Non-CBRA, CFRA), a network (e.g., a base station) assigns a preamble to a UE on a downlink (DL) control channel (Physical Downlink Control Channel (PDCCH)), and the UE transmits the preamble assigned by the network. Non-contention-free random access is a network-initiated random access procedure, and can be used, for example, at the time of handover, at the start or restart of DL transmission (at the start or restart of UL transmission of DL retransmission instruction information), etc.

[0023] 2 is a diagram illustrating an example of contention-based random access. First, a UE receives in advance information (PRACH configuration information) indicating a configuration of a random access channel (PRACH) (PRACH configuration, RACH configuration) through system information (e.g., at least one of MIB (Material Information Block) or SIB (System Information Block)) or higher layer signaling (e.g., RRC (Radio Resource Control) signaling).

[0024] In the present disclosure, higher layer signaling may be, for example, any one of Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling, broadcast information, and the like, or a combination thereof.

[0025] The MAC signaling may use, for example, a MAC Control Element (MAC CE), a MAC Protocol Data Unit (PDU), etc. The broadcast information may be, for example, a Master Information Block (MIB), a System Information Block (SIB), Remaining Minimum System Information (RMSI), Other System Information (OSI), etc.

[0026] In the example of Figure 2A, first, the UE receives PRACH configuration information and Remaining Minimum System Information (RMSI) through a Synchronization Signal Block (SSB). An SSB is a signal block that includes at least one of a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and a Physical Broadcast Channel (PBCH). An SSB may also be referred to as an SS / PBCH block.

[0027] The PRACH configuration information may include, for example, a plurality of physical cell IDs (PCIs) defined for each cell, a plurality of preambles (e.g., preamble formats) defined for each cell, time resources (e.g., system frame numbers, subframe numbers) and frequency resources (e.g., an offset (prach-FrequencyOffset) indicating the start position of 6 resource blocks (PRBs: Physical Resource Blocks)) used for PRACH transmission, etc.

[0028] As shown in FIG. 2A, when the UE transitions from an idle (RRC_IDLE) state to an RRC connected (RRC_CONNECTED) state (e.g., at the time of initial access), or when the UE is in an RRC connected state but UL synchronization is not established (e.g., at the start or restart of UL transmission), the UE randomly selects one of multiple preambles indicated by the PRACH configuration information and transmits the selected preamble via PRACH (Message 1).

[0029] When the base station detects the preamble, it transmits a Random Access Response (RAR) in response (Message 2). If the UE fails to receive the RAR within a predetermined period (RAR window) after transmitting the preamble, it increases the transmission power of the PRACH and transmits (resends) the preamble again. Note that increasing the transmission power during retransmission is also called power ramping.

[0030] Upon receiving the RAR, the UE adjusts the UL transmission timing based on the timing advance (TA) included in the RAR to establish UL synchronization. The UE also transmits a control message (Message 3) of higher layers (L2 / L3: Layer 2 / Layer 3) using the UL resources specified by the UL grant included in the RAR. The control message includes the UE identifier (UE-ID). The UE identifier may be, for example, a Cell-Radio Network Temporary Identifier (C-RNTI) if the UE is in an RRC connected state, or a UE-ID of a higher layer such as a System Architecture Evolution-Temporary Mobile Subscriber Identity (S-TMSI) if the UE is in an idle state.

[0031] The base station transmits a collision resolution message in response to the control message from the higher layer (message 4). The collision resolution message is transmitted based on the user equipment identifier included in the control message. A user equipment that successfully detects the collision resolution message transmits an acknowledgement (ACK) in Hybrid Automatic Repeat reQuest (HARQ) to the network. This transitions the UE from idle state to an RRC connected state.

[0032] On the other hand, if a UE fails to detect the collision resolution message, it determines that a collision has occurred, reselects a preamble, and repeats the random access procedure of messages 1 to 4. When the radio base station detects that the collision has been resolved by an ACK from the user terminal, it transmits an UL grant to the UE. The UE starts transmitting UL data using the UL resources allocated by the UL grant.

[0033] In the above-described contention-based random access, when a UE desires to transmit UL data, it can autonomously initiate a random access procedure. Furthermore, after UL synchronization is established, UL data is transmitted using UL resources assigned specifically to the user terminal by an UL grant, enabling highly reliable UL transmission.

[0034] In NR Rel. 16, a random access procedure using fewer steps than the existing four steps is being considered. One example is a random access procedure using two steps. The random access procedure using two steps is also called a two-step random access procedure, a two-step RACH, or a two-step RACH.

[0035] A two-step RACH may consist of a first step of transmission from the UE to the network and a second step of transmission from the network to the UE (see FIG. 2B).

[0036] For example, in the first step, at least one of an UL signal and an UL channel including a preamble and a message may be transmitted from the UE to the network (base station). The preamble may be configured to play a role similar to that of message 1 (PRACH) in the existing random access procedure. The message may be configured to play a role similar to that of message 3 (PUSCH) in the existing random access procedure. Note that the preamble and the message transmitted in the first step may be referred to as message A (Msg. A) or a first message.

[0037] In the second step, at least one of a DL signal and a DL channel including a response and contention-resolution may be transmitted from the network (base station) to the UE. The response may be configured to play a role similar to that of message 2 (random access response (RAR) transmitted by PDSCH) in the existing random access procedure. The contention resolution may be configured to play a role similar to that of message 4 (PDSCH) in the existing random access procedure. Note that the message transmitted in the second step may be referred to as message B (Msg. B) or a second message.

[0038] As mentioned above, when different types of transmitting and receiving points are supported due to the expansion of UL coverage, there has been insufficient consideration on how to control the random access procedure (e.g., transmission of PRACH, etc.). If the PRACH transmission operation is not controlled appropriately, there is a risk of communication degradation.

[0039] Therefore, the inventors have devised an appropriate PRACH transmission method to the central TRP and receiving point.

[0040] Hereinafter, embodiments according to the present disclosure will be described in detail with reference to the drawings. Wireless communication methods according to the embodiments may be applied independently or in combination.

[0041] (Setting the receiving point) The UE may assume that a reception point ID (Rx point ID) corresponding to an identifier of a reception point (e.g., PCI, etc.) is set by at least one of higher layer signaling, MAC control element, and Downlink Control Information (DCI). For example, an RRC parameter (X [bit], N ID Rxpoint ) is set to the UE by RRC signaling. ID Rxpoint 10 is an example of a table showing the correspondence between X and reception point ID, and shows an example where X=8, Rx point ID={0, 1, ..., 255}.

[0042] For example, when the UE receives an SSB (at least one of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS)) in initial access, the UE may assume that the SSB contains information about the reception point ID. Alternatively, the UE may assume that other system information (RMSI) received based on the SSB contains information about the reception point ID, or that both the SSB and the RMSI contain information about the reception point ID.

[0043] The receiving point ID may be the same as that of the central TRP, or may be newly defined for the receiving point (e.g., N ID Rxpoint ). Also, a predetermined number of bits (for example, 1) indicating the presence of a receiving point and a physical cell ID (PCI) (N) notified using the SSS are used. ID (1) Alternatively, the receiving point ID may be assumed by the number of bits (e.g., 2) indicating the presence of a receiving point and the PCI (N ID (2) ) may assume a reception point ID.

[0044] PCI(N) assigned to UE ID cell ) is the above N ID (1) (For example, N ID (1) ={0,1,…,335}) and the above N ID (2) (For example, N ID (2) ={0,1,2}) and N ID cell =3N ID (1) +N ID (2) It may be assumed that it can be found from

[0045] The identifier of a central TRP may be associated with the identifier of a reception point within the cell coverage of the central TRP. For example, it may be assumed that the reception point ID is assigned based on the sector within the cell coverage of the central TRP. In FIG. 4, the reception point ID is assigned based on the sector within the cell coverage of the central TRP. ID Rxpoint Here is an example of assigning =0 to 2.

[0046] The association between the central TRP and the reception point may be configured as Carrier Aggregation (CA) (for example, the central TRP is a PCell and the reception point is an SCell) or as Dual Connectivity (DC).

[0047] If a reception point ID (Rx point ID) is not configured in the UE, the UE may not assume UL transmissions (e.g. PRACH, PUSCH, PUCCH, etc.) to the reception point, in other words, the UE may assume UL transmissions to the central TRP of the configured identifier.

[0048] The above setting of the reception points may be applied to any of the following first aspect, second aspect, and other aspects.

[0049] (Wireless communication method) In the following embodiment, a four-step RACH will be described. In addition, in a two-step RACH, message A includes Msg.1 (or information equivalent to Msg.1) and Msg.3 (or information equivalent to Msg.3) of the four-step RACH, and message B includes Msg.2 (or information equivalent to Msg.2) and Msg.4 (or information equivalent to Msg.4) of the four-step RACH, but this is not limiting.

[0050] The following contention may be applied to at least one of a 4-step and 2-step contention-based random access procedure and a 4-step and 2-step non-contention-based random access procedure. When a 4-step RACH is applied to a non-contention-based random access procedure, a step (0th step) may be set before the first step in which a DL signal instructing (or triggering) the transmission of message 1 is notified to the UE.

[0051] In the present disclosure, the terms transmission / reception point, reference signal group, antenna port group, control resource set (CORESET) group, etc. may be read interchangeably.

[0052] In the present disclosure, message 1, random access preamble, random access channel (PRACH), RACH preamble, etc. may be read interchangeably.

[0053] In the present disclosure, the type of transmission / reception point may refer to either a central TRP or a transmission / reception point.

[0054] In the present disclosure, the terms sector, panel, cell, cell group, carrier, component carrier, etc. may be read interchangeably.

[0055] (First aspect) In a first aspect, the UE may determine the PRACH transmission destination during initial access based on the type of transmission / reception point. For example, the UE may transmit the PRACH during initial access to the central TRP regardless of whether the DL signal received by the UE from the central TRP includes information about the reception point.

[0056] When the UE receives a DL signal (e.g., SSB and RMSI) in initial access, regardless of whether the Reception Point ID is included, the UE shall ID cell ) to transmit the PRACH (message 1).

[0057] In the example of FIG. 5, after the UE receives an SSB from the central TRP (1), the UE sends a PRACH to the central TRP (2).

[0058] In this case, even if the reception point does not support PRACH reception or if the reception point is not configured in the UE, network connection in UL coverage extension is possible.

[0059] When retransmitting the PRACH, the UE may switch the destination of the PRACH from the central TRP to the reception point based on a predetermined condition. The UE may control the PRACH transmission and retransmission based on at least one of the following cases 1-1 to 1-3, for example.

[0060] Case 1-1 First, a UE that receives a DL signal (e.g., at least one of SSB and RMSI) including a receiving point ID first receives a central TRP (N ID cell) and then, if a Random Access Response (RAR) is not received, the UE may perform at least one of reselecting the random access preamble and power ramping before transmitting a PRACH (Message 1) to the Central TRP (N ID cell ) may be assumed. At this time, power ramping may be performed based on information notified from the network (for example, power Ramping Step={dB0, dB2, dB4, dB6}).

[0061] When reselecting a random access preamble and power ramping are performed when the random access preamble is retransmitted, the configuration may be such that both reselecting a random access preamble and power ramping are performed, or the configuration may be such that only one of them is performed.

[0062] In the example of Figure 6, after the UE receives the SSB (and RMSI) from the central TRP (1), the UE transmits the PRACH to the central TRP (2). If the UE fails to receive the RAR corresponding to the PRACH, the UE performs at least one of reselecting the random access preamble and power ramping, and then retransmits the PRACH to the central TRP (3).

[0063] If the UE cannot receive the RAR even after exceeding the maximum number of PRACH retransmissions configured for the UE, the UE may consider transmitting the PRACH to the receiving point (4). In this case, the maximum number of retransmissions may be selected from information notified by the network (e.g., preamble Trans Max={n3,n4,n5,n6,n7,n8,n10,n20,n50,n100,n200}).

[0064] When the UE transmits a PRACH to a reception point, the UE may apply the transmission power when the UE last transmitted a PRACH to the central TRP, or may apply the transmission power when the UE first transmitted a PRACH to the central TRP. Alternatively, the UE may be notified by the network of information regarding the power of the PRACH (Random Access Channel (RACH) transmission power) for transmission to the reception point. The information regarding the power of the PRACH transmission to the reception point may be notified to the UE by the network together with information regarding the maximum number of PRACH transmissions to the central TRP.

[0065] In the example of FIG. 6, after the operations (1) to (3), the UE transmits the PRACH to the receiving point (4).

[0066] According to Case 1-1, even if the PRACH transmission from the UE does not reach the central TRP due to the communication environment (e.g., the influence of other cells, the position of the UE, etc.), the PRACH can be transmitted to a reception point with a closer reach by switching the PRACH transmission destination.

[0067] <Case 1-2> First, the UE that receives the SSB containing the receiving point ID first sends the central TRP (N ID cell ) after which, if the UE fails to receive the RAR, the UE may be expected to retransmit the PRACH to the receiving point before reselecting the random access preamble and power ramping.

[0068] In the example of Figure 7, after the UE receives the SSB (and RMSI) from the central TRP (1), the UE transmits the PRACH to the central TRP (2). If the UE cannot receive the RAR corresponding to the transmitted PRACH, it retransmits the PRACH to the receiving point (3). In this case, the UE retransmits the PRACH to the receiving point (3) before reselecting the random access preamble and power ramping.

[0069] If the UE is unable to receive the RAR after retransmitting the PRACH to the central TRP and the receiving point before reselecting the random access preamble and power ramping, the UE shall perform at least one of reselecting the random access preamble and power ramping and then retransmit the PRACH to the central TRP (N ID cell ) (4). At this time, power ramping may be performed based on information notified from the network (for example, power Ramping Step={dB0, dB2, dB4, dB6}).

[0070] As in case 1-1, when reselecting a random access preamble and power ramping are performed when the random access preamble is retransmitted, the configuration may be such that both reselecting a random access preamble and power ramping are performed, or the configuration may be such that only one of them is performed.

[0071] In the example of FIG. 7, after the operations (1) to (3), the UE performs at least one of reselecting a random access preamble and power ramping, and then transmits a PRACH to the central TRP (4).

[0072] In Case 1-2, the PRACH transmission destination is switched to the reception point before power ramping, so there is a possibility that the RAR can be received without power ramping, which can reduce the power consumption of the UE.

[0073] <Cases 1-3> The UE may be configured to perform either of the above-described cases 1-1 or 1-2 according to information included in the DL signal received from the central TRP.

[0074] For example, in initial access, a setting may be made to perform either case 1-1 or 1-2 depending on information regarding the PRACH retransmission destination of the UE included in the SSB received from the central TRP.

[0075] According to Cases 1-3, the UE can flexibly connect to both the central TRP and the receiving point network.

[0076] (Second aspect) In a second aspect, the UE may determine the PRACH transmission destination at the time of initial access based on whether or not the reception point ID is set. For example, if the DL signal received by the UE from the central TRP includes information about the reception point, the UE may transmit the PRACH at the time of initial access to the reception point.

[0077] In the example of Figure 8, after the UE receives an SSB from the central TRP (1), it transmits a PRACH to the reception point based on the reception point ID included in the SSB (and / or RMSI) (2). In this case, the UE can transmit the PRACH to a reception point closer to the central TRP, thereby reducing the power consumption of the UE.

[0078] If the DL signal received by the UE from the central TRP does not include information about the reception point, the UE may transmit an UL transmission to the central TRP. For example, if at least one of the SSB and RMSI received in the initial access does not include a reception point ID, the UE may transmit an UL transmission to the central TRP (N ID cell ) (see FIG. 5 above).

[0079] When retransmitting the PRACH, the UE may switch the destination of the PRACH from the reception point to the central TRP based on a predetermined condition. The UE may control the PRACH transmission and retransmission based on at least one of the following cases 2-1 to 2-3.

[0080] <Case 2-1> First, a UE that receives a DL signal (for example, at least one of SSB and RMSI) including a receiving point ID first identifies a receiving point (N ID Rxpoint ) and then, if the UE is unable to receive the RAR, it may perform at least one of reselecting the random access preamble and power ramping before transmitting the PRACH (message 1) to the receiving point (N ID Rxpoint ) may be assumed. At this time, power ramping may be performed based on information notified from the network (for example, power Ramping Step={dB0, dB2, dB4, dB6}).

[0081] When reselecting a random access preamble and power ramping are performed when the random access preamble is retransmitted, the configuration may be such that both are performed, or that only one of them is performed.

[0082] In the example of Figure 9, after the UE receives the SSB (and RMSI) from the central TRP (1), the UE transmits the PRACH to the receiving point (2). If the UE cannot receive the RAR corresponding to the PRACH, it retransmits the PRACH to the receiving point after performing at least one of reselecting the random access preamble and power ramping (3).

[0083] If the UE cannot receive the RAR even after the maximum number of PRACH retransmissions configured in the UE has been exceeded, the UE may consider transmitting the PRACH to the central TRP (4). In this case, the maximum number of retransmissions may be selected from information notified by the network (e.g., preamble Trans Max={n3,n4,n5,n6,n7,n8,n10,n20,n50,n100,n200}).

[0084] When the UE transmits a PRACH to a reception point, the UE may apply the transmission power used when the UE last transmitted a PRACH to the reception point, or the transmission power used when the UE first transmitted a PRACH to the reception point. Alternatively, the UE may be notified by the network of information regarding the RACH transmission power for transmission to the central TRP. The information regarding the power of the PRACH transmission to the central TRP may be notified to the UE by the network together with information regarding the maximum number of PRACH transmissions to the reception point.

[0085] In the example of FIG. 9, after the operations (1) to (3), the UE transmits a PRACH to the central TRP (4).

[0086] According to case 2-1, even if the UE cannot connect (or reconnect) to the reception point, it can still connect to the central TRP.

[0087] <Case 2-2> First, the UE that receives the SSB containing the receiving point ID first ID Rxpoint ) after which, if the UE fails to receive the RAR, the UE may be expected to retransmit the PRACH to the central TRP before reselecting the random access preamble and power ramping.

[0088] In the example of Figure 10, after the UE receives the SSB (and RMSI) from the central TRP (1), the UE transmits the PRACH to the receiving point (2). If the UE cannot receive the RAR corresponding to the transmitted PRACH, the UE retransmits the PRACH to the central TRP (3). In this case, the UE retransmits the PRACH to the central TRP (3) before reselecting the random access preamble and power ramping.

[0089] If the UE is unable to receive the RAR after retransmitting the PRACH to the central TRP and the receiving point before reselecting the random access preamble and power ramping, the UE shall reselect the random access preamble and / or power ramping and then transmit the PRACH to the receiving point (N ID Rxpoint ) (4). At this time, power ramping may be performed based on information notified from the network (for example, power Ramping Step={dB0, dB2, dB4, dB6}).

[0090] As in case 2-1, when reselecting a random access preamble and power ramping are performed when the random access preamble is retransmitted, the configuration may be such that both reselecting a random access preamble and power ramping are performed, or the configuration may be such that only one of them is performed.

[0091] In the example of FIG. 10, after the operations (1) to (3), the UE reselects a random access preamble, performs power ramping, and then transmits a PRACH to the receiving point (4).

[0092] According to Case 2-2, when the central TRP is within the line of sight (LOS) from the UE and the receiving point is outside the line of sight (NLOS), the UE can connect to the central TRP.

[0093] <Case 2-3> The UE may be configured to perform either of the above-described cases 2-1 or 2-2 according to information included in the DL signal received from the central TRP.

[0094] For example, in initial access, a setting may be made to perform either case 2-1 or 2-2 depending on information regarding the PRACH retransmission destination of the UE included in an SSB received from the network.

[0095] According to Case 2-3, flexible connection is possible in both the central TRP and the receiving point networks.

[0096] (Other aspects) <Determining the transmission destination based on the PRACH bandwidth> The UE may determine the transmission destination of the PRACH based on the value of the bandwidth of the PRACH.

[0097] For example, the subcarrier spacing (Δf RA When Δf for PRACH and Δf for PUSCH are configured for the UE, the UE may assume that the PRACH transmission destination is a reception point that uses the subcarrier spacing. In this case, the UE may be notified of X by at least one of RRC signaling, MAC-CE, and DCI.

[0098] <Method for determining transmission destination using PRACH sequence> The UE may determine the transmission destination of the PRACH according to the PRACH sequence.

[0099] The UE may assume that different PRACH preambles are configured for each TRP. For example, it may assume that two different preambles are configured for the central TRP and other base stations (reception points). It may also assume that X different preambles are configured for the central TRP and other base stations (reception points). In this case, the UE may be notified of X by at least one of RRC signaling, MAC-CE, and DCI.

[0100] Here, the PRACH preamble may include a preamble for contention-based random access and a preamble for non-contention-based random access. The preamble for contention-based random access may include a group of sequences whose received power is smaller than a predetermined value (e.g., Group A) and a group of sequences whose received power is larger than a predetermined value (e.g., Group B) (see FIG. 11).

[0101] A sequence in which the received power of the PRACH is greater than a predetermined value (e.g., N con Among the collision-type preambles, N i ≧N A If Group B is set, the UE may assume that the PRACH transmission destination is the reception point. con Among the collision-type preambles, N i ≧N A If Group B) satisfying the above is not configured, the UE may assume that the PRACH destination is the central TRP.

[0102] Also, if the sequence length of the preamble is the first value (for example, the shortest value (for example, L RA When a PRACH format with a preamble length of 1 (for example, the shortest value (for example, L RA When a PRACH format with 0x0 ...

[0103] Also, if the sequence length of the preamble is a second value (for example, the longest value (for example, L RA When a PRACH format with a preamble length of 2 (e.g., 1) is configured, the UE may assume that the PRACH destination is the central TRP. RA When a PRACH format with 0x0 ...

[0104] Note that information about the PRACH configuration (e.g., prach-ConfigurationIndex) may be included in information about the RACH configuration (e.g., RACH-ConfigGeneric). Also, the PRACH format may be configured in the UE by the information about the PRACH configuration (e.g., prach-ConfigurationIndex). In this case, the sequence length of the preamble (e.g., L RA = 839 or 139) is determined by the PRACH format, and the shorter the preamble sequence length, the fewer the number of PRACH resource blocks (the longer the preamble sequence length, the more PRACH resource blocks there are), so it can be assumed that the PRACH format will differ depending on the TRP.

[0105] <Method for determining transmission destination based on PRACH transmission timing> The UE may determine the transmission destination of the PRACH based on the transmission occasion of the PRACH. The UE may assume that the transmission occasion of the PRACH is set separately for each base station (e.g., a central TRP and a reception point).

[0106] For example, when a PRACH configuration index is set such that the PRACH transmission start symbol position is not a predetermined value (e.g., 0), the UE may assume that the PRACH transmission destination is the reception point. On the other hand, when the PRACH transmission start symbol is other than the predetermined value, the UE may assume that the PRACH transmission destination is the central TRP.

[0107] <Method for determining transmission destination based on PDCCH monitoring opportunities> The UE may determine the transmission destination of the PRACH based on the symbol position monitored in the PDCCH monitoring occasion where the RAR is received.

[0108] For example, if a predetermined (eg, even) SSB index is configured for the UE, the UE may assume that the PRACH destination is a reception point.

[0109] In addition, the symbol position to be monitored by the PDCCH monitoring opportunity may be determined by a predetermined number of lower-order bits (e.g., 4 bits) of information regarding PDCCH configuration included in at least one of the SSB index and MIB (e.g., prach-ConfigSIB1).

[0110] In this case, the SSB index corresponds to the transmitting beam of the UE and the receiving beam of the TRP, so if the SSB index is different, the beam is different and different types of TRP can be assumed.

[0111] (wireless communication system) The configuration of a wireless communication system according to an embodiment of the present disclosure will be described below. In this wireless communication system, communication is performed using any one of the wireless communication methods according to the above embodiments of the present disclosure or a combination thereof.

[0112] 12 is a diagram illustrating an example of a schematic configuration of a wireless communication system according to an embodiment. The wireless communication system 1 may be a system that realizes communication using Long Term Evolution (LTE) or 5th generation mobile communication system New Radio (5G NR) specified by the Third Generation Partnership Project (3GPP).

[0113] The wireless communication system 1 may also support dual connectivity between multiple Radio Access Technologies (RATs) (Multi-RAT Dual Connectivity (MR-DC)). MR-DC may include dual connectivity between LTE (Evolved Universal Terrestrial Radio Access (E-UTRA)) and NR (E-UTRA-NR Dual Connectivity (EN-DC)), dual connectivity between NR and LTE (NR-E-UTRA Dual Connectivity (NE-DC)), etc.

[0114] In EN-DC, the LTE (E-UTRA) base station (eNB) is the master node (MN), and the NR base station (gNB) is the secondary node (SN). In NE-DC, the NR base station (gNB) is the MN, and the LTE (E-UTRA) base station (eNB) is the SN.

[0115] The wireless communication system 1 may support dual connectivity between multiple base stations within the same RAT (for example, dual connectivity in which both the MN and the SN are NR base stations (gNBs) (NR-NR Dual Connectivity (NN-DC))).

[0116] The wireless communication system 1 may include a base station 11 that forms a macrocell C1 with a relatively wide coverage, and base stations 12 (12a-12c) that are located within the macrocell C1 and form small cells C2 that are smaller than the macrocell C1. A user terminal 20 may be located within at least one of the cells. The locations and numbers of the cells and user terminals 20 are not limited to the embodiment shown in the figure. Hereinafter, when there is no need to distinguish between the base stations 11 and 12, they will be collectively referred to as base station 10.

[0117] The user terminal 20 may be connected to at least one of the multiple base stations 10. The user terminal 20 may utilize at least one of carrier aggregation (CA) using multiple component carriers (CC) and dual connectivity (DC).

[0118] Each CC may be included in at least one of a first frequency band (Frequency Range 1 (FR1)) and a second frequency band (Frequency Range 2 (FR2)). The macro cell C1 may be included in FR1, and the small cell C2 may be included in FR2. For example, FR1 may be a frequency band of 6 GHz or less (sub-6 GHz), and FR2 may be a frequency band above 24 GHz (above-24 GHz). Note that the frequency bands and definitions of FR1 and FR2 are not limited to these, and for example, FR1 may be a frequency band higher than FR2.

[0119] Furthermore, the user terminal 20 may perform communication using at least one of Time Division Duplex (TDD) and Frequency Division Duplex (FDD) in each CC.

[0120] The multiple base stations 10 may be connected by wire (for example, optical fiber conforming to the Common Public Radio Interface (CPRI), an X2 interface, or the like) or wirelessly (for example, NR communication). For example, when NR communication is used as a backhaul between the base stations 11 and 12, the base station 11 corresponding to the upper station may be called an Integrated Access Backhaul (IAB) donor, and the base station 12 corresponding to the relay station (relay) may be called an IAB node.

[0121] The base station 10 may be connected to the core network 30 directly or via another base station 10. The core network 30 may include, for example, at least one of an Evolved Packet Core (EPC), a 5G Core Network (5GCN), a Next Generation Core (NGC), and the like.

[0122] The user terminal 20 may be a terminal compatible with at least one of communication methods such as LTE, LTE-A, and 5G.

[0123] An Orthogonal Frequency Division Multiplexing (OFDM)-based radio access scheme may be used in the radio communication system 1. For example, Cyclic Prefix OFDM (CP-OFDM), Discrete Fourier Transform Spread OFDM (DFT-s-OFDM), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), or the like may be used in at least one of the downlink (DL) and uplink (UL).

[0124] The radio access scheme may also be called a waveform. Note that in the wireless communication system 1, other radio access schemes (for example, other single-carrier transmission schemes, other multi-carrier transmission schemes) may be used as the UL and DL radio access schemes.

[0125] In the wireless communication system 1, a downlink shared channel (Physical Downlink Shared Channel (PDSCH)) shared by each user terminal 20, a broadcast channel (Physical Broadcast Channel (PBCH)), a downlink control channel (Physical Downlink Control Channel (PDCCH)), etc. may be used as the downlink channel.

[0126] Furthermore, in the wireless communication system 1, an uplink shared channel (Physical Uplink Shared Channel (PUSCH)) shared by each user terminal 20, an uplink control channel (Physical Uplink Control Channel (PUCCH)), a random access channel (Physical Random Access Channel (PRACH)), etc. may be used as an uplink channel.

[0127] The PDSCH transmits user data, higher layer control information, System Information Block (SIB), etc. The PUSCH may transmit user data, higher layer control information, etc. Furthermore, the PBCH may transmit Master Information Block (MIB).

[0128] Lower layer control information may be transmitted by the PDCCH. The lower layer control information may include, for example, Downlink Control Information (DCI) including scheduling information for at least one of the PDSCH and the PUSCH.

[0129] Note that the DCI for scheduling the PDSCH may be referred to as a DL assignment, a DL DCI, etc., and the DCI for scheduling the PUSCH may be referred to as an UL grant, a UL DCI, etc. Note that the PDSCH may be interpreted as DL data, and the PUSCH may be interpreted as UL data.

[0130] A control resource set (CORESET) and a search space may be used to detect the PDCCH. The CORESET corresponds to resources to search for DCI. The search space corresponds to a search region and a search method for PDCCH candidates. One CORESET may be associated with one or more search spaces. The UE may monitor a CORESET associated with a certain search space based on the search space configuration.

[0131] One search space may correspond to PDCCH candidates corresponding to one or more aggregation levels. One or more search spaces may be called a search space set. Note that the terms "search space," "search space set," "search space setting," "search space set setting," "CORESET," "CORESET setting," etc. in the present disclosure may be read interchangeably.

[0132] The PUCCH may transmit uplink control information (UCI) including at least one of channel state information (CSI), acknowledgement information (which may be called, for example, Hybrid Automatic Repeat reQuest ACKnowledgement (HARQ-ACK), ACK / NACK, etc.), and scheduling request (SR). The PRACH may transmit a random access preamble for establishing a connection with a cell.

[0133] In the present disclosure, downlink, uplink, etc. may be expressed without adding "link." Also, various channels may be expressed without adding "Physical" to the beginning.

[0134] In the wireless communication system 1, a synchronization signal (SS), a downlink reference signal (DL-RS), etc. may be transmitted. In the wireless communication system 1, a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), a demodulation reference signal (DMRS), a positioning reference signal (PRS), a phase tracking reference signal (PTRS), etc. may be transmitted as DL-RS.

[0135] The synchronization signal may be, for example, at least one of a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS). A signal block including the SS (PSS, SSS) and the PBCH (and DMRS for the PBCH) may be referred to as an SS / PBCH block, an SS Block (SSB), or the like. Note that the SS, SSB, and the like may also be referred to as reference signals.

[0136] Furthermore, in the wireless communication system 1, a sounding reference signal (SRS), a demodulation reference signal (DMRS), etc. may be transmitted as an uplink reference signal (UL-RS). Note that the DMRS may also be called a user equipment-specific reference signal (UE-specific reference signal).

[0137] (base station) 13 is a diagram showing an example of the configuration of a base station according to an embodiment. The base station 10 includes a control unit 110, a transceiver unit 120, a transceiver antenna 130, and a transmission line interface 140. Note that the base station may include one or more of each of the control unit 110, the transceiver unit 120, the transceiver antenna 130, and the transmission line interface 140.

[0138] In this example, the functional blocks of the characteristic parts of the present embodiment are mainly shown, and it may be assumed that the base station 10 also has other functional blocks necessary for wireless communication. Some of the processing of each unit described below may be omitted.

[0139] The control unit 110 performs overall control of the base station 10. The control unit 110 can be configured from a controller, a control circuit, and the like that are explained based on common understanding in the technical field to which the present disclosure relates.

[0140] The control unit 110 may control signal generation, scheduling (e.g., resource allocation, mapping), etc. The control unit 110 may control transmission and reception using the transceiver unit 120, the transceiver antenna 130, and the transmission path interface 140, measurement, etc. The control unit 110 may generate data to be transmitted as signals, control information, sequences, etc., and transfer them to the transceiver unit 120. The control unit 110 may perform call processing (setting up, releasing, etc.) of communication channels, status management of the base station 10, management of radio resources, etc.

[0141] The transceiver unit 120 may include a baseband unit 121, a radio frequency (RF) unit 122, and a measurement unit 123. The baseband unit 121 may include a transmission processing unit 1211 and a reception processing unit 1212. The transceiver unit 120 may be configured with a transmitter / receiver, an RF circuit, a baseband circuit, a filter, a phase shifter, a measurement circuit, a transceiver circuit, etc., which are described based on common understanding in the technical field related to the present disclosure.

[0142] The transmitting / receiving unit 120 may be configured as an integrated transmitting / receiving unit, or may be composed of a transmitting unit and a receiving unit. The transmitting unit may be composed of a transmission processing unit 1211 and an RF unit 122. The receiving unit may be composed of a reception processing unit 1212, an RF unit 122, and a measurement unit 123.

[0143] The transmitting and receiving antenna 130 can be configured from an antenna described based on common understanding in the technical field to which the present disclosure pertains, such as an array antenna.

[0144] The transceiver 120 may transmit the above-mentioned downlink channel, synchronization signal, downlink reference signal, etc. The transceiver 120 may receive the above-mentioned uplink channel, uplink reference signal, etc.

[0145] The transceiver 120 may form at least one of a transmission beam and a reception beam using digital beamforming (for example, precoding), analog beamforming (for example, phase rotation), or the like.

[0146] The transceiver 120 (transmission processing unit 1211) may perform Packet Data Convergence Protocol (PDCP) layer processing, Radio Link Control (RLC) layer processing (e.g., RLC retransmission control), Medium Access Control (MAC) layer processing (e.g., HARQ retransmission control), etc. on data, control information, etc. obtained from the control unit 110, and generate a bit string to be transmitted.

[0147] The transceiver 120 (transmission processor 1211) may perform transmission processing such as channel coding (which may include error correction coding), modulation, mapping, filtering, Discrete Fourier Transform (DFT) processing (if necessary), Inverse Fast Fourier Transform (IFFT) processing, precoding, and digital-to-analog conversion on the bit string to be transmitted, and output a baseband signal.

[0148] The transmitting / receiving unit 120 (RF unit 122) may perform modulation to a radio frequency band, filtering, amplification, etc. on the baseband signal, and transmit the radio frequency band signal via the transmitting / receiving antenna .

[0149] On the other hand, the transmitting / receiving unit 120 (RF unit 122) may perform amplification, filtering, demodulation to a baseband signal, etc. on the radio frequency band signal received by the transmitting / receiving antenna .

[0150] The transceiver 120 (reception processing unit 1212) may apply reception processing such as analog-to-digital conversion, Fast Fourier Transform (FFT) processing, Inverse Discrete Fourier Transform (IDFT) processing (if necessary), filtering, demapping, demodulation, decoding (which may include error correction decoding), MAC layer processing, RLC layer processing, and PDCP layer processing to the acquired baseband signal, thereby acquiring user data, etc.

[0151] The transceiver 120 (measurement unit 123) may perform measurements on the received signal. For example, the measurement unit 123 may perform Radio Resource Management (RRM) measurements, Channel State Information (CSI) measurements, etc. based on the received signal. The measurement unit 123 may measure received power (e.g., Reference Signal Received Power (RSRP)), received quality (e.g., Reference Signal Received Quality (RSRQ), Signal to Interference plus Noise Ratio (SINR), Signal to Noise Ratio (SNR)), signal strength (e.g., Received Signal Strength Indicator (RSSI)), propagation path information (e.g., CSI), etc. The measurement results may be output to the control unit 110.

[0152] The transmission path interface 140 may transmit and receive signals (backhaul signaling) between devices included in the core network 30, other base stations 10, etc., and may acquire and transmit user data (user plane data), control plane data, etc. for the user terminal 20.

[0153] The transmitting section and receiving section of the base station 10 in the present disclosure may be configured by at least one of the transmitting / receiving section 120, the transmitting / receiving antenna 130, and the transmission path interface 140.

[0154] The transceiver 120 may transmit DL signals (e.g., PDCCH, PDSCH, SSB, PBCH, etc.) to the terminal. The transceiver 120 may also receive UL signals (e.g., PUCCH, PUSCH, PRACH, etc.) transmitted from the terminal. The control unit 110 may determine the terminal based on the received UL signals.

[0155] The transmitting / receiving unit 120 may receive a random access preamble transmitted from a terminal based on whether or not the DL signal includes information about the second transmitting / receiving point (first aspect, second aspect).

[0156] The transmitting / receiving unit 120 may transmit a random access response corresponding to the random access preamble to the terminal (first aspect, second aspect).

[0157] (user terminal) 14 is a diagram showing an example of the configuration of a user terminal according to one embodiment. The user terminal 20 includes a control unit 210, a transceiver unit 220, and a transceiver antenna 230. Note that the user terminal 20 may include one or more of each of the control unit 210, the transceiver unit 220, and the transceiver antenna 230.

[0158] Note that this example mainly shows functional blocks of the characteristic parts of the present embodiment, and it may be assumed that the user terminal 20 also has other functional blocks necessary for wireless communication. Some of the processing of each unit described below may be omitted.

[0159] The control unit 210 performs overall control of the user terminal 20. The control unit 210 can be configured from a controller, a control circuit, and the like that are explained based on common understanding in the technical field to which the present disclosure relates.

[0160] The control unit 210 may control signal generation, mapping, etc. The control unit 210 may also control transmission and reception, measurement, etc. using the transceiver unit 220 and the transceiver antenna 230. The control unit 210 may generate data, control information, sequences, etc. to be transmitted as signals, and transfer them to the transceiver unit 220.

[0161] The transceiver unit 220 may include a baseband unit 221, an RF unit 222, and a measurement unit 223. The baseband unit 221 may include a transmission processing unit 2211 and a reception processing unit 2212. The transceiver unit 220 may be configured from a transmitter / receiver, an RF circuit, a baseband circuit, a filter, a phase shifter, a measurement circuit, a transceiver circuit, etc., which are described based on common understanding in the technical field related to the present disclosure.

[0162] The transmitting / receiving unit 220 may be configured as an integrated transmitting / receiving unit, or may be composed of a transmitting unit and a receiving unit. The transmitting unit may be composed of a transmission processing unit 2211 and an RF unit 222. The receiving unit may be composed of a reception processing unit 2212, an RF unit 222, and a measurement unit 223.

[0163] The transmitting / receiving antenna 230 can be configured as an antenna described based on common understanding in the technical field to which the present disclosure pertains, such as an array antenna.

[0164] The transceiver 220 may receive the above-mentioned downlink channel, synchronization signal, downlink reference signal, etc. The transceiver 220 may transmit the above-mentioned uplink channel, uplink reference signal, etc.

[0165] The transceiver 220 may form at least one of a transmission beam and a reception beam using digital beamforming (for example, precoding), analog beamforming (for example, phase rotation), or the like.

[0166] The transceiver 220 (transmission processing unit 2211) may perform PDCP layer processing, RLC layer processing (e.g., RLC retransmission control), MAC layer processing (e.g., HARQ retransmission control), etc. on data, control information, etc. obtained from the control unit 210, and generate a bit string to be transmitted.

[0167] The transceiver 220 (transmission processor 2211) may perform transmission processing such as channel coding (which may include error correction coding), modulation, mapping, filtering, DFT processing (if necessary), IFFT processing, precoding, and digital-to-analog conversion on the bit string to be transmitted, and output a baseband signal.

[0168] Whether or not to apply DFT processing may be based on the setting of transform precoding. When transform precoding is enabled for a certain channel (e.g., PUSCH), the transceiver unit 220 (transmission processing unit 2211) may perform DFT processing as the transmission processing to transmit the channel using a DFT-s-OFDM waveform, and when transform precoding is not enabled, the transceiver unit 220 may not perform DFT processing as the transmission processing.

[0169] The transmitting / receiving unit 220 (RF unit 222) may perform modulation to a radio frequency band, filtering, amplification, etc. on the baseband signal, and transmit the radio frequency band signal via the transmitting / receiving antenna 230.

[0170] On the other hand, the transmitting / receiving unit 220 (RF unit 222) may perform amplification, filtering, demodulation to a baseband signal, etc. on the radio frequency band signal received by the transmitting / receiving antenna 230.

[0171] The transceiver 220 (reception processing unit 2212) may apply reception processing such as analog-to-digital conversion, FFT processing, IDFT processing (if necessary), filtering, demapping, demodulation, decoding (which may include error correction decoding), MAC layer processing, RLC layer processing, and PDCP layer processing to the acquired baseband signal to acquire user data, etc.

[0172] The transceiver 220 (measurement unit 223) may perform measurements on the received signal. For example, the measurement unit 223 may perform RRM measurement, CSI measurement, etc. based on the received signal. The measurement unit 223 may measure received power (e.g., RSRP), received quality (e.g., RSRQ, SINR, SNR), signal strength (e.g., RSSI), propagation path information (e.g., CSI), etc. The measurement results may be output to the control unit 210.

[0173] The transmitting section and receiving section of the user terminal 20 in the present disclosure may be configured by at least one of the transmitting / receiving section 220 and the transmitting / receiving antenna 230.

[0174] The transceiver unit 220 may receive a DL signal (e.g., PDCCH, PDSCH, SSB, PBCH, etc.) transmitted from a first transceiver point (e.g., a central TRP). The transceiver point 220 may also transmit a UL signal (e.g., PUCCH, PUSCH, PRACH, etc.) to at least one of the first transceiver point and a second transceiver point (e.g., a reception point) whose DL transmission is restricted by the first transceiver point. The control unit 210 may determine the transceiver point from which to transmit a random access preamble based on at least one of the type of the transceiver point, information included in the DL signal (e.g., PCI, reception point ID, etc.), and the number of transmissions.

[0175] The control unit 210 may determine the transmission / reception point from which to transmit the random access preamble based on whether or not the DL signal includes information about the second transmission / reception point (e.g., a reception point ID) (first aspect, second aspect).

[0176] If the transmitting / receiving unit 220 cannot receive a random access response corresponding to the random access preamble, the control unit 210 may change the transmitting / receiving point from which the random access preamble is retransmitted (first aspect, second aspect).

[0177] If the random access response cannot be received even after the maximum number of transmissions of the random access preamble has been exceeded, the control unit 210 may change the transmission / reception point from which the random access preamble is retransmitted (first aspect, second aspect).

[0178] If a random access response corresponding to the initial random access preamble cannot be received, the control unit 210 may change the transmission / reception point from which the random access preamble is retransmitted, and if a random access response cannot be received from the changed retransmission destination even after the maximum number of transmissions of the random access preamble has been exceeded, the control unit 210 may again change the transmission / reception point from which the random access preamble is retransmitted (first aspect, second aspect).

[0179] (Hardware configuration) The block diagrams used to explain the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. Furthermore, the method for realizing each functional block is not particularly limited. That is, each functional block may be realized using a single device that is physically or logically coupled, or may be realized using two or more physically or logically separated devices that are directly or indirectly connected (for example, using wires, wirelessly, etc.) and these multiple devices. The functional block may also be realized by combining the single device or multiple devices with software.

[0180] Here, the functions include, but are not limited to, judgment, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, election, establishment, comparison, assumption, expectation, deeming, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs transmission may be called a transmitting unit, transmitter, etc. As mentioned above, the implementation method of each is not particularly limited.

[0181] For example, a base station, a user terminal, etc. according to an embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. Fig. 15 is a diagram illustrating an example of the hardware configuration of a base station and a user terminal according to an embodiment. The above-described base station 10 and user terminal 20 may be physically configured as a computer device including a processor 1001, a memory 1002, a storage 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

[0182] In the present disclosure, terms such as apparatus, circuit, device, section, and unit may be used interchangeably. The hardware configurations of the base station 10 and the user terminal 20 may be configured to include one or more of the devices shown in the drawings, or may be configured to exclude some of the devices.

[0183] For example, although only one processor 1001 is shown, there may be multiple processors. Furthermore, processing may be performed by one processor, or processing may be performed by two or more processors simultaneously, serially, or in other ways. Furthermore, processor 1001 may be implemented by one or more chips.

[0184] Each function in the base station 10 and the user terminal 20 is realized, for example, by loading predetermined software (programs) onto hardware such as a processor 1001 and a memory 1002, causing the processor 1001 to perform calculations, control communication via the communication device 1004, and control at least one of reading and writing data in the memory 1002 and the storage 1003.

[0185] The processor 1001, for example, runs an operating system to control the entire computer. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, a register, etc. For example, at least a part of the above-mentioned control unit 110 (210), transmission / reception unit 120 (220), etc. may be realized by the processor 1001.

[0186] The processor 1001 also reads programs (program codes), software modules, data, etc. from at least one of the storage 1003 and the communication device 1004 into the memory 1002, and executes various processes in accordance with these. The programs used are those that cause a computer to execute at least some of the operations described in the above-described embodiments. For example, the control unit 110 (210) may be realized by a control program stored in the memory 1002 and running on the processor 1001, and the other functional blocks may be realized in a similar manner.

[0187] The memory 1002 is a computer-readable recording medium and may be configured by at least one of, for example, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a random access memory (RAM), or other suitable storage medium. The memory 1002 may also be referred to as a register, a cache, a main memory, or the like. The memory 1002 may store executable programs (program codes), software modules, and the like for implementing a wireless communication method according to an embodiment of the present disclosure.

[0188] Storage 1003 is a computer-readable recording medium and may be constituted by at least one of, for example, a flexible disk, a floppy disk, a magneto-optical disk (e.g., a compact disc (e.g., a Compact Disc ROM (CD-ROM)), a digital versatile disc, a Blu-ray disc), a removable disk, a hard disk drive, a smart card, a flash memory device (e.g., a card, stick, key drive), a magnetic stripe, a database, a server, or other suitable storage medium. Storage 1003 may also be referred to as a secondary storage device.

[0189] The communication device 1004 is hardware (transmission / reception device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, or a communication module. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc. to realize at least one of frequency division duplex (FDD) and time division duplex (TDD). For example, the above-mentioned transmission / reception unit 120 (220), transmission / reception antenna 130 (230), etc. may be realized by the communication device 1004. The transmission / reception unit 120 (220) may be implemented as a transmission unit 120a (220a) and a reception unit 120b (220b) that are physically or logically separated.

[0190] The input device 1005 is an input device (for example, a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives input from the outside. The output device 1006 is an output device (for example, a display, a speaker, a light emitting diode (LED) lamp, etc.) that outputs to the outside. The input device 1005 and the output device 1006 may be integrated into one device (for example, a touch panel).

[0191] Furthermore, each device, such as the processor 1001 and the memory 1002, is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

[0192] Furthermore, the base station 10 and the user terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized using such hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

[0193] (Variation) Note that terms explained in the present disclosure and terms necessary for understanding the present disclosure may be replaced with terms having the same or similar meanings. For example, a channel, a symbol, and a signal (signal or signaling) may be interchangeable. A signal may also be a message. A reference signal may be abbreviated as RS, and may also be called a pilot, pilot signal, etc. depending on the applicable standard. A component carrier (CC) may also be called a cell, frequency carrier, carrier frequency, etc.

[0194] A radio frame may be composed of one or more periods (frames) in the time domain. Each of the one or more periods (frames) constituting a radio frame may be called a subframe. Furthermore, a subframe may be composed of one or more slots in the time domain. A subframe may have a fixed time length (e.g., 1 ms) that is independent of numerology.

[0195] Here, the numerology may be a communication parameter applied to at least one of transmission and reception of a signal or channel, and may indicate at least one of, for example, a subcarrier spacing (SCS), a bandwidth, a symbol length, a cyclic prefix length, a transmission time interval (TTI), the number of symbols per TTI, a radio frame structure, a specific filtering process performed by a transceiver in the frequency domain, and a specific windowing process performed by a transceiver in the time domain.

[0196] A slot may be composed of one or more symbols in the time domain (such as an Orthogonal Frequency Division Multiplexing (OFDM) symbol or a Single Carrier Frequency Division Multiple Access (SC-FDMA) symbol), and may be a time unit based on numerology.

[0197] A slot may include multiple minislots. Each minislot may consist of one or multiple symbols in the time domain. A minislot may also be called a subslot. A minislot may consist of fewer symbols than a slot. A PDSCH (or PUSCH) transmitted in a time unit larger than a minislot may be called PDSCH (PUSCH) mapping type A. A PDSCH (or PUSCH) transmitted using a minislot may be called PDSCH (PUSCH) mapping type B.

[0198] A radio frame, a subframe, a slot, a minislot, and a symbol all represent time units for transmitting signals. The radio frame, the subframe, the slot, the minislot, and the symbol may be referred to by other names corresponding to the radio frame, the subframe, the slot, the minislot, and the symbol. Note that the time units such as a frame, a subframe, a slot, a minislot, and a symbol in the present disclosure may be interchangeable.

[0199] For example, one subframe may be referred to as a TTI, or multiple consecutive subframes may be referred to as a TTI, or one slot or one minislot may be referred to as a TTI. That is, at least one of a subframe and a TTI may be a subframe (1 ms) in existing LTE, a period shorter than 1 ms (for example, 1-13 symbols), or a period longer than 1 ms. Note that the unit representing the TTI may be called a slot, minislot, etc., instead of a subframe.

[0200] Here, TTI refers to, for example, the smallest time unit for scheduling in wireless communication. For example, in an LTE system, a base station performs scheduling to allocate radio resources (such as frequency bandwidth and transmission power that can be used by each user terminal) to each user terminal in TTI units. However, the definition of TTI is not limited to this.

[0201] The TTI may be a transmission time unit for a channel-encoded data packet (transport block), a code block, a code word, etc., or may be a processing unit for scheduling, link adaptation, etc. When a TTI is given, the time interval (e.g., the number of symbols) to which a transport block, a code block, a code word, etc. is actually mapped may be shorter than the TTI.

[0202] When one slot or one minislot is called a TTI, one or more TTIs (i.e., one or more slots or one or more minislots) may be the minimum time unit for scheduling. Also, the number of slots (minislots) constituting the minimum time unit for scheduling may be controlled.

[0203] A TTI having a time length of 1 ms may be called a regular TTI (TTI in 3GPP Rel. 8-12), normal TTI, long TTI, regular subframe, normal subframe, long subframe, slot, etc. A TTI shorter than a regular TTI may be called a shortened TTI, short TTI, partial or fractional TTI, shortened subframe, short subframe, minislot, subslot, slot, etc.

[0204] In addition, a long TTI (e.g., a normal TTI, a subframe, etc.) may be interpreted as a TTI having a time length of more than 1 ms, and a short TTI (e.g., a shortened TTI, etc.) may be interpreted as a TTI having a TTI length shorter than the TTI length of a long TTI and equal to or greater than 1 ms.

[0205] A resource block (RB) is a resource allocation unit in the time domain and the frequency domain, and may include one or more consecutive subcarriers in the frequency domain. The number of subcarriers included in an RB may be the same regardless of numerology, for example, 12. The number of subcarriers included in an RB may also be determined based on numerology.

[0206] In addition, an RB may include one or more symbols in the time domain and may have a length of one slot, one minislot, one subframe, or one TTI. One TTI, one subframe, etc. may each be composed of one or more resource blocks.

[0207] Note that one or more RBs may also be called a physical resource block (PRB), a sub-carrier group (SCG), a resource element group (REG), a PRB pair, an RB pair, etc.

[0208] Furthermore, a resource block may be composed of one or more resource elements (REs). For example, one RE may be a radio resource region of one subcarrier and one symbol.

[0209] A Bandwidth Part (BWP), which may also be referred to as a fractional bandwidth, may represent a subset of contiguous common resource blocks (RBs) for a given numerology on a given carrier, where the common RBs may be identified by their index relative to a common reference point of the carrier. PRBs may be defined in a given BWP and numbered within that BWP.

[0210] The BWP may include an UL BWP (a BWP for UL) and a DL BWP (a BWP for DL). One or more BWPs may be configured for a UE within one carrier.

[0211] At least one of the configured BWPs may be active, and the UE may not expect to transmit or receive a given signal / channel outside the active BWP. Note that the terms "cell," "carrier," etc. in this disclosure may be read as "BWP."

[0212] The above-described structures of radio frames, subframes, slots, minislots, symbols, etc. are merely examples. For example, the number of subframes included in a radio frame, the number of slots per subframe or radio frame, the number of minislots included in a slot, the number of symbols and RBs included in a slot or minislot, the number of subcarriers included in an RB, the number of symbols in a TTI, the symbol length, the cyclic prefix (CP) length, etc. may be changed in various ways.

[0213] Furthermore, the information, parameters, etc. described in the present disclosure may be expressed using absolute values, may be expressed using relative values ​​from a predetermined value, or may be expressed using other corresponding information. For example, a radio resource may be indicated by a predetermined index.

[0214] The names used for parameters and the like in this disclosure are not intended to be limiting in any way. Furthermore, the mathematical expressions and the like using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not intended to be limiting in any way.

[0215] The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

[0216] Furthermore, information, signals, etc. may be output from a higher layer to a lower layer and / or from a lower layer to a higher layer. Information, signals, etc. may be input / output via multiple network nodes.

[0217] Input and output information, signals, etc. may be stored in a specific location (for example, memory) or may be managed using a management table. Input and output information, signals, etc. may be overwritten, updated, or added. Output information, signals, etc. may be deleted. Input information, signals, etc. may be transmitted to another device.

[0218] Notification of information is not limited to the aspects / embodiments described in the present disclosure, and may be performed using other methods. For example, notification of information in the present disclosure may be performed by physical layer signaling (e.g., Downlink Control Information (DCI) and Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, broadcast information (Master Information Block (MIB) and System Information Block (SIB)), Medium Access Control (MAC) signaling), other signals, or a combination thereof.

[0219] Note that the physical layer signaling may be called Layer 1 / Layer 2 (L1 / L2) control information (L1 / L2 control signal), L1 control information (L1 control signal), etc. Furthermore, the RRC signaling may be called an RRC message, such as an RRC connection setup message or an RRC connection reconfiguration message. Furthermore, the MAC signaling may be notified using, for example, a MAC Control Element (CE).

[0220] Furthermore, notification of specified information (e.g., notification that "it is X") is not limited to explicit notification, but may be made implicitly (e.g., by not notifying the specified information or by notifying other information).

[0221] The determination may be made by a value represented by one bit (0 or 1), by a Boolean value represented by true or false, or by a comparison of numerical values ​​(e.g., comparison with a predetermined value).

[0222] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0223] Software, instructions, information, etc. may also be transmitted or received over a transmission medium. For example, if software is transmitted from a website, server, or other remote source using wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and / or wireless technologies (such as infrared, microwave), then these wired and / or wireless technologies are included within the definition of transmission media.

[0224] As used in this disclosure, the terms "system" and "network" may be used interchangeably. A "network" may refer to devices included in the network (e.g., base stations).

[0225] In the present disclosure, terms such as "precoding," "precoder," "weight (precoding weight)," "Quasi-Co-Location (QCL)," "Transmission Configuration Indication state (TCI state)," "spatial relation," "spatial domain filter," "transmit power," "phase rotation," "antenna port," "antenna port group," "layer," "number of layers," "rank," "resource," "resource set," "resource group," "beam," "beam width," "beam angle," "antenna," "antenna element," "panel," etc. may be used interchangeably.

[0226] In this disclosure, terms such as "base station (BS)," "radio base station," "fixed station," "NodeB," "eNB (eNodeB)," "gNB (gNodeB)," "access point," "transmission point (TP)," "reception point (RP)," "transmission / reception point (TRP)," "panel," "cell," "sector," "cell group," "carrier," "component carrier," etc. may be used interchangeably. Base stations may also be referred to by terms such as macrocell, small cell, femtocell, picocell, etc.

[0227] A base station can accommodate one or more (e.g., three) cells. When a base station accommodates multiple cells, the overall coverage area of ​​the base station can be divided into multiple smaller areas, and each smaller area can be provided with communication service by a base station subsystem (e.g., a small indoor base station (Remote Radio Head (RRH))). The term "cell" or "sector" refers to a part or the entire coverage area of ​​a base station and / or base station subsystem that provides communication service within this coverage.

[0228] In this disclosure, the terms "Mobile Station (MS)," "user terminal," "User Equipment (UE)," "terminal," etc. may be used interchangeably.

[0229] A mobile station may also be referred to as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

[0230] At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a wireless communication device, etc. At least one of the base station and the mobile station may be a device mounted on a mobile object, or the mobile object itself. The mobile object may be a vehicle (e.g., a car, an airplane, etc.), an unmanned mobile object (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). At least one of the base station and the mobile station may also include devices that do not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an Internet of Things (IoT) device such as a sensor.

[0231] Furthermore, a base station in the present disclosure may be read as a user terminal. For example, the aspects / embodiments of the present disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple user terminals (which may be called, for example, Device-to-Device (D2D) or Vehicle-to-Everything (V2X)). In this case, the user terminal 20 may be configured to have the functions of the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, terms such as an uplink channel and a downlink channel may be read as a side channel.

[0232] Similarly, the user terminal in the present disclosure may be read as a base station, in which case the base station 10 may be configured to have the functions of the user terminal 20 described above.

[0233] In the present disclosure, an operation described as being performed by a base station may be performed by its upper node in some cases. It is apparent that in a network including one or more network nodes having a base station, various operations performed for communication with a terminal may be performed by the base station, one or more network nodes other than the base station (such as, but not limited to, a Mobility Management Entity (MME) and a Serving-Gateway (S-GW)), or a combination thereof.

[0234] Each aspect / embodiment described in this disclosure may be used alone, in combination, or switched depending on the implementation. Furthermore, the order of the processing procedures, sequences, flowcharts, etc. of each aspect / embodiment described in this disclosure may be changed unless inconsistent. For example, the methods described in this disclosure present elements of various steps using an example order, and are not limited to the specific order presented.

[0235] Each aspect / embodiment described in the present disclosure may be applied to a system using Long Term Evolution (LTE), LTE-Advanced (LTE-A), LTE-Beyond (LTE-B), SUPER 3G, IMT-Advanced, 4th generation mobile communication system (4G), 5th generation mobile communication system (5G), Future Radio Access (FRA), New-Radio Access Technology (RAT), New Radio (NR), New radio access (NX), Future generation radio access (FX), Global System for Mobile communications (GSM (registered trademark)), CDMA2000, Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, Ultra-WideBand (UWB), Bluetooth (registered trademark), or any other suitable wireless communication method, or a next-generation system based on or enhanced thereon. In addition, multiple systems may be applied in combination (for example, a combination of LTE or LTE-A and 5G).

[0236] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0237] As used in this disclosure, any reference to an element using a designation such as "first," "second," etc. does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must in some way precede the second element.

[0238] The term "determining," as used in this disclosure, may encompass a wide variety of actions. For example, "determining" may be considered to be judging, calculating, computing, processing, deriving, investigating, looking up, search, inquiry (e.g., looking up in a table, database, or another data structure), ascertaining, etc.

[0239] Additionally, "determining" may be considered to be "determining" receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), etc.

[0240] Also, "decision" may be considered to be "deciding" resolving, selecting, choosing, establishing, comparing, etc. In other words, "decision" may be considered to be "deciding" on some action.

[0241] Furthermore, "judgment (decision)" may be interpreted as "assuming," "expecting," "considering," or the like.

[0242] As used in this disclosure, the terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access."

[0243] In this disclosure, when two elements are connected, they may be considered to be "connected" or "coupled" to one another using one or more wires, cables, printed electrical connections, etc., as well as using electromagnetic energy having wavelengths in the radio frequency range, microwave range, light (both visible and invisible) range, etc., as some non-limiting and non-exhaustive examples.

[0244] In the present disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "coupled" may also be interpreted in the same way as "different."

[0245] When used in this disclosure, the terms "include," "including," and variations thereof are intended to be inclusive, similar to the term "comprising." Furthermore, when used in this disclosure, the term "or" is not intended to be an exclusive or.

[0246] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0247] Although the invention according to the present disclosure has been described in detail above, it is clear to those skilled in the art that the invention according to the present disclosure is not limited to the embodiments described in the present disclosure. The invention according to the present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the invention as defined by the description of the claims. Therefore, the description of the present disclosure is intended to be illustrative and explanatory and does not impose any limiting meaning on the invention according to the present disclosure.

Claims

1. a receiving unit that receives downlink control information (DCI) transmitted from a first transmission / reception point; a transmitter configured to transmit an UL signal to at least one of the first transmission / reception point and the second transmission / reception point; a control unit that, if the DCI includes information indicating the existence of the second transmission / reception point, decides to transmit a random access preamble to the second transmission / reception point, and, if the DCI does not include information indicating the existence of the second transmission / reception point, decides to transmit the random access preamble to the first transmission / reception point.

2. receiving Downlink Control Information (DCI) transmitted from a first transmission / reception point; If the DCI includes information indicating the presence of the second transmission / reception point, determining to transmit a random access preamble to the second transmission / reception point, and if the DCI does not include information indicating the presence of the second transmission / reception point, determining to transmit the random access preamble to the first transmission / reception point; and transmitting an UL signal to at least one of the first transmission / reception point and the second transmission / reception point.

3. A system including a terminal and a base station, The terminal a receiving unit that receives downlink control information (DCI) transmitted from a first transmission / reception point; a transmitter configured to transmit an UL signal to at least one of the first transmission / reception point and the second transmission / reception point; a control unit that, when the DCI includes information indicating the presence of the second transmission / reception point, determines to transmit a random access preamble to the second transmission / reception point, and, when the DCI does not include information indicating the presence of the second transmission / reception point, determines to transmit the random access preamble to the first transmission / reception point; The base station A control unit that controls the transmission of the DCI.

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