Terminal, base station, and communication method

Abstract

This terminal is provided with: a control circuit that, in a plurality of time resources including a first time resource in which a frequency band is divided into a plurality of bands, selects a random access channel transmission opportunity on the basis of a threshold value for received electric power; and a transmission circuit that transmits a random access channel signal using the transmission opportunity.

Description

Terminal, base station and communication method

[0001] The present disclosure relates to a terminal, a base station, and a communication method.

[0002] The 3rd Generation Partnership Project (3GPP) has completed the physical layer specifications for Release 18 NR (New Radio access technology) as a functional extension of 5th Generation mobile communication systems (5G). NR supports enhanced mobile broadband (eMBB) to meet the requirements of high speed and large capacity, as well as ultra-reliable and low latency communication (URLLC) (see, for example, Non-Patent Documents 1-6).

[0003] 3GPP TS 38.211 V18.1.0, "NR; Physical channels and modulation (Release 18)," December 20233GPP TS 38.212 V18.1.0, "NR; Multiplexing and channel coding (Release 18)," December 20233GPP TS 38.213 V18.1.0, "NR; Physical layer procedure for control (Release 18)," December 20233GPP TS 38.214 V18.1.0, "NR; Physical layer procedures for data (Release 18)," December 20233GPP TS 38.215 V18.1.0, "NR; Physical layer measurements (Release 18)," December 20233GPP TS 38.331 V18.0.0, "NR; Radio Resource Control (RRC) protocol specification (Release 18)", December 2023

[0004] However, there is room for further study on the method of selecting resources for the random access channel.

[0005] Non-limiting examples of the present disclosure contribute to providing a terminal, a base station, and a communication method that can improve the efficiency of resource selection for a random access channel.

[0006] A terminal according to one embodiment of the present disclosure includes a control circuit that selects a transmission opportunity for a random access channel based on a threshold for received power in a plurality of time resources including a first time resource in which a frequency band is divided into a plurality of bands, and a transmission circuit that transmits a signal of the random access channel using the transmission opportunity.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium.

[0008] According to an embodiment of the present disclosure, resources for a random access channel can be appropriately selected.

[0009] Further advantages and benefits of one embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features.

[0010] Diagram showing an example of a duplex methodDiagram showing an example of Dynamic Subband non-overlapping full duplex (SBFD)Block diagram showing an example configuration of a part of a base stationBlock diagram showing an example configuration of a part of a terminalBlock diagram showing an example configuration of a base stationBlock diagram showing an example configuration of a terminalSequence diagram showing an example operation of a base station and a terminalDiagram showing an example selection of Physical Random Access Channel (PRACH) resourcesDiagram showing an example arrangement of Random Access Channel occasions (RO)Diagram showing an example selection of PRACH resourcesDiagram showing an example selection of PRACH resourcesDiagram showing an example arrangement of RODiagram showing an example configurationDiagram showing an example arrangement of RODiagram of an exemplary architecture of a 3GPP NR systemDiagram of an exemplary functional division in 5G O-RAN

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] [Regarding Subband Non-Overlapping Full Duplex (SBFD)] "Study on the Evolution of NR Duplex Operation" was discussed as a Study Item in Release 18. One of the main topics of this Study Item is support for subband non-overlapping full duplex (SBFD, also known as Cross Division Duplex (XDD)).

[0013] Figure 1 is a diagram showing an example of the Duplex system. In Figure 1, the vertical axis represents frequency and the horizontal axis represents time. Also, in Figure 1, "U" represents uplink transmission and "D" represents downlink transmission.

[0014] FIG. 1(a) shows an example of half-duplex Time Division Duplex (TDD). In FIG. 1(a), a terminal (UE: User Equipment) is a terminal connected to a base station (e.g., gNB). In the half-duplex shown in FIG. 1(a), the transmission direction (e.g., downlink or uplink) in a certain time resource may be common between the base station and the terminal. For example, the transmission direction in a certain time resource does not differ between terminals.

[0015] FIG. 1(b) shows an example of SBFD. In SBFD, a frequency resource (or a frequency band) is divided into multiple bands (e.g., subbands, RB sets, subbands, or sub-BWPs (Bandwidth Parts)), and transmission in different directions (e.g., downlink or uplink) is supported for each subband. In SBFD, a terminal transmits and receives data in either the uplink or downlink in a certain time resource, but does not transmit or receive data in the other direction. On the other hand, in SBFD, a base station can transmit and receive data in both the uplink and downlink simultaneously. There may be cases where a terminal does not use resources in the transmission direction in a certain time resource (e.g., resources indicated by dotted lines in FIG. 1(b)).

[0016] Although not shown in Fig. 1, a guard band may be arranged between an uplink subband (UL subband: U) and a downlink subband (DL subband: D). The guard band may be used to reduce cross link interference (CLI) between different transmission directions (links).

[0017] In the following description, a symbol on which SBFD operation or control is performed is called an "SBFD symbol." A symbol on which SBFD operation or control is not performed (for example, a symbol different from an SBFD symbol) may also be called a "non-SBFD symbol." For example, a slot configured with SBFD symbols may also be called an "SBFD slot," and a slot configured with non-SBFD symbols may also be called a "non-SBFD slot."

[0018] The subband configuration is expressed as {X...X}, where X represents the UL subband (U) or DL ​​subband (D). The order of notation corresponds to the order in which the subbands are arranged. For example, the subband configuration in Figure 1(b) is expressed as {DUD}.

[0019] [SBFD Symbol and SBFD-Compatible Terminal] The SBFD symbol may be configured using (for example, by changing) a legacy symbol (existing symbol) such as a DL symbol, a UL symbol, or a Flexible symbol. For example, the SBFD symbol may be configured using a DL symbol. The legacy symbol is configured by, for example, RRC signaling (for example, TDD-UL-DL-ConfigCommon). Here, the non-SBFD symbol is, for example, a symbol that is not an SBFD symbol (for example, a legacy symbol and a symbol not used as an SBFD symbol).

[0020] An SBFD-capable terminal (e.g., SBFD-aware UE) is a terminal that supports SBFD operation and control. An SBFD-capable terminal can acquire SBFD-related configuration, such as the frequency and time domain locations of subbands. An SBFD-incapable terminal (e.g., non-SBFD-aware UE) is a terminal that does not support SBFD operation and control. For example, an SBFD-incapable terminal does not recognize SBFD symbols, and therefore, even if a legacy symbol is set (or changed) to an SBFD symbol, it will recognize the symbol as a legacy symbol and operate accordingly.

[0021] [Regarding Random Access Channel (RACH) Transmission on SBFD Symbols] For example, when DL symbols are used as SBFD symbols, SBFD-compatible terminals can use SBFD subbands as UL resources. Therefore, when supporting RACH transmission on SBFD symbols, it is possible to increase Physical Random Access Channel (PRACH) resources (e.g., PRACH transmission opportunities, also referred to as RACH occasions (ROs)) in the time domain compared to existing methods. Increasing ROs can reduce RACH transmission delays, reduce inter-terminal collisions, and improve coverage through long preamble formats or PRACH repetition (e.g., repeated transmissions).

[0022] Figure 2 shows an example of RACH resource (RO) allocation on SBFD symbols. In the example of Figure 2, slot #0 is a slot consisting of DL symbols (e.g., referred to as a "DL slot"), slots #1, #2, and #3 are slots consisting of SBFD symbols (e.g., referred to as "SBFD slots"), and slot #4 is a slot consisting of UL symbols (e.g., referred to as a "UL slot"). Also, in the example of Figure 2, the subband configuration in the SBFD slot is {DUD}. In the example of Figure 2, PRACH resources (RO) are allocated to the UL subbands of slot #2 and slot #3. In this way, by supporting RACH transmission on SBFD symbols, it is possible to increase PRACH resources in the time domain compared to existing methods.

[0023] On the other hand, when PRACH transmission on the UL subband is supported, the PRACH transmission on the UL subband may cause UE-to-UE interference (e.g., UE-to-UE interference or UL-to-UE CLI) to DL reception on the DL subband, potentially resulting in degradation of DL performance.

[0024] For example, in Contention-based random access (CBRA), a terminal selects a resource and a preamble to use from multiple PRACH resource and preamble candidates configured in a cell and transmits a PRACH signal. Furthermore, the PRACH signal is transmitted when the terminal needs to transmit, and is not always transmitted. Therefore, a base station cannot identify in advance which terminal will use which PRACH resource to transmit the PRACH, making it difficult for the base station to control inter-terminal interference. This is because the magnitude of inter-terminal interference can vary depending on the relationship between an interfering terminal (e.g., an aggressor terminal) and an interfering terminal (e.g., a victim terminal). For example, interference is likely to be large when terminals are located close to each other. Therefore, when supporting PRACH transmission in SBFD symbols, it is expected that a method for reducing inter-terminal interference will be considered.

[0025] In a non-limiting example of the present disclosure, a method for reducing inter-terminal interference in PRACH transmissions in SBFD symbols is described.

[0026] [Overview of Communication System] A communication system according to an embodiment of the present disclosure may include, for example, a base station 100 (e.g., gNB) shown in Figures 3 and 5, and a terminal 200 (e.g., UE) shown in Figures 4 and 6. A plurality of base stations 100 and a plurality of terminals 200 may exist in the communication system.

[0027] 3 is a block diagram illustrating an example configuration of a portion of a base station 100 according to an embodiment of the present disclosure. In the base station 100 illustrated in FIG. 3, a control unit (e.g., corresponding to a control circuit) sets transmission opportunities (e.g., ROs) for a random access channel, which are selected based on a threshold for the received power of a terminal 200, in a plurality of time resources including time resources (e.g., SBFD symbols) in which a frequency band is divided into a plurality of bands. A receiving unit (e.g., corresponding to a receiving circuit) receives a signal of a random access channel (PRACH) using the transmission opportunities.

[0028] 4 is a block diagram illustrating a configuration example of a portion of a terminal 200 according to an embodiment of the present disclosure. In the terminal 200 illustrated in FIG. 4, a control unit (e.g., corresponding to a control circuit) selects a transmission opportunity (e.g., RO) for a random access channel based on a threshold for received power in a plurality of time resources including time resources (e.g., SBFD symbols) in which a frequency band is divided into a plurality of bands. A transmission unit (e.g., corresponding to a transmission circuit) transmits a signal of a random access channel (PRACH) using the transmission opportunity.

[0029] [Configuration of Base Station] Fig. 5 is a block diagram showing an example configuration of a base station 100 according to an embodiment of the present disclosure. In Fig. 5, the base station 100 includes a receiving unit 101, a demapping unit 102, a demodulation and decoding unit 103, a preamble detection unit 104, a scheduling unit 105, an RO control unit 106, a control information holding unit 107, a data and control information generation unit 108, an encoding and modulation unit 109, a mapping unit 110, and a transmission unit 111.

[0030] For example, at least one of the demapping unit 102, demodulation / decoding unit 103, scheduling unit 105, RO control unit 106, control information holding unit 107, data / control information generation unit 108, coding / modulation unit 109, and mapping unit 110 may be included in the control unit shown in Figure 3, and the receiving unit 101 may be included in the receiving unit shown in Figure 3.

[0031] The receiving unit 101 performs reception processing such as down-conversion or A / D conversion on a signal received via an antenna, and outputs the processed received signal to the demapping unit 102 .

[0032] The demapping unit 102 performs resource demapping on the received signal (for example, an uplink signal) input from the receiving unit 101 , and outputs the modulated signal to the demodulation and decoding unit 103 and the preamble detection unit 104 .

[0033] The demodulation and decoding section 103 demodulates and decodes the modulated signal input from the demapping section 102 , for example, and outputs the decoding result to the scheduling section 105 .

[0034] For example, the preamble detection section 104 detects a preamble (for example, a PRACH signal) transmitted in the PRACH from the modulated signal input from the demapping section 102 and outputs the detection result to the scheduling section 105 .

[0035] The scheduling unit 105 may perform scheduling for the terminals 200, for example. The scheduling unit 105 schedules transmission and reception for each terminal 200 based on, for example, at least one of the decoding result input from the demodulation and decoding unit 103, the preamble detection result input from the preamble detection unit 104, information input from the RO control unit 106 (including, for example, PRACH configuration information), and control information input from the control information holding unit 107, and instructs the data and control information generation unit 108 to generate at least one of data and control information. The scheduling unit 105 also instructs the data and control information generation unit 108 to transmit the PRACH configuration information input from the RO control unit 106 to the terminals 200 as signaling information. The scheduling unit 105 also outputs control information related to the terminals 200 to the control information holding unit 107.

[0036] The RO control unit 106 determines, for example, PRACH resources on SBFD symbols (e.g., positions and number in the frequency domain and time domain), PRACH resources on non-SBFD symbols (e.g., positions and number in the frequency domain and time domain), and information used for selecting PRACH resources (e.g., information related to thresholds) based on control information (e.g., information related to SBFD) input from the control information holding unit 107. The RO control unit 106 may determine PRACH configuration information (e.g., including PRACH transmission power) associated with the PRACH resource (RO). The RO control unit 106 outputs the determined PRACH configuration information to the scheduling unit 105.

[0037] The control information holding unit 107 holds, for example, control information set in each terminal 200. The control information may include, for example, information related to SBFD. The control information holding unit 107 may output the held information to each component of the base station 100 (for example, the scheduling unit 105 and the RO control unit 106) as necessary.

[0038] The data and control information generating unit 108 generates at least one of data and control information, for example, in accordance with an instruction from the scheduling unit 105, and outputs a signal including the generated data or control information to the coding and modulation unit 109. The generated data may include, for example, signaling information of higher layers (for example, PRACH configuration information).

[0039] The coding and modulation section 109 codes and modulates, for example, the signal (for example, data, control information) input from the data and control information generation section 108 and outputs the modulated signal to the transmission section 111 .

[0040] Mapping section 110 performs resource mapping on the modulated signal input from coding and modulation section 109 , for example, and outputs the transmission signal to transmitting section 111 .

[0041] The transmitter 111 performs transmission processing such as D / A conversion, up-conversion, or amplification on the signal input from the mapping unit 110, and transmits the radio signal obtained by the transmission processing from the antenna to the terminal 200.

[0042] [Terminal Configuration] Fig. 6 is a block diagram showing an example configuration of terminal 200 according to one aspect of the present disclosure. In Fig. 6, terminal 200 includes receiving section 201, demapping section 202, demodulation and decoding section 203, RO selection section 204, control section 205, control information holding section 206, preamble generation section 207, data and control information generation section 208, coding and modulation section 209, mapping section 210, and transmission section 211.

[0043] For example, at least one of the demapping unit 202, demodulation / decoding unit 203, RO selection unit 204, control unit 205, control information storage unit 206, preamble generation unit 207, data / control information generation unit 208, coding / modulation unit 209, and mapping unit 210 may be included in the control unit shown in Figure 4, and the transmission unit 211 may be included in the transmission unit shown in Figure 4.

[0044] The receiving unit 201 performs reception processing such as down-conversion or A / D conversion on a received signal received via an antenna, and outputs the processed received signal to the demapping unit 202 .

[0045] The demapping unit 202 performs resource demapping on the received signal input from the receiving unit 201 , for example, and outputs the modulated signal to the demodulation and decoding unit 203 .

[0046] The demodulation / decoding unit 203 demodulates and decodes the modulated signal input from the demapping unit 202, and outputs the decoding result to the control unit 205. The decoding result may include, for example, at least one of upper layer signaling information and downlink control information.

[0047] The RO selection unit 204 selects a PRACH resource (RO) to use based on, for example, control information input from the control information storage unit 206 (for example, PRACH setting information, information related to SBFD (for example, information related to slot configuration, information related to subband configuration, or information related to selection of PRACH resource)), and outputs information related to the selected PRACH resource (PRACH resource information) to the control unit 205.

[0048] The control unit 205 may determine whether or not to transmit or receive data or control information, or whether or not to transmit a PRACH, based on, for example, the decoding result (e.g., data or control information) input from the demodulation and decoding unit 203, the PRACH resource information input from the RO selection unit 204, and the control information input from the control information storage unit 206. For example, if the determination result indicates that data or control information is to be transmitted, the control unit 205 may instruct the data and control information generation unit 208 to generate at least one of data and control information. Furthermore, for example, if PRACH transmission is to be transmitted, the control unit 205 may instruct the preamble generation unit 207 to generate a preamble signal based on the PRACH resource information. Furthermore, the control unit 205 outputs, for example, control information related to the terminal 200 to the control information storage unit 206.

[0049] The control information holding unit 206 holds, for example, control information input from the control unit 205, and outputs the held information to each component (for example, the RO selection unit 204 and the control unit 205) as necessary.

[0050] For example, in accordance with an instruction from the control section 205 , the preamble generation section 207 generates a preamble signal to be transmitted in the PRACH (for example, a PRACH signal) and outputs the generated preamble signal to the mapping section 210 .

[0051] The data and control information generating unit 208 generates data or control information according to instructions from the control unit 205 , for example, and outputs a signal including the generated data or control information to the encoding and modulation unit 209 .

[0052] The coding and modulation section 209 codes and modulates the signal input from the data and control information generation section 208 , for example, and outputs the modulated signal to the mapping section 210 .

[0053] Mapping section 210 performs resource mapping on the modulated signal input from coding and modulation section 209 or the preamble signal input from preamble generation section 207 , and outputs the transmission signal to transmission section 211 .

[0054] The transmitter 211 performs transmission processing such as D / A conversion, up-conversion, or amplification on the signal input from the mapping unit 210, and transmits the radio signal obtained by the transmission processing from an antenna to the base station 100.

[0055] [Operations of Base Station 100 and Terminal 200] An example of operations in the base station 100 and terminal 200 having the above configuration will be described.

[0056] FIG. 7 is a sequence diagram showing an example of the operation of the base station 100 and the terminal 200. In FIG.

[0057] In FIG. 7, the base station 100 determines, for example, a setting (configuration) related to SBFD or PRACH (S101).

[0058] The base station 100 transmits, for example, upper layer signaling information including the determined configuration information to the terminal 200 (S102). The transmission of the signaling information may be, for example, a notification by a System Information Block (SIB) or a notification by terminal-specific (terminal-individual) signaling information.

[0059] The terminal 200 selects a PRACH resource (RO) to be used for transmitting the PRACH from available PRACH resources based on, for example, configuration information included in signaling information transmitted from the base station 100 (S103).

[0060] The terminal 200 transmits a PRACH (for example, a preamble signal) based on the selected PRACH resource, and the base station 100 receives the PRACH (S104).

[0061] [PRACH Resource Selection Method] A PRACH resource (RO) selection method in terminal 200 (e.g., RO selection unit 204) will be described. Note that base station 100 (e.g., RO control unit 106) may set PRACH resources available to terminal 200, for example, assuming a PRACH resource selection method implemented by terminal 200.

[0062] Terminal 200 selects a PRACH resource (RO) to use for PRACH transmission, for example, in accordance with a threshold for the received power of a signal at terminal 200 or a rule related to time resources (for example, symbols). Note that the threshold and the rule may be configured in terminal 200 by base station 100 or may be defined in advance.

[0063] An example of a method for selecting a PRACH resource will now be described.

[0064] <Method 1> In method 1, terminal 200 selects an RO to use for PRACH transmission based on a comparison of a threshold for PRACH transmission in an RO on an SBFD symbol and a threshold for PRACH transmission in an RO on a non-SBFD symbol with the received power of the signal.

[0065] The received power of the signal may be, for example, Synchronization Signal-Reference Signal Received Power (SS-RSRP), which is also called, for example, SS / physical broadcast channel (PBCH) block (SSB)-RSRP.

[0066] Furthermore, the threshold for the received power (e.g., SS-RSRP) may include, for example, a threshold for determining whether PRACH transmission is possible (threshold of PRACH transmission) and a threshold for determining the number of transmissions (number of repetitions) in PRACH repetition (repeated transmission), as follows:

[0067] For example, thresholds corresponding to SBFD symbols and non-SBFD symbols, respectively (for example, thresholds associated with SBFD symbols and non-SBFD symbols, respectively) may be set as the threshold for PRACH transmission and the threshold for the number of PRACH repetitions.

[0068] Furthermore, for example, threshold values ​​corresponding to one or more repetition numbers may be set as the threshold value for the number of PRACH repetitions.

[0069] An example of RO selection (for example, determination of whether to transmit PRACH and the number of repetitions) based on SS-RSRP and each threshold in terminal 200 will be described below.

[0070] (Threshold for PRACH Transmission in SBFD Symbol) For example, when SS-RSRP is equal to or greater than a threshold, terminal 200 may transmit PRACH in an RO on an SBFD symbol associated with the threshold. On the other hand, for example, when SS-RSRP is less than the threshold, terminal 200 does not transmit PRACH in an RO on an SBFD symbol associated with the threshold.

[0071] The threshold for PRACH transmission in the SBFD symbol may be set by, for example, an individual parameter linked to the RO of the SBFD symbol. For example, to set the threshold for PRACH transmission in the SBFD symbol, a higher layer parameter linked to the RO of the SBFD symbol (for example, rsrp-ThresholdSSB of the RACH-ConfigCommon IE) may be reused. Note that the threshold for PRACH transmission in the SBFD symbol may be defined in advance in a standard, or may be notified to terminal 200 by other information different from the higher layer parameter.

[0072] (Threshold for PRACH Transmission in Non-SBFD Symbols) For example, when SS-RSRP is equal to or greater than a threshold, terminal 200 may transmit PRACH in an RO on a non-SBFD symbol associated with the threshold. On the other hand, for example, when SS-RSRP is less than the threshold, terminal 200 does not transmit PRACH in an RO on a non-SBFD symbol associated with the threshold.

[0073] The threshold for PRACH transmission in non-SBFD symbols may be set by, for example, an individual parameter associated with the RO of the non-SBFD symbol. For example, to set the threshold for PRACH transmission in non-SBFD symbols, a higher layer parameter associated with the RO of the non-SBFD symbol (for example, rsrp-ThresholdSSB of the RACH-ConfigCommon IE) or the like may be reused. Note that the threshold for PRACH transmission in non-SBFD symbols may be defined in advance in a standard, or may be notified to terminal 200 by other information different from the higher layer parameter.

[0074] (Threshold for Number of PRACH Repetitions in SBFD Symbol) For example, when SS-RSRP is less than a threshold, terminal 200 transmits PRACH repetitions the number of times corresponding to the threshold in RO on the SBFD symbol associated with the threshold.

[0075] The threshold value of the number of PRACH repetitions in the SBFD symbol may be used when RACH repetition is applied to terminal 200. Furthermore, the threshold value of the number of PRACH repetitions in the SBFD symbol may be set in terminal 200 by a higher layer parameter (configuration), may be defined in advance in a standard, or may be notified to terminal 200 by other information different from the higher layer parameter.

[0076] (Threshold for Number of RACH Repetitions in Non-SBFD Symbols) For example, when SS-RSRP is less than a threshold, terminal 200 transmits PRACH repetitions the number of times corresponding to the threshold in RO on a non-SBFD symbol associated with the threshold.

[0077] The threshold value for the number of PRACH repetitions in non-SBFD symbols may be used when RACH repetition is applied to terminal 200. Furthermore, the threshold value for the number of PRACH repetitions in non-SBFD symbols may be set in terminal 200 by higher layer parameters (configuration), may be defined in advance in a standard, or may be notified to terminal 200 by other information different from the higher layer parameters.

[0078] Examples of threshold values ​​have been described above.

[0079] Next, an example of a procedure for selecting a PRACH resource (RO) and determining the number of PRACH repetitions in terminal 200 (for example, an SBFD-compatible terminal) will be described. Note that, when PRACH repetition is not applied, terminal 200 performs the following (Procedure 1) and does not need to perform other procedures.

[0080] (Procedure 1) Terminal 200 selects an RO of a symbol type corresponding to a threshold value where SS-RSRP is equal to or greater than the threshold value and is closer to SS-RSRP (for example, closest to SS-RSRP) from among the "threshold value for PRACH transmission in SBFD symbols" and the "threshold value for PRACH transmission in non-SBFD symbols."

[0081] For example, the terminal 200 may perform the following operations.

[0082] Terminal 200 selects RO on the SBFD symbol when SS-RSRP is equal to or greater than the "threshold for PRACH transmission in an SBFD symbol" and less than the "threshold for PRACH transmission in a non-SBFD symbol."

[0083] If the SS-RSRP is equal to or greater than the "threshold for PRACH transmission in a non-SBFD symbol" and less than the "threshold for PRACH transmission in an SBFD symbol", the terminal 200 selects RO on a non-SBFD symbol.

[0084] If the SS-RSRP is equal to or greater than the "threshold for PRACH transmission in SBFD symbols" and equal to or greater than the "threshold for PRACH transmission in non-SBFD symbols," the terminal 200 selects an RO of a symbol type associated with a threshold value closer to the SS-RSRP (for example, the threshold value with the higher setting value of the two threshold values).

[0085] Terminal 200 does not transmit PRACH when SS-RSRP is less than the "threshold for PRACH transmission in SBFD symbols" and less than the "threshold for PRACH transmission in non-SBFD symbols."

[0086] (Procedure 2) When a threshold for the number of PRACH repetitions is set for the symbol type corresponding to the RO selected in procedure 1, terminal 200 determines the number of PRACH repetitions based on a comparison between SS-RSRP and the threshold for the number of PRACH repetitions. That is, in method 1, when transmitting PRACH repetitions, terminal 200 selects multiple ROs in either SBFD symbols or non-SBFD symbols.

[0087] An example of the procedure for selecting a PRACH resource (RO) and determining the number of PRACH repetitions in terminal 200 has been described above.

[0088] FIG. 8 shows an example of the relationship between the SS-RSRP and the threshold in Method 1.

[0089] In the example of Figure 8, the "threshold for PRACH transmission in non-SBFD symbols" and the "threshold for the number of PRACH repetitions in non-SBFD symbols" are shown on the left side of the arrow (vertical axis) indicating the value of SS-RSRP, and the "threshold for PRACH transmission in SBFD symbols" and the "threshold for the number of PRACH repetitions in non-SBFD symbols" are shown on the right side.

[0090] In the example of Fig. 8, thresholds for 2, 4, and 8 PRACH repetitions (three thresholds) are set in non-SBFD symbols, and a threshold for 2 PRACH repetitions (one threshold) is set in SBFD symbols. As shown in Fig. 8, the PRACH transmission operation in terminal 200 is classified into the following six cases depending on the SS-RSRP value.

[0091] (Case 1) Case 1 is a case where SS-RSRP is equal to or greater than the threshold for both the "threshold for PRACH transmission in SBFD symbols" and the "threshold for PRACH transmission in non-SBFD symbols," and SS-RSRP is equal to or greater than the "threshold for two PRACH repetitions in SBFD symbols."

[0092] In Case 1, of the two PRACH transmission thresholds, the threshold closest to the SS-RSRP is the "threshold for PRACH transmission in the SBFD symbol," so terminal 200 selects the RO on the SBFD symbol and performs PRACH transmission in the RO on the SBFD symbol. Also, in Case 1, SS-RSRP is equal to or greater than the threshold for two PRACH repetitions in the SBFD symbol, so terminal 200 performs PRACH transmission without PRACH repetition (i.e., single PRACH transmission) in the RO on the SBFD symbol.

[0093] (Case 2) Case 2 is a case where the SS-RSRP is equal to or greater than the threshold for both the "threshold for PRACH transmission in SBFD symbols" and the "threshold for PRACH transmission in non-SBFD symbols," and the SS-RSRP is less than the "threshold for two PRACH repetitions in SBFD symbols."

[0094] In Case 2, of the two PRACH transmission thresholds, the threshold closest to SS-RSRP is the "threshold for PRACH transmission in the SBFD symbol," so terminal 200 selects RO on the SBFD symbol and performs PRACH transmission in the RO on the SBFD symbol. Also, in Case 2, SS-RSRP is less than the threshold for two PRACH repetitions in the SBFD symbol, so terminal 200 performs two PRACH repetition transmissions in the RO on the SBFD symbol.

[0095] (Case 3) Case 3 is a case where SS-RSRP is less than the "threshold for PRACH transmission in SBFD symbols" and is greater than or equal to the "threshold for PRACH transmission in non-SBFD symbols," and SS-RSRP is less than the "threshold for two PRACH repetitions in non-SBFD symbols" and is greater than or equal to the "threshold for four PRACH repetitions in non-SBFD symbols."

[0096] In Case 3, terminal 200 selects an RO on a non-SBFD symbol and performs PRACH transmission in the RO on the non-SBFD symbol. Also, in Case 3, SS-RSRP is less than the threshold for two PRACH repetitions in a non-SBFD symbol and is greater than or equal to the threshold for four PRACH repetitions in a non-SBFD symbol, so terminal 200 performs two PRACH repetition transmissions in the RO on the non-SBFD symbol.

[0097] (Case 4) Case 4 is a case where SS-RSRP is less than the "threshold for PRACH transmission in SBFD symbols" and is greater than or equal to the "threshold for PRACH transmission in non-SBFD symbols," and SS-RSRP is less than the "threshold for four PRACH repetitions in non-SBFD symbols" and is greater than or equal to the "threshold for eight PRACH repetitions in non-SBFD symbols."

[0098] In Case 4, terminal 200 selects an RO on a non-SBFD symbol and performs PRACH transmission in the RO on the non-SBFD symbol. Also, in Case 4, SS-RSRP is less than the threshold of four PRACH repetitions in a non-SBFD symbol and is greater than or equal to the threshold of eight PRACH repetitions in a non-SBFD symbol, so terminal 200 performs four PRACH repetition transmissions in the RO on the non-SBFD symbol.

[0099] (Case 5) Case 5 is a case where SS-RSRP is less than the "threshold for PRACH transmission in SBFD symbols" and is greater than or equal to the "threshold for PRACH transmission in non-SBFD symbols", and SS-RSRP is less than the "threshold for eight PRACH repetitions in non-SBFD symbols".

[0100] In Case 5, terminal 200 selects an RO on a non-SBFD symbol and performs PRACH transmission in the RO on the non-SBFD symbol. Also, in Case 5, since SS-RSRP is less than the threshold of eight PRACH repetitions in a non-SBFD symbol, terminal 200 performs eight PRACH repetition transmissions in the RO on the non-SBFD symbol.

[0101] (Case 6) Case 6 is a case where SS-RSRP is less than the “threshold for PRACH transmission in SBFD symbols” and less than the “threshold for PRACH transmission in non-SBFD symbols.” In Case 6, terminal 200 does not perform PRACH transmission.

[0102] An example of the relationship between SS-RSRP and the threshold value in Method 1 has been described above.

[0103] In this way, by using thresholds set for SBFD symbols and non-SBFD symbols, terminal 200 can determine which PRACH resource (RO) of SBFD symbols or non-SBFD symbols to use for transmission, and the number of repetition transmissions.

[0104] Fig. 9 shows an example of RO placement based on Method 1. Note that, for simplicity of explanation, PRACH repetition is not shown in Fig. 9.

[0105] In the example of FIG. 9, an RO (RO#0) on an SBFD symbol is set in Slot#3, and an RO (RO#1) on a non-SBFD symbol (UL symbol) is set in Slot#4.

[0106] Here, for example, as in the example of FIG. 8, a case will be described in which the "threshold for PRACH transmission in SBFD symbols" is set higher than the "threshold for PRACH transmission in non-SBFD symbols."

[0107] In this case, among SBFD-compatible terminals, terminal 200 with a high SS-RSRP (for example, when SS-RSRP is equal to or greater than the "threshold for PRACH transmission in SBFD symbols") selects RO#0 (SBFD symbol) and transmits PRACH in RO#0. Also, terminal 200 with a low SS-RSRP (for example, when SS-RSRP is less than the "threshold for PRACH transmission in SBFD symbols" and equal to or greater than the "threshold for PRACH transmission in non-SBFD symbols") selects RO#1 (non-SBFD symbol) and transmits PRACH in RO#1.

[0108] For example, the higher the SS-RSRP, the lower the UL transmission power at terminal 200 can be, so even if PRACH transmission (UL transmission) is performed on an SBFD symbol, the impact on other subbands (e.g., DL subbands) on that SBFD symbol is small, and therefore, interference between terminals can be kept low.

[0109] On the other hand, it is expected that the lower the SS-RSRP, the higher the UL transmission power in terminal 200. Therefore, when the SS-RSRP is low (for example, when the SS-RSRP is less than the "threshold for PRACH transmission in SBFD symbols" and greater than or equal to the "threshold for PRACH transmission in non-SBFD symbols"), PRACH transmission (UL transmission) is performed on non-SBFD symbols (UL symbols), thereby making it possible to avoid the occurrence of inter-terminal interference on SBFD symbols.

[0110] In this way, by setting the "threshold for PRACH transmission in SBFD symbols" higher than the "threshold for PRACH transmission in non-SBFD symbols", it is possible to reduce interference between terminals in PRACH transmission on SBFD symbols.

[0111] Furthermore, because UL transmission on SBFD symbols may cause degradation of DL performance due to interference between terminals, the UL transmission power may differ between SBFD symbols and non-SBFD symbols. Therefore, the PRACH repetition threshold may correspond to different numbers for SBFD symbols and non-SBFD symbols. For example, even if the PRACH repetition thresholds corresponding to SBFD symbols and non-SBFD symbols are set to the same SS-RSRP value, different repetition numbers may be associated with SBFD symbols and non-SBFD symbols. For example, if the transmission power of SBFD symbols is lower than the transmission power of non-SBFD symbols, the SS-RSRP threshold may be set so that the repetition number for SBFD symbols is higher than the repetition number for non-SBFD symbols. This makes it possible to compensate for the low transmission power on SBFD symbols by the repetition number. Furthermore, for example, by setting the SS-RSRP threshold so that the number of repetitions of SBFD symbols is smaller than the number of repetitions of non-SBFD symbols, the number of PRACH transmissions on SBFD symbols can be reduced, thereby reducing the occurrence of inter-terminal interference in SBFD symbols.

[0112] As described above, according to method 1, the PRACH transmission threshold and the PRACH repetition count threshold are set separately for SBFD symbols and non-SBFD symbols, allowing terminal 200 to select whether to use RO on SBFD symbols or RO on non-SBFD symbols for PRACH transmission and PRACH repetition transmission. This reduces inter-terminal interference on SBFD symbols and improves DL reception performance in SBFD symbols.

[0113] <Method 2> In method 2, similarly to method 1, terminal 200 selects an RO to use for PRACH transmission based on a comparison of a threshold for PRACH transmission in an RO on an SBFD symbol and a threshold for PRACH transmission in an RO on a non-SBFD symbol with the received power of a signal (e.g., SS-RSRP).

[0114] Furthermore, in method 2, terminal 200 selects both ROs for SBFD symbols and ROs for non-SBFD symbols for PRACH repetition, instead of selecting either one of ROs for SBFD symbols or ROs for non-SBFD symbols as in method 1. For example, when transmitting PRACH repetitions, terminal 200 may perform PRACH transmission using ROs that can be used in both symbol types without limiting the symbol type. For example, to determine the number of PRACH repetitions, terminal 200 may align (share) the "PRACH repetition threshold" between SBFD symbols and non-SBFD symbols, or may use a "PRACH repetition threshold" that is set for either SBFD symbols or non-SBFD symbols.

[0115] An example of a procedure for selecting a PRACH resource (RO) and determining the number of PRACH repetitions in terminal 200 (for example, an SBFD-compatible terminal) will be described below.

[0116] In Method 2, the terminal 200 may perform an operation (determination) by replacing (Procedure 2) in Method 1 with the following (Procedure 2'). Note that the terminal 200 may perform the operation of (Procedure 2) when the conditions of (Procedure 2') are not met (for example, when the threshold is not satisfied).

[0117] (Procedure 2′) In procedure 1, if the SS-RSRP is equal to or greater than the threshold for both the “threshold for PRACH transmission in SBFD symbols” and the “threshold for PRACH transmission in non-SBFD symbols” and a threshold for the number of PRACH repetitions is set, terminal 200 determines the number of PRACH repetitions based on a comparison between SS-RSRP and the threshold for the number of PRACH repetitions.

[0118] In this case, the threshold for the number of PRACH repetitions may be set commonly for SBFD symbols and non-SBFD symbols, or a threshold set for either the SBFD symbols or the non-SBFD symbols may be applied. Furthermore, when the number of PRACH repetitions is multiple, terminal 200 may perform PRACH repetition transmission using both RO on SBFD symbols and RO on non-SBFD symbols.

[0119] An example of the procedure for selecting a PRACH resource (RO) and determining the number of PRACH repetitions in terminal 200 has been described above.

[0120] FIG. 10 shows an example of the relationship between the SS-RSRP and the threshold in Method 2.

[0121] In the example of Figure 10, the "threshold for PRACH transmission in non-SBFD symbols" and the "threshold for the number of PRACH repetitions in non-SBFD symbols" are shown on the left side of the arrow (vertical axis) indicating the value of SS-RSRP, and the "threshold for PRACH transmission in SBFD symbols" and the "threshold for the number of PRACH repetitions in non-SBFD symbols" are shown on the right side.

[0122] In the example of Fig. 10, thresholds (three thresholds) for 2, 4, and 8 PRACH repetitions are set in non-SBFD symbols, and thresholds (two thresholds) for 2 and 4 PRACH repetitions are set in SBFD symbols. As shown in Fig. 10, the same values ​​are set as the thresholds for 2 and 4 PRACH repetitions in non-SBFD symbols and SBFD symbols.

[0123] As shown in FIG. 10, the PRACH transmission operation in terminal 200 is classified into the following six cases depending on the SS-RSRP value.

[0124] (Case 1) Case 1 is a case where SS-RSRP is equal to or greater than the threshold for both the "threshold for PRACH transmission in SBFD symbols" and the "threshold for PRACH transmission in non-SBFD symbols," and SS-RSRP is equal to or greater than the "threshold for two PRACH repetitions."

[0125] In Case 1, of the two PRACH transmission thresholds, the threshold closest to the SS-RSRP is the "threshold for PRACH transmission in the SBFD symbol," so terminal 200 selects the RO on the SBFD symbol and performs PRACH transmission in the RO on the SBFD symbol. Also, in Case 1, the SS-RSRP is equal to or greater than the threshold for two PRACH repetitions, so terminal 200 performs PRACH transmission without PRACH repetition (i.e., single PRACH transmission) in the RO on the SBFD symbol.

[0126] (Case 2) Case 2 is a case where SS-RSRP is equal to or greater than the threshold for both the "threshold for PRACH transmission in SBFD symbols" and the "threshold for PRACH transmission in non-SBFD symbols," and SS-RSRP is less than the "threshold for two PRACH repetitions" and equal to or greater than the "threshold for four PRACH repetitions." In Case 2, terminal 200 selects an RO on an SBFD symbol and an RO on a non-SBFD symbol, and transmits two PRACH repetitions in the RO on the SBFD symbol and the RO on the non-SBFD symbol.

[0127] (Case 3) Case 3 is a case where SS-RSRP is equal to or greater than the threshold for both the "threshold for PRACH transmission in SBFD symbols" and the "threshold for PRACH transmission in non-SBFD symbols," and SS-RSRP is less than the "threshold for four PRACH repetitions" and equal to or greater than the "threshold for eight PRACH repetitions." In Case 3, terminal 200 selects an RO on an SBFD symbol and an RO on a non-SBFD symbol, and transmits four PRACH repetitions in the RO on the SBFD symbol and the RO on the non-SBFD symbol.

[0128] (Case 4) Case 4 is a case where SS-RSRP is less than the “threshold for PRACH transmission in SBFD symbols” and is equal to or greater than the “threshold for PRACH transmission in non-SBFD symbols,” and SS-RSRP is less than the “threshold for four PRACH repetitions” and is equal to or greater than the “threshold for eight PRACH repetitions.” In Case 4, terminal 200 selects an RO on a non-SBFD symbol and transmits four PRACH repetitions in the RO on the non-SBFD symbol.

[0129] (Case 5) Case 5 is a case where SS-RSRP is less than the “threshold for PRACH transmission in SBFD symbols,” is greater than or equal to the “threshold for PRACH transmission in non-SBFD symbols,” and is less than the “threshold for eight PRACH repetitions.” In Case 5, terminal 200 selects an RO on a non-SBFD symbol and transmits eight PRACH repetitions in the RO on the non-SBFD symbol.

[0130] (Case 6) Case 6 is a case where SS-RSRP is less than the “threshold for PRACH transmission in SBFD symbols” and less than the “threshold for PRACH transmission in non-SBFD symbols.” In Case 6, terminal 200 does not perform PRACH transmission.

[0131] An example of the relationship between SS-RSRP and the threshold value in Method 2 has been described above.

[0132] Thus, according to method 2, by setting the PRACH transmission threshold and the PRACH repetition count threshold so that PRACH transmission can be performed using both SBFD symbol RO and non-SBFD symbol RO, terminal 200 can select both RO on SBFD symbols and RO on non-SBFD symbols. This reduces interference between terminals on SBFD symbols and improves DL reception performance for SBFD symbols. Furthermore, with method 2, resources for both SBFD symbol RO and non-SBFD symbol RO can be used for PRACH transmission (e.g., repetition transmission), thereby reducing PRACH transmission delay.

[0133] Note that method 2 may also be applied when it is permitted to allocate resources for one RO across SBFD symbols and non-SBFD symbols. In this case, for example, in the above-described (Case 1), terminal 200 selects an RO for the SBFD symbol and performs one PRACH transmission, but when an RO that spans SBFD symbols and non-SBFD symbols is available, terminal 200 may perform PRACH transmission using an RO that spans SBFD symbols and non-SBFD symbols.

[0134] <Method 3> In method 3, terminal 200 selects an RO to use for PRACH transmission based on a rule regarding the priority of SBFD symbols and non-SBFD symbols in addition to comparing a threshold for PRACH transmission in an RO on an SBFD symbol and a threshold for PRACH transmission in an RO on a non-SBFD symbol with the received power of a signal (for example, SS-RSRP).

[0135] Note that the same thresholds as those in Method 1 may be used as the thresholds for PRACH transmission in each RO of SBFD symbols and non-SBFD symbols (for example, the threshold for PRACH transmission and the threshold for the number of PRACH repetitions).

[0136] Terminal 200 (for example, an SBFD-compatible terminal) selects an RO according to the following procedure. Note that, when PRACH repetition is not applied, terminal 200 performs the following (Procedure 1) and (Procedure 2), and does not need to perform other procedures.

[0137] (Procedure 1) Terminal 200 determines whether to use RO on a non-SBFD symbol or RO on an SBFD symbol in accordance with a priority rule. That is, terminal 200 determines a symbol type for performing PRACH transmission in accordance with a priority rule.

[0138] (Procedure 2) Based on the symbol type determined in procedure 1, terminal 200 selects an RO available for PRACH transmission based on either the "threshold for PRACH transmission in SBFD symbols" or the "threshold for PRACH transmission in non-SBFD symbols" and the SS-RSRP.

[0139] For example, if the SS-RSRP is equal to or greater than the threshold for PRACH transmission corresponding to the symbol type determined in procedure 1, terminal 200 selects an RO on a symbol of the symbol type determined in procedure 1.

[0140] Furthermore, for example, if the SS-RSRP is not greater than or equal to the threshold for PRACH transmission corresponding to the symbol type determined in procedure 1 (if it is less than the threshold), and is greater than or equal to the threshold for PRACH transmission corresponding to a symbol type not selected in procedure 1, the terminal 200 may apply one of the following methods.

[0141] The first method is a method of not changing the symbol type ("no change of symbol type"). In this case, terminal 200 does not perform PRACH transmission. This makes it possible to prohibit transmission using non-priority symbol types according to the priority rule, thereby simplifying the determination in terminal 200. Furthermore, for example, when transmission using SBFD symbols is prohibited, it is possible to reduce interference between terminals.

[0142] The second method is to change the symbol type ("symbol type change"). In this case, terminal 200 selects an RO on a symbol of a symbol type that is not selected (not prioritized) in procedure 1. This can improve the transmission opportunity of the PRACH.

[0143] Furthermore, for example, when the SS-RSRP is less than the threshold for both the "threshold for PRACH transmission in SBFD symbols" and the "threshold for PRACH transmission in non-SBFD symbols", terminal 200 does not perform PRACH transmission.

[0144] (Procedure 3) When a threshold for the number of PRACH repetitions is set for the symbol types selected in procedures 1 and 2, terminal 200 determines the number of PRACH repetitions based on a comparison between SS-RSRP and the threshold for the number of PRACH repetitions.

[0145] An example of the procedure for selecting a PRACH resource (RO) and determining the number of PRACH repetitions in terminal 200 has been described above.

[0146] Next, an example of the priority rules will be described.

[0147] As the priority rule, for example, the following rule may be applied. The priority rule may be defined in advance or may be notified to the terminal 200 by configuration. For example, the setting of the priority rule may include setting the type of rule to be applied and setting whether the rule is enabled or disabled.

[0148] (Example Rule 1) In Example 1, RO on SBFD symbols is preferentially selected whenever possible. For example, for PRACH transmission to request high-priority UL data transmission, RO on non-SBFD symbols can be used in addition to SBFD symbols, but for low-priority UL data, RO on SBFD symbols can be used and RO on non-SBFD symbols may not be used.

[0149] By having terminal 200 (e.g., an SBFD-compatible terminal) use RO on SBFD symbols preferentially over RO on non-SBFD symbols, the probability that non-SBFD-compatible terminals will be able to use RO on non-SBFD symbols increases, thereby, for example, reducing the collision probability of PRACH transmissions and improving fairness in RO usage between SBFD-compatible terminals and SBFD-non-compatible terminals.

[0150] (Rule Example 2) In Example 2, when power ramping is not applied, ROs on SBFD symbols are selected in preference to ROs on non-SBFD symbols, and when power ramping is applied, ROs on non-SBFD symbols are selected in preference to ROs on SBFD symbols.

[0151] When power ramping is applied, the PRACH transmission power increases, and interference between terminals increases. In this case, terminal 200 can suppress the increase in interference between terminals by preferentially selecting non-SBFD symbols. When power ramping is not applied, as in Rule Example 1, fairness in RO use between SBFD-compatible terminals and SBFD-incompatible terminals can be improved.

[0152] (Example Rule 3) In Example 3, when the PRACH transmit power is less than a threshold, an RO on an SBFD symbol is selected with priority over an RO on a non-SBFD symbol, and when the PRACH transmit power is equal to or greater than the threshold, an RO on a non-SBFD symbol is selected with priority over an RO on an SBFD symbol.

[0153] The threshold value of the PRACH transmission power may be defined in advance or may be notified to terminal 200 by configuration, for example.

[0154] When the PRACH transmission power increases (for example, when it is equal to or greater than a threshold), inter-terminal interference increases, and therefore, terminal 200 can suppress the increase in inter-terminal interference by selecting a non-SBFD symbol. When the PRACH transmission power does not increase (for example, when it is less than a threshold), as with rule example 1, fairness in RO use between SBFD-compatible terminals and SBFD-incompatible terminals can be improved.

[0155] (Example Rule 4) In Example 4, a preferred (or used) symbol type is configured using a semi-static configuration (e.g., notification using a SIB) or dynamic notification (e.g., notification in a UE-specific PDCCH or a group common PDCCH). For example, the preferred symbol type may be notified by a 1-bit flag.

[0156] For example, the setting and notification of the prioritized symbol type may differ for each terminal 200. For example, for a cell edge terminal which tends to have a low SS-RSRP, the use of RO of a non-SBFD symbol can be configured to reduce interference between terminals in the SBFD symbol.

[0157] In Example 4, for example, it is possible to set which symbol type to select depending on the terminals 200 accommodated by the base station 100 or the traffic situation. For example, it is possible to set the symbol type taking into consideration whether an increase in inter-terminal interference is tolerable in DL reception of SBFD symbols. This improves the flexibility of RO selection.

[0158] An example of the priority rules has been described above.

[0159] FIG. 11 shows an example of the relationship between SS-RSRP and a threshold in Method 3.

[0160] In the example of Figure 11, the "threshold for PRACH transmission in non-SBFD symbols" and the "threshold for the number of PRACH repetitions in non-SBFD symbols" are shown on the left side of the arrow (vertical axis) indicating the value of SS-RSRP, and the "threshold for PRACH transmission in SBFD symbols" and the "threshold for the number of PRACH repetitions in SBFD symbols" are shown on the right side.

[0161] In the example of Fig. 11, similarly to method 1 (Fig. 8), thresholds (three thresholds) are set for 2, 4, and 8 PRACH repetitions in non-SBFD symbols, and a threshold (one threshold) is set for 2 PRACH repetitions in SBFD symbols. As shown in Fig. 11, the thresholds are set in the same way as in Fig. 8, but the RO selection method differs between method 3 and method 1. Therefore, the PRACH transmission operation in terminal 200 is classified into the following eight cases depending on the SS-RSRP value.

[0162] In the example of FIG. 11, the condition (second method) in which the symbol type is changed in (Procedure 2) described above is assumed.

[0163] 11 , Cases 1a to 1e indicate cases in which non-SBFD symbols are selected in Procedure 1. When non-SBFD symbols are selected in Procedure 1, terminal 200 selects PRACH resources (e.g., whether to transmit PRACH and the number of PRACH repetitions) corresponding to one of the cases divided into Cases 1a to 1e based on a comparison of SS-RSRP with the "threshold for PRACH transmission in non-SBFD symbols" and the "threshold for the number of PRACH repetitions in non-SBFD symbols."

[0164] In FIG. 11, Cases 2a to 2c show cases in which the SBFD symbol is selected in Procedure 1.

[0165] Case 2a is a case where SS-RSRP is equal to or greater than the “threshold for PRACH transmission in an SBFD symbol” and equal to or greater than the “threshold for two PRACH repetitions.” In Case 2a, terminal 200 selects an RO on the SBFD symbol and performs PRACH transmission without PRACH repetition in the RO on the SBFD symbol.

[0166] Case 2b is a case where SS-RSRP is equal to or greater than the “threshold for PRACH transmission in an SBFD symbol” and less than the “threshold for two PRACH repetitions.” In Case 2b, terminal 200 selects an RO on the SBFD symbol and transmits two PRACH repetitions in the RO on the SBFD symbol.

[0167] Case 2c is a case where SS-RSRP is less than the "threshold for PRACH transmission in SBFD symbols." In the example of FIG. 11, it is assumed that the symbol type is changed in procedure 2, and therefore, in Case 2c, terminal 200 changes the symbol type to be used to a non-SBFD symbol. Then, terminal 200 performs a PRACH transmission operation of one of Cases 1b to 1e based on SS-RSRP. Note that in the example of FIG. 11, Case 1a cannot be selected because the "threshold for the number of PRACH repetitions of two in non-SBFD symbols" is lower than the "threshold for PRACH transmission in SBFD symbols."

[0168] An example of the relationship between SS-RSRP and the threshold value in Method 3 has been described above.

[0169] As described above, according to Method 3, a rule for the priority of symbol types is set, and then the PRACH transmission threshold and the PRACH repetition count threshold are set separately for SBFD symbols and non-SBFD symbols. As a result, terminal 200 selects whether to use RO on SBFD symbols or RO on non-SBFD symbols for PRACH transmission and PRACH repetition transmission. This reduces interference between terminals on SBFD symbols and improves DL reception performance in SBFD symbols.

[0170] In addition, in Method 3, the use of priority rules enables PRACH resource selection based on more detailed selection criteria or selection criteria depending on the situation than when PRACH resource selection (determination) is performed using thresholds alone, thereby improving the flexibility of RO selection.

[0171] <Method 4> In method 4, similarly to method 3, terminal 200 selects an RO to use for PRACH transmission based on a comparison of a threshold for PRACH transmission in an RO on an SBFD symbol and a threshold for PRACH transmission in an RO on a non-SBFD symbol with the received power of a signal (for example, SS-RSRP), and also based on a rule regarding the priority of SBFD symbols and non-SBFD symbols.

[0172] Method 4 describes a method for selecting an RO to be used when terminal 200 retransmits a PRACH after a PRACH transmission failure (e.g., when there is no response to the PRACH transmission (e.g., Msg 2)) (e.g., a method for selecting a transmission method to be used based on a received power value (SS-RSRP) lower than that of the previous transmission).

[0173] For example, terminal 200 may select a transmission method when SS-RSRP is equal to or greater than a threshold for the symbol type currently selected by terminal 200 and is less than a threshold that is closer to (e.g., nearest to) the SS-RSRP. That is, when PRACH transmission fails, terminal 200 selects an RO to be used for PRACH retransmission based on a comparison between an SS-RSRP value (power value) that is lower than the SS-RSRP value used to select an RO in the PRACH transmission and thresholds related to PRACH transmission (e.g., the PRACH transmission threshold and the PRACH repetition count threshold).

[0174] As an example, if terminal 200 fails to transmit two repetitions for a certain symbol type (e.g., if SS-RSRP is less than the threshold for two repetitions), and then attempts to transmit PRACH again, terminal 200 may consider that SS-RSRP is less than a lower threshold (e.g., the threshold for four repetitions), and may perform PRACH transmission with the number of repetitions set to four.

[0175] This operation corresponds to, for example, changing from a currently corresponding Case to a next lower Case in a certain symbol type Case (Cases 1a to 1e or Cases 2a to 2c) shown in Fig. 11. Also, Fig. 11 assumes a case where the symbol type is changed in procedure 2, and therefore terminal 200 may change the symbol type as the next transmission method if this change in Case (change in transmission method) causes the PRACH transmission threshold for the selected symbol type to be lowered.

[0176] In the following description, one transmission method is also referred to as a "level."

[0177] FIG. 12 shows an example of changing the transmission method when the PRACH transmission fails.

[0178] In the example of Figure 12, the "threshold for PRACH transmission in non-SBFD symbols" and the "threshold for the number of PRACH repetitions in non-SBFD symbols" are shown on the left side of the arrow (vertical axis) indicating the value of SS-RSRP, and the "threshold for PRACH transmission in SBFD symbols" and the "threshold for the number of PRACH repetitions in SBFD symbols" are shown on the right side.

[0179] In the example of Figure 12, as with Method 3 (Figure 11), thresholds for 2, 4, and 8 PRACH repetitions (three thresholds) are set in non-SBFD symbols, and a threshold for 2 PRACH repetitions (one threshold) is set in SBFD symbols.

[0180] 12, the rule for the priority of symbol types is assumed to be Rule Example 1 described in Method 3. The example of Fig. 12 also assumes the condition (second method) where the symbol type is changed in (Procedure 2) described in Method 3.

[0181] 12, the SS-RSRP measured by terminal 200 is indicated by the circle on the vertical axis. In this case, terminal 200 may perform PRACH transmission in the following order of levels, for example, depending on the failure of PRACH transmission.

[0182] (Level 1) Terminal 200 selects the SBFD symbol as the symbol type according to the priority rule, and selects a transmission method of Case 2a (for example, a single PRACH transmission in RO on the SBFD symbol) based on a comparison between SS-RSRP and a threshold. As shown in Fig. 12, Level 1 (Case 2a) is a transmission method in which SS-RSRP is equal to or greater than the "threshold of two PRACH repetitions in the SBFD symbol."

[0183] (Level 2) If PRACH transmission at level 1 fails, terminal 200 changes to a transmission method (level 2) that is closer to (for example, nearest to) SS-RSRP and is less than the "threshold of two PRACH repetitions in an SBFD symbol," which is the threshold that SS-RSRP exceeds at level 1. That is, terminal 200 selects a transmission method of Case 2b (for example, transmitting two PRACH repetitions in an RO on an SBFD symbol). As shown in Fig. 12 , level 2 (Case 2b) is a transmission method in which SS-RSRP is considered to exceed the "threshold of PRACH transmission in an SBFD symbol."

[0184] (Level 3) If PRACH transmission at level 2 fails, terminal 200 changes to a transmission method (level 3) that is closer to SS-RSRP (for example, nearest) and is less than the "PRACH transmission threshold in SBFD symbols," which is the threshold at which SS-RSRP is deemed to be exceeded at level 2. In FIG. 12 , there are no PRACH transmission methods at SBFD symbols lower than level 2, and since it is assumed that the symbol type will be changed, terminal 200 changes the symbol type to a non-SBFD symbol and selects the transmission method of Case 1b (for example, transmitting two PRACH repetitions in RO on a non-SBFD symbol). As shown in FIG. 12 , level 3 (Case 1b) is a transmission method at which SS-RSRP is deemed to be equal to or greater than the "threshold of four PRACH repetitions at non-SBFD symbols."

[0185] (Level 4) If PRACH transmission at level 3 fails, terminal 200 changes to a transmission method (level 4) that is closer to SS-RSRP (for example, nearest) and is less than the "threshold of four PRACH repetitions in non-SBFD symbols," which is the threshold at which SS-RSRP is considered to be higher at level 3. For example, terminal 200 selects the transmission method of Case 1c (for example, transmitting four PRACH repetitions in RO on non-SBFD symbols). As shown in FIG. 12 , level 4 (Case 1c) is a transmission method at which SS-RSRP is considered to be equal to or greater than the "threshold of eight PRACH repetitions in non-SBFD symbols."

[0186] (Level 5) If PRACH transmission at level 4 fails, terminal 200 changes to a transmission method (level 5) that is closer to (for example, nearest to) SS-RSRP and is less than the "threshold of eight PRACH repetitions in non-SBFD symbols," which is the threshold at which SS-RSRP is considered to be higher at level 4. For example, terminal 200 selects the transmission method of Case 1d (for example, eight PRACH repetitions transmitted in RO on non-SBFD symbols).

[0187] An example of changing the transmission method when PRACH transmission fails has been described above.

[0188] Thus, according to method 4, when terminal 200 retransmits PRACH after a PRACH transmission failure, it can increase the likelihood of successful PRACH transmission by changing the transmission method (level) to one that is used when the SS-RSRP is lower than the actually measured SS-RSRP value. This can reduce the delay time required for the RACH procedure.

[0189] <Method 5> In method 5, terminal 200 selects an RO to be used for PRACH transmission based on a comparison between a threshold for each type of RO and the received power of a signal (for example, SS-RSRP).

[0190] The RO type may be set in association with, for example, a configuration that configures the RO. A different PRACH transmission threshold and a different PRACH repetition count threshold may be set for each RO type. Furthermore, multiple RO types may be set within an SBFD symbol.

[0191] Terminal 200 (for example, an SBFD-compatible terminal) selects an RO according to the following procedure. The following procedure is applied by extending the procedure of method 1 and replacing "selection of symbol type" with "selection of RO type." Furthermore, the number of RO types is not limited to two, and three or more RO types may be supported. Note that, if PRACH repetition is not applied, terminal 200 performs procedure 1 but does not need to perform procedure 2. Furthermore, method 5 can also be applied to methods other than method 1 by replacing "selection of symbol type" with "selection of RO type."

[0192] (Procedure 1) Terminal 200 selects an RO of an RO type corresponding to a threshold value for PRACH transmission that is equal to or greater than the SS-RSRP threshold and is closer to the SS-RSRP (for example, closest to the SS-RSRP) from among the PRACH transmission threshold values ​​associated with multiple RO types.

[0193] For example, the terminal 200 may perform the following operations.

[0194] If the SS-RSRP is equal to or greater than the threshold for PRACH transmission of one RO type, terminal 200 selects an RO of the RO type corresponding to the threshold.

[0195] If the SS-RSRP is equal to or greater than the PRACH transmission thresholds for multiple RO types, the terminal 200 selects an RO of an RO type for which the SS-RSRP is equal to or greater than the threshold and corresponds to a threshold value closer to the SS-RSRP (e.g., the most recent).

[0196] If the SS-RSRP is less than the PRACH transmission threshold for any RO type, terminal 200 does not transmit PRACH.

[0197] (Procedure 2) When a threshold for the number of PRACH repetitions is set for the RO type corresponding to the RO selected in procedure 1, terminal 200 determines the number of PRACH repetitions based on a comparison between SS-RSRP and the threshold for the number of PRACH repetitions.

[0198] An example of the procedure for selecting a PRACH resource (RO) and determining the number of PRACH repetitions in terminal 200 has been described above.

[0199] Fig. 13 shows an example of RO placement based on Method 5. Note that, for simplicity of explanation, PRACH repetition is not shown in Fig. 13.

[0200] In the example of Fig. 13, resources of an RO corresponding to RO type #0 (RO#0) and resources of an RO corresponding to RO type #1 (RO#1) are configured in Slot#3. As shown in Fig. 13, RO#0 is adjacent to the DL subband. Also, as shown in Fig. 13, RO#1 is adjacent to RO#0 but not adjacent to the DL subband.

[0201] Here, a case will be described in which the threshold for PRACH transmission in RO type #0 is set higher than the threshold for PRACH transmission in RO type #1.

[0202] In this case, among SBFD-compatible terminals, terminal 200 with a high SS-RSRP (for example, when SS-RSRP is equal to or greater than the threshold for PRACH transmission in RO type #0) selects RO #0 and transmits PRACH in RO #0. Also, terminal 200 with a low SS-RSRP (for example, when SS-RSRP is less than the threshold for PRACH transmission in RO type #0 and SS-RSRP is equal to or greater than the threshold for PRACH transmission in RO type #1) selects RO #1 and transmits PRACH in RO #1.

[0203] For example, the higher the SS-RSRP, the lower the UL transmission power required for terminal 200, so even if PRACH transmission (UL transmission) is performed in RO#0, the impact on other subbands (e.g., DL subbands) is small, and therefore, interference between terminals can be kept low.

[0204] On the other hand, since the lower the SS-RSRP, the higher the UL transmission power in terminal 200 is expected to be, the higher the transmission power of the PRACH in RO#1 will be than the transmission power of the PRACH in RO#0, which may result in increased inter-terminal interference. In contrast, as shown in FIG. 13 , the frequency resources used for PRACH transmission in RO#1 are allocated farther away from the frequency resources of the DL subband than the frequency resources used for PRACH transmission in RO#0. Therefore, when the SS-RSRP is low (for example, when the SS-RSRP is less than the threshold for PRACH transmission in RO type #0 and is equal to or greater than the threshold for PRACH transmission in RO type #1), the inter-terminal interference caused by PRACH transmission in RO#1 (UL transmission) on reception in the DL subband (DL reception) can be reduced.

[0205] For example, guard bands between channels are used to separate (move apart) resources used for transmission and reception in order to reduce inter-channel interference. Similarly, in method 5, as shown in FIG. 13, when a PRACH is transmitted in RO#1, resources in RO#0 can be used like a guard band between PRACH transmission (UL transmission) and reception in the DL subband (DL reception), thereby reducing inter-terminal interference. In this way, even within the same symbol (e.g., SBFD symbol), by arranging different RO types according to the positional relationship with the DL subband, it is possible to reduce inter-terminal interference in PRACH transmission on the SBFD symbol.

[0206] As described above, according to method 5, the PRACH transmission threshold and the PRACH repetition count threshold are set individually for each RO type, allowing terminal 200 to select which RO of the RO type to use for PRACH transmission and PRACH repetition transmission. This reduces inter-terminal interference on SBFD symbols and improves DL reception performance for SBFD symbols.

[0207] Furthermore, method 5 can reduce inter-terminal interference by confining it to ROs within SBFD symbols, thereby reducing the impact on SBFD-incompatible terminals. For example, an SBFD-compatible terminal with a low SS-RSRP does not need to use ROs on non-SBFD symbols, so it is possible to reduce inter-terminal interference without increasing the collision probability when non-SBFD-compatible terminals transmit PRACH.

[0208] Note that, in Figure 13, an example has been described in which multiple ROs are placed within one SBFD symbol, but this is not limited to this, and method 5 can also be applied, for example, even when an RO is placed in each of multiple SBFD symbols.

[0209] Above, an example of a method for selecting PRACH resources has been described.

[0210] As described above, in this embodiment, terminal 200 selects an RO (transmission opportunity) to be used for PRACH transmission based on the threshold for SS-RSRP for multiple symbols including the SBFD symbol, and transmits a PRACH signal using the selected RO. This reduces interference between terminals during PRACH transmission in the SBFD symbol. Therefore, this embodiment can improve the efficiency of PRACH resource selection.

[0211] (Other Embodiments) (1) In one embodiment of the present disclosure, a configuration such as that shown in FIG. 14 may be assumed as PRACH resource configuration for SBFD-compatible terminals. In FIG. 14, "additionalRACH-SBFD-ConfigList-r19" is an example of a PRACH configuration for SBFD-compatible terminals. For example, in FIG. 14, PRACH resources are configured for SBFD-incompatible terminals by "rach-ConfigCommon" or "additionalRACH-ConfigList-r17," and PRACH resources are configured for SBFD-compatible terminals by "additionalRACH-SBFD-ConfigList-r19." PRACH resource configuration for SBFD-compatible terminals is realized by adding different parameters for SBFD-compatible terminals.

[0212] (2) In one embodiment of the present disclosure, a PRACH transmission power limit may be applied in combination to reduce inter-UE interference in SBFD symbols. For example, a power offset may be applied when transmitting the PRACH in the SBFD symbol as a method for limiting the PRACH transmission power. For example, the following equation (1) may be applied:

[0213] where P PRACH,b,f,c (i) denotes the PRACH transmit power in the active UL BWP "b", carrier "f", cell "c", and transmission opportunity "i", and P CMAX,f,c represents the maximum transmission power of the terminal, and P PRACH,target,f,c represents the target received power set by the higher layer, and PL b,f,crepresents the path loss, and sbfd_offset represents the power offset to be applied to the SBFD symbol.

[0214] For example, by setting a negative value to sbfd_offset, it is possible to reduce the PRACH transmission power compared to non-SBFD symbols to which sbfd_offset is not applied. Note that when transmitting multiple PRACHs using PRACH repetition, different transmission powers may be used for each RO. In addition to reducing inter-terminal interference by PRACH resource selection, applying a PRACH transmission power restriction can further reduce inter-terminal interference due to PRACH transmission.

[0215] (3) In one embodiment of the present disclosure, instead of the thresholds in the SBFD symbols (e.g., the PRACH transmission threshold and the PRACH repetition count threshold) and the thresholds in the non-SBFD symbols (e.g., the PRACH transmission threshold and the PRACH repetition count threshold), an "RO threshold for an SBFD-compatible terminal" and an "RO threshold for an SBFD-non-compatible terminal (or a shared RO threshold)" may be used. For example, these thresholds may be defined as follows. A modified example of Method 1 will be shown below as an example.

[0216] <Threshold for PRACH Transmission in RO for SBFD-Compatible Terminal> For example, when SS-RSRP is equal to or greater than a threshold, terminal 200 may transmit PRACH in the RO for SBFD-compatible terminal linked to the threshold. The threshold may be set by an individual parameter linked to the RO for the SBFD-compatible terminal, and, for example, a higher layer parameter linked to the RO for the SBFD-compatible terminal (for example, rsrp-ThresholdSSB of the RACH-ConfigCommon IE) may be reused.

[0217] <Threshold for PRACH Transmission in RO for SBFD Non-Supporting Terminal (or Shared RO)> Terminal 200 may transmit PRACH in the RO for SBFD non-supporting terminal, for example, when SS-RSRP is equal to or greater than a threshold. The threshold may be set by an individual parameter associated with the RO for the SBFD non-supporting terminal, or, for example, a higher layer parameter associated with the RO for the SBFD non-supporting terminal (for example, rsrp-ThresholdSSB of the RACH-ConfigCommon IE) may be reused.

[0218] <Threshold for the number of PRACH repetitions in an RO for SBFD-compatible terminal> For example, when the SS-RSRP is less than a threshold, in an RO associated with the threshold, terminal 200 may transmit the PRACH by repetition in the RO for SBFD-compatible terminal a number of times corresponding to the threshold. Note that this threshold may be used when RACH repetition is applied.

[0219] <Threshold for the number of RACH repetitions in an RO for SBFD non-compatible terminals (or a shared RO)> When the SS-RSRP is less than a threshold, in an RO associated with the threshold, the terminal 200 may transmit the PRACH by repetition in the RO for SBFD non-compatible terminals a number of times corresponding to the threshold. Note that this threshold may be used when RACH repetition is applied.

[0220] Examples of threshold values ​​have been described above.

[0221] The terminal 200 (for example, an SBFD-compatible terminal) selects an RO using the above threshold value in the following procedure. As an example, an example of a change in Method 1 is shown below. In the following, the RO types are represented as "RO for SBFD-compatible terminal" and "RO for SBFD-incompatible terminal."

[0222] (Procedure 1) Terminal 200 selects an RO type (e.g., an RO for an SBFD-compatible terminal or an RO for a non-SBFD-compatible terminal) corresponding to a threshold value for which SS-RSRP is equal to or greater than the threshold value and for which SS-RSRP is closer (e.g., nearest) from among the "threshold value for PRACH transmission in an RO for an SBFD-compatible terminal" and the "threshold value for PRACH transmission in an RO for a non-SBFD-compatible terminal."

[0223] (Procedure 2) When a threshold value for the number of PRACH repetitions is set for the RO type selected in procedure 1, terminal 200 determines the number of PRACH repetitions based on SS-RSRP.

[0224] FIG. 15 shows an example of the use of an RO for an SBFD-compatible terminal and an RO for an SBFD-incompatible terminal.

[0225] In Figure 15, RO#0-0 and RO#0-1 are ROs for SBFD-compatible terminals, and RO#1-0 is an RO for SBFD-non-compatible terminals. As shown in Figure 15, ROs for SBFD-compatible terminals can be placed in non-SBFD symbols as well as SBFD symbols. Since the PRACH transmission processing in SBFD-compatible terminals, including non-SBFD symbols, can be separated from existing processing (for example, PRACH transmission processing in SBFD-non-compatible terminals), the complexity when an SBFD-compatible terminal uses an RO of a non-SBFD symbol (for example, linking SSB and RO, allocating RO in PRACH repetition transmission, etc.) can be reduced compared to the case of separation by symbol type.

[0226] (4) In an embodiment of the present disclosure, the definition of the threshold is not limited to the above example. For example, instead of the "threshold for PRACH transmission in SBFD symbols," it may be defined as "threshold for single PRACH transmission in SBFD symbols" (e.g., threshold for PRACH transmission without repetition in SBFD symbols). Also, instead of the "threshold for PRACH transmission in non-SBFD symbols," it may be defined as "threshold for single PRACH transmission in non-SBFD symbols" (e.g., threshold for PRACH transmission without repetition in non-SBFD symbols).

[0227] (5) In one embodiment of the present disclosure, the measurement value (e.g., received power) compared with the threshold value is not limited to SS-RSRP and may be another measurement value (measurement quantity). For example, a threshold based on another measurement quantity may be applied instead of SS-RSRP. For example, thresholds based on SS-Reference Signal Received Quality (RSRQ) (or SSB-RSRQ), SSB-Signal to Interference and Noise Ratio (SINR) (or SS-SINR), Channel State Information (CSI)-RSRP, CSI-RSRQ, or CSI-SINR may be applied.

[0228] Furthermore, the parameter used in selecting the PRACH resource (RO) is not limited to a measured value such as SS-RSRP, and may be, for example, a method based on whether or not the terminal 200 is located at the cell edge. For example, the closer the terminal 200 is to the cell edge, the more likely it is that the UL transmission power is set to be high. Therefore, for example, in the above-described embodiment, "when SS-RSRP is less than a threshold" may be replaced with "when terminal 200 is located at the cell edge," and "when SS-RSRP is equal to or greater than a threshold" may be replaced with "when terminal 200 is not located at the cell edge." Note that the location of terminal 200 may be estimated from, for example, received power or may be identified from information related to the location of terminal 200.

[0229] (6) In the above embodiment, the unit of time domain resources is not limited to symbols and slots, and may be other time domain resources or other combinations of time domain resources.

[0230] Furthermore, in the above embodiment, a case where SBFD is applied is described, but an embodiment of the present disclosure may be applied in addition to SBFD as long as the transmission direction (e.g., DL or UL) is set in multiple bands (e.g., subbands) obtained by dividing the frequency band.

[0231] In the above-described embodiments, values ​​such as the number of subbands, the number of DL subbands, the number of UL subbands, the number of slots, the number of symbols, and the number of repetitions are merely examples and are not limited to these. Also, the subband configurations used in the above-described embodiments are merely examples, and the number of subbands and the arrangement order of DL subbands and UL subbands are not limited to these.

[0232] (Supplementary Note) Information indicating whether the terminal 200 supports the functions, operations, or processes described in the above-described embodiments may be transmitted (or notified) from the terminal 200 to the base station 100, for example, as capability information or capability parameters of the terminal 200.

[0233] The capability information may include an information element (IE) that individually indicates whether or not the terminal 200 supports at least one of the functions, operations, or processes described in the above-described embodiments. Alternatively, the capability information may include an information element that indicates whether or not the terminal 200 supports a combination of any two or more of the functions, operations, or processes described in the above-described embodiments.

[0234] For example, the base station 100 may determine (or decide or assume) functions, operations, or processes that the terminal 200 that transmitted the capability information supports (or does not support) based on the capability information received from the terminal 200. The base station 100 may perform operations, processes, or controls according to the determination result based on the capability information. For example, the base station 100 may control resource configuration of a random access channel based on the capability information received from the terminal 200.

[0235] Note that the fact that terminal 200 does not support some of the functions, operations, or processes described in the above-described embodiments may be interpreted as meaning that such some of the functions, operations, or processes are restricted in terminal 200. For example, information or a request regarding such restrictions may be notified to base station 100.

[0236] Information regarding the capabilities or limitations of terminal 200 may, for example, be defined in a standard, or may be implicitly notified to base station 100 in association with information known at base station 100 or information transmitted to base station 100.

[0237] (Control Signal) In the present disclosure, a downlink control signal (or downlink control information) related to an embodiment of the present disclosure may be, for example, a signal (or information) transmitted in a Physical Downlink Control Channel (PDCCH) of a physical layer, or a signal (or information) transmitted in a Medium Access Control Control Element (MAC CE) or Radio Resource Control (RRC) of a higher layer. Furthermore, the signal (or information) is not limited to being notified by a downlink control signal, but may be predefined in a specification (or standard) or preconfigured in a base station and a terminal.

[0238] In the present disclosure, an uplink control signal (or uplink control information) related to an embodiment of the present disclosure may be, for example, a signal (or information) transmitted in a PUCCH of a physical layer, or a signal (or information) transmitted in a MAC CE or RRC of a higher layer. Furthermore, the signal (or information) is not limited to being notified by an uplink control signal, but may be predefined in a specification (or standard) or preconfigured in a base station and a terminal. Furthermore, the uplink control signal may be replaced with, for example, uplink control information (UCI), 1st stage sidelink control information (SCI), or 2nd stage SCI.

[0239] (Base Station) In an embodiment of the present disclosure, the base station may be a Transmission Reception Point (TRP), a cluster head, an access point, a Remote Radio Head (RRH), an eNodeB (eNB), a gNodeB (gNB), a Base Station (BS), a Base Transceiver Station (BTS), a parent device, a gateway, or the like. In sidelink communication, a terminal may play the role of a base station. Instead of a base station, a relay device that relays communication between an upper node and a terminal may be used. Alternatively, a roadside unit may be used.

[0240] (Uplink / Downlink / Sidelink) An embodiment of the present disclosure may be applied to, for example, any of the uplink, downlink, and sidelink. For example, an embodiment of the present disclosure may be applied to a Physical Uplink Shared Channel (PUSCH), a Physical Uplink Control Channel (PUCCH), or a Physical Random Access Channel (PRACH) in the uplink, a Physical Downlink Shared Channel (PDSCH), a PDCCH, or a Physical Broadcast Channel (PBCH) in the downlink, or a Physical Sidelink Shared Channel (PSSCH), a Physical Sidelink Control Channel (PSCCH), or a Physical Sidelink Broadcast Channel (PSBCH) in the sidelink.

[0241] The PDCCH, PDSCH, PUSCH, and PUCCH are examples of a downlink control channel, a downlink data channel, an uplink data channel, and an uplink control channel, respectively. The PSCCH and PSSCH are examples of a sidelink control channel and a sidelink data channel. The PBCH and PSBCH are examples of a broadcast channel, and the PRACH is an example of a random access channel.

[0242] (Data Channel / Control Channel) An embodiment of the present disclosure may be applied to, for example, either a data channel or a control channel. For example, the channel in an embodiment of the present disclosure may be replaced with any of the data channels PDSCH, PUSCH, and PSSCH, or the control channels PDCCH, PUCCH, PBCH, PSCCH, and PSBCH.

[0243] (Reference Signal) In one embodiment of the present disclosure, a reference signal is, for example, a signal known by both a base station and a mobile station, and may also be called a Reference Signal (RS) or a pilot signal. The reference signal may be any of a Demodulation Reference Signal (DMRS), a Channel State Information - Reference Signal (CSI-RS), a Tracking Reference Signal (TRS), a Phase Tracking Reference Signal (PTRS), a Cell-specific Reference Signal (CRS), or a Sounding Reference Signal (SRS).

[0244] (Time Interval) In one embodiment of the present disclosure, the unit of time resource is not limited to one or a combination of slots and symbols, but may be, for example, a time resource unit such as a frame, a superframe, a subframe, a slot, a time slot, a subslot, a minislot, a symbol, an Orthogonal Frequency Division Multiplexing (OFDM) symbol, a Single Carrier-Frequency Division Multiplexing Access (SC-FDMA) symbol, or another time resource unit. Furthermore, the number of symbols included in one slot is not limited to the number of symbols exemplified in the above-mentioned embodiment, and may be another number of symbols.

[0245] (Frequency Band) An embodiment of the present disclosure may be applied to either a licensed band or an unlicensed band.

[0246] (Communication) An embodiment of the present disclosure may be applied to communication between a base station and a terminal (Uu link communication), communication between terminals (Sidelink communication), or Vehicle to Everything (V2X) communication. For example, the channel in an embodiment of the present disclosure may be replaced with any of PSCCH, PSSCH, Physical Sidelink Feedback Channel (PSFCH), PSBCH, PDCCH, PUCCH, PDSCH, PUSCH, or PBCH.

[0247] An embodiment of the present disclosure may be applied to a terrestrial network, a non-terrestrial network (NTN) using a satellite or a high altitude pseudo satellite (HAPS), or a terrestrial network in which transmission delay is large compared to the symbol length or slot length, such as a network with a large cell size or an ultra-wideband transmission network.

[0248] (SBFD) In ​​one embodiment of the present disclosure, operations on uplink, downlink, and sidelink symbols may be applied to symbols (e.g., SBFD symbols) on which SBFD (Subband Non-Overlapping Full Duplex, Subband Full Duplex) operations or controls are performed. In SBFD symbols, a frequency domain (or frequency resource, frequency band) is divided into multiple frequency domains (e.g., subbands, RB sets, subbands, or sub-BWPs (Bandwidth Parts)). A terminal transmits and receives in different directions (e.g., downlink or uplink) in units of subbands, which are the divided domains. In SBFD symbols, a terminal may transmit and receive in one direction, either uplink or downlink, but not in the other direction. On the other hand, a base station may be capable of transmitting and receiving on both the uplink and downlink simultaneously. SBFD symbols may have a smaller frequency domain available for downlink transmission than symbols that transmit and receive only downlink transmission. Also, SBFD symbols may have a smaller frequency domain available for uplink transmission than symbols that transmit and receive only uplink transmission.

[0249] In addition, in the SBFD symbol, a terminal may transmit and receive uplink and downlink simultaneously. In this case, the frequency domain in which the terminal transmits and the frequency domain in which the terminal receives may not be adjacent, but may be separated by a frequency interval (also called a frequency gap).

[0250] In addition, different transmission and reception directions in subband units, which are divided areas, may include transmission and reception of side links.

[0251] (XDD: Cross Division Duplex) In one embodiment of the present disclosure, the operation for uplink, downlink, and sidelink symbols may be applied to symbols (e.g., full duplex symbols) where full duplex operation or control is performed. In a full duplex symbol, both the terminal and the base station can simultaneously transmit and receive on the uplink and downlink. In a full duplex symbol, the terminal and the base station may simultaneously transmit and receive in an available frequency region (or frequency resource, frequency band), or may simultaneously transmit and receive in a partial frequency region (i.e., transmission or reception may be performed in other frequency regions). In this case, the frequency region in which the base station or terminal transmits and receives may not be adjacent, but may have a frequency interval (also called a frequency gap). Furthermore, for the purpose of, for example, reducing interference, either the terminal or the base station may simultaneously transmit and receive (i.e., the other may transmit or receive).

[0252] In addition, full duplex operation may be applied to an operation in which a terminal can simultaneously transmit and receive sidelinks, or to an operation in which a terminal can simultaneously transmit and receive sidelinks and uplinks or downlinks.

[0253] (Antenna Port) In one embodiment of the present disclosure, an antenna port refers to a logical antenna (antenna group) consisting of one or more physical antennas. For example, an antenna port does not necessarily refer to a single physical antenna, but may refer to an array antenna consisting of multiple antennas. For example, the number of physical antennas that an antenna port is composed of is not specified, and the antenna port may be specified as the smallest unit by which a terminal station can transmit a reference signal. Furthermore, an antenna port may also be specified as the smallest unit by which a weighting of a precoding vector is multiplied.

[0254] <5G NR System Architecture and Protocol Stack> The 5G NR system architecture generally assumes an NG-RAN (Next Generation - Radio Access Network) including gNBs. The gNBs provide UE-side termination of the NG radio access user plane (SDAP / PDCP / RLC / MAC / PHY) and control plane (RRC) protocols. The gNBs are connected to each other via an Xn interface. The gNBs are also connected to a Next Generation Core (NGC) via a Next Generation (NG) interface, more specifically to an Access and Mobility Management Function (AMF) (e.g., a specific core entity that performs AMF) via an NG-C interface, and to a User Plane Function (UPF) (e.g., a specific core entity that performs UPF) via an NG-U interface. The NG-RAN architecture is shown in Figure 16 (see, for example, 3GPP TS 38.300 v15.6.0, section 4).

[0255] <RRC connection setup and reconfiguration procedure> This shows the NAS part of the interaction between the UE, gNB, and AMF (5GC entity) when the UE transitions from RRC_IDLE to RRC_CONNECTED (see TS 38.300 v15.6.0).

[0256] RRC is a higher layer signaling protocol used to configure the UE and gNB. The AMF prepares UE context data (including, for example, PDU session context, security keys, UE radio capabilities, UE security capabilities, etc.) and sends it to the gNB along with an INITIAL CONTEXT SETUP REQUEST. The gNB then activates AS security together with the UE. This is done by the gNB sending a SecurityModeCommand message to the UE, and the UE responding with a SecurityModeComplete message to the gNB. The gNB then sends an RRCReconfiguration message to the UE, and upon receiving an RRCReconfigurationComplete from the UE, the gNB performs reconfiguration to set up Signaling Radio Bearer 2 (SRB2) and Data Radio Bearer (DRB). For signaling-only connections, the steps related to RRCReconfiguration are omitted because SRB2 and DRB are not set up. Finally, the gNB notifies the AMF that the setup procedure is complete with an INITIAL CONTEXT SETUP RESPONSE.

[0257] Therefore, the present disclosure provides a 5th Generation Core (5GC) entity (e.g., AMF, SMF, etc.) that includes: a control circuit that, upon operation, establishes a Next Generation (NG) connection with a gNodeB; and a transmitter that, upon operation, transmits an initial context setup message to the gNodeB via the NG connection so that a signaling radio bearer between the gNodeB and a user equipment (UE) is set up. Specifically, the gNodeB transmits Radio Resource Control (RRC) signaling, including a resource allocation configuration information element (IE), to the UE via the signaling radio bearer. The UE then transmits in uplink or receives in downlink based on the resource allocation configuration.

[0258] <QoS Control> The 5G Quality of Service (QoS) model is based on QoS flows and supports both QoS flows that require a guaranteed flow bit rate (Guaranteed Bit Rate QoS flows (GBR)) and QoS flows that do not require a guaranteed flow bit rate (non-GBR QoS flows). Thus, at the NAS level, a QoS flow is the finest granularity of QoS classification in a PDU session. A QoS flow is identified within a PDU session by a QoS Flow ID (QFI) carried in an encapsulation header over the NG-U interface.

[0259] For each UE, 5GC establishes one or more PDU sessions. For each UE, the NG-RAN establishes, for example, at least one Data Radio Bearer (DRB) for each PDU session. Additional DRBs for the QoS flows of that PDU session can be configured later (when this is up to the NG-RAN). The NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in the UE and 5GC associate UL and DL packets with QoS flows, while AS-level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0260] (Open-RAN) The base station described in each embodiment (for example, a 5G NR base station called a gNB) may be configured with three functional modules: a Centralized Unit (CU), a Distributed Unit (DU), and a Radio Unit (RU).

[0261] A CU may be referred to as a centralized node, aggregation node, central station, aggregation station, or centralized unit. A DU may be referred to as an O-RAN Distributed Unit (O-DU), distributed node, distributed station, or distributed unit. An RU may be referred to as an O-RAN Radio Unit (O-RU), radio equipment, radio node, radio station, antenna unit, or radio unit.

[0262] There are several split options for the functional split configuration (or functional split point) between CU, DU, and RU. The term "functional split point" is sometimes referred to as "split," "option," or "split option."

[0263] Examples of "division options" include the following division options 1 to 8. The functions of the base station described in each embodiment may be divided into a CU, a DU, and an RU by any of the following division options 1 to 8. For example, the CU, DU, and RU may be functionally divided, or the functions may be divided only between the CU and DU or only between the DU and RU. (1) Segmentation option 1: Between RRC (radio resource control) and PDCP (2) Segmentation option 2: Between PDCP and RLC (High-RLC) (3) Segmentation option 3: Between High-RLC and Low-RLC (4) Segmentation option 4: Between RLC (Low-RLC) and MAC (High-MAC) (5) Segmentation option 5: Between High-MAC and Low-MAC (6) Segmentation option 6: Between MAC (Low-MAC) and PHY (High-PHY) (7) Segmentation option 7: Between High-PHY and Low-PHY (8) Segmentation option 8: Between PHY (Low-PHY) and RF

[0264] The functional split point between the CU and O-DU may be split option 2. The section between the CU and O-DU is called midhaul, and the F1 interface is specified by 3GPP. The section between the O-DU and O-RU is called fronthaul, and the functional split point may be split option 7-2x, which is adopted as the O-RAN fronthaul specification.

[0265] Figure 17 shows an example of functionally dividing the gNB base station functions into CU, O-DU, and O-RU using Split Option 2 and Split Option 7-2x.

[0266] The CU may have, for example, a radio resource control (RRC) function, a service data adaptation protocol (SDAP) function, and a packet data convergence protocol (PDCP) function.

[0267] The O-DU may include, for example, a radio link control (RLC) function, a MAC function, and a higher physical layer (HIGH-PHY) function. The HIGH-PHY function may include an encoding function, a scrambling function, a modulation function, a layer mapping function, a precoding function, and a resource element (RE) mapping function for downlink (DL) transmission. The HIGH-PHY function may also include a decoding function, a descrambling function, a demodulation function, a layer demapping function, and a resource element (RE) demapping function for uplink (UL) reception.

[0268] The O-RU may have, for example, a LOW-PHY function and an RF function. The LOW-PHY function may also have, for downlink transmission, a beamforming function, an IFFT (Inverse First Fourier Transform) + CP (Cyclic Prefix) assignment function, and a D / A (Digital to Analog) conversion function. The LOW-PHY function may also have, for uplink reception, an A / D (Analog to Digital) conversion function, a CP removal + FFT (First Fourier Transform) function, and a beamforming function.

[0269] In addition, if the O-DU does not have a precoding function, the O-RU may have a precoding function.

[0270] The O-RU may have a function related to LBT (listen before talk). The evolving common public radio interface (eCPRI) is specified as the communication method between the O-DU and the O-RU in Split Option 7-2x. In Split Option 7-2x, eCPRI transmits and receives sampling sequences of the in-phase (I) and quadrature (Q) components of the OFDM signal in the frequency domain, as well as information used for beamforming in the antenna and time synchronization signals.

[0271] Information transmitted by the signals described in each embodiment (PDCCH, PUCCH, PDSCH, PUSCH, MAC CE, RRC, etc.) may be transmitted between the O-DU and the O-RU via the eCPRI User Plane (U-Plane) or Control Plane (C-Plane).

[0272] When the functions described in each embodiment are performed in the O-RU by functional division, the O-DU may control the O-RU by transmitting information for controlling the functions via a control signal (e.g., eCPRI) between the O-DU and the O-RU.

[0273] When the functions described in each embodiment are performed in the O-DU by functional division, the O-RU may receive the results of the functions performed in the O-DU via a control signal (e.g., eCPRI) and control the O-RU based on the received results.

[0274] The CU, O-DU, and O-RU may be deployed in physically different devices with their respective functions connected by optical fiber or the like, or some or all of their functions may be deployed in the same physical device.

[0275] The CU and O-DU may be logical entities implemented as software running on a server in the cloud or the like as a virtualized RAN (virtual Radio Access Network: vRAN). Also, some or all of the functions of the CU and O-DU may be provided as a virtualized network function (Network Functions Virtualization: NFV) service.

[0276] The transceiver does not have to be a radio transceiver, but may be, for example, a network transceiver, an optical transceiver, etc. The radio resources allocated by the O-DU may be resources for wireless communication between the O-RU and the UE.

[0277] The present disclosure can be realized in software, hardware, or software in conjunction with hardware.

[0278] Each functional block used in the description of the above embodiments may be partially or entirely realized as an LSI, which is an integrated circuit, and each process described in the above embodiments may be partially or entirely controlled by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may also be called an IC, system LSI, super LSI, or ultra LSI.

[0279] The integrated circuit method is not limited to LSI, and may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0280] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology may be used to integrate functional blocks. The application of biotechnology, etc. is also a possibility.

[0281] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a radio transceiver and processing / control circuitry. The radio transceiver may include a receiver and a transmitter, or both functions. The radio transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0282] The communication devices are not limited to portable or mobile devices, but also include any kind of non-portable or fixed equipment, devices, and systems, such as smart home devices (such as home appliances, lighting equipment, smart meters or measuring devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0283] Communications include data communications via cellular systems, wireless LAN systems, communication satellite systems, and the like, as well as data communications via combinations of these.

[0284] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0285] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0286] A terminal according to one embodiment of the present disclosure includes a control circuit that selects a transmission opportunity for a random access channel based on a threshold for received power in a plurality of time resources including a first time resource in which a frequency band is divided into a plurality of bands, and a transmission circuit that transmits a signal of the random access channel using the transmission opportunity.

[0287] In one embodiment of the present disclosure, the control circuit selects the transmission opportunity based on a first threshold for transmitting the random access channel in the first time resource and a second threshold for transmitting the random access channel in a second time resource different from the first time resource.

[0288] In one embodiment of the present disclosure, the control circuitry selects a plurality of the transmission opportunities in either the first time resource or the second time resource when repeatedly transmitting the signal.

[0289] In one embodiment of the present disclosure, the control circuitry selects multiple transmission opportunities in both the first time resource and the second time resource when repeatedly transmitting the signal.

[0290] In one embodiment of the present disclosure, the control circuit selects the transmission opportunity based on a first threshold for transmitting the random access channel in the first time resource, a second threshold for transmitting the random access channel in a second time resource different from the first time resource, and a rule for prioritizing the first time resource and the second time resource.

[0291] In one embodiment of the present disclosure, when transmission of the signal fails, the control circuit selects the transmission opportunity to be used for retransmitting the signal based on a comparison of a power value lower than the received power with the first threshold and the second threshold.

[0292] In one embodiment of the present disclosure, the control circuit selects the transmission opportunity based on a threshold value for each type of the transmission opportunity.

[0293] A base station according to one embodiment of the present disclosure includes: a control circuit that sets transmission opportunities for a random access channel, the transmission opportunities being selected based on a threshold for a received power of a terminal, in a plurality of time resources including a first time resource in which a frequency band is divided into a plurality of bands; and a receiving circuit that receives a signal of the random access channel using the transmission opportunities.

[0294] In a communication method according to one embodiment of the present disclosure, a terminal selects a transmission opportunity for a random access channel based on a threshold for received power in a plurality of time resources including a first time resource in which a frequency band is divided into a plurality of bands, and uses the transmission opportunity to transmit a signal of the random access channel.

[0295] In a communication method according to one embodiment of the present disclosure, a base station sets transmission opportunities for a random access channel in a plurality of time resources including a first time resource in which a frequency band is divided into a plurality of bands, the transmission opportunities being selected based on a threshold for a received power of a terminal, and receives a signal of the random access channel using the transmission opportunities.

[0296] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2024-013292, filed on January 31, 2024, are incorporated herein by reference in their entirety.

[0297] One embodiment of the present disclosure is useful in wireless communication systems.

[0298] 100 Base station 101, 201 Receiving unit 102, 202 Demapping unit 103, 203 Demodulation and decoding unit 104 Preamble detection unit 105 Scheduling unit 106 RO control unit 107, 206 Control information holding unit 108, 208 Data and control information generation unit 109, 209 Encoding and modulation unit 110, 210 Mapping unit 111, 211 Transmission unit 200 Terminal 204 RO selection unit 205 Control unit 207 Preamble generation unit

Claims

1. A terminal comprising: a control circuit that selects a transmission opportunity for a random access channel based on a threshold for received power in a plurality of time resources including a first time resource in which a frequency band is divided into a plurality of bands; and a transmission circuit that uses the transmission opportunity to transmit a signal of the random access channel.

2. The terminal of claim 1, wherein the control circuit selects the transmission opportunity based on a first threshold for transmitting the random access channel in the first time resource and a second threshold for transmitting the random access channel in a second time resource different from the first time resource.

3. The terminal according to claim 2, wherein the control circuit selects a plurality of the transmission opportunities in either the first time resource or the second time resource when repeatedly transmitting the signal.

4. The terminal of claim 2, wherein the control circuitry selects a plurality of the transmission opportunities in both the first time resource and the second time resource when repeatedly transmitting the signal.

5. The terminal of claim 1, wherein the control circuit selects the transmission opportunity based on a first threshold for transmitting the random access channel in the first time resource, a second threshold for transmitting the random access channel in a second time resource different from the first time resource, and a rule for prioritizing the first time resource and the second time resource.

6. The terminal according to claim 5, wherein the control circuit, when the transmission of the signal fails, selects the transmission opportunity to be used for retransmitting the signal based on a comparison of a power value lower than the received power with the first threshold and the second threshold.

7. The terminal according to claim 1, wherein the control circuit selects the transmission opportunity based on a threshold value for each type of the transmission opportunity.

8. A base station comprising: a control circuit that sets transmission opportunities for a random access channel, selected based on a threshold for the received power of a terminal, in a plurality of time resources including a first time resource in which a frequency band is divided into a plurality of bands; and a receiving circuit that receives a signal of the random access channel using the transmission opportunities.

9. A communication method, in which a terminal selects a transmission opportunity for a random access channel based on a threshold for received power in a plurality of time resources including a first time resource in which a frequency band is divided into a plurality of bands, and transmits a signal of the random access channel using the transmission opportunity.

10. A communication method, in which a base station sets transmission opportunities for a random access channel, which are selected based on a threshold for the received power of a terminal, in a plurality of time resources including a first time resource in which a frequency band is divided into a plurality of bands, and receives a signal of the random access channel using the transmission opportunities.

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